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Discussion of Audio Compression

notes by ff123

Link to new server: http://ff123.net/

64 kbit/s Listening Test Underway! (07/23/02)
Test Concluded (07/27/02)

 

Encoding

Time and Frequency Domain Signatures of Various MP3 Codecs
Identifying MP3 Codecs
MP3 Codecs Not Recommended
Recommended MP3 Encoder at 128 kbit/s
Bug in older FhG "Alternate" codec; also reports of bad sound
Bug in Recent FhG "FastEnc"
Out-of-phase quirk in FhG 1.0/1.2 build 63 codec
MP3ENC "clicking noises" when encoding a tone sweep at 256kbs
"Dropouts" in MP3Enc/Alternate Codecs
FhG VBR
Comparative Ranking of FhG VBR using Fatboy.wav
FhG CBR Beats VBR using velvet.wav
Encoding mp3 in Mono
Spectral Views of Various Codecs at 128 kbs
Ringing Artifacts in Lame
Test for Ringing
What does "ringing" look like?
Ringing Redux
Early Opinions of mp3PRO
Listening Tests of mp3PRO, WMA8 and MP3 at low bitrates

Decoding

Dithering in MP3 decoders
Verifying DiskWrite vs. Playback of MP3 files in Winamp 2.666
Nawhead's and bAdDuDeX's Listening Tests of the MAD decoder
Added Clipping
Listening test of Auto-Attenuation Feature within MAD
Convert l3dec 24-bit output to .wav
Take the MAD Challenge

Miscellaneous

My Audio Samples Page
Links
Analytical Model of the Ear
Web Statistical Analysis Tool for listening tests
Program to Perform Multiple Testing using Bootstrap Resampling
Filename randomizer for listening tests
ABX pval calculator
Analysis of Ethan Winer's Bit-Depth Test (4/13/02)
ABC/HR Audio Comparison Tool (5/10/02)

Evaluation of My Hearing

My (and others) audiogram
Test your hearing cutoff
Test your hearing, Part 2
Test your hearing, Part 3

Various Listening Tests

Intro: How to interpret my listening tests
How I conduct my listening tests
How real listening tests are conducted

Artifact Training Page
Group Listening Tests of Various Formats at 128 kbit/s
Second Group Listening Test of Various Formats at 128 kbit/s

Test for Pre-Echo using Castanets
Test using Radiohead's "Anyone Can Play Guitar"
Test using Spahm
Test using Applaud
Test using Fatboy
Test using Pearl Jam's "Daughter"
Test using male opera voice
Test using Velvet
Test using "Test For Echo" by Rush
Test using "Lyin' Eyes" by the Eagles
Test using "Peaceful, Easy Feeling" by the Eagles
Test using "Duel of the Fates" from the soundtrack of Star Wars I

 

Where to find me: I hang out at r3mix's forum or at Dibrom's Project Mayhem


News:

05/10/02: Added ABC/HR Audio Comparison Tool
04/13/02: Added analysis of Ethan Winer's Bit-Depth Test
01/25/02: Added Artifact Training page.
01/18/02: Added ABX pval calculator
01/12/02: Added results from second Group Listening Test at 128 kbit/s
10/14/01: Added filename randomizer for listening tests
10/11/01: Added web statistical analysis tool
08/20/01: Added Group Listening Tests at 128 kbit/s
07/15/01: Revised the page on clipping -- added clipping only occurs during decoding
06/23/01: Starting a low bitrates Listening Tests page
06/13/01: Early opinions of mp3pro, by people whose ears I trust;
06/13/01: Added spectral view of mp3pro
06/08/01: Revised the conv2wav utility to include optional switches for samplerate and
          number of channels
05/30/01: Added the MAD Challenge
05/25/01: Added listening test of MAD's auto-attenuation feature
05/09/01: FastEnc bug fixed in MusicMatch Jukebox 6.10.0148Beta
04/14/01: Removed the bandwidth page.  I now feel this is misleading information.
04/08/01: Added Ringing Redux page:  listening tests of ringing.wav by bAdDuDeX
03/30/01: New in the Test for Ringing: results from the Digital Ear
03/24/01: Added Spectral View of Various Codecs at 128 kbs.
03/24/01: Added "Duel of the Fates" listening test; includes test of Ogg Vorbis beta 4,
          WMA 8, Psytel AAC, and Liquifier Pro 5 AAC at 128 kbs average
03/22/01: Added "Peaceful, Easy Feeling" listening test; includes test of Ogg Vorbis
          beta 4 and WMA 8
03/20/01: Added "Lyin' Eyes" listening test; first test of Ogg Vorbis beta 4
03/17/01: Oops.  Revised the CBR 128 recommendation to explicitly call out --athtype 2
          Caught by Hans Heijden.
03/04/01: Added Recommended MP3 Encoder at 128 kbit/s
03/01/01: Added page on EarGuy's digital ear
02/25/01: Added signatures from Sound Forge 5.0; FastEnc appears to be fixed.
02/23/01: Added Lame 3.88 alpha 9 --r3mix and FhG VBR 90% to listening test of castanets.wav
02/16/01: Added Identifying MP3 Codecs
02/16/01: Added Test For Echo listening test
02/14/01: Added page on MP3Enc dropouts
02/02/01: Added some tips for encoding in mono
01/27/01: Added a program to convert 24-bit ASCII output of l3dec to .wav
01/21/01: Modified Bug in Alternate codec page -- added spectral views of codecs
01/20/01: Added What does "ringing" look like page
01/19/01: Added Test for Ringing page
01/05/01: Added Ringing Artifacts in Lame
01/04/01: Modified FhG VBR page to include behavior of MMJB 6
01/02/01: Added separate audiogram using my Beyerdynamic DT990 Pro's
12/30/00: Added my audiogram
12/29/00: Added page showing FhG CBR beating VBR using velvet.wav
12/27/00: Added Normalizing to Reduce Clipping page
12/26/00: Added Velvet listening test
12/25/00: Added a ranking of FhG VBR compared with CBR
12/24/00: Added test using a male voice singing opera.
12/21/00: Added page comparing Winamp's Disk Writer against waveOut.
12/21/00: Added page showing what MAD dithering looks like vs. Winamp 2.666
12/18/00: Added list of mp3 encoders which are not recommended
12/09/00: Added Fatboy listening test
12/09/00: Dropping AudioCatalyst/Xing 2.1 from further listening tests
12/09/00: Added Nawhead's and bAdDuDeX's listening tests of the MAD decoder
12/09/00: Acquired a pair of Grado SR325 headphones; my high-frequency cutoff
          has not changed
12/07/00: Added signatures for MusicMatch Jukebox 6 -- similar to Sound Forge 4.5h
11/27/00: I'll be dropping future tests of QDesign MVP 2.1 and adding the FhG codec
          inside Liquid Audio's Liquifier Pro 5.0.  Signature looks funky.
11/24/00: Added Applaud listening test
11/23/00: Added section on how real (scientific) listening tests are conducted
11/23/00: Added section on how I conduct my listening tests
11/22/00: Added an intro: how to interpret my listening tests
11/21/00: Started spahm listening test
11/20/00: Added Bandwidth page (started filling in table)
11/18/00: Added Test your hearing, part 3
11/16/00: Added Test your hearing, Part 2
11/12/00: Added listening tests at 128kbs using Radiohead clip
11/12/00: Added more pictures to the signatures page; can now distinguish between the
          different flavors of the FhG "Alternate" codec.
11/11/00: Added some pictures of pre-echo
11/11/00: Added "Bug in Sound Forge implementation of FhG "FastEnc"
11/10/00: Bug in "Alternate" codec is not limited to 256kbs
11/09/00: Added out-of-phase plots for "FastEnc" and Qdesign, which incidentally
          also show the cutoffs at 128kbs.
11/09/00: Added Qdesign MVP 1.2.51 signature
11/08/00: Updated Bug in Fhg "Alternate" codec to show MusicMatch 5.10 output.
11/07/00: Hopefully sorted out the FhG "Alternate" vs. "FastEnc" codec story.
11/07/00: David Robinson figured out that Sound Forge's synthesized sweep is
          partly to blame for the MP3ENC distortion in the 16 to 22kHz region
          (the other part of the blame must go to the codec).