mpg123, Fast MP3 Player for Linux and UNIX systems

mpg123 - Fast console MPEG Audio Player and decoder library

mpg123 is a real time MPEG 1.0/2.0/2.5 audio player/decoder for layers 1,2 and 3 (MPEG 1.0 layer 3 aka MP3 most commonly tested). Among others working with Linux, MacOSX, FreeBSD, SunOS4.1.3, Solaris 2.5, HPUX 9.x, SGI Irix and Cygwin or plain MS Windows.
It is free software licensed under LGPL 2.1 (the officially released sources, some files in subversion repository may differ).

Upcoming features...

Fixed-point optimizations (including ARM assembler code), unicode filenames on Windows. At least;-)

Top News

2009-06-29 Thomas: ARM testers?

We got fresh ARM assembly code in SVN that wants to get tested before a mpg123 1.9 release. We need someone running it on the real hardware to report about real world performance. Please have a go with the snapshot and speak up (preferred is to the devel mailing list, mail to the maintainer is fine).

ISO MPEG compliance

This is a rough log of an automated compliance test on the mpg123 webserver (Athlon-XP, GNU/Linux), using each one test bitstream from the ISO MPEG reference set. At least the floating point output should really be close enough to the reference.

Regarding the method: This is comparing mpg123's output (with gapless code deactivated) from reference bitstreams to the reference output. A simple RMS error measure is employed, relative to full scale, just summing over mono or stereo data indiscriminently. This is my interpretation of the rules... maximum allowed RMS=8.80967e-06, maximum signal difference 6.10352e-05.

compliance test for mpg123-20090703000000 First decoder in this list will be tested first, then generic: Supported decoders: SSE 3DNowExt 3DNow MMX i586 i386 generic Testing default decoder... ==== Layer 1 ==== --> 16 bit signed integer output fl1.bit: RMS=4.364373e-06 (PASS) maxdiff=7.629395e-06 (PASS) fl2.bit: RMS=4.353138e-06 (PASS) maxdiff=7.629395e-06 (PASS) fl3.bit: RMS=4.348759e-06 (PASS) maxdiff=7.688999e-06 (PASS) fl4.bit: RMS=4.403421e-06 (PASS) maxdiff=7.629395e-06 (PASS) fl5.bit: RMS=4.323457e-06 (PASS) maxdiff=7.688999e-06 (PASS) fl6.bit: RMS=4.389618e-06 (PASS) maxdiff=7.688999e-06 (PASS) fl7.bit: RMS=3.826083e-06 (PASS) maxdiff=7.629395e-06 (PASS) fl8.bit: RMS=4.362205e-06 (PASS) maxdiff=7.629395e-06 (PASS) --> 32 bit integer output fl1.bit: RMS=1.966499e-08 (PASS) maxdiff=1.518056e-07 (PASS) fl2.bit: RMS=1.971040e-08 (PASS) maxdiff=1.117587e-07 (PASS) fl3.bit: RMS=2.002126e-08 (PASS) maxdiff=1.378357e-07 (PASS) fl4.bit: RMS=1.903406e-08 (PASS) maxdiff=1.266599e-07 (PASS) fl5.bit: RMS=3.629701e-08 (PASS) maxdiff=1.192093e-07 (PASS) fl6.bit: RMS=3.123047e-08 (PASS) maxdiff=1.788139e-07 (PASS) fl7.bit: RMS=1.768818e-08 (PASS) maxdiff=8.568168e-08 (PASS) fl8.bit: RMS=1.857690e-08 (PASS) maxdiff=8.568168e-08 (PASS) --> 32 bit floating point output fl1.bit: RMS=1.966507e-08 (PASS) maxdiff=1.518056e-07 (PASS) fl2.bit: RMS=1.971032e-08 (PASS) maxdiff=1.117587e-07 (PASS) fl3.bit: RMS=2.002131e-08 (PASS) maxdiff=1.378357e-07 (PASS) fl4.bit: RMS=1.903395e-08 (PASS) maxdiff=1.266599e-07 (PASS) fl5.bit: RMS=3.629702e-08 (PASS) maxdiff=1.192093e-07 (PASS) fl6.bit: RMS=3.123049e-08 (PASS) maxdiff=1.788139e-07 (PASS) fl7.bit: RMS=1.768797e-08 (PASS) maxdiff=8.568168e-08 (PASS) fl8.bit: RMS=1.857691e-08 (PASS) maxdiff=8.568168e-08 (PASS) ==== Layer 2 ==== --> 16 bit signed integer output fl10.bit: RMS=3.512100e-06 (PASS) maxdiff=7.629395e-06 (PASS) fl11.bit: RMS=3.837267e-06 (PASS) maxdiff=7.629395e-06 (PASS) fl12.bit: RMS=3.901071e-06 (PASS) maxdiff=7.629395e-06 (PASS) fl13.bit: RMS=4.379583e-06 (PASS) maxdiff=7.629395e-06 (PASS) fl14.bit: RMS=4.112578e-06 (PASS) maxdiff=7.688999e-06 (PASS) fl15.bit: RMS=4.388568e-06 (PASS) maxdiff=7.688999e-06 (PASS) fl16.bit: RMS=4.147495e-06 (PASS) maxdiff=7.688999e-06 (PASS) --> 32 bit integer output fl10.bit: RMS=1.777913e-08 (PASS) maxdiff=8.381903e-08 (PASS) fl11.bit: RMS=1.789437e-08 (PASS) maxdiff=9.313226e-08 (PASS) fl12.bit: RMS=1.780945e-08 (PASS) maxdiff=8.195639e-08 (PASS) fl13.bit: RMS=1.760690e-08 (PASS) maxdiff=4.470348e-08 (PASS) fl14.bit: RMS=3.641389e-08 (PASS) maxdiff=1.192093e-07 (PASS) fl15.bit: RMS=2.416479e-08 (PASS) maxdiff=1.788139e-07 (PASS) fl16.bit: RMS=1.922802e-08 (PASS) maxdiff=1.490116e-07 (PASS) --> 32 bit floating point output fl10.bit: RMS=1.777907e-08 (PASS) maxdiff=8.381903e-08 (PASS) fl11.bit: RMS=1.789437e-08 (PASS) maxdiff=9.313226e-08 (PASS) fl12.bit: RMS=1.780943e-08 (PASS) maxdiff=8.195639e-08 (PASS) fl13.bit: RMS=1.760693e-08 (PASS) maxdiff=4.470348e-08 (PASS) fl14.bit: RMS=3.641389e-08 (PASS) maxdiff=1.192093e-07 (PASS) fl15.bit: RMS=2.416472e-08 (PASS) maxdiff=1.788139e-07 (PASS) fl16.bit: RMS=1.922769e-08 (PASS) maxdiff=1.490116e-07 (PASS) ==== Layer 3 ==== --> 16 bit signed integer output compl.bit: RMS=4.300908e-06 (PASS) maxdiff=7.688999e-06 (PASS) --> 32 bit integer output compl.bit: RMS=1.904423e-08 (PASS) maxdiff=1.415610e-07 (PASS) --> 32 bit floating point output compl.bit: RMS=1.904423e-08 (PASS) maxdiff=1.415610e-07 (PASS) Now the generic decoder: ==== Layer 1 ==== --> 16 bit signed integer output fl1.bit: RMS=4.364373e-06 (PASS) maxdiff=7.629395e-06 (PASS) fl2.bit: RMS=4.353138e-06 (PASS) maxdiff=7.629395e-06 (PASS) fl3.bit: RMS=4.348747e-06 (PASS) maxdiff=7.629395e-06 (PASS) fl4.bit: RMS=4.403421e-06 (PASS) maxdiff=7.629395e-06 (PASS) fl5.bit: RMS=4.323446e-06 (PASS) maxdiff=7.629395e-06 (PASS) fl6.bit: RMS=4.389573e-06 (PASS) maxdiff=7.688999e-06 (PASS) fl7.bit: RMS=3.826083e-06 (PASS) maxdiff=7.629395e-06 (PASS) fl8.bit: RMS=4.362205e-06 (PASS) maxdiff=7.629395e-06 (PASS) --> 32 bit integer output fl1.bit: RMS=1.852264e-08 (PASS) maxdiff=1.129229e-07 (PASS) fl2.bit: RMS=1.858920e-08 (PASS) maxdiff=9.639189e-08 (PASS) fl3.bit: RMS=1.860519e-08 (PASS) maxdiff=9.080395e-08 (PASS) fl4.bit: RMS=1.827816e-08 (PASS) maxdiff=9.802170e-08 (PASS) fl5.bit: RMS=3.011849e-08 (PASS) maxdiff=1.245644e-07 (PASS) fl6.bit: RMS=2.662860e-08 (PASS) maxdiff=1.455192e-07 (PASS) fl7.bit: RMS=1.738850e-08 (PASS) maxdiff=8.288771e-08 (PASS) fl8.bit: RMS=1.799578e-08 (PASS) maxdiff=8.079223e-08 (PASS) --> 32 bit floating point output fl1.bit: RMS=1.853064e-08 (PASS) maxdiff=1.126900e-07 (PASS) fl2.bit: RMS=1.860675e-08 (PASS) maxdiff=9.685755e-08 (PASS) fl3.bit: RMS=1.861782e-08 (PASS) maxdiff=9.080395e-08 (PASS) fl4.bit: RMS=1.829747e-08 (PASS) maxdiff=9.685755e-08 (PASS) fl5.bit: RMS=3.145808e-08 (PASS) maxdiff=1.192093e-07 (PASS) fl6.bit: RMS=2.694313e-08 (PASS) maxdiff=1.490116e-07 (PASS) fl7.bit: RMS=1.740548e-08 (PASS) maxdiff=8.940697e-08 (PASS) fl8.bit: RMS=1.800653e-08 (PASS) maxdiff=8.195639e-08 (PASS) ==== Layer 2 ==== --> 16 bit signed integer output fl10.bit: RMS=3.512100e-06 (PASS) maxdiff=7.629395e-06 (PASS) fl11.bit: RMS=3.837267e-06 (PASS) maxdiff=7.629395e-06 (PASS) fl12.bit: RMS=3.901071e-06 (PASS) maxdiff=7.629395e-06 (PASS) fl13.bit: RMS=4.379583e-06 (PASS) maxdiff=7.629395e-06 (PASS) fl14.bit: RMS=4.112572e-06 (PASS) maxdiff=7.629395e-06 (PASS) fl15.bit: RMS=4.388568e-06 (PASS) maxdiff=7.688999e-06 (PASS) fl16.bit: RMS=4.147492e-06 (PASS) maxdiff=7.688999e-06 (PASS) --> 32 bit integer output fl10.bit: RMS=1.753398e-08 (PASS) maxdiff=9.825453e-08 (PASS) fl11.bit: RMS=1.761345e-08 (PASS) maxdiff=8.195639e-08 (PASS) fl12.bit: RMS=1.753216e-08 (PASS) maxdiff=7.753260e-08 (PASS) fl13.bit: RMS=1.748657e-08 (PASS) maxdiff=4.121102e-08 (PASS) fl14.bit: RMS=2.851873e-08 (PASS) maxdiff=1.147855e-07 (PASS) fl15.bit: RMS=2.142128e-08 (PASS) maxdiff=1.455192e-07 (PASS) fl16.bit: RMS=1.823392e-08 (PASS) maxdiff=9.615906e-08 (PASS) --> 32 bit floating point output fl10.bit: RMS=1.755612e-08 (PASS) maxdiff=9.872019e-08 (PASS) fl11.bit: RMS=1.763760e-08 (PASS) maxdiff=8.195639e-08 (PASS) fl12.bit: RMS=1.754899e-08 (PASS) maxdiff=7.823110e-08 (PASS) fl13.bit: RMS=1.750654e-08 (PASS) maxdiff=4.097819e-08 (PASS) fl14.bit: RMS=2.884949e-08 (PASS) maxdiff=1.148474e-07 (PASS) fl15.bit: RMS=2.161260e-08 (PASS) maxdiff=1.452863e-07 (PASS) fl16.bit: RMS=1.831598e-08 (PASS) maxdiff=9.685755e-08 (PASS) ==== Layer 3 ==== --> 16 bit signed integer output compl.bit: RMS=4.300908e-06 (PASS) maxdiff=7.688999e-06 (PASS) --> 32 bit integer output compl.bit: RMS=1.878697e-08 (PASS) maxdiff=1.431908e-07 (PASS) --> 32 bit floating point output compl.bit: RMS=1.880739e-08 (PASS) maxdiff=1.415610e-07 (PASS)

Depending on what integer quality mode you choose at compile time (and the decoder in use), the 16bit output can vary between PASS and LIMITED for fully or limited accuracy compliance. But keep in mind: For the integer output, you have to give +-1 for rounding... that's what I append to any integer number read from some measurement device anyway, by default. That minimum possible deviation already brings the output close (or over) the border of full compliance... that really does not mean that the output sounds bad! It shall be noted that a measure to improve subjective quality, namely the dithering before rounding to integers, can also increase the theoretical decoding error.
In the end, RMS values in the order of 10 to the power of -5 should sound just fine. To get 16bit output to PASS, you usually need to enable proper rounding using the --enable-int-quality configure flag. It is not on by default because it mostly (yeah, there are odd cases) needs somewhat more CPU time and the simple truncation is fine for most people...

For comparisong with other decoders (as well as older incarnations of the mpg123 engine), have a read of the Underbit compliance tests. Actually, my testing method follows that example, including their quoting of ISO MPEG rules.

Needed computing power

A test (GNU/Linux OS) with 0.60-beta2 showed 3% to 4% CPU usage on decoding high quality VBR MP3 with a pentiumII laptop with 366MHz, while a pentium 100MHz can easily handle two mpg123 instances in realtime (plus the mixing daemon that works on decoded data).

Also, we have reports from such devices as nintendo DS or Sony PSP, or various embedded systems...

Michael said once upon a time

Just for info: mpg123 plays an average 128bps stream, with about 66% in full quality on an AMD 486-133MHz machine.