[x264-devel] AVC Decoder Configuration Record

[Jason Garrett-Glaser]

On Wed, Dec 15, 2010 at 1:35 AM, herbert westmacott
<herbie.westmacott at gmail.com> wrote:
> On 14 December 2010 23:23, Jason Garrett-Glaser <jason at x264.com> wrote:
>>> aligned(8) class AVCDecoderConfigurationRecord {
>>> unsigned int(8) configurationVersion = 1;
>>> unsigned int(8) AVCProfileIndication;
>>> unsigned int(8) profile_compatibility;
>>> unsigned int(8) AVCLevelIndication;
>>> bit(6) reserved = ‘111111’b;
>>> unsigned int(2) lengthSizeMinusOne;
>>> bit(3) reserved = ‘111’b;
>>> unsigned int(5) numOfSequenceParameterSets;
>>> for (i=0; i< numOfSequenceParameterSets; i++) {
>>> unsigned int(16) sequenceParameterSetLength ;
>>> bit(8*sequenceParameterSetLength) sequenceParameterSetNALUnit;
>>> }
>>> unsigned int(8) numOfPictureParameterSets;
>>> for (i=0; i< numOfPictureParameterSets; i++) {
>>> unsigned int(16) pictureParameterSetLength;
>>> bit(8*pictureParameterSetLength) pictureParameterSetNALUnit;
>>> }
>>> }
>>
>> x264 does not generate any such structure.  Such a structure is not
>> part of the H.264 spec.
>>
> Hi Jason
>
> I know this isnt part of the H264 spec its defined in the ISO/IEC
> 14496-15.  The muxers insert this record into the stream so maybe best
> to post this question on ffmpeg-devel mailing list.
>
> My question to libx264 was really is it possible to tell it what
> length value to choose for the NALUnitLength in the AVC payload. if
> this entry is specified incorrectly for example in the Decoder record
> then the player cannot playback the stream.

x264 doesn't "choose" the length.  That doesn't make sense.  It's the
job of the muxer to write the correct length for the stream it
receives.

Jason