[FFmpeg-devel] [PATCH] Improved analysis of h264 bitstreams with no B frames

Michael Niedermayer michaelni at gmx.at
Sun May 8 16:45:46 CEST 2011

On Sun, May 08, 2011 at 07:53:54AM -0400, Mike Scheutzow wrote:
> Michael Niedermayer wrote:
>> On Sat, May 07, 2011 at 12:03:48PM -0400, Mike Scheutzow wrote:
>>> The sps.constraint_set0_flag indicates that the bitstream is baseline profile,
>>> which means the stream has no B-pictures.  This patch fixes trac0088.
>> sps.constraint_set_flags&1 indicates no B frames
>> but no B frames does not implicate low_delay=1.
> It seems to me that's exactly what the other code in FFmpeg assumes.
> FFmpeg currently uses low_delay=0 to set has_b_frames=1 which then  
> rejects PTS==DTS for I and P pictures.
> Which assumption do you prefer to change?

the variable "has_b_frames" is misnamed, it shouldnt be named like that
its semantically == h->sps.num_reorder_frames

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