[vlc-devel] drop-late-frames behaviour

PROMONET Michel michel.promonet at thalesgroup.com
Wed Apr 4 09:58:14 CEST 2012

	Hi Rémi,

I will try to take times to look in src/input/*. 
I was wondering it was elaborate in modules/demux/mpeg/h264.c or modules/packaetizer/h264.c but I did not catch the links between manipulated structure and the picture_t in src/video_output/video_output.c.

The information I looking for is to understand if this check is based on :
- internal computing base on received frames
- parameter setting h264-fps ...
- rtcp timestamp
- rtp timestamp
- something else ?

Do you think this is the right place for this kind of question or I should use an other VLC mailing list ?

Thanks for your help,



-----Message d'origine-----
De : Rémi Denis-Courmont [mailto:remi at remlab.net] 
Envoyé : mardi 3 avril 2012 21:07
À : vlc-devel at videolan.org
Cc : PROMONET Michel
Objet : Re: [vlc-devel] drop-late-frames behaviour


Le mardi 3 avril 2012 21:36:21 PROMONET Michel, vous avez écrit :
> We use H264 stream with differents GOP, frames rates, and specially low
> frame rates in case of backward streaming. As we are using VLC in a
> plugins, setting ":drop-late-frames=0" is refused (considered as unsafe if
> I read correctly libvlc-module.c), then this setting seems not usable in
> such usage.

Nobody really considered allowing that option in plugins, so it was left 
blacklisted. But I don't think it would really fix the problem. In fact, it 
tends to make things worse as it can keep the CPU badly overbooked.

> Could you help me to understand how is it is compute ?

I don't know all the details myself. The discard logic proper is in 
src/video_output/video_output.c, but the clock synchronization, and buffering 
is mostly in src/input/*.

Rémi Denis-Courmont

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