What are the limits of openmax encoder/decoder on Raspberry PI?

[Sebastian Dröge]

On Do, 2013-10-24 at 13:45 +0200, Augusto Destrero wrote:
> Hi there,
> what are the performance limits of openmax encoder/decoder on Raspberry PI?
> 
> I explain better my question with an example: is it possibile to decode a 
> mpeg4 FULL HD 30fps file and concurrently re-encoding it in h264 using 
> gstreamer openmax in real time?
> 
> I have a performance problem decoding a FULL HD video stream in real time and 
> I suspect the bottleneck is in the hardware decoder/encoder of the Rpi. The 
> CPU idle is good, but the hardware decoder/encoder doesn't show itself there, 
> is it?

The performance problem will most likely be the copying of the raw video
frames from the VideoCore to the CPU, then back to the VideoCore.
Currently no zerocopy is possible from GStreamer between the OpenMAX
encoders and decoders, but depending on how exactly your pipeline looks
and what you want to do this can be implemented.

> How can I see if the performance limit of the hardware is reached? Is there 
> some logging mechanism?
> 

Well, AFAIK there is no way to get performance information from the
VideoCore. Once it's loaded you'll see that the CPU is mostly unused
although stuff is still slow.

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