[gst-devel] Transcoding with gstreamer

David Given dg at cowlark.com
Fri Nov 26 07:55:23 CET 2004

On Thursday 25 November 2004 19:51, you wrote:
> > Should I upgrade to the latest CVS?
> Before reporting bugs? Definately.

Well, I've attempted to upgrade to using CVS rather than the Debian packages. 
In the process I've rediscovered why I decided why the Debian packages are a 
good idea... talk about dependency hell!

I've installed gstreamer, gst-plugins, gst-ffmpeg, gst-editor and gst-player. 
Everything built pretty much first time except for one minor issue with 
gst-plugins: the gst/alpha directory doesn't get its makefile built by 
configure, so I just edited the root makefile not to build that directory and 
it all went fine.

goom and synaesthesia both work fine now, at reasonable frame rates, and at 
100% CPU time, although I've yet to get anything working properly through 
gst-editor --- it keeps hanging and locking up and generally behaving oddly. 
gst-launch is fine.

(Incidentally, various typos in the gst-launch command line can result in 
strange crashes --- anyone interested?)

Next idiotic newbie question!

Trying to use gstreamer to repackage an mpeg file as an avi, without actually 
doing any transcoding, I've come up with this:

gst-launch \
 filesrc location=infile.mpg ! ffdemux_mpeg name=demux \
 avimux name=mux ! filesink location=out.avi \
 { demux.video_0 ! queue ! mux.video_0 } \
 { demux.audio_0 ! queue ! mux.audio_0 }

(Newlines inserted to make it more readable.)

Now, I would expect this to either (a) work or (b) fail if the video and audio 
types aren't compatible. Instead it does (c), which is to hang. Any 
suggestions as to why?

(The reason why I'm asking all this, BTW, is that I'm building a media box. 
gstreamer looks to be ideal for the actual video processing part of things. I 
can then write the front end in ruby, which can talk to both gstreamer and 
gtk2; with the occasional custom gstreamer filter in ordinary C, it should 
all be understandable, flexible, highly maintainable and as a bonus it may 
even work. I have yet to find any media system quite as elegant as gstreamer. 
At the risk of sounding like a total fanboy, way cool! But first I have to 
understand it.)

+- David Given --McQ-+ 
|  dg at cowlark.com    | C:\DOS, C:\DOS\RUN, RUN\DOS\RUN
| (dg at tao-group.com) | 
+- www.cowlark.com --+ 

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