[gst-devel] MPEG2 Linear PCM

Wim Taymans wim.taymans at chello.be
Sat Feb 22 15:12:02 CET 2003

On Sat, 2003-02-22 at 21:37, Martin Soto wrote:
> Hi all!


> First of all, let me tell you that GStreamer really rocks! I'm still
> learning plugin development, but already can tell that the framework is
> excellent.  Thanks a lot for such a good job!

Thanks :)

> And now my question.  I'd like to be able to play the linear PCM sound
> from a couple of DVDs I have around.  These are normal video DVDs (not
> DVD audio) with sound encoded as PCM for better quality.
> My first problem was that the standard mpegdemux element is not able to
> extract the PCM streams.  I already hacked it to do so, and at least I'm
> being able to get some raw data from the PCM stream (I'll gladly submit
> a patch as soon as I'm sure that the data I'm extracting makes sense).

I personally don't have any PCM VOB, can you provide me a link to one?
If you create a bugzilla patch I can take a look at your code, if you

> The second problem is the decoding of the sound data itself.  This is
> not completely trivial and I was wondering if there is already in
> GStreamer an element that is able to do that.  Otherwise, I may try to
> write one, but wouldn't like to duplicate work if possible.  According
> to the Xine source code,
> http://members.freemail.absa.co.za/ginggs/dvd/mpeg2_lpcm.txt contains a
> proper description of the format. 
> So, if there's such an element, I'd appreciate you to point me to it. 
> Otherwise, a suggestion of an element that I could use as sample to
> start with would, be very useful.

There is no plugin for lpcm yet. If you want to make one, I suggest to
take a look at gstmad.c, it's a good example of a fullfeatured chain
based plugin, the gsm decoder plugin is a good starting point for an
lpcm decoder. 

Don't hesitate to ask any questions here or in IRC (irc.freenode.org



> Cheers,
> M. S. 
Wim Taymans <wim.taymans at chello.be>

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