Hi all,

Is it the case that lossy compression changes the pitch of the original wav slightly? (pitch not tempo). I was messing about with a sample I took from a cd and to me it appears to change in pitch when encoded.

mp3 @ 128 varied the most, aps was still different, even ogg up to Q10 varied from the original.

The sample in question was :
Apoptygma Berzerk - Kathy's Song (Ferry Corsten Remix)
As position 03:12 there is a massive crash/kick with drawn out echo, it is this echo which seems to change pitch with the lossy encodes.

Has anyone else ever experienced this or am I going insane

Thanks again,
J.

Mind uploading a (lossless[flac or similar])sample, so others can have a listen?

Can you ABX?

I've uploaded a sample in the Uploads section:

Its RAR compressed, only 1.5MB clip. Source - CDDA ripped with EAC.

http://www.hydrogenaudio.org/forums/index....showtopic=26022

I encoded it to mp3 with:
128 : lame --alt-preset cbr 128
192 : lame --alt-preset cbr 192
aps : lame --alt-preset standard

and used OggDrop to do the oggs..

I'm sure there is a slight pitch change going on..

J.

Hi June,

To satisfy your own curiosity and to proove to others here there is a problem it's probably wise to carry out some ABX tests first. These can also help to proove whether your going mad or not .

Some further reading: What is a blind ABX test ?

Hi,

Thanks for the info, I've just used WinABX and I think I am indeed going insane. All I can think of is this type of sound is affecting my ears in that when I quickly switch sample it appears the 2nd (encoded) sample is different, but judging by my ABX results it is not; I guess my ear drums were still vibrating from the first sample and thus the 2nd sample would appear to have a different pitch.

Panic over.. phew!

Thanks again.

With lame there is a noise - pretty sure its smearing from preecho.

Very easy on 128k, not too hard on APS either. Aotuv Q6 is either free of this or I'm too tired. MPC Q5 is not affected, though I concentrated on other noises without great success.

128k lame 3.96.1:

foo_abx v1.2 report
foobar2000 v0.8.3
2004/08/15 22:04:39

File A: file://D:\Documents and Settings\Administrator\Desktop\apoptygma berzerk - kathys song (ferry corsten remix) (cdda clip).wav
File B: file://H:\temp\abx tests\apoptygma berzerk - kathys song (ferry corsten remix) (cdda clip).mp3

22:04:40 : Test started.
22:05:06 : 01/01 50.0%
22:05:16 : 02/02 25.0%
22:05:20 : 03/03 12.5%
22:05:24 : 04/04 6.3%
22:05:27 : 05/05 3.1%
22:05:31 : 06/06 1.6%
22:05:36 : 07/07 0.8%
22:05:39 : 08/08 0.4%
22:05:50 : 09/09 0.2%
22:06:03 : 10/10 0.1%
22:06:14 : Test finished.

----------
Total: 10/10 (0.1%)

Lame APS 3.96.1:

foo_abx v1.2 report
foobar2000 v0.8.3
2004/08/15 22:07:29

File A: file://D:\Documents and Settings\Administrator\Desktop\apoptygma berzerk - kathys song (ferry corsten remix) (cdda clip).wav
File B: file://H:\temp\abx tests\apoptygma berzerk - kathys song (ferry corsten remix) (cdda clip).mp3

22:07:30 : Test started.
22:08:04 : 01/01 50.0%
22:08:08 : 01/02 75.0%
22:08:20 : 01/03 87.5%
22:08:35 : 02/04 68.8%
22:08:38 : Trial reset.
22:08:53 : 01/01 50.0%
22:09:10 : 02/02 25.0%
22:09:15 : 03/03 12.5%
22:09:23 : 04/04 6.3%
22:09:36 : 05/05 3.1%
22:10:49 : 06/06 1.6%
22:10:57 : 07/07 0.8%
22:11:19 : 07/08 3.5%
22:11:31 : 08/09 2.0%
22:11:47 : 08/10 5.5%
22:12:50 : 09/11 3.3%
22:13:22 : 10/12 1.9%
22:14:21 : 11/13 1.1%
22:15:13 : 12/14 0.6%
22:15:23 : Test finished.

----------
Total: 14/18 (1.5%)

MPC Q5:

foo_abx v1.2 report
foobar2000 v0.8.3
2004/08/15 22:25:10

File A: file://D:\Documents and Settings\Administrator\Desktop\apoptygma berzerk - kathys song (ferry corsten remix) (cdda clip).wav
File B: file://H:\temp\abx tests\apoptygma berzerk - kathys song (ferry corsten remix) (cdda clip).mpc

22:25:12 : Test started.
22:25:40 : 01/01 50.0%
22:25:57 : 02/02 25.0%
22:26:17 : 03/03 12.5%
22:26:28 : 04/04 6.3%
22:26:39 : 05/05 3.1%
22:26:59 : 05/06 10.9%
22:27:24 : 05/07 22.7%
22:27:55 : 06/08 14.5%
22:28:05 : 06/09 25.4%
22:28:14 : 07/10 17.2%
22:28:31 : 07/11 27.4%
22:28:41 : 08/12 19.4%
22:28:51 : 08/13 29.1%
22:29:34 : 08/14 39.5%
22:29:54 : 09/15 30.4%
22:30:17 : 10/16 22.7%
22:30:32 : Test finished.

----------
Total: 10/16 (22.7%)

Aotuv b2 Q6:

foo_abx v1.2 report
foobar2000 v0.8.3
2004/08/15 22:33:37

File A: file://D:\Documents and Settings\Administrator\Desktop\apoptygma berzerk - kathys song (ferry corsten remix) (cdda clip).wav
File B: file://H:\temp\abx tests\apoptygma berzerk - kathys song (ferry corsten remix) (cdda clip).ogg

22:33:39 : Test started.
22:34:19 : 01/01 50.0%
22:34:27 : 02/02 25.0%
22:35:22 : 03/03 12.5%
22:35:33 : 03/04 31.3%
22:35:42 : 04/05 18.8%
22:36:01 : 05/06 10.9%
22:36:42 : 05/07 22.7%
22:37:12 : 06/08 14.5%
22:37:18 : 07/09 9.0%
22:37:29 : 08/10 5.5%
22:38:01 : 09/11 3.3%
22:38:33 : 09/12 7.3%
22:38:48 : 09/13 13.3%
22:39:53 : 10/14 9.0%
22:40:32 : 11/15 5.9%
22:41:07 : 11/16 10.5%
22:41:13 : Test finished.

----------
Total: 11/16 (10.5%)