[FFmpeg-user] Concatenated H.264 or H.265 might not play correctly.drop=#

Luke Davis l1 at newanswertech.com
Tue Jul 22 22:29:25 CEST 2014

On Tue, 22 Jul 2014, Carl Eugen Hoyos wrote:

> Luke Davis <l1 <at> newanswertech.com> writes:
>> [sdp  <at>  0x1fcc0a0] Concatenated H.264 or H.265
>> might not play correctly.drop=5
>> The drop number increases over time.
>> The source is sending 15 FPS, with a keyframe every 5.
>> So my questions are:
>> 1.  What damage is actually happening to my outgoing
>> stream here, and is this a problem that can eventually
>> disrupt the stream?  I assume it is frames being
>> dropped?
> Only you can answer this question.

No, I can't, else I wouldn't have asked it.

I will rephrase it, however.  What is happening when this error is raised? Am I 
correct that it's dropping frames?  Is the drop cumulative?  In other words, 
when it says "drop=25", does that mean 25 frames have been dropped over the life 
of the feed?  These have been my assumptions.

  >> 2.  Is there any way to solve this, other than not
>> using H264?  I can use MPEG video, but the quality
>> is less (looks noticeably worse).
> That is expected, H264 is the best video codec with
> usable speed.

Yes, indeed it is expected.  But I will rephrase that question too: am I doing 
something wrong that prompts this error, or is this error to be expected in all 
transactions involving H.264 streams?
Can I do something different in order to avoid these dropped frames?
Are they being dropped because of the UDP transport, because of local 
processing, or for some other reason?
If it was transport related, I would expect to see other errors (regarding time 
synch), which I'm not.

>> 4.  What about this timebase warning?  What am I
>> doing wrong to cause that?
> Please test current FFmpeg git head before reporting
> issues here.
> (This was fixed.)

Is it sufficient to daily pull and recompile:
http://ffmpeg.org/releases/ffmpeg-snapshot.tar.bz2 (updated Jul. 22)

(Using git itself to keep a tree updated is not practical in my 
environment--ephemeral cloud machine instances)


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