[gst-devel] Transcoding with gstreamer

[Jan Schmidt]

On Thu, 2004-11-25 at 11:04 +0000, David Given wrote:
> Has anyone had any luck encoding video in any of the various standard formats 
> with gstreamer? I can't seem to find an mpeg muxer, for example. Is this kind 
> of thing expected to work?

I don't know about mpeg muxing, but I use things like the attached
script to convert DV to theora.

> And does anyone know why frequently when experimenting with a pipeline I 
> frequently just get:
> 
> $ gst-launch-0.8 filesrc location=Neverending\ Story.xm ! mikmod ! tee ! 
> osssink { queue ! goom ! spider ! xvimagesink }
> RUNNING pipeline ...
> ERROR: pipeline doesn't want to play.
> Segmentation fault

The segfault obviously isn't good. If there's a sensible stacktrace, it
would be nice to see it in bugzilla.

the pipeline not wanting to play makes sense though - it isn't correct.
You need to specify that you also want the queue connected to the tee,
thus:

gst-launch-0.8 filesrc location=Neverending\ Story.xm ! mikmod ! tee
name=t ! osssink { t. ! queue ! goom ! xvimagesink } 

Probably, you also want to ensure that goom outputs 25fps (or similar),
and use a colorspace converter to ensure xvimagesink will get a format
it can handle:

gst-launch-0.8 filesrc location=Neverending\ Story.xm ! mikmod ! tee
name=t ! osssink { t. ! queue ! goom ! video/x-raw-rgb,framerate=25.0 !
ffmpegcolorspace ! xvimagesink } 

If that crashes, it's almost certainly a mikmod bug.

> This is using the Debian packages off Alioth (which seem to be missing 
> gst-editor-0.8, BTW). AFAICT, the pipeline *looks* all right. 

Yeah, that maintainer sure is a big slacker ;)

J.