Re: [LAD] Library for accurate time stamping using a DLL

From: Olivier Guilyardi <ml@email-addr-hidden>
Date: Tue Feb 03 2009 - 15:30:40 EET

Paul Davis wrote:
> On Tue, 2009-01-27 at 13:49 +0100, Olivier Guilyardi wrote:
>
>> For example, in FFmpeg, each audio and video packets are tagged using a PTS
>> which is computed using av_gettime() which calls gettimeofday().
>
> this should be considered a bug and reported as such to the FFmpeg group
> (preferably with a patch to make it use clock_gettime() if available).
> gettimeofday is a non-linear, non-mononotic clock if ntp is used. it is
> not suitable for timestamping in this way. without ntp, it will work
> better, but it is still subject to potential non-monotonicity.

I just wanted to let you know that an interesting discussion is going on the
ffmpeg-devel mailing list, about choosing a time source, NTP effects, and A/V
synchronization. It is named "libavdevice: PTS stability and risks of drift".

-- 
  Olivier
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Received on Tue Feb 3 16:15:02 2009

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