Best quality given a maximum bit rate

Patent metadata

Field	Value
Publication number	US-9344721-B2
Application number	US-201114125458-A
Country	US
Kind code	B2
Filing date	Jun 23, 2011
Priority date	Jun 23, 2011
Publication date	May 17, 2016
Grant date	May 17, 2016

Abstract

The present invention relates to flow control of a digital data stream that is to be transmitted with limited bit rate. The present invention provides a mix between CQ and CB. This in order to, in real time, ensure best possible quality of a data stream given a maximum available band with. This is useful both when saving a data stream to a data storage with a limited size and when playing the data stream in real time. In particular the invention relates to a method for flow control of a digital data stream that is to be sent with a limited transmission bit rate R. The method comprises encoding each data frame of a digital data stream into an encoded data frame comprising n quality layers and thereafter balancing the output of the encoder in order to achieve a constant bit rate on the output. The invention also relates to a corresponding data recorder and computer program.

First claim

The invention claimed is:

1. A method for flow control of a first digital data stream ( 201 ), that is to be sent with a limited transmission bit rate R, said method comprising the following steps:
setting up an encoder ( 210 ) in constant quality mode, corresponding to a target quality, resulting in a variable bit rate;
encoding, with the encoder ( 210 ), each data frame ( 202 ) of the first digital data stream ( 201 ) into an encoded frame ( 202 ′) comprising n quality layers ( 112 );
for each encoded frame storing as many of the n quality layers ( 212 ) as possible in an output buffer ( 230 ) utilising a defined maximum frame size for each encoded frame;
accumulating the remaining free space of the output buffer ( 220 ) for coming data frames; and
if all quality layers ( 212 ) cannot be stored in the output buffer ( 220 ) under the defined maximum frame size, then throwing away the remaining quality layers ( 605 ).

2. The method for flow control according to claim 1 , wherein the defined maximum frame size for each encoded frame, is a target frame size ( 403 , 503 , 603 ) defined by the transmission bit rate R, plus free space accumulated from previous frame or frames ( 504 ).

3. The method for flow control according to claim 1 , wherein the defined maximum frame size for each encoded frame is the free space available in said output buffer ( 220 ).

4. The method for flow control according to claim 1 , wherein the target quality results in a variable bit rate, which varies below and above the transmission bit rate R.

5. The method for flow control according to claim 1 , wherein the target quality is at least one of visually or mathematically lossless.

6. The method for flow control according to claim 1 , wherein the length of the output buffer ( 220 ) is 5-100 data frames ( 202 ).

7. The method for flow control according to claim 1 , wherein the encoder ( 210 ) is a JPEG2000 encoder.

8. The method for flow control according to claim 1 , wherein the first digital data stream ( 201 ) is a video stream.

9. The method for flow control according to according to claim 1 , wherein the first digital data stream ( 201 ) is an audio stream.

10. The method for flow control according to claim 1 , wherein the transmission bit rate R varies over time and wherein the method further comprises the step of continuously changing the target quality of the encoder ( 210 ) based on the transmission bit rate R.

11. The method for flow control according to claim 1 , wherein the output buffer is also utilised by a second digital data stream.

12. An apparatus ( 200 ) for controlling the flow of a first digital data stream ( 201 ) that is to be transmitted with a limited transmission bit rate R, the apparatus comprising:
an encoder ( 210 ) configured to encode each data frame ( 202 ) in the first digital data stream ( 201 ) into an encoded frame ( 202 ′), the encoded frame ( 202 ′) comprising a first number of quality layers ( 212 ), representing successive quality refinements of the data frame ( 202 );
an output buffer ( 220 ) with a throughout defined by the limited bit rate R; and
a controller ( 230 ) configured to:
set up the encoder ( 210 ) in constant quality mode, corresponding to a target quality, resulting in a variable bit rate;
for each encoded frame ( 202 ′) store as many of the n quality layers as possible in the output buffer ( 220 ); utilising a defined maximum frame size ( 403 , 503 , 603 ) for each encoded frame;
accumulate the remaining free space of the output buffer for coming data frames; and
if all quality layers ( 212 ) cannot be stored in the output buffer ( 220 ), then throw away the remaining quality layers ( 605 ).

13. The apparatus ( 200 ) for flow control according to claim 12 , wherein the defined maximum frame size for each encoded frame, is a target frame size ( 403 , 503 , 603 ) defined by the transmission bit rate R, plus free space accumulated from previous frame or frames ( 504 ).

14. The apparatus ( 200 ) for flow control according to claim 12 , wherein the defined maximum frame size for each encoded frame is the free space available in said output buffer ( 220 ).

15. The apparatus ( 200 ) for flow control according to claim 12 , wherein the target quality results in a variable bit rate which varies below and above the transmission bit rate R.

16. The apparatus ( 200 ) for flow control according to claim 12 , wherein the target quality is at least one of visually or mathematically lossless.

17. The apparatus ( 200 ) for flow control according to claim 12 , wherein the length of the output buffer is 5-100 data frames ( 102 ).

18. The apparatus ( 200 ) for flow control according to claim 12 , wherein the encoder is a JPEG2000 encoder.

19. The apparatus ( 200 ) for flow control according to claim 12 , wherein the first digital data stream ( 201 ) is a video stream.

20. The apparatus ( 200 ) for flow control according to claim 12 , wherein the first digital data stream ( 201 ) is an audio stream.

21. The apparatus ( 200 ) for flow control according to claim 12 , wherein the transmission bit rate R varies over time and wherein the buffer controller ( 120 ) is further configured to continuously adapt the target quality based on the transmission bit rate R.

22. The apparatus ( 200 ) for flow control according to claim 12 , wherein the output buffer is also utilised by a second digital data stream.

23. A non-transitory computer program product comprising at least one computer-readable storage medium having computer-readable program code instructions embodied therein, the instructions being configured such that, when executed on a computer, cause the computer to execute the steps of the method according to claim 1 .

Assignees

• Dikvall Henrik
• Saab Ab

Inventors

• Dikvall Henrik

Classifications

• H04N19/15 Primary

  by monitoring actual compressed data size at the memory before deciding storage at the transmission buffer · CPC title

• H04N19/36

  Scalability techniques involving formatting the layers as a function of picture distortion after decoding, e.g. signal-to-noise [SNR] scalability · CPC title

• H04N19/103

  Selection of coding mode or of prediction mode · CPC title

• H04N19/00193 Primary

  Electricity · mapped topic

• H04N19/152 Primary

  by measuring the fullness of the transmission buffer · CPC title