> >> I'm currently using GStreamer to play mp3 files. I'm > >> trying to move > >> all mp3 decoding to the DSP but I'm unable to find any > >> useful info on > >> the matter. > > > > May I ask why you're trying to move mp3 decoding to the > > DSP? Are the > > mp3s the sound track/effects for a game, etc., so you want to have > > more CPU cycles to do useful work? > > Yes, it's an emulator actually, and mp3 decoding is > noticeably stealing CPU cycles.
Ok, I just wanted to check that your reason was something valid and indeed it is. <snip> > >> So, obviuosly a different solution is needed but I coudn't > >> find any > >> documentation whatsoever. :) Anyone can help here? > > > > Are there any existing OpenMAX mp3 decoders targetted at the > > TMS320c64x DSP? > > If not, it would probably not be too painful to port one > (where pain > > is all relative, but at least this would be less painful > than trying > > on the more constrained and 8bit-less c55 ;) > > > > Thats what the wiki article I quoted seems to imply, but it's > not very clear and I couldn't find any further info. There's > a multimedia framework diagram suggesting that there are > OpenMAX audio codecs that run in the DSP via DSP-bridge, but > not sure if this applies to maemo 5 and there's no info on > how to use them. I must admit that I've not done any DSP work on the c64, though I did pay attention to it when the N900 was originally announced (and I thought I'd get a Pandora to fill the gap until it was shipped, glad I didn't pin my hopes on that now ;). Anyway I imagine some of the Nokians (and others) will know from first hand experience so please someone jump in if I've got the wrong idea. So yes, my understanding is that that is exactly what's involved, therefore it should be possible to write an OpenMAX compliant codec that uses the DSP bridge to transfer data back and forth to a decoder running on the DSP. There were docs and examples on one of the websites (this one iirc: https://gforge.ti.com/gf/project/omapbridge/ and DSP coding docs on this site: http://www.ti.com/sc/docs/psheets/man_dsp.htm), not sure about the OpenMAX docs, but I guess there will be example code floating about somewhere (or you might just wrap the DSP bridge interface stuff directly in a Gstreamer plugin and skip the OpenMax stuff completely). I think that writing/porting this should be reasonably straight-forward, optimising it less so, but at least afaiu the code shouldn't need major changes to get rid of 8bit types. However.... on the N8x0 devices it was not possible to directly output audio from the DSP due to a lack of api docs (it would need a re-write of the DSP kernel or reverse engineering the DSP audio codec api, which are things that would now be good for Mer, but would take some time, but that's another story). I don't know if it is currently (or would be relatively easily) possible to output audio directly from the N900's DSP. This is something you should try to find out, as on the N8x0, needing to pass data both to and back from the DSP (in this case for SBC encoding) clobbered video decoding on the CPU (CPU load was lower with SBC encoding on the DSP, but something, presumably memory contention due to the way the data was passed to and fro for both the DSP and framebuffer, dropped the mplayer decoded framerate down from iirc ~25fps to ~1fps). I imagine/hope the N900 + DSP bridge setup is better, but I really don't know. Does anyone know? Could a Nokian tell us about the possibility of direct audio output from the DSP and how efficient the data passing is in the absence of direct audio output? Cheers, Simon _______________________________________________ maemo-developers mailing list maemo-developers@maemo.org https://lists.maemo.org/mailman/listinfo/maemo-developers
