Question regarding use of interleaved and deinterleaved elements in processing chain

[Sebastian Dröge]

On Wed, 2016-08-24 at 22:03 +0200, public-hk at ind.rwth-aachen.de wrote:
> 
> > That's exactly the problem: you have to put a queue element after
> > each deinterleave pad for adding this new thread.
>  
> Thank you, that was the trick I was looking for ;-)
> 
> For those who will run into the same problem: If you connect the
> interleaver to alsasink, you will
> in addition need to provide a channel mask by setting the property
> "channel-positions" properly.
> Otherwise, the interleaver will not connect to alsasink.
> And if you set that property, you will need to link against the
> gstreamer-audio library in order to set the
> correct GValue type (type GST_TYPE_AUDIO_CHANNEL_POSITION).

You can also let it use the channel position of the input btw.

Instead of interleave you might also want to use audiointerleave, which
is the new version of the element and generally works better.

> And finally: we have a soundcard running which has 196 channels. The
> interleave gstreamer plugin has a limitation
> to expect a maximum of 64 channels only: In line 63 of interleaver.h,
> the limitatin is given as
> 
> gint default_channels_ordering_map[64];
> 
> By connecting 196 channels, this limit does not really stop the
> interleaver from returning requested pads as it seems.
> But it will cause a segmentatin fault later. Setting the 64 to 196
> solved this problem. The same modification maybe done in line 275 in
> file interleave.c. But I have to admit those 196 channels are really
> an unexpected hardware setting.

We currently only have support for 64 positioned channels, but more
unpositioned should be useful and relatively easy to support.

Do you want to provide your patch? Instead of making the array bigger,
for > 64 channels you would use an unpositioned layout
(GST_AUDIO_CHANNEL_POSITION_UNPOSITIONED) and can leave the array
empty.

-- 
Sebastian Dröge, Centricular Ltd · http://www.centricular.com
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