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Bad Sample, Bad Test, or Good Ears
EricJ2190
post Apr 17 2013, 03:55
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Recently, I have been ABXing my music with foobar2000 to decide on the format and bitrate to use on my phone. Most of my results seem unsurprising, but one group's music seems to compress quite poorly. I have included a sample where I seem to be able to ABX on qaac -V 127 and lame V0. Nero AAC Q1.0 came out a bit better, though it also produced the highest bitrate at 404 Kbps. I seriously doubt this is my ears, so I was wondering if this is just a really hard sample or if I might be screwing up my tests. I noticed that the original has quite a bit of clipping. Could this make it more difficult to compress transparently?

Results and Samples: http://www.hydrogenaudio.org/forums/index....howtopic=100450
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saratoga
post Apr 17 2013, 04:02
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If the original is clipping, you may want to apply replaygain (or just reduce the peak level a couple dB manually) before encoding to make sure it doesn't clip even worse after transcoding to lossy.
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EricJ2190
post Apr 17 2013, 22:20
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I think you are right. I did a quick test with the original with qaac -V 91 both before and after reducing it by 3 dB in Audacity. I went from 20/20 to 9/20.

Original:
CODE
foo_abx 1.3.4 report
foobar2000 v1.2.4
2013/04/17 17:03:08

File A: E:\abx\original.flac
File B: E:\abx\qtaac-tvbr91.m4a

17:03:08 : Test started.
17:03:17 : 01/01  50.0%
17:03:28 : 02/02  25.0%
17:03:35 : 03/03  12.5%
17:03:42 : 04/04  6.3%
17:03:52 : 05/05  3.1%
17:03:57 : 06/06  1.6%
17:04:04 : 07/07  0.8%
17:04:09 : 08/08  0.4%
17:04:15 : 09/09  0.2%
17:04:23 : 10/10  0.1%
17:04:29 : 11/11  0.0%
17:04:35 : 12/12  0.0%
17:04:42 : 13/13  0.0%
17:04:48 : 14/14  0.0%
17:04:54 : 15/15  0.0%
17:04:59 : 16/16  0.0%
17:05:03 : 17/17  0.0%
17:05:10 : 18/18  0.0%
17:05:16 : 19/19  0.0%
17:05:22 : 20/20  0.0%
17:05:33 : Test finished.

----------
Total: 20/20 (0.0%)


Original -3dB:
CODE
foo_abx 1.3.4 report
foobar2000 v1.2.4
2013/04/17 17:05:48

File A: E:\abx\original-alt.flac
File B: E:\abx\qtaac-tvbr91-alt.m4a

17:05:48 : Test started.
17:06:01 : 01/01  50.0%
17:06:09 : 01/02  75.0%
17:06:19 : 01/03  87.5%
17:06:33 : 01/04  93.8%
17:06:45 : 02/05  81.3%
17:06:55 : 02/06  89.1%
17:07:04 : 02/07  93.8%
17:07:13 : 03/08  85.5%
17:07:19 : 04/09  74.6%
17:07:30 : 04/10  82.8%
17:07:38 : 04/11  88.7%
17:07:56 : 05/12  80.6%
17:08:09 : 05/13  86.7%
17:08:27 : 06/14  78.8%
17:08:41 : 06/15  84.9%
17:08:50 : 06/16  89.5%
17:08:58 : 07/17  83.4%
17:09:09 : 08/18  76.0%
17:09:21 : 08/19  82.0%
17:09:33 : 09/20  74.8%
17:09:42 : 10/21  66.8%
17:09:49 : Test finished.

----------
Total: 10/21 (66.8%)
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