[maemo-developers] [maemo-developers] Xvideo support for Nokia 770?

From: Devesh.Kothari at nokia.com Devesh.Kothari at nokia.com
Date: Thu Feb 8 17:29:02 EET 2007

>-----Original Message-----
>From: maemo-developers-bounces at maemo.org 
>[mailto:maemo-developers-bounces at maemo.org] On Behalf Of ext 
>Siarhei Siamashka
>Sent: 08 February, 2007 09:16
>To: maemo-developers at maemo.org
>Subject: Re: [maemo-developers] Xvideo support for Nokia 770?
>It would be probably a good idea to discuss different 
>possibilities for improving multimedia support on 770/N800.
>Now we have a fast JIT scaler that runs on ARM core, it solves 
>all the video resolution related performance problems. I'm 
>going to work on improving quality, performance and its 
>inclusion into upstream ffmpeg library, this task is in my 
>nearest plans:
>As for the ways of improving multimedia support on Nokia 770, 
>it may be done in the following ways (in no particular order):
>1. Continue ffmpeg optimizations (motion compensation 
>functions, finetune idct, have a look at the possibilities to 
>optimize codecs other than mpeg4 and its variants) 2. 
>Implement Xvideo extension support for Nokia 770 (using 
>scaling done on ARM core) 3. Implement XvMC in some way (using 
>C55x DSP for it as it is supposedly good for IDCT and motion 
>compensation stuff) 4. Improve GStreamer plugins (replacements 
>for dspfbsink and dspmpeg4sink running on ARM core, it could 
>probably improve mpeg4 playback performance a lot and allow 
>using higher video bitrates and resolutions that are currently 
>available in MPlayer) 5. Try to relay color format conversion 
>and scaling to DSP. If it works as expected, video scaling can 
>be done with almost zero overhead for ARM core. Theoretically 
>the same trick could probably also work for GStreamer if video 
>output sink can provide its own buffer (::buffer_alloc). The 
>first step would be to try just doing nonscaled color format 
>conversion. If it is successful, some more advanced stuff can 
>be tried such as JIT dynamic code generation on C55x.
>6. Try porting vorbis decoder (tremor) to DSP 7. Try porting 
>libmpeg2 to DSP. With audio decoding and scaling done on ARM 
>core, it might improve overall mpeg2 playback performance, I 
>wonder if nonconverted DVD video playback is even 
>theoretically possible on Nokia 770.
>That's quite a big list and it contains some things that might 
>be generally nice to have, but have relatively low practical 
>value and are actually not worth efforts implementing :)
>There are two issues that need to be solved for this all to 
>become reality:
>1. We need some way of applying community developed upgrades 
>for core system components such as xserver and xlib (if we go 
>after Xvideo support on Nokia 770). They must be easy to 
>install by end users, otherwise this all development does not 
>make much sense. It would be also nice to integrate these 
>improvements into official firmware later, but I wonder if 
>Nokia has spare resources for doing this integration and its 
>quality assurance.

>2. Reliable information that is detailed enough for performing 
>graphics and audio output from DSP, see 

Again throwing some options in the air
1. Dump DSP. If I remember the driver for the audio chip is in the omap
tree. So (probably never tried) is to remove all dsp related components
from the image, and then have everything purely on ARM [maybe worth a
2. use ALSA DSP


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