Austin Che wrote: > Jesse Guardiani <[EMAIL PROTECTED]> wrote: > > >> And no, before you ask, I don't think it's not Nokia's fault. gstreamer >> is just unexpectedly buggy. Too bad ALSA doesn't support inline mp3 >> decoders... life would be easier for all of us... >> > > I've been wondering: what is the performance hit for not going > through gstreamer? So based on my understanding, going through > gstreamer, the mp3 is decoded on the DSP. Supposing it was decoded > on the cpu and sent out through alsa, which of the following is > likely to be true: > > - The CPU wouldn't be able to handle it (playback would skip) >
No, not even close. It doesn't use anywhere near that much CPU. Even with a separate process running transcoding the decoded mp3 into SBC packets (think a2dpd from the bluetooth-alsa package) we still don't get skipping, though doing other things at the same time will cause skipping sometimes. > - The CPU could handle it just as well as the DSP but the rest of > the system might be less usable > - The battery life would decrease (how much?) > Yes, mostly it's a battery life issue. But decoding mp3 in software does take a bit of available CPU, so you can't do quite as much simultaneously. > - some other reason this wouldn't work well? > Nah. Battery and multi-tasking. Those are the primary concerns, I think. > And the related question is: given an existing program that sends > stuff out to ALSA and doesn't use gstreamer, how difficult is it > generally to port it so that it works properly? No porting necessary, really. mplayer comes with a decoder called libmp3. It's not optimized for ARM or anything, and it compiles without any problems. We don't use it in Kagu for A2DP though because there is another decoder out there called ffmp3 which doesn't use floating point math, so it's a little more efficient on ARM. > By this, I'm > thinking of a typical C program that plays mp3 files. Would it > likely require a complete rework of the code structure or is it > probably a "trivial" replacement of function calls? > Trivial. You could always optimize it by re-writing it to do everything with fixed point math, but it's not strictly necessary, at least on the n800. -- Jesse Guardiani Programmer/Sys Admin [EMAIL PROTECTED] _______________________________________________ maemo-developers mailing list maemo-developers@maemo.org https://lists.maemo.org/mailman/listinfo/maemo-developers
