[FFmpeg-devel] Problem with initial dts in h264
Mon Dec 7 07:30:29 CET 2009
On 12/06/2009 07:15 PM, Michael Niedermayer wrote:
> On Sun, Dec 06, 2009 at 03:26:30PM -0800, John Stebbins wrote:
>> A recent change has caused the initial dts in h264 streams returned by
>> av_read_frame to be incorrect. The commit was r20599.
>> This is especially obnoxious when the reader does a seek before
> send a patch that resets pts_buffer in av_read_frame_flush()
> (assuming its tested& works of course)
> There may be further bugfixes needed but this one seems obviously missing
I thought that something should be resetting pts_buffers, but didn't
know where that should be done. So thanks for the pointer. I think
that av_read_frame_flush should also be called from av_find_stream_info
since pts_buffer is modified during this function. My patch does this.
I did some testing, and this patch fixes the problem I saw. But as you
noted, there seems to be more bugs. I'm now seeing the dts start out
ok. But it looks like st->codec->has_b_frames starts out at 2, changes
to 0 on the second packet, then changes to 2 again a bit later. When it
changes back to 2, dts once again gets the wrong value for a sequence of
several packets. It appears that the change in delay screws up the
ordering in pts_buffers.
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