Help with transcoding h264 encoded TS on raspberry pi

[Sebastian Dröge]

On Sa, 2013-12-14 at 08:47 +0100, Stefan Simon wrote:
> Guys,
> 
> 
> I'd like to sincerely thank you for your great support, I was able to
> make the 1.2 work, no more issues with ghosting (unless I use
> videoscale), pipelines work as expected. I was wondering if openmax
> videoscale and deinterlace are planned, because this would help a lot.

It's not planned currently but would be a good idea if someone wants to
spend the time on that. However this will only be useful with some
further architectural improvements in gst-omx to allow generic zerocopy
passing of data between different gst-omx elements, if possible at all
on the RPi. Which would surprise me, as the OpenMAX implementation on
the RPi is rather inflexible in that regard.

The other alternative would be to create the scaling/deinterlacing
components inside the decoder (or encoder) and directly tunnel them to
the decoder (or encoder) component inside a single element.

Or one could implement a way to allow tunneling between the components
of multiple different gst-omx elements.

Without any of this you will copy the video memory to the GPU and back
to the CPU for every single gst-omx component, which will be rather slow
and most likely not fast enough for your use case.

>  One more question if I may. How does one handle multiple audio tracks
> correctly in my use case? 

The demuxer will add a new srcpad for every audio stream. You would then
select the correct one based on the tags or the PID of the stream. You
could also link them all to an input-selector element to allow switching
between the different audio streams at runtime.

See the implementation of playbin for an example.

-- 
Sebastian Dröge, Centricular Ltd - http://www.centricular.com
Expertise, Straight from the Source
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