Lossless Audio Codecs: Windows Media Audio 9 Lossless (.wma) vs. Monkey's Audio (.ape)

Background

Unlike lossy codecs such as MP3, the mathematically-lossless audio codecs provide compression with no loss in quality. They are perfect for archiving digital audio with 2:1-3:1 compression ratio.

Monkey’s Audio is a popular lossless codecs developed by Matthew T. Ashland. It has been freely available on the net for a few years. The latest stable version (as of Dec 03) is 3.97 and an alpha version of 3.98 is under testing after a really long waiting since the release of 3.97.

Audio files encoded in Monkey’s Audio normally have suffix .ape. Players like Winamp can support Monkey’s Audio within an input plug-in. And Foobar2000 has native support for this format. Although there’s some people declare they have a plug-in for XMMS under Linux platform, I myself have never got one and am unable to play APE files under Linux.

Windows Media Audio actually is the name of Microsoft’s solution for digital audio. WMA codecs once were only lossy, but with the release of Windows Media Encoder 9 Series in early 2003, Microsoft provides the option of lossless compression by Windows Media Audio 9 Lossless codecs. With the significant influence that Microsoft has, WMA is trying to win more and more support from consumer electronics vendors and online service providers. This could be a significant advantage over other codecs to win the consumer market share.

On Windows platform, the encoder and player of both aforementioned formats are freely available. That means using these codecs on your Windows PC won’t cause your any additional cost. But how is their performances in terms of compression ratio, encoding time and playback CPU consumption? Will WMA lossless beat APE not only with vendors’ support but also performance?

We are going to see the answers at the end of this page.

Evaluation procedure

  1. Setup test environment, see Appendix 1 for details.
  2. The input to encoders is in a single file of .wav format, which I extracted from 3 CDs and representing three different genres, see Appendix 2.
  3. Use WMA Encoder to compress the .wav file into .wma format with preset profile (File Archive -> Lossless Quality Audio, VBR 100), record performance measurements.
  4. Use Monkey’s Audio to compress the .wav file into .ape format in Normal mode, record performance measurements.
  5. Use Windows Media Player and foobar2000 to play each types of the file and evaluate CPU consumption roughly by observing Task Manager. Note that I turned off all switchable postprocessing for both players, i.e., no visualization, no surround effect, etc.

Performance Comparison

  Original (MB) Compressed (MB) Ratio (%) Encoding Time (s) Speed (MB/s) Playback CPU Load
(Avg/Peak %)
Brahms - Violinkonzert, Doppelkonzert - Classical
WMA 758.95 319.59 0.4211 259 2.93 5/10
APE 758.95 320.07 0.4217 184 4.13 3/5
 
Nicholas Gunn - The Music of the Grand Canyon - New Age
WMA 539.28 326.98 0.6063 235 2.29 5/8
APE 539.28 326.82 0.6060 190 2.84 3/6
 
Eagles - Hell Freezes Over - Rock
WMA 748.35 468.58 0.6262 290 2.58 8/13
APE 748.35 468.51> 0.6261 277 2.70 3/5

Conclusions

I would say that WMA still have a long way to achieve the same performance as APE, in whatever terms evaluated here:

  1. The only test it slightly outperforms APE is the compression ratio of Classical test sample at the cost of a significant difference of encoding time.
  2. Generally it costs more CPU time to playback than APE.
  3. Although for Rock test sample here WMA almost has the same encoding performance as APE, the playback of the sample falls further behind APE than other samples of different genres.

[Update 27 Aug 2004] For a report on comparison tests of more lossless encoders, visit w.speek’s page.

Appendix 1 - Evaluation environment configurations

Encoders WMA Windows Media Encoder 9 Series, v9.00.00.2980
  APE Monkey's Audio v3.97
     
Players WMA Windows Media Player, v9.00.00.3075
  APE foobar2000, v0.7.3, Unicode version
     
Hardware CPU Intel P4 2.4B/533Mhz
  RAM DDR266 1024MB
  Chipset Intel 845G
  Sound SoundMAX Integrated Digital Audio
  Harddisk Maxtor 6Y080L0
     
Software OS WindowsXP Professional SP1, v5.1.2600

Appendix 2 - Three CDs each of different genre under test

Title Genre Cover

BRAHMS
Violinkonzert, Violin Concerto
Doppelkonzert, Double Concerto

António Meneses
Berliner Philharmoniker
Herbert von Karajan

Label: Karajan Gold
CD DDD 439 007-2 GHS (1983)

Classical violinkonzert-doppelkonzert.jpg

Eagles
Hell Freezes Over (1994)
Label: Geffen Records

Rock hellfreezesover.jpg

Nicholas Gunn
The Music of the Grand Canyon
National Parks Series (1996)

Label: Real Music

New Age greatcanyon.jpg

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