gstreamer x264enc matroskamux issue

[Chuck Crisler]

Tim, why does 'zerolatency' reduce quality in transcoding? He is reading
from a file so I would think that there shouldn't be any jitter concern.

On Thu, Oct 25, 2012 at 3:51 PM, Tim-Philipp Müller <t.i.m at zen.co.uk> wrote:

> On Thu, 2012-10-25 at 20:49 +0200, paul.praet at telenet.be wrote:
>
>
> > I am trying to convert a DVD to mkv file with gstreamer. The pipeline
> > I use is:
> >
> > gst-launch -evv multifilesrc location="VTS_01_%d.VOB" index=1 ! dvddemux
> name=demuxer \
> >  matroskamux name=mux ! filesink location=test.mkv \
> >  demuxer.current_video ! queue ! mpeg2dec ! x264enc ! mux. \
> >  demuxer.current_audio ! queue ! ffdec_ac3 ! lamemp3enc ! mux
> > [nothing happens anymore]
>
> The queues are probably too small (more precisely: the audio queue).
> x264enc will by default consume a few seconds' worth of frames before it
> outputs the first encoded frame. The audio queue needs to be able to
> contain that much audio data as well then (otherwise the demuxer will
> get blocked and stop outputting more video too, and nothing happens any
> more).
>
> So in short, try:
>
>   ! queue max-size-bytes=0 max-size-buffers=0
> max-size-time=10000000000 ! ..
>
> (or x264enc tune=zerolatency to find out if that is the problem - but
> this is not a good setting for transcoding, since it will reduce
> quality)
>
> Cheers
>  -Tim
>
>
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