[gst-devel] Why audio extract on flv won't preroll?

Tim-Philipp Müller t.i.m at zen.co.uk
Thu Sep 17 11:36:18 CEST 2009

On Wed, 2009-09-16 at 16:47 -0700, Shawn McMurdo wrote:

> Can anyone at least comment on whether my pipeline is correct?

The pipeline is correct in principle. You might want the audioresample
first and the audioconvert directly in front of wavenc though, because
wavenc only accepts little endian pcm audio, so your pipeline might not
work on big endian machines because audioresample only processes pcm
audio in native endianness. That isn't related to your problem though.

Decodebin2 works here because it uses multiqueue which handles buffering
more correctly and dynamically for certain files, whereas decodebin uses
more or less fixed size queues, which don't work for badly interleaved
files and many HD video files.

Recent versions of decodebin2 should work fine with all files, and I'm
not aware of any problems with it. If you have files that don't work
with it, please file a bug (or upgrade to a more recent gst-plugins-base
if you're not using the latest), thanks!


> From: Shawn McMurdo <shawn_mcmurdo at yahoo.com>
> To: Gstreamer Devel <gstreamer-devel at lists.sourceforge.net>
> Sent: Monday, September 14, 2009 5:19:13 PM
> Subject: [gst-devel] Why audio extract on flv won't preroll?
> Hi,
> I am trying to do an audio extract on various types of videos.
> Using decodebin as shown below on this video:
> http://www.shawnim.com/ax/balboa.flv
> causes gstreamer to hang in the preroll.
> The same pipeline works on other flvs and wmvs.
> Can anyone explain why this is happening?
> I am running gstreamer 0.10.24 on Fedora 11
> (
> The pipeline I am using is:
> gst-launch-0.10 -m -t -v filesrc location=$1 ! decodebin !
> audioconvert ! audio/x-raw-int,channels=1,width=16,depth=16 !
> audioresample ! audio/x-raw-int,rate=16000 ! wavenc ! filesink
> location=$1.wav
> The output from running this pipeline is:
> http://www.shawnim.com/ax/balboa.out
> BTW, decodebin2 works on this file but seems to have trouble with
> other files.
> Any explanations or pointer appreciated.
> Thanks.
> Shawn
> ------------------------------------------------------------------------------
> Come build with us! The BlackBerry&reg; Developer Conference in SF, CA
> is the only developer event you need to attend this year. Jumpstart your
> developing skills, take BlackBerry mobile applications to market and stay 
> ahead of the curve. Join us from November 9&#45;12, 2009. Register now&#33;
> http://p.sf.net/sfu/devconf
> _______________________________________________ gstreamer-devel mailing list gstreamer-devel at lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/gstreamer-devel

More information about the gstreamer-devel mailing list