Dynamic selection of parameter sets for transcoding media data

• US 8,635,357 B2
• Filed: 09/08/2010
• Issued: 01/21/2014
• Est. Priority Date: 09/08/2009
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Ebersviller, Matthew Robert
• Primary Examiner(s): TANG, KAREN C
• Application Number:
  US12/877,594
• Publication Number:
  US 20110060792A1
• Time in Patent Office: 1,231 Days
• Field of Search: 709/203, 709/231, 709/232
• US Class Current: 709/231
• CPC Class Codes: H04N 19/102 characterised by the element, parameter or selection affected or controlled by the adaptive coding
• CPC Class Codes: H04N 19/154 Measured or subjectively estimated visual quality after decoding, e.g. measurement of distortion use of rate-distortion criteria H04N19/147
• CPC Class Codes: H04N 19/196 being specially adapted for the computation of encoding parameters, e.g. by averaging previously computed encoding parameters processing of motion vectors H04N19/513
• CPC Class Codes: H04N 19/40 using video transcoding, i.e. partial or full decoding of a coded input stream followed by re-encoding of the decoded output stream
• CPC Class Codes: H04N 19/46 Embedding additional information in the video signal during the compression process H04N19/517, H04N19/68, H04N19/70 take precedence
• CPC Class Codes: H04N 19/61 in combination with predictive coding

Abstract

An iterative operation is performed at a computing device to identify a parameter set for an initial segment. A parameter set for an initial segment includes a plurality of encoding parameters and values assigned to the encoding parameters. The initial segment is re-encoded using the parameter set, thereby generating a transcoded segment. In some embodiments, the transcoded segment is transmitted to a client computing device that presents media represented by the transcoded segment.

Claims

1. A method for distributing media data, the method comprising:

performing, by a device including a processor, an iterative operation until a final parameter set is selected for transcoding an initial segment, wherein each iteration of the iterative operation comprises;

transcoding the initial segment into a plurality of transcoded segments using parameter sets in a current generation of parameter sets;

calculating fitness scores of each transcoded segment in the plurality of transcoded segments;

determining whether a generation limit has been reached;

determining whether at least one of the fitness scores exceeds a fitness score threshold;

in response to the generation limit being reached or at least one of the fitness scores exceeding the fitness score threshold, outputting a given transcoded segment, the given transcoded segment being the transcoded segment generated by the iterative operation that has a fitness score greater than the fitness scores of each other transcoded segment generated by the iterative operation, and setting a parameter set employed for transcoding the initial segment into the given transcoded segment as the final parameter set; and

in response to the generation limit not being reached and none of the fitness scores exceeding the fitness score threshold;

calculating selection probabilities of the parameter sets in the current generation of parameter sets; and

performing the following steps until a new generation of parameter sets includes a threshold number of parameter sets;

selecting parent parameter sets based on the selection probabilities of the parameter sets in the current generation of parameter sets; and

generating a child parameter set in the new generation of parameter sets by recombining values of encoding parameters in the parent parameter sets; and

setting the new generation of parameter sets as the current generation of parameter sets; and

generating, by the device, a transcoded media data stream comprising the given transcoded segment.

2. The method of claim 1, further comprising:

transmitting, by the device, the transcoded media data stream to a client device via a computer communications network.

3. The method of claim 1,

wherein the method further comprises:

receiving, by the device, an initial media data stream;

dividing, by the device, the initial media data stream into a plurality of initial segments, the initial segment being in the plurality of initial segments;

performing, by the device, the iterative operation for each initial segment in the plurality of initial segments; and

wherein generating the transcoded media data stream comprises;

generating the transcoded media data stream such that the transcoded media data stream comprises a plurality of given transcoded segments, the plurality of given transcoded segments being generated by transcoding the plurality of initial segments.

4. The method of claim 3, further comprising:

transmitting, by the device, the transcoded media data stream to a client device via a computer network.

5. The method of claim 4,

wherein the initial media data stream represents video that is substantially live;

and

wherein the transcoded media data stream represents video that is substantially live.

6. The method of claim 1, wherein the method further comprises:

identifying, by the device, a representative segment of a media data stream, the representative segment being the initial segment; and

transcoding the media data stream into the transcoded media data stream using the final parameter set.

7. The method of claim 6, wherein identifying the representative segment comprises identifying a busiest segment of the initial media data stream.

8. The method of claim 1, further comprising:

receiving, by the device, via a computer communications network, a request for a media file that stores the initial media data stream; and

transmitting, by the device, the media file to a client device in response to the request.

9. The method of claim 1, wherein the new generations of parameter sets generated by each successive iteration of the iterative operation generate transcoded segments that have higher similarity to the initial segment than transcoded segments that result from transcoding the initial segment using the new generations of parameter sets generated by earlier iterations of the iterative operation.

10. The method of claim 1,

wherein the initial segment is encoded according to a first video encoding standard;

and

wherein trans coding the initial segment comprises;

transcoding the initial segment such that the transcoded segment is formatted according to a second video encoding standard, the first video encoding standard being different than the second video encoding standard.

11. The method of claim 1, wherein transcoding the initial segment comprises:

transcoding the initial segment such that the transcoded segment has a lower bit rate than the initial segment.

12. The method of claim 1, wherein the respective parameter sets include encoding parameters selected from a group comprising:

a parameter indicating a motion estimation method, a parameter indicating a motion estimation range, a parameter indicating a quantization scale between I-frames and P-frames, a parameter indicating a quantization scale difference between P-frames and B-frames, a parameter indicating a quantization parameter curve compression value, a parameter indicating a maximum keyframe interval, a parameter indicating a minimum keyframe interval, a parameter indicating a complexity blur parameter, a parameter indicating a quantization blur parameter, a parameter indicating a motion estimation compare function, a parameter indicating whether to use an in-loop deblocking filter, a parameter indicating a scene change threshold, a parameter indicating whether to add B-frames into a normal reference list, a parameter indicating whether to allow or disallow B-frames to use weight prediction options, a parameter indicating whether to allow each macroblock to use different references, a parameter indicating whether to allow or disallow skipping of P-macroblocks that do not appear to change, a parameter indicating whether to allow or disallow an encoder to use access unit delimiters, a value indicating whether to allow or disallow the encoder to choose which coefficients to round up or down, a parameter indicating a minimum quantizer, a parameter indicating a maximum quantizer, a parameter indicating a minimum step of a quantization parameter, a parameter indicating a number of frame to reference, a parameter indicating a predicting mode, a parameter indicating allowed combinations of partitions in macroblocks, a parameter indicating a maximum number of B-frames between keyframes, a parameter indicating how adaptive B-frame look ahead is, a parameter indicating an entropy encoder, a parameter indicating an alpha value for use in in-loop deblocking, a parameter indicating a beta value for use in in-loop deblocking, a parameter indicating a constant quality mode, and a parameter indicating algorithms used for both subpixel motion searching and partition decisions.

13. A system comprising:

a processor; and

a memory communicatively coupled to the processor, the memory having stored therein computer-executable instructions comprising;

a parameter identification module configured to perform an iterative operation until a final parameter set is selected to transcode an initial segment, wherein each iteration of the iterative operation comprises;

transcode an initial segment into a plurality of transcoded segments using parameter sets in a current generation of parameter sets;

calculate fitness scores of each transcoded segment in the plurality of transcoded segments;

determine whether a generation limit has been reached;

determine whether one of the fitness scores exceeds a fitness score threshold;

in response to the generation limit being reached or at least one of the fitness scores exceeding the fitness score threshold, output a given transcoded segment, the given transcoded segment being the transcoded segment generated by the iterative operation that has a fitness score greater than the fitness scores of each other transcoded segment generated by the iterative operation, and set a parameter set employed for transcoding the initial segment into the given transcoded segment as the final parameter set; and

in response to the generation limit not being reached and none of the fitness scores exceeding the fitness score threshold;

calculate selection probabilities of the parameter sets in the current generation of parameter sets; and

perform the following steps until a new generation of parameter sets includes a threshold number of parameter sets;

 

select parent parameter sets based on the selection probabilities of the parameter sets in the current generation of parameter sets; and

 

generate a child parameter set in the new generation of parameter sets by recombining values of encoding parameters in the parent parameter sets; and

set the new generation of parameter sets as the current generation of parameter sets; and

a transcoder configured to generate a transcoded media data stream comprising the given transcoded segment.

14. The system of claim 13, wherein the parameter identification module is further configured to:

receive an initial media data stream;

divide the initial media data stream into a plurality of initial segments that includes the initial segment;

transcode each initial segment in the plurality of initial segments into given transcoded segments using parameter sets generated by performing the iterative operation; and

wherein the transcoder is further configured to generate the transcoded media data stream such that the transcoded media data stream comprises the given transcoded segments.

15. The system of claim 14,

wherein the initial media data stream represents video that is substantially live;

and

wherein the transcoded media data stream represents video that is substantially live.

16. The system of claim 13, wherein the parameter identification module is further configured to

identify a representative segment of a media data stream, the representative segment being the initial segment, and the transcoder is further configured to

transcode the media data stream into the transcoded media data stream using the final parameter set.

17. The system of claim 16, wherein the representative is a busiest segment of the media file.

18. A non-transitory computer readable medium having instructions stored thereon that, in response to execution, cause system including a processor to perform operations comprising:

performing an iterative operation until a final parameter set is selected for transcoding an initial segment, wherein each iteration of the iterative operation comprises;

transcoding the initial segment into a plurality of transcoded segments using parameter sets in a current generation of parameter sets;

calculating fitness scores of each transcoded segment in the plurality of transcoded segments;

determining whether a generation limit has been reached;

determining whether one of the fitness scores exceeds a fitness score threshold;

in response to the generation limit being reached or at least one of the fitness scores exceeding the fitness score threshold, outputting a given transcoded segment, the given transcoded segment being the transcoded segment generated by the iterative operation that has a fitness score greater than the fitness scores of each other transcoded segment generated by the iterative operation, and setting a parameter set employed for transcoding the initial segment into the given transcoded segment as the final parameter set; and

in response to the generation limit not being reached and none of the fitness scores exceeding the fitness score threshold;

calculating selection probabilities of the parameter sets in the current generation of parameter sets; and

performing the following steps until a new generation of parameter sets includes a threshold number of parameter sets;

selecting parent parameter sets based on the selection probabilities of the parameter sets in the current generation of parameter sets; and

generating a child parameter set in the new generation of parameter sets by recombining values of encoding parameters in the parent parameter sets; and

setting the new generation of parameter sets as the current generation of parameter sets; and

generating a transcoded media data stream comprising the given transcoded segment.

19. The non-transitory computer readable medium of claim 18, the operations further comprising transmitting the transcoded media data stream to a client device via a computer communications network.

20. The non-transitory computer readable medium of claim 18,

the operations further comprising:

receiving an initial media data stream;

dividing the initial media data stream into a plurality of initial segments, the initial segment being in the plurality of initial segments;

performing the iterative operation for each initial segment in the plurality of initial segments; and

wherein generating the transcoded media data stream comprises;

generating the transcoded media data stream such that the transcoded media data stream comprises a plurality of given transcoded segments, the plurality of given transcoded segments being generated by transcoding the plurality of initial segments.

21. The non-transitory computer readable medium of claim 20, the operations further comprising transmitting the transcoded media data stream to a client device via a computer network.

22. The non-transitory computer readable medium of claim 18, wherein the initial media data stream represents video that is substantially live, and wherein the transcoded media data stream represents video that is substantially live.

23. The non-transitory computer readable medium of claim 18, the operations further comprising:

identifying a representative segment of a media data stream, the representative segment being the initial segment; and

transcoding the media data stream into the transcoded media data stream using the final parameter set.

24. The non-transitory computer readable medium of claim 23, wherein identifying the representative segment comprises identifying a busiest segment of the initial media data stream.

25. The non-transitory computer readable medium of claim 18, the operations further comprising:

receiving, via a computer communications network, a request for a media file that stores the initial media data stream; and

transmitting the media file to a client device in response to the request.

26. The non-transitory computer readable medium of claim 18, wherein the new generations of parameter sets generated by each successive iteration of the iterative operation generate transcoded segments that have higher similarity to the initial segment than transcoded segments that result from transcoding the initial segment using the new generations of parameter sets generated by earlier iterations of the iterative operation.

27. A system comprising:

means for performing an iterative operation until a final parameter set is selected for transcoding an initial segment, wherein each iteration of the iterative operation comprises;

transcoding the initial segment into a plurality of transcoded segments using parameter sets in a current generation of parameter sets;

calculating fitness scores of each transcoded segment in the plurality of transcoded segments;

determining whether a generation limit has been reached;

determining whether one of the fitness scores exceeds a fitness score threshold;

in response to the generation limit being reached or at least one of the fitness scores exceeding the fitness score threshold, outputting a given transcoded segment, the given transcoded segment being the transcoded segment generated by the iterative operation that has a fitness score greater than the fitness scores of each other transcoded segment generated by the iterative operation, and setting a parameter set employed for transcoding the initial segment into the given transcoded segment as the final parameter set; and

in response to the generation limit not being reached and none of the fitness scores exceeding the fitness score threshold;

calculating selection probabilities of the parameter sets in the current generation of parameter sets; and

performing the following steps until a new generation of parameter sets includes a threshold number of parameter sets;

selecting parent parameter sets based on the selection probabilities of the parameter sets in the current generation of parameter sets; and

generating a child parameter set in the new generation of parameter sets by recombining values of encoding parameters in the parent parameter sets; and

setting the new generation of parameter sets as the current generation of parameter sets; and

means for generating a transcoded media data stream comprising the given transcoded segment.