On 31 December 2007, Frantisek Dufka wrote: > Igor Stoppa wrote: > > Having the audio path open, but no dsp tack loaded (arm audio) sets the > > clock to 400MHz. > > Interesting, so, umm, there is way to play audio from ARM side directly? > What I tried is to play BBC radio in home screen applet which activated > only pcm2 task and arm clock dropped from 400 to 330. That lead me to > conclusion that there is no way to output audio with arm clock at > 400Mhz. Why there are pcm tasks (used when streaming internet radio) if > we could output audio from arm side without limiting ARM clock? Siarhei > apparently used a way to output audio without activating DSP from > mplayer, how?
I did not do anything special. ARM clock frequency just remains at 400MHz when using esd or sdl for audio output. I did some benchmarks and it became clear that it is now faster not to touch dsp mp3 task and just do all the decoding on ARM core. In addition, my hack which used dspmp3sink from MPlayer, now has problems with audio/video synchronization in OS2008. So looks like it is a good time to drop it. Using DSP for MP3 audio was a useful trick on Nokia 770 and OS2006, but right now everything is reversed for N800/N810 and OS2008. Anyway, my guess also was that pcm dsp task is used in osso-esd, maybe it makes sense to check its sources more thoroughfully. Looks like we will have a lot of new discoveries with OS2008 :) As ARM core is quite fast in N8x0, probably it would make sense to try keeping DSP out of the way whenever possible (restrict it to 133MHz only, keep DSP tasks which are fast enough to run at this frequency, port all the other DSP tasks to ARM)? That is unless improvements to support more intelligent DSP clock frequency selection are still possible. But for those interested in C55x development, Nokia 770 is still a very interesting device as it runs DSP at full speed. _______________________________________________ maemo-developers mailing list maemo-developers@maemo.org https://lists.maemo.org/mailman/listinfo/maemo-developers
