Switch to mpg123 decoder for mp3

Midnight

Hi,

I'd suggest to switch to mpg123 as default decoder for mp3 files. The libmad decoder produces some low level noise, that can be heard (especially with good headphones) in silent passages of a track (or between two tracks). It's also easy to reproduce if you activate software mixer and turn down mpd volume.
Steps to reproduce the noise with libmad:
1. turn down mpd volume (software mixer)
2. turn up volume of your amp
3. play a mp3

With mpg123 or other file formats (FLAC, Vorbis) there is absolutely no noise. I've tested this on runeaudio and also on my PC (with two different output devices).

Also mpg123 is still activley developed while libmad's last version dates to 2004.

FauDrei

How you do this?

Should mpd be recompiled or are there other ways to use mpg123 for mp3 decoding?

Midnight

The runeaudio mpd currently does not have the mpg123 decoder built in, it has to be recompiled. Currently you can only switch from libmad to ffmpeg decoder:

decoder {
    plugin "mad"
    enabled "no"
}
decoder {
   plugin "ffmpeg"
   enabled "yes"
}

PS: I did not check mpg123 on runeaudio, but it solves the problem on my PC.

ACX

Hi Midnight, as always thank you for the hint. Yesterday night we recompiled MPD with mpg123 support, so tonight we will give it a try.
Curiously, while experimenting with different kernel versions (I'm currently using a custom build of 3.12-7), I had troubles with MP3 reproduction over USB, but NOT with FLAC, and I still haven't found the cause behind that. So I want to see if this decoder introduces improvements on that front too.

FauDrei

So, if I recompile mpd with enabled mpg123 - I just add:

decoder {
    plugin "mpg123"
    enabled "yes"
}

in /etc/mpd.conf?

Midnight

AFAIK all decoder plugins are enabled by default. But you have to disable mad, because it has a higher priority than mpg123.