Package: mpd Version: 0.14.2-2 Severity: normal Between version 0.13.2-3lenny1 and 0.14.2-2, mpd has gotten much worse at mp3[1] sound playback on armel. It seems to be using a *lot* more cpu.
I noticed that when I'm running the stable version, mpd's cpu usage on my
thecus while playing a mp3 is often below 1%. With the unstable version, it
never gets below 20-30%.
This isn't just about CPU load numbers of course. It's about reliably getting
clear playback under load without audio glitches caused by the buffer running
dry, etc. I can reproduce this at will, on two separate arm machines. They are:
turtle: a thecus N2100, with this:
Bus 002 Device 002: ID 041e:3040 Creative Technology, Ltd SoundBlaster
Live! 24-bit External SB0490
box: a qnap ts-109 with the following cheap usb sound dongle:
Bus 002 Device 005: ID 0d8c:000c C-Media Electronics, Inc. Audio Adapter
My first guess is that something has been rewritten and is using floating
point, at which of course, arm sucks[2]. Grepping for "float" in the new source
tree certianly turns up a dozen more than in the old.
pcm_resample_libsamplerate.c looked particularly likely, at a
guess. But configuring --disable-lsr didn't help. Nor did trying
all the samplerate_converter settings, much.
I'm still learning toward it being due to floating point, but
since mpd has become threaded, arm threading innefficies also
seem plausible.
--
see shy jo
[1] I think ogg is also affected, but I've been testing with mp3s only.
[2] armel sucks less, but let's face it: w/o cpu-specific optimised builds,
it still sucks :-)
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