[gst-devel] Synchronisation Question

Wim Taymans wim.taymans at chello.be
Mon Feb 12 17:51:52 CET 2001


On 12 Feb 2001 15:11:22 +0000, Andrew Stevens wrote:
> Dear gstreamers,
> 
> 
> The project I'm developing on (mjpeg.sourceforge.net) currently uses the
> usual *ix ad-hocery to provide tools MJPEG capture/simple editting and
> MPEG encoding.   Gstreamer would seem the obvious home.  However, I'm a
> bit unclear from a glance over the archives as to the feasibility of
> some necessary synchronisation mechansims.

Welcome :-)

> 
> The key issues would be:
> 
> - Accurately synchronising muxing of audio and video from capture
> hardware based on time-stamp information.

currently all buffers have a timestamp attached to them which can be
used to sync the muxing
process.  Buffers can contain anything from video frames to audio
samples. 

> 
> - Communicating sync adjustment information from the demux to the muxing
> stages of transcoding pipelines.

again no problem with our current infrastructure.

> 
> Are there any thoughts or work in progress on these issues?

You might want to check out a few example programs to transcode various
media types, all
in test/

mp1tomp1
mp2tomp1
mp2toavi
mp3tovorbis
avi2mpg

there are a few sample capture programs too:

vidcapture (v4l to mjpeg)
vidcapture2 (v4l to DivX :-))

They used to work at some point in the past, I didn't try them lately so
they might not
work...

We are currently working on an infrastructure that will allow accurate
seeking, which I believe
is something you will need too.

A new infrastructure for typing the pads (to ensure every element is
talking about the same
media types) is being constructed. 


Wim


> 
> 
> many thanks,
> 
>       Andrew
> 
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