[vlc-devel] [PATCH] access module for BlackMagic SDI cards

Steinar H. Gunderson sgunderson at bigfoot.com
Sun Oct 3 17:57:59 CEST 2010

On Mon, Sep 27, 2010 at 01:15:36AM +0200, Steinar H. Gunderson wrote:
> As this is my first VLC code (the patches I sent earlier were started after
> this) I'm sure there are coding style issues, and probably also others.  In
> particular, I'm very unsure how the PTS/DTS handling in VLC is supposed to
> work; if I crank down --sdi-caching to values around 50, VLC starts
> complaining about the _audio_ being late to the mux, even though the audio
> and video are locked together with the same PTS, and I push the video through
> x264. I've traced this around a bit and it may or may not be related to the
> fact that the stream PTS is converted to the system PTS with some jitter
> conversion thrown in, but I haven't really been able to figure out why this
> happens.

I figured out why this is. The copy packetizer delays the stream by one block
in order to set i_length from the pts. Given that the later TS mux seems to
distrust the i_length anyway (even though I take care to get it correct :-/),
this seems a bit pointless in my case. Can I do anything about it? Is this
i_length correction really needed?

/* Steinar */
Homepage: http://www.sesse.net/

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