[maemo-developers] GStreamer, mp3 playback and the DSP

[From: javicq]

Simon Pickering wrote:
> 
> 
>> 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.


Simon Pickering wrote:
> 
> 
>> The only thing i got so far is this paragraph from the wiki:
>> 
>> http://wiki.maemo.org/Documentation/Maemo_5_Developer_Guide/Ar
> chitecture/Multimedia_Domain#Audio_Codecs
>> 
>> Most of the audio encoders and decoders are wrapped under the 
>> OpenMAX IL interface [OMAX], which abstracts the codec 
>> specific implementation (which in general can run on ARM or 
>> DSP). Unless a different solution is needed (due e.g. to 
>> sourcing problems, performance requirements or to fulfill 
>> some specific use cases) all the audio codecs will be running 
>> on the ARM side to simplify the audio architecture and to 
>> avoid the additional latency and load over the data path due 
>> to the routing of the audio data first to DSP and then back to ARM. 
>> 
>> 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.
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