Synchronize gnlcompositions without gnltimeline

[Jason Gerard DeRose]

On Thu, Sep 6, 2012 at 11:24 AM, Ralph <ralph.gucwa at racelogic.co.uk> wrote:

> I'm using gnonlin for playback of video files. In my pipeline I have two
> gnlcomposition objects: one for video and the other for audio.  When I
> played standard resolution XVID files the synchronization between audio and
> video was satisfactory, but now when I started playing high resolution H264
> files the video lags behind the audio noticably.  How can I synchronize
> audio and video without using gnltimeline object?  My application is WPF C#
> and I'm using C# Bindings and OSSBuild (GStreamer WinBuilds v0.10.7, Beta
> 04), unfortunately those libraries are very old and gnonlin doesn't contain
> gnltimeline.
>

AFAIK, gnltimeline is an element that hasn't existed in gnonlin for quite
some time (googling suggests it hasn't been present since GStreamer 0.8).
So you're already using the correct, modern element with gnlcomposition.

In my experience, the sync is okay doing playback with gnonlin, but
depending on how far you are from a keyframe, the playback will hang as you
switch from one segment of video to the next, and sometimes it will never
catch up with the audio.

To fix this, gnonlin would need to preroll the next video segment while
playing the current one, which should give smooth, uninterrupted playback
on multi-core systems fairly easily.

Based on how gnonlin works, it shouldn't really be able to introduce sync
problems itself, unless you build your compositions incorrectly. But there
could be sync issues with the particular codecs and containers you're
working with.

If you can, try the same test on a faster computer, see if that improves
things.


>
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