On 30 December 2007, Frantisek Dufka wrote: > Krischan Keitsch wrote: > > I was wondering if the device really needs to run at 300MHz (220MHz dsp) > > for mp3 playback? Is the max dsp power needed for such a task? Or would > > 220MHz (177MHz dsp) or 165MHz (85MHz dsp) be sufficient? Would a lower > > dsp scaling save even more battery? > > Well, yes it looks a bit simplistic now. Even if you play audio decoded > by ARM cpu (ogg, real audio) it seems to lock ARM core to 330 and dsp to > 220Mhz. I suppose it is because you need pcm dsp task running for audio > output and any active dsp task locks it to 220Mhz (and thus cpu to 330). > I wonder if it is just simple implementation that can be tuned in next > firmwares or there is some fundamental problem (like changing dsp clock > of already running dsp task may break it so it is hardcoded to 220).
ARM cpu frequency is apparently not locked at 330MHz when using pcm dsp task. That's why it is faster to do MP3 decoding on ARM core with the current OS2008 firmware. Extra 70MHz of ARM core frequency are more than enough to handle MP3 and there are even some resources left to speed up video decoding. It is interesting if it is possible to lock ARM/DSP frequency at 400/166 instead of 330/220 when playing video. That would probably improve built-in player performance on some heavy bitrate/resolution videos. Also it is interesting to know what is the difference in power consumption between 400/166 and 330/220 modes? _______________________________________________ maemo-developers mailing list maemo-developers@maemo.org https://lists.maemo.org/mailman/listinfo/maemo-developers
