IPB

Welcome Guest ( Log In | Register )

 
Reply to this topicStart new topic
Comparing codecs by comparing waveforms
TarShoduze
post Aug 9 2013, 09:50
Post #1





Group: Members
Posts: 6
Joined: 6-August 13
Member No.: 109489



I have compared Vorbis to MP3 by:
1. Preparing a WAV file from a CD.
2. Encoding the WAV to MP3 at 192kbps.
3. Encoding the WAV to Vorbis, trying to match the MP3's filesize.
4. Opening the WAV, MP3, and Vorbis in Audacity (audio editor) to check which codec represents the original WAV closest.

So far, Vorbis is closer to the original WAV.
Am I doing this wrong?
Go to the top of the page
+Quote Post
bandpass
post Aug 9 2013, 10:09
Post #2





Group: Members
Posts: 323
Joined: 3-August 08
From: UK
Member No.: 56644



Yes, very wrong -- these are perceptual audio codecs, and audio is perceived using your ears, not by eyeballing waveform graphs.
Go to the top of the page
+Quote Post
dhromed
post Aug 9 2013, 10:58
Post #3





Group: Members
Posts: 1245
Joined: 16-February 08
From: NL
Member No.: 51347



QUOTE
check which codec represents the original WAV closest


Lossy codecs are designed to take away as much as possible. Matching the waveform picture means nothing at all.
Go to the top of the page
+Quote Post
db1989
post Aug 9 2013, 13:49
Post #4





Group: Super Moderator
Posts: 5174
Joined: 23-June 06
Member No.: 32180



In addition, comparing waveforms in the time domain is often confounding due to perceptually benevolent but visually significant alterations in phase, etc. The frequency domain is more informative. However, neither are considered a valid metric for assessing lossy compression here. Double-blind listening tests are the only recommended method. Please read #8 of the Terms Of Service, as I must assume you have not done so already.
Go to the top of the page
+Quote Post
Alexxander
post Aug 9 2013, 14:43
Post #5





Group: Members
Posts: 456
Joined: 15-November 04
Member No.: 18143



As I read once in some post on this board: You don't listen with your eyes.
Go to the top of the page
+Quote Post
pdq
post Aug 9 2013, 16:36
Post #6





Group: Members
Posts: 3311
Joined: 1-September 05
From: SE Pennsylvania
Member No.: 24233



Two waveforms can look almost identical but sound very different, of they can look very different but sound almost the same.
Go to the top of the page
+Quote Post

Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 



RSS Lo-Fi Version Time is now: 24th April 2014 - 10:24