MP3 Performance Testing

I built gmu for iz2s to compare against rockbox and see what I could dig up on the stutter problem.  I'm lazy so I only built the mpg123 codec library for gmu, but as a bonus that codec comes with the standalone mpg123 command line player.  Now the standalone mpg123 executable linked against libmpg123.so works fine, but gmu stutters just like rockbox.  So opened up top in an ssh window to investigate.  The standalone exe uses very little memory, and no threads or SDL.  It seemed to hover around 12% CPU.  GMU used about 6MB (and might have been leaking more) launched several threads, one of which used about 15% CPU and another which used about 5%.  At 6MB, there was memory to spare, so I think we can rule that out as the stutter problem.  So I think that leaves SDL and pthreads.  That 5% CPU process stands out as suspicious.  Is the SDL event loop or screen refresh code keeping the processor that busy?  Hopefully the event loop is doing nothing.  So screen refreshing?  Hmm, I think maybe gmu can run without the screen.  I'll have to read up on that. 

Anyhow 5% still doesn't seem all that bad, so I'll have to look at the pthread context switching.  Perhaps major improvements have been made in recent years.

In other news, I traded one of my troublesome 4GB SD cards for an older 2GB card which seems to make the zipit happier.  It's already survived several reboots and one actual SD card removal on my ubooted zipit.  Right not it's loaded up with the new z2lite userland, which runs the rockbox I built for wejp's userland just fine.  No stuttering, so far.  It also appears to be able to change codecs on the fly, and it even kept track of rockbox theme changes.  Now I just gotta grab a few of the ipod video 320x240 themes and try them out.  The "retroTape" theme looks like fun, while "Big info" and "DriveBox" might be good for the car.

Here's the zipit running the "Big info" theme.  I think I can read that from the driver seat.