CA2561088A1 - Transmitting recorded material - Google Patents
Transmitting recorded material Download PDFInfo
- Publication number
- CA2561088A1 CA2561088A1 CA002561088A CA2561088A CA2561088A1 CA 2561088 A1 CA2561088 A1 CA 2561088A1 CA 002561088 A CA002561088 A CA 002561088A CA 2561088 A CA2561088 A CA 2561088A CA 2561088 A1 CA2561088 A1 CA 2561088A1
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- Canada
- Prior art keywords
- recording
- receiver
- playing
- section
- buffer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/10—Digital recording or reproducing
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L47/00—Traffic control in data switching networks
- H04L47/10—Flow control; Congestion control
- H04L47/22—Traffic shaping
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L47/00—Traffic control in data switching networks
- H04L47/10—Flow control; Congestion control
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
- H04L65/60—Network streaming of media packets
- H04L65/61—Network streaming of media packets for supporting one-way streaming services, e.g. Internet radio
- H04L65/612—Network streaming of media packets for supporting one-way streaming services, e.g. Internet radio for unicast
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
- H04L65/60—Network streaming of media packets
- H04L65/70—Media network packetisation
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
- H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
- H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
- H04N19/188—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being a video data packet, e.g. a network abstraction layer [NAL] unit
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
- H04N19/44—Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
- H04N19/60—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding
- H04N19/61—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding in combination with predictive coding
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/20—Servers specifically adapted for the distribution of content, e.g. VOD servers; Operations thereof
- H04N21/23—Processing of content or additional data; Elementary server operations; Server middleware
- H04N21/234—Processing of video elementary streams, e.g. splicing of video streams, manipulating MPEG-4 scene graphs
- H04N21/23406—Processing of video elementary streams, e.g. splicing of video streams, manipulating MPEG-4 scene graphs involving management of server-side video buffer
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/20—Servers specifically adapted for the distribution of content, e.g. VOD servers; Operations thereof
- H04N21/23—Processing of content or additional data; Elementary server operations; Server middleware
- H04N21/24—Monitoring of processes or resources, e.g. monitoring of server load, available bandwidth, upstream requests
- H04N21/2401—Monitoring of the client buffer
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/60—Network structure or processes for video distribution between server and client or between remote clients; Control signalling between clients, server and network components; Transmission of management data between server and client, e.g. sending from server to client commands for recording incoming content stream; Communication details between server and client
- H04N21/63—Control signaling related to video distribution between client, server and network components; Network processes for video distribution between server and clients or between remote clients, e.g. transmitting basic layer and enhancement layers over different transmission paths, setting up a peer-to-peer communication via Internet between remote STB's; Communication protocols; Addressing
- H04N21/633—Control signals issued by server directed to the network components or client
- H04N21/6332—Control signals issued by server directed to the network components or client directed to client
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/60—Network structure or processes for video distribution between server and client or between remote clients; Control signalling between clients, server and network components; Transmission of management data between server and client, e.g. sending from server to client commands for recording incoming content stream; Communication details between server and client
- H04N21/63—Control signaling related to video distribution between client, server and network components; Network processes for video distribution between server and clients or between remote clients, e.g. transmitting basic layer and enhancement layers over different transmission paths, setting up a peer-to-peer communication via Internet between remote STB's; Communication protocols; Addressing
- H04N21/643—Communication protocols
- H04N21/64322—IP
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/60—Network structure or processes for video distribution between server and client or between remote clients; Control signalling between clients, server and network components; Transmission of management data between server and client, e.g. sending from server to client commands for recording incoming content stream; Communication details between server and client
- H04N21/65—Transmission of management data between client and server
- H04N21/658—Transmission by the client directed to the server
- H04N21/6587—Control parameters, e.g. trick play commands, viewpoint selection
Abstract
Recorded material such as video is transmitted in compressed form to a receiver, which has a buffer for smoothing differences between the data rate received and that consumed by a decoder that follows. The whole of the recording is analysed to determine a point at which to commence playing such that no buffer underflow can occur; the decoder commences playing only when this point has been reached.
Description
The present invention is concerned with methods and apparatus for transmitting recorded material, such as video, audio of other material to be played in real time, over a network.
According to one aspect of the present invention there is provided a method of transmitting a recording comprising:
- commencing transmission thereof;
- holding received data in a receiver buffer; and - commencing playing of said received data;
characterised by the steps of analysing the whole of the recording to determine a point at which to commence playing such that no buffer underflow can occur;
and commencing playing only when this point has been reached.
In another aspect, the invention provides a method of transmitting a recording comprising:
- commencing transmission thereof;
- holding received data in a receiver buffer; and - commencing playing of said received data;
characterised by the steps of:
analysing the whole of the recording to identify a first section at the beginning thereof which meets the condition that it covers a playing time interval greater than or equal to the maximum of the timing error for a following section of any length, each timing error being defined as the extent to which the transmission time of the respective following section exceeds its playing time interval; and causing the receiver to commencing playing only after said first section has been received.
Further aspects of the invention are set out in the claims Some embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:
Figure 1 is a block diagram of a transmission system embodying the invention;
Figure 2 is a timing diagram;
Figure3 is a flowchart explaining the operation of the control unit shown in Figure 1;
According to one aspect of the present invention there is provided a method of transmitting a recording comprising:
- commencing transmission thereof;
- holding received data in a receiver buffer; and - commencing playing of said received data;
characterised by the steps of analysing the whole of the recording to determine a point at which to commence playing such that no buffer underflow can occur;
and commencing playing only when this point has been reached.
In another aspect, the invention provides a method of transmitting a recording comprising:
- commencing transmission thereof;
- holding received data in a receiver buffer; and - commencing playing of said received data;
characterised by the steps of:
analysing the whole of the recording to identify a first section at the beginning thereof which meets the condition that it covers a playing time interval greater than or equal to the maximum of the timing error for a following section of any length, each timing error being defined as the extent to which the transmission time of the respective following section exceeds its playing time interval; and causing the receiver to commencing playing only after said first section has been received.
Further aspects of the invention are set out in the claims Some embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:
Figure 1 is a block diagram of a transmission system embodying the invention;
Figure 2 is a timing diagram;
Figure3 is a flowchart explaining the operation of the control unit shown in Figure 1;
Figure 4 is a flowchart explaining an alternative mode of operation of the control unit;
and Figure 5 is a flowchart explaining a yet further version.
In Figure 1, a streamer 1 contains (or has access to) a store 11 in which are stored files each being a compressed version of a video sequence, encoded using a conventional compression algorithm such as that defined in the ITU standard H.261 or H.263, or one of the ISO MPEG standards. Naturally one may store similar recordings of further video sequences, but this is not important to the principles of operation.
By "bit-rate" here is meant the bit-rate generated by the original encoder and consumed by the ultimate decoder; in general this is not the same as the rate at which the streamer actually transmits, which will be referred to as the transmitting bit-rate. It should also be noted that these files are generated at a variable bit-rate (VBR) - that is, the number of bits generated for any particular frame of the video depends on the picture content. Consequently, references above to low (etc.) bit-rate refer to the average bit-rate.
The server has a transmitter 12 which serves to output data via a network 2 to a terminal 3. The transmitter is conventional, perhaps operating with a well known protocol such as TCP/IP. A control unit 13 serves in conventional manner to receive requests from the terminal for delivery of a particular sequence, and to read packets of data from the store 11 for sending to the transmitter 12 as and when the transmitter is able to receive them. Here it is assumed that the data are read out as discrete packets, often one packet per frame of video, though the possibility of generating more than one packet for a single frame is not excluded. (Whilst is in principle possible for a single packet to contain data for more than one frame, this is not usually of much interest in practice).
Note that these packets are not necessarily related to any packet structure used on the network 2.
The terminal 3 has a receiver 31, a buffer 32, and a decoder 33.
Some networks (including TCP/IP networks) have the characteristic that the available transmitting data rate fluctuates according to the degree of loading on the network.
Some theoretical discussion'is in order at this point.
and Figure 5 is a flowchart explaining a yet further version.
In Figure 1, a streamer 1 contains (or has access to) a store 11 in which are stored files each being a compressed version of a video sequence, encoded using a conventional compression algorithm such as that defined in the ITU standard H.261 or H.263, or one of the ISO MPEG standards. Naturally one may store similar recordings of further video sequences, but this is not important to the principles of operation.
By "bit-rate" here is meant the bit-rate generated by the original encoder and consumed by the ultimate decoder; in general this is not the same as the rate at which the streamer actually transmits, which will be referred to as the transmitting bit-rate. It should also be noted that these files are generated at a variable bit-rate (VBR) - that is, the number of bits generated for any particular frame of the video depends on the picture content. Consequently, references above to low (etc.) bit-rate refer to the average bit-rate.
The server has a transmitter 12 which serves to output data via a network 2 to a terminal 3. The transmitter is conventional, perhaps operating with a well known protocol such as TCP/IP. A control unit 13 serves in conventional manner to receive requests from the terminal for delivery of a particular sequence, and to read packets of data from the store 11 for sending to the transmitter 12 as and when the transmitter is able to receive them. Here it is assumed that the data are read out as discrete packets, often one packet per frame of video, though the possibility of generating more than one packet for a single frame is not excluded. (Whilst is in principle possible for a single packet to contain data for more than one frame, this is not usually of much interest in practice).
Note that these packets are not necessarily related to any packet structure used on the network 2.
The terminal 3 has a receiver 31, a buffer 32, and a decoder 33.
Some networks (including TCP/IP networks) have the characteristic that the available transmitting data rate fluctuates according to the degree of loading on the network.
Some theoretical discussion'is in order at this point.
As shown in Figure 2, an encoded video sequence consists of N packets. Each packet has a header containing a time index ti (i=0 ... N-1 ) (in terms of real display time - e.g.
this could be the video frame number) and contains b; bits. This analysis assumes that packet i must be completely received before it can be decoded (i.e. one must buffer the whole packet first).
In a simple case, each packet corresponds to one frame, and the time-stamps ti increase monotonically, that is, ti+1 ~ ti for all i. If however a frame can give rise to two or more packets (each with the same ti) then ti+1 >- t; . If frames can run out of capture-and-display sequence (as in MPEG) then the ti do not increase monotonically.
Also, in practice, some frames may be dropped, so that there will be no frame for a particular value of t; .
These times are relative. Suppose the receiver has received packet 0 and starts decoding packet 0 at time tet+ to. At "time nova' of t,ef + tg the receiver has received packet tR (and possibly more packets too) and has just started to decode packet g.
Packets g to h-1 are in the buffer. Note that (in the simple case) if h = g +
1 then the buffer contains packet g only. At time tef + t~ the decoder is required to start decoding packet j. Therefore, at that time tef + t~ the decoder will need to have received all packets up to and including packet j.
The time available from now up tO tef + t; is (tef + t~) - (tef + tR) = t; -t8. (1 ) The data to be sent in that time are that for packets h to j, viz.
.%
bi (2) i=h which at a transmitting rate R will require a transmission duration i bi i-n (3) R
This is possible only if this transmission duration is less than or equal to the time available, i.e. when the currently available transmitting rate R satisfies the inequality b;
i-h < tj - t8 (4) R
this could be the video frame number) and contains b; bits. This analysis assumes that packet i must be completely received before it can be decoded (i.e. one must buffer the whole packet first).
In a simple case, each packet corresponds to one frame, and the time-stamps ti increase monotonically, that is, ti+1 ~ ti for all i. If however a frame can give rise to two or more packets (each with the same ti) then ti+1 >- t; . If frames can run out of capture-and-display sequence (as in MPEG) then the ti do not increase monotonically.
Also, in practice, some frames may be dropped, so that there will be no frame for a particular value of t; .
These times are relative. Suppose the receiver has received packet 0 and starts decoding packet 0 at time tet+ to. At "time nova' of t,ef + tg the receiver has received packet tR (and possibly more packets too) and has just started to decode packet g.
Packets g to h-1 are in the buffer. Note that (in the simple case) if h = g +
1 then the buffer contains packet g only. At time tef + t~ the decoder is required to start decoding packet j. Therefore, at that time tef + t~ the decoder will need to have received all packets up to and including packet j.
The time available from now up tO tef + t; is (tef + t~) - (tef + tR) = t; -t8. (1 ) The data to be sent in that time are that for packets h to j, viz.
.%
bi (2) i=h which at a transmitting rate R will require a transmission duration i bi i-n (3) R
This is possible only if this transmission duration is less than or equal to the time available, i.e. when the currently available transmitting rate R satisfies the inequality b;
i-h < tj - t8 (4) R
Note that this is the condition for satisfactory reception and decoding of packet j:
satisfactory transmission of the whole of the remaining sequence requires that this condition be satisfied for all j = h ... N-1.
For reasons that will become apparent, we rewrite Equation (4) as:
.%
bi . '=R - (t; - th-~ ) <_ th-1 - t~ (5) J J
Note that t; - th-~ _ ~ (ti - t;_, ) _ ~ °ti where °ti = ti - ti_, .
i=h i=h Also, we define °~i = (bi / R) - °ti Note that th-, - tK is the difference between the time-stamp of the most recently received packet in the buffer and the time stamp of the least recently received packet in the buffer - i.e. the one that we have just started to decode.
Then the condition is i °~; ~ th-, - t8 i=h For a successful transmission up to the last packet N-1, this condition must be satisfied for any possible j, viz. , Max;=h ~ °~i ' th-. - tR
i=h The left-hand side of Equation (7) represents the maximum timing error that may occur from the transmission of packet h up to the end of the sequence, and the condition states, in effect that this error must not exceed the ability of the receiver buffer to accommodate it, given its current contents. For convenience, we will label the left hand side of Equation (7) as Th - i.e.
Th = Maxi=h -' ~ °~i i=h So that Equation (7) may be written as Th ~ th-i - tg Consider the situation at time rg = to, that is, when the decoder is to commence decoding of the first packet. In the general case, the above condition will not be satisfied when there is only one packet in the buffer (h=1 ). The receiver waits for the buffer contents to reach a satisfactory level before it commenced decoding.
Using the 5 above condition, it becomes apparent that the receiver should wait at least until the buffer contains packet H-1 where H is the smallest value of h for which the condition Tn -< th_~ _ to (10) is satisfied.
In this embodiment of the invention, one of the functions of the control unit 13 is that, each time it sends a packet to the transmitter 12, it evaluates the test embodied in Equation 10.
Figure 3 is a flowchart showing operation of the control unit. At step 101 a packet counter is reset. Then (102) the first packet (or on subsequent iterations, the next packet) is read from the store 11 and sent to the transmitter 12. At step 103, the control unit computes the value of Tn. At this point, the counter n points to the last packet sent, whereas Equation (10) is formulated for the last packet sent being h-1.
Consequently the calculation at step 103 is of Tn+, and the test performed at step 104 is whether Tn+~ <_ tn - to .
If this test is not passed, the packet counter is incremented at 106 and control returns to step 102 where, as soon as the transmitter is ready to accept it, a further packet is read out and transmitted. If the test is passed, then it is known that the receiver is safe to begin decoding as soon as it has received this packet. Therefore at step 105 the control unit sends to the transmitter a "start" message to be sent to the receiver.
When the receiver receives this start message, it begins decoding. If there is any possibility of messages being received in a different order from that in which they were sent, then the start message should contain the packet index n so that the receiver may check that packet n has actually been received before it commences decoding.
Alternatively, the transmitter could send values of T"+1 to the receiver, and the receiver itself performs the test.
Following the sending of the "start" message, the packet counter is incremented at 107 and another frame transmitted at 108: these steps are repeated until the end of the file is reached, this being recognised at 109 and the process terminates at 110.
satisfactory transmission of the whole of the remaining sequence requires that this condition be satisfied for all j = h ... N-1.
For reasons that will become apparent, we rewrite Equation (4) as:
.%
bi . '=R - (t; - th-~ ) <_ th-1 - t~ (5) J J
Note that t; - th-~ _ ~ (ti - t;_, ) _ ~ °ti where °ti = ti - ti_, .
i=h i=h Also, we define °~i = (bi / R) - °ti Note that th-, - tK is the difference between the time-stamp of the most recently received packet in the buffer and the time stamp of the least recently received packet in the buffer - i.e. the one that we have just started to decode.
Then the condition is i °~; ~ th-, - t8 i=h For a successful transmission up to the last packet N-1, this condition must be satisfied for any possible j, viz. , Max;=h ~ °~i ' th-. - tR
i=h The left-hand side of Equation (7) represents the maximum timing error that may occur from the transmission of packet h up to the end of the sequence, and the condition states, in effect that this error must not exceed the ability of the receiver buffer to accommodate it, given its current contents. For convenience, we will label the left hand side of Equation (7) as Th - i.e.
Th = Maxi=h -' ~ °~i i=h So that Equation (7) may be written as Th ~ th-i - tg Consider the situation at time rg = to, that is, when the decoder is to commence decoding of the first packet. In the general case, the above condition will not be satisfied when there is only one packet in the buffer (h=1 ). The receiver waits for the buffer contents to reach a satisfactory level before it commenced decoding.
Using the 5 above condition, it becomes apparent that the receiver should wait at least until the buffer contains packet H-1 where H is the smallest value of h for which the condition Tn -< th_~ _ to (10) is satisfied.
In this embodiment of the invention, one of the functions of the control unit 13 is that, each time it sends a packet to the transmitter 12, it evaluates the test embodied in Equation 10.
Figure 3 is a flowchart showing operation of the control unit. At step 101 a packet counter is reset. Then (102) the first packet (or on subsequent iterations, the next packet) is read from the store 11 and sent to the transmitter 12. At step 103, the control unit computes the value of Tn. At this point, the counter n points to the last packet sent, whereas Equation (10) is formulated for the last packet sent being h-1.
Consequently the calculation at step 103 is of Tn+, and the test performed at step 104 is whether Tn+~ <_ tn - to .
If this test is not passed, the packet counter is incremented at 106 and control returns to step 102 where, as soon as the transmitter is ready to accept it, a further packet is read out and transmitted. If the test is passed, then it is known that the receiver is safe to begin decoding as soon as it has received this packet. Therefore at step 105 the control unit sends to the transmitter a "start" message to be sent to the receiver.
When the receiver receives this start message, it begins decoding. If there is any possibility of messages being received in a different order from that in which they were sent, then the start message should contain the packet index n so that the receiver may check that packet n has actually been received before it commences decoding.
Alternatively, the transmitter could send values of T"+1 to the receiver, and the receiver itself performs the test.
Following the sending of the "start" message, the packet counter is incremented at 107 and another frame transmitted at 108: these steps are repeated until the end of the file is reached, this being recognised at 109 and the process terminates at 110.
The preceding description assumes that the control unit performs this calculation each time it sends a packet to the transmitter, which is computationally quite intensive. An alternative is to perform the calculation less often, perhaps once every five packets, which reduces the amount of computation but may result in the buffering of more , frames than is necessary.
Another alternative is to complete the computation as soon as it is able to do so (i.e.
without waiting for the next packet) and then send a start message (with starting packet number) to the receiver. A yet further alternative is to perform the computation before transmitting any packets at all. Once the value of h is determined, we then transmit packets 0 to h-1 in reverse order (packet h -1, packet h - 2, ... packet 0).
In this case it ceases to be necessary to transmit an explicit "start" command. Standard receivers that support UDP transport protocol are able to reorder packets, and will automatically .
wait until packet 0 has arrived before commencing decoding. In fact, it is sufficient that packet 0 is withheld until after packets 1 to h -1 have been sent (whose order is immaterial).
This however precludes the possibility of taking into account changes in the transmitting data rate R during the waiting period, and is therefore satisfactory only if such changes are not expected.
Observe (by inspection of Equation (3)) that the significance of the rate R is in calculating the time taken to send packets h to j. Therefore the actual rate used to transmit packets 0 to h -1 is of no consequence as it does not affect the result.
Another attractive option is to perform as much as possible of the computation in advance. If a system in which only one value of R is possible, or permitted, then the computation of Tn+, at step 103 and the test of step 104 can be performed in advance for each frame up to the point where the test is passed, and the result recorded in the file, for example by recording the corresponding value of n in a separate field at the start of the file, or by attaching a special flag to frame n itself. Thus in Figure 3, steps 103 and 104 would be replaced by the test "is current value of n equal to the value of n stored in the file?"; or "does current frame contain the start flag?".
Alternatively the separate field (or flag) could be forwarded to the receiver and this recognition process performed at the receiving end.
Figure 4 shows a flowchart of a process for dealing with the situation where the transmitting data rate R varies. In principle this involves Th for every packet and storing this value in the packet header. In practice however it is necessary to compute them for a sufficient number of frames (perhaps 250 frames at 25 frames per second) at the beginning of the sequence that one is confident that the test will be passed within this period. Unfortunately, the calculation of Th involves the value of R, which is of course unknown at the time of this pre-processing. Therefore we proceed by calculating Th for a selection of possible values of R, for example (if RA is the average bit rate of the file in question) Ri = O.SRA
R2 = 0.7RA
Rs = R,a R4 =1.3RA
Rs = 2Rn So each packet h has these five precalculated values of Th stored in it. If required (for the purposes to be discussed below) one may also store the relative time position at which the maximum in Equation (8)) occurs, that is, ~thmax - tjmax -th wheretjmax is the value of j in Equation 8 for which Th is obtained.
In this case the flowchart proceeds as follows following transmission of frame n:
112: interrogate the transmitter 12 to determine the available transmitting rate R;
103A:EITHER - in the event that R corresponds to one of the rates for which Tn has been precalculated - read this value from the store;
OR - in the event that R does not so correspond, read from the store the value of Th (and, if required, thmux) that correspond to the highest one (R -) of the rates R,...RS that is less than the actual value of R, and estimate Th from it;
104A: Apply the testTn+, + 0 <- tn - to , where d is a fixed safety margin;
Continue as before.
The estimate of Th could be performed simply by using the value Tn-associated with R -;
this would work, but since it would overestimate Th it would result, at times, in the receiver waiting longer than necessary. Another option would be by linear (or other) interpolation between the values of Th stored for the two values of R, ... RS
each side of the actual value R. However, our preferred approach is to calculate an estimate according to:
Another alternative is to complete the computation as soon as it is able to do so (i.e.
without waiting for the next packet) and then send a start message (with starting packet number) to the receiver. A yet further alternative is to perform the computation before transmitting any packets at all. Once the value of h is determined, we then transmit packets 0 to h-1 in reverse order (packet h -1, packet h - 2, ... packet 0).
In this case it ceases to be necessary to transmit an explicit "start" command. Standard receivers that support UDP transport protocol are able to reorder packets, and will automatically .
wait until packet 0 has arrived before commencing decoding. In fact, it is sufficient that packet 0 is withheld until after packets 1 to h -1 have been sent (whose order is immaterial).
This however precludes the possibility of taking into account changes in the transmitting data rate R during the waiting period, and is therefore satisfactory only if such changes are not expected.
Observe (by inspection of Equation (3)) that the significance of the rate R is in calculating the time taken to send packets h to j. Therefore the actual rate used to transmit packets 0 to h -1 is of no consequence as it does not affect the result.
Another attractive option is to perform as much as possible of the computation in advance. If a system in which only one value of R is possible, or permitted, then the computation of Tn+, at step 103 and the test of step 104 can be performed in advance for each frame up to the point where the test is passed, and the result recorded in the file, for example by recording the corresponding value of n in a separate field at the start of the file, or by attaching a special flag to frame n itself. Thus in Figure 3, steps 103 and 104 would be replaced by the test "is current value of n equal to the value of n stored in the file?"; or "does current frame contain the start flag?".
Alternatively the separate field (or flag) could be forwarded to the receiver and this recognition process performed at the receiving end.
Figure 4 shows a flowchart of a process for dealing with the situation where the transmitting data rate R varies. In principle this involves Th for every packet and storing this value in the packet header. In practice however it is necessary to compute them for a sufficient number of frames (perhaps 250 frames at 25 frames per second) at the beginning of the sequence that one is confident that the test will be passed within this period. Unfortunately, the calculation of Th involves the value of R, which is of course unknown at the time of this pre-processing. Therefore we proceed by calculating Th for a selection of possible values of R, for example (if RA is the average bit rate of the file in question) Ri = O.SRA
R2 = 0.7RA
Rs = R,a R4 =1.3RA
Rs = 2Rn So each packet h has these five precalculated values of Th stored in it. If required (for the purposes to be discussed below) one may also store the relative time position at which the maximum in Equation (8)) occurs, that is, ~thmax - tjmax -th wheretjmax is the value of j in Equation 8 for which Th is obtained.
In this case the flowchart proceeds as follows following transmission of frame n:
112: interrogate the transmitter 12 to determine the available transmitting rate R;
103A:EITHER - in the event that R corresponds to one of the rates for which Tn has been precalculated - read this value from the store;
OR - in the event that R does not so correspond, read from the store the value of Th (and, if required, thmux) that correspond to the highest one (R -) of the rates R,...RS that is less than the actual value of R, and estimate Th from it;
104A: Apply the testTn+, + 0 <- tn - to , where d is a fixed safety margin;
Continue as before.
The estimate of Th could be performed simply by using the value Tn-associated with R -;
this would work, but since it would overestimate Th it would result, at times, in the receiver waiting longer than necessary. Another option would be by linear (or other) interpolation between the values of Th stored for the two values of R, ... RS
each side of the actual value R. However, our preferred approach is to calculate an estimate according to:
T., _ (Ti- + °t-a"ax )R- - °t-i R (11) Where R - is the highest one of the rates R, ... RS that is less than the actual value of R, T; is the precalculated Th for this rate, °t; m~ is the time from t; at which Ti- is obtained (i.e. is the accompanying value of °thmaX). In the event that this method returns a negative value, we set it to zero.
Note that this is only an estimate, as Th is a nonlinear function of rate.
However with this method T;' is always higher than the true value and automatically provides a safety margin (so that the margin 0 shown above may be omitted).
Note that these equations are valid for the situation where the encoding process generates two or more packets (with equal t;) for one frame, and for the situation encountered in MPEG with bidirectional prediction where the frames are transmitted in the order in which they need to be decoded, rather than in order of ascending ti.
We will now describe an alternative embodiment in which the mathematics is converted into an equivalent form which however, rather than performing the calculations for each packet individually, makes use of calculations already made for a preceding packet.
Recalling Equation(8):
Th =Max' N ~ ~ ~ °~i !=h i=h which may be rewritten Th=Max E°~i,Max'-N-~~~°~i+ ~°~;~ (12) i=h j=h+I i=h i=h+1 = Max ~O~h , Max' N ~ ~°~~, + E °~i ~~
j=h+1 i=h+I
= 0~ +Max ~0 Max'=N ~ ~ E °~. ~~
~l ~ j=h+1 ;=h+1 =DEh +Max{O,Th+I } (13) Provided that Th+, >- 0 , which will be true at the beginning of the file;
this becomes Tn -Tn+I +Deh (14) Or generally Tu+~ = Ta - ~~~
To+i = Ta+~ - 0~~+~ = TQ - DEp - O~o+~
a+n-i Tu+n = Ta - ~ 0~;
!=G
If b=h-a then n-1 Tn =Ta -~ 0~~ (15) a=a substituting De; = R - Ot; and Ot; = t; - t;_, "-' b. n-' "-' b.
Tn =Ta -~-' +~Ot~ =Tu -~-' +(tn_, -tu-y (16) r=~ R .=p t=a R
If a=0, then If a=1, then Th = To - ~ b~ ~- (tn-, - t-~ ) Tn = T - ~ b' + (th_, - to ) r=o R r=i R
Consider the test Tn ~ tn-i _ to which may be written br Tp-~ R+(tn_,-to)<-tu-,-to (17) l=G
if a=0, this becomes To - ~ b. < +t-~ - to ( 18) =o R
Noting that r_, is a meaningless quantity (appearing on both sides on the inequality) so that it can be given any value, it is convenient to define t_, as equal to to, whence we obtain "-' b.
To < ~ R . ( 19) r=o "-' b.
5 (or,ifa=1: T,<_~ -') ;_, R
Thus the test of Equation (10) T" < t"-1 _ to could instead be written "-' b.
To <_ ~ R (20) .=o 10 Then the first test (h=1 ) is Test 1:
To<bo?
R
1 x_1 Or, if we defineZ.r =To --~b; , the first test is Z, <_ 0 ?
R ~=o The second test is ZZ <_ 0 The xth test is Zx <_ 0 r x-1 But Zx+1 = To - 1 ~ 6r = To - 1 ~ 6r - bx = Zx - bx R ;=o R r=o R R
So each test can update the previous value of Z, as shown in the flowchart of Figure 5.
First, at Step 201, To is calculated in accordance with Equation (8), then (Step 202) Zo is set equal to To. At step 203 a packet counter is reset. Then (204) the first packet (or on subsequent iterations, the next packet) is read from the store 11 and sent to the transmitter 12. At step 205, the control unit computes the value of Zn+,, and the test performed at step 206 as to whether Z~+, <_ 0 . If the test is passed, then it is known that the receiver is safe to begin decoding as soon as it has received this packet.
Therefore at step 207 the control unit sends to the transmitter a "start"
message to be sent to the receiver. When the receiver receives this start message, it begins decoding. The packet counter is incremented at 208 and control returns to step where, as soon as the transmitter is ready to accept it, a further packet is read out and transmitted.
The step 201 of calculating To could be done in advance and the values stored.
This procedure could of course be adapted, in a similar manner to that previously described, to accommodate different values of R.
It is not essential that this process begin with To. One could start with T, (in which case the first test is T, <_ 0 ?) or, if one chooses always to buffer at least two (or more) packets one could start with T2, etc.
Although the example given is for encoded video, the same method can be applied to encoded audio or indeed any other material that is to be played in real time.
If desired, in multiple-rate systems, these methods may be used in combination with the rate-switching method described in our international patent application W004/086721.
Note that this is only an estimate, as Th is a nonlinear function of rate.
However with this method T;' is always higher than the true value and automatically provides a safety margin (so that the margin 0 shown above may be omitted).
Note that these equations are valid for the situation where the encoding process generates two or more packets (with equal t;) for one frame, and for the situation encountered in MPEG with bidirectional prediction where the frames are transmitted in the order in which they need to be decoded, rather than in order of ascending ti.
We will now describe an alternative embodiment in which the mathematics is converted into an equivalent form which however, rather than performing the calculations for each packet individually, makes use of calculations already made for a preceding packet.
Recalling Equation(8):
Th =Max' N ~ ~ ~ °~i !=h i=h which may be rewritten Th=Max E°~i,Max'-N-~~~°~i+ ~°~;~ (12) i=h j=h+I i=h i=h+1 = Max ~O~h , Max' N ~ ~°~~, + E °~i ~~
j=h+1 i=h+I
= 0~ +Max ~0 Max'=N ~ ~ E °~. ~~
~l ~ j=h+1 ;=h+1 =DEh +Max{O,Th+I } (13) Provided that Th+, >- 0 , which will be true at the beginning of the file;
this becomes Tn -Tn+I +Deh (14) Or generally Tu+~ = Ta - ~~~
To+i = Ta+~ - 0~~+~ = TQ - DEp - O~o+~
a+n-i Tu+n = Ta - ~ 0~;
!=G
If b=h-a then n-1 Tn =Ta -~ 0~~ (15) a=a substituting De; = R - Ot; and Ot; = t; - t;_, "-' b. n-' "-' b.
Tn =Ta -~-' +~Ot~ =Tu -~-' +(tn_, -tu-y (16) r=~ R .=p t=a R
If a=0, then If a=1, then Th = To - ~ b~ ~- (tn-, - t-~ ) Tn = T - ~ b' + (th_, - to ) r=o R r=i R
Consider the test Tn ~ tn-i _ to which may be written br Tp-~ R+(tn_,-to)<-tu-,-to (17) l=G
if a=0, this becomes To - ~ b. < +t-~ - to ( 18) =o R
Noting that r_, is a meaningless quantity (appearing on both sides on the inequality) so that it can be given any value, it is convenient to define t_, as equal to to, whence we obtain "-' b.
To < ~ R . ( 19) r=o "-' b.
5 (or,ifa=1: T,<_~ -') ;_, R
Thus the test of Equation (10) T" < t"-1 _ to could instead be written "-' b.
To <_ ~ R (20) .=o 10 Then the first test (h=1 ) is Test 1:
To<bo?
R
1 x_1 Or, if we defineZ.r =To --~b; , the first test is Z, <_ 0 ?
R ~=o The second test is ZZ <_ 0 The xth test is Zx <_ 0 r x-1 But Zx+1 = To - 1 ~ 6r = To - 1 ~ 6r - bx = Zx - bx R ;=o R r=o R R
So each test can update the previous value of Z, as shown in the flowchart of Figure 5.
First, at Step 201, To is calculated in accordance with Equation (8), then (Step 202) Zo is set equal to To. At step 203 a packet counter is reset. Then (204) the first packet (or on subsequent iterations, the next packet) is read from the store 11 and sent to the transmitter 12. At step 205, the control unit computes the value of Zn+,, and the test performed at step 206 as to whether Z~+, <_ 0 . If the test is passed, then it is known that the receiver is safe to begin decoding as soon as it has received this packet.
Therefore at step 207 the control unit sends to the transmitter a "start"
message to be sent to the receiver. When the receiver receives this start message, it begins decoding. The packet counter is incremented at 208 and control returns to step where, as soon as the transmitter is ready to accept it, a further packet is read out and transmitted.
The step 201 of calculating To could be done in advance and the values stored.
This procedure could of course be adapted, in a similar manner to that previously described, to accommodate different values of R.
It is not essential that this process begin with To. One could start with T, (in which case the first test is T, <_ 0 ?) or, if one chooses always to buffer at least two (or more) packets one could start with T2, etc.
Although the example given is for encoded video, the same method can be applied to encoded audio or indeed any other material that is to be played in real time.
If desired, in multiple-rate systems, these methods may be used in combination with the rate-switching method described in our international patent application W004/086721.
Claims (11)
1. A method of transmitting a recording comprising:
- commencing transmission thereof;
- holding received data in a receiver buffer; and - commencing playing of said received data;
characterised by the steps of analysing the whole of the recording to determine a point at which to commence playing such that no buffer underflow can occur; and commencing playing only when this point has been reached.
- commencing transmission thereof;
- holding received data in a receiver buffer; and - commencing playing of said received data;
characterised by the steps of analysing the whole of the recording to determine a point at which to commence playing such that no buffer underflow can occur; and commencing playing only when this point has been reached.
2. A method of transmitting a recording comprising:
- commencing transmission thereof;
- holding received data in a receiver buffer; and - commencing playing of said received data;
characterised by the steps of:
analysing the whole of the recording to identify a first section at the beginning thereof which meets the condition that it covers a playing time interval greater than or equal to the maximum of the timing error for a following section of any length, each timing error being defined as the extent to which the transmission time of the respective following section exceeds its playing time interval; and causing the receiver to commencing playing only after said first section has been received.
- commencing transmission thereof;
- holding received data in a receiver buffer; and - commencing playing of said received data;
characterised by the steps of:
analysing the whole of the recording to identify a first section at the beginning thereof which meets the condition that it covers a playing time interval greater than or equal to the maximum of the timing error for a following section of any length, each timing error being defined as the extent to which the transmission time of the respective following section exceeds its playing time interval; and causing the receiver to commencing playing only after said first section has been received.
3. A method according to claim 2 comprising, after transmission of said first portion, transmitting an instruction to the receiver to commence playing.
4. A method according to claim 2 comprising transmitting to the receiver an instruction specifying the first section and wherein the receiver commences playing when it recognises that the first section is in the buffer.
5. A method according to claim 2 in which the analysis comprises:
(a) at the transmitter, computing said maximum timing error values for different portions of the sequence, and (b) at the receiver, comparing the values with the buffer contents to recognise when said first section is in the buffer.
(a) at the transmitter, computing said maximum timing error values for different portions of the sequence, and (b) at the receiver, comparing the values with the buffer contents to recognise when said first section is in the buffer.
6. A method according to claim 2 comprising withholding transmission of an initial part of the recording until the remainder of said first section has been transmitted;
transmitting said initial part; and wherein the receiver commences playing only when said initial part is received.
transmitting said initial part; and wherein the receiver commences playing only when said initial part is received.
7. A method according to claim 2,3, 4 or 6 including performing the analysis in advance and marking the identified section in the recording.
8. A method according to any one of claims 2 to 6 where said analysis includes computing, in advance, timing error values corresponding to a plurality of transmitting data rates and storing them; and subsequently estimating therefrom an error value corresponding to an actual transmitting data rate.
9. A method according to any one of the preceding claims in which the analysis comprises testing a timing error parameter evaluated for successive portions of the recording, wherein the timing error parameter is firstly calculated in respect of a first or early portion of the recording and the timing error parameter for subsequent portions is obtained by updating the parameter obtained for the preceding portion.
10. A method according to any one of the preceding claims in which the recording is a video recording.
11. A method according to any one of the preceding claims in which the recording is an audio recording.
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Families Citing this family (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB0306973D0 (en) * | 2003-03-26 | 2003-04-30 | British Telecomm | Transmitting video |
WO2008009111A1 (en) * | 2006-07-19 | 2008-01-24 | Dragonwave Inc. | Expedited communication traffic handling apparatus and methods |
EP2101503A1 (en) * | 2008-03-11 | 2009-09-16 | British Telecommunications Public Limited Company | Video coding |
JP5171413B2 (en) * | 2008-06-16 | 2013-03-27 | 三菱電機株式会社 | Content transmission device, content reception device, and content transmission method |
US8942490B2 (en) * | 2008-07-08 | 2015-01-27 | Yin-Chun Blue Lan | Method of high performance image compression |
EP2200319A1 (en) | 2008-12-10 | 2010-06-23 | BRITISH TELECOMMUNICATIONS public limited company | Multiplexed video streaming |
EP2219342A1 (en) | 2009-02-12 | 2010-08-18 | BRITISH TELECOMMUNICATIONS public limited company | Bandwidth allocation control in multiple video streaming |
EP2408204A1 (en) | 2010-07-12 | 2012-01-18 | British Telecommunications public limited company | Video streaming |
WO2012001339A1 (en) | 2010-06-30 | 2012-01-05 | British Telecommunications Public Limited Company | Video streaming |
EP2426923A1 (en) | 2010-09-02 | 2012-03-07 | British Telecommunications Public Limited Company | Adaptive streaming of video at different quality levels |
US11076187B2 (en) | 2015-05-11 | 2021-07-27 | Mediamelon, Inc. | Systems and methods for performing quality based streaming |
US10298985B2 (en) | 2015-05-11 | 2019-05-21 | Mediamelon, Inc. | Systems and methods for performing quality based streaming |
Family Cites Families (64)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4419699A (en) * | 1979-10-12 | 1983-12-06 | Rca Corporation | Digital on video recording and playback system |
US5025458A (en) * | 1989-10-30 | 1991-06-18 | International Business Machines Corporation | Apparatus for decoding frames from a data link |
US6389010B1 (en) * | 1995-10-05 | 2002-05-14 | Intermec Ip Corp. | Hierarchical data collection network supporting packetized voice communications among wireless terminals and telephones |
US20020100052A1 (en) * | 1999-01-06 | 2002-07-25 | Daniels John J. | Methods for enabling near video-on-demand and video-on-request services using digital video recorders |
US5430485A (en) * | 1993-09-30 | 1995-07-04 | Thomson Consumer Electronics, Inc. | Audio/video synchronization in a digital transmission system |
AU1572995A (en) | 1994-02-11 | 1995-08-29 | Newbridge Networks Corporation | Method of dynamically compensating for variable transmission delays in packet networks |
DE69525556T2 (en) * | 1994-03-21 | 2002-09-12 | Avid Technology Inc | Device and method executed on a computer for real-time multimedia data transmission in a distributed computer arrangement |
US5534937A (en) * | 1994-04-14 | 1996-07-09 | Motorola, Inc. | Minimum-delay jitter smoothing device and method for packet video communications |
US5874997A (en) * | 1994-08-29 | 1999-02-23 | Futuretel, Inc. | Measuring and regulating synchronization of merged video and audio data |
US5598352A (en) * | 1994-09-30 | 1997-01-28 | Cirrus Logic, Inc. | Method and apparatus for audio and video synchronizing in MPEG playback systems |
US5953350A (en) * | 1995-03-13 | 1999-09-14 | Selsius Systems, Inc. | Multimedia client for multimedia/hybrid network |
US6003030A (en) * | 1995-06-07 | 1999-12-14 | Intervu, Inc. | System and method for optimized storage and retrieval of data on a distributed computer network |
US6169843B1 (en) * | 1995-12-01 | 2001-01-02 | Harmonic, Inc. | Recording and playback of audio-video transport streams |
JP3063859B2 (en) * | 1996-01-08 | 2000-07-12 | インターナシヨナル・ビジネス・マシーンズ・コーポレーシヨン | Method and file server for delivering multimedia files |
US6148135A (en) * | 1996-01-29 | 2000-11-14 | Mitsubishi Denki Kabushiki Kaisha | Video and audio reproducing device and video decoding device |
US5768527A (en) * | 1996-04-23 | 1998-06-16 | Motorola, Inc. | Device, system and method of real-time multimedia streaming |
US5918013A (en) * | 1996-06-03 | 1999-06-29 | Webtv Networks, Inc. | Method of transcoding documents in a network environment using a proxy server |
US5931922A (en) | 1996-07-01 | 1999-08-03 | Sun Microsystems, Inc. | Media server system for preventing FIFO buffer underflow during multiple channel startup by waiting until buffer receives plurality of data blocks before enabling buffer to transmit received data |
US6366614B1 (en) * | 1996-10-11 | 2002-04-02 | Qualcomm Inc. | Adaptive rate control for digital video compression |
US5949410A (en) * | 1996-10-18 | 1999-09-07 | Samsung Electronics Company, Ltd. | Apparatus and method for synchronizing audio and video frames in an MPEG presentation system |
US6016307A (en) * | 1996-10-31 | 2000-01-18 | Connect One, Inc. | Multi-protocol telecommunications routing optimization |
GB9706394D0 (en) | 1997-03-27 | 1997-05-14 | Nds Ltd | Improvements in or relating to compressing a digital signal |
US5923655A (en) * | 1997-06-10 | 1999-07-13 | E--Net, Inc. | Interactive video communication over a packet data network |
US6014694A (en) * | 1997-06-26 | 2000-01-11 | Citrix Systems, Inc. | System for adaptive video/audio transport over a network |
US6101221A (en) * | 1997-07-31 | 2000-08-08 | Lsi Logic Corporation | Video bitstream symbol extractor for use in decoding MPEG compliant video bitstreams meeting 2-frame and letterboxing requirements |
US6397251B1 (en) * | 1997-09-02 | 2002-05-28 | International Business Machines Corporation | File server for multimedia file distribution |
JP4150083B2 (en) * | 1997-09-25 | 2008-09-17 | ソニー株式会社 | Encoded stream generation apparatus and method, and editing system and method |
US6028928A (en) * | 1997-09-26 | 2000-02-22 | Mullaney; Julian Sean | Telephone subscriber line module |
JP3063838B2 (en) * | 1997-10-02 | 2000-07-12 | 日本電気株式会社 | Audio / video synchronous playback apparatus and method |
US6195368B1 (en) * | 1998-01-14 | 2001-02-27 | Skystream Corporation | Re-timing of video program bearing streams transmitted by an asynchronous communication link |
JPH11262001A (en) * | 1998-03-16 | 1999-09-24 | Hitachi Denshi Ltd | Method for calculating time stamp value in encoding transmission system |
EP1034538B1 (en) | 1998-06-12 | 2004-12-15 | Koninklijke Philips Electronics N.V. | Transferring compressed audio via a playback buffer |
US6377573B1 (en) | 1998-06-15 | 2002-04-23 | Siemens Information And Communication Networks, Inc. | Method and apparatus for providing a minimum acceptable quality of service for a voice conversation over a data network |
US6452922B1 (en) * | 1998-06-19 | 2002-09-17 | Nortel Networks Limited | Method and apparatus for fallback routing of voice over internet protocol call |
US6587641B1 (en) * | 1998-07-21 | 2003-07-01 | Matsushita Electric Industrial Co., Ltd. | Apparatus for simultaneously writing and outputting data stream |
US6976208B1 (en) * | 1998-11-03 | 2005-12-13 | International Business Machines Corporation | Progressive adaptive time stamp resolution in multimedia authoring |
US6704288B1 (en) * | 1999-10-07 | 2004-03-09 | General Instrument Corporation | Arrangement for discovering the topology of an HFC access network |
US7096481B1 (en) * | 2000-01-04 | 2006-08-22 | Emc Corporation | Preparation of metadata for splicing of encoded MPEG video and audio |
US6792047B1 (en) * | 2000-01-04 | 2004-09-14 | Emc Corporation | Real time processing and streaming of spliced encoded MPEG video and associated audio |
US6678332B1 (en) * | 2000-01-04 | 2004-01-13 | Emc Corporation | Seamless splicing of encoded MPEG video and audio |
US8151306B2 (en) * | 2000-01-14 | 2012-04-03 | Terayon Communication Systems, Inc. | Remote control for wireless control of system including home gateway and headend, either or both of which have digital video recording functionality |
JP2001230821A (en) * | 2000-02-16 | 2001-08-24 | Sony Corp | Data repeater and method, and serving medium |
GB0028113D0 (en) | 2000-05-15 | 2001-01-03 | Band X Ltd | Communication system and method |
JP4690628B2 (en) * | 2000-05-26 | 2011-06-01 | アカマイ テクノロジーズ インコーポレイテッド | How to determine which mirror site should receive end-user content requests |
US6771703B1 (en) * | 2000-06-30 | 2004-08-03 | Emc Corporation | Efficient scaling of nonscalable MPEG-2 Video |
EP1182875A3 (en) * | 2000-07-06 | 2003-11-26 | Matsushita Electric Industrial Co., Ltd. | Streaming method and corresponding system |
AU2002220927B2 (en) | 2000-12-15 | 2006-03-16 | British Telecommunications Public Limited Company | Transmission and reception of audio and/or video material |
US7251833B2 (en) * | 2000-12-29 | 2007-07-31 | International Business Machines Corporation | Digital media delivery with local cache and streaming tokens |
JP2002232573A (en) * | 2001-01-31 | 2002-08-16 | Nec Corp | Mobile communication terminal, mobile communication system and service providing device |
JP2002271389A (en) * | 2001-03-07 | 2002-09-20 | Hitachi Telecom Technol Ltd | Packet processor and packet processing method |
EP1410217A4 (en) * | 2001-04-02 | 2006-09-20 | Akamai Tech Inc | Scalable, high performance and highly available distributed storage system for internet content |
DE10125017A1 (en) | 2001-05-22 | 2002-12-05 | Siemens Ag | Method for providing services in a data transmission network and associated components |
US6931071B2 (en) * | 2001-08-31 | 2005-08-16 | Stmicroelectronics, Inc. | Apparatus and method for synchronizing video and audio MPEG streams in a video playback device |
US7646816B2 (en) | 2001-09-19 | 2010-01-12 | Microsoft Corporation | Generalized reference decoder for image or video processing |
JP2003209807A (en) * | 2002-01-10 | 2003-07-25 | Canon Inc | Moving picture reproducing method and apparatus |
JP3655249B2 (en) * | 2002-03-05 | 2005-06-02 | 松下電器産業株式会社 | Data receiving / reproducing method and data communication apparatus |
JP4875285B2 (en) * | 2002-04-26 | 2012-02-15 | ソニー株式会社 | Editing apparatus and method |
JP2004015114A (en) * | 2002-06-03 | 2004-01-15 | Funai Electric Co Ltd | Digital broadcast recording device and digital broadcast system provided with the same |
US7343087B2 (en) * | 2002-11-12 | 2008-03-11 | Matsushita Electric Industrial Co., Ltd. | Data stream playback device and method, digital broadcast receiver and related computer program |
EP1593107A4 (en) * | 2003-02-13 | 2010-08-18 | Nokia Corp | Method for signaling client rate capacity in multimedia streaming |
US9325998B2 (en) * | 2003-09-30 | 2016-04-26 | Sharp Laboratories Of America, Inc. | Wireless video transmission system |
JP2005167420A (en) * | 2003-11-28 | 2005-06-23 | Toshiba Corp | Video audio reproducing apparatus |
JP4039417B2 (en) * | 2004-10-15 | 2008-01-30 | 株式会社日立製作所 | Recording / playback device |
US7620137B2 (en) * | 2004-11-13 | 2009-11-17 | Microsoft Corporation | System and method for clock drift correction for broadcast audio/video streaming |
-
2004
- 2004-03-26 GB GBGB0406901.9A patent/GB0406901D0/en not_active Ceased
-
2005
- 2005-03-16 JP JP2007504458A patent/JP4782770B2/en not_active Expired - Fee Related
- 2005-03-16 US US10/593,587 patent/US8064470B2/en active Active
- 2005-03-16 KR KR1020067022190A patent/KR101165105B1/en active IP Right Grant
- 2005-03-16 CN CN2005800096501A patent/CN1939030B/en active Active
- 2005-03-16 CA CA002561088A patent/CA2561088A1/en not_active Abandoned
- 2005-03-16 WO PCT/GB2005/001011 patent/WO2005093995A2/en active Application Filing
- 2005-03-16 EP EP05718057.2A patent/EP1735946B1/en active Active
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2011
- 2011-05-06 JP JP2011103804A patent/JP2011193512A/en active Pending
Also Published As
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EP1735946A2 (en) | 2006-12-27 |
GB0406901D0 (en) | 2004-04-28 |
JP2007531365A (en) | 2007-11-01 |
JP2011193512A (en) | 2011-09-29 |
KR20070028360A (en) | 2007-03-12 |
CN1939030A (en) | 2007-03-28 |
CN1939030B (en) | 2010-05-05 |
US20080025340A1 (en) | 2008-01-31 |
EP1735946B1 (en) | 2013-10-16 |
JP4782770B2 (en) | 2011-09-28 |
US8064470B2 (en) | 2011-11-22 |
KR101165105B1 (en) | 2012-07-12 |
WO2005093995A2 (en) | 2005-10-06 |
WO2005093995A3 (en) | 2007-07-12 |
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