Separate audio feeds to front/side/rear channels

[drunkahol]

I've got an issue at work requiring the streaming of TV audio feeds to a telephone system to let the traders listen to TV channels by dialing the right number.  I am using gst-launch to capture the 6 channels as separate left/right stereo channels and send them across the network.

For simplicity, I had hoped to play these 3 stereo feeds through front/side/rear channels of a single suitable sound card, but am having problems.

Whilst the following works

# gst-launch audiotestsrc volume=0.250 freq=300 ! audioconvert ! alsasink device=front &
# gst-launch audiotestsrc volume=0.250 freq=400 ! audioconvert ! alsasink device=side &
# gst-launch audiotestsrc volume=0.250 freq=500 ! audioconvert ! alsasink device=reat &

(although only as root) I get the right tone in each channel.

But,

# gst-launch filesrc location=test.ogg ! decodebin ! audioconvert ! alsasink device=front &

gives me:
Setting pipeline to PAUSED ...
Pipeline is PREROLLING ...
ERROR: from element /GstPipeline:pipeline0/GstDecodeBin:decodebin0/GstOggDemux:oggdemux0: Internal data stream error.
Additional debug info:
gstoggdemux.c(3450): gst_ogg_demux_loop (): /GstPipeline:pipeline0/GstDecodeBin:decodebin0/GstOggDemux:oggdemux0:
stream stopped, reason not-negotiated
ERROR: pipeline doesn't want to preroll.
Setting pipeline to NULL ...
Freeing pipeline ...

Leaving the "device=front" part off allows the audio to play.

Is there something I need to do to get the Ogg stream in the right format to play back on front/side/rear? Also, is there any way of listing which devices are available for alsasink?  I've poked around endlessly with alsa configs etc and there doesn't seem to be anything.

Thanks

Duncan

[Wim Taymans]

On Wed, 2010-08-25 at 03:07 -0700, drunkahol wrote:

> # gst-launch filesrc location=test.ogg ! decodebin ! audioconvert ! alsasink
> device=front &
>
> gives me:
> Setting pipeline to PAUSED ...
> Pipeline is PREROLLING ...
> ERROR: from element
> /GstPipeline:pipeline0/GstDecodeBin:decodebin0/GstOggDemux:oggdemux0:
> Internal data stream error.
> Additional debug info:
> gstoggdemux.c(3450): gst_ogg_demux_loop ():
> /GstPipeline:pipeline0/GstDecodeBin:decodebin0/GstOggDemux:oggdemux0:
> stream stopped, reason not-negotiated
> ERROR: pipeline doesn't want to preroll.
> Setting pipeline to NULL ...
> Freeing pipeline ...
>
> Leaving the "device=front" part off allows the audio to play.

You need to add audioresample before alsasink, this is likely a case
where the samplerate of the ogg file is not supported natively by the
front device, which by default doesn't do automatic resampling.

>
> Is there something I need to do to get the Ogg stream in the right format to
> play back on front/side/rear? Also, is there any way of listing which
> devices are available for alsasink?  I've poked around endlessly with alsa
> configs etc and there doesn't seem to be anything.

aplay -L is probably what you are looking for.

Wim



>
> Thanks
>
> Duncan
>



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[drunkahol]

Thanks Wim, that's fixed the issue.

Duncan