I found an artifact after encoding into the opus format.
The artifact appears around 5-6s in the right channel. The synthesizer sound was felt somewhat weird and pricked.
I converted the source with or without the SoX resampler, and in both cases the same artifact was heard.
Quite clear @96k. Although too subtle @128k to ABX for me , I think someone else can find the artifact @128k as well.
Here's my ABX logs.
@96k + SoX mod2 (48k)
foo_abx 1.3.4 report
foobar2000 v1.3.6
2015/01/18 19:53:11
File A: D:\Music\fripSide - only my railgun\01. only my railgun.flac
File B: D:\Music\Rip\01. only my railgun_96.opus
19:53:11 : Test started.
19:53:57 : 01/01 50.0%
19:54:12 : 02/02 25.0%
19:54:30 : 03/03 12.5%
19:54:49 : 04/04 6.3%
19:55:14 : 05/05 3.1%
19:55:30 : 06/06 1.6%
19:55:42 : 07/07 0.8%
19:56:18 : 07/08 3.5%
19:56:54 : 08/09 2.0%
19:57:26 : 08/10 5.5%
19:58:11 : 09/11 3.3%
19:59:24 : 09/12 7.3%
19:59:44 : 09/13 13.3%
20:00:09 : 10/14 9.0%
20:00:22 : 11/15 5.9%
20:01:05 : 12/16 3.8%
20:01:35 : 13/17 2.5%
20:01:55 : 14/18 1.5%
20:03:13 : 15/19 1.0%
20:03:20 : Test finished.
----------
@96k w/o SoX (i.e. Speex resampler employed in opusenc)
foo_abx 1.3.4 report
foobar2000 v1.3.6
2015/01/18 20:04:38
File A: D:\Music\fripSide - only my railgun\01. only my railgun.flac
File B: D:\Music\Rip\01. only my railgun_96_woSoX.opus
20:04:38 : Test started.
20:05:30 : 01/01 50.0%
20:05:48 : 02/02 25.0%
20:06:28 : 03/03 12.5%
20:11:04 : 04/04 6.3%
20:11:33 : 05/05 3.1%
20:11:56 : 06/06 1.6%
20:12:09 : 07/07 0.8%
20:12:42 : 08/08 0.4%
20:12:44 : Test finished.
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Total: 8/8 (0.4%)
@128k w/o SoX (failed)
foo_abx 1.3.4 report
foobar2000 v1.3.6
2015/01/18 20:15:00
File A: D:\Music\fripSide - only my railgun\01. only my railgun.flac
File B: D:\Music\Rip\01. only my railgun_128.opus
20:15:00 : Test started.
20:15:59 : 01/01 50.0%
20:16:32 : 02/02 25.0%
20:16:51 : 02/03 50.0%
20:17:21 : 02/04 68.8%
20:17:51 : 03/05 50.0%
20:18:09 : 04/06 34.4%
20:18:27 : 04/07 50.0%
20:18:53 : 05/08 36.3%
20:19:16 : 06/09 25.4%
20:20:46 : 07/10 17.2%
20:21:50 : 07/11 27.4%
20:22:04 : 08/12 19.4%
20:22:23 : 09/13 13.3%
20:22:36 : 10/14 9.0%
20:22:48 : 10/15 15.1%
20:24:32 : 10/16 22.7%
20:24:35 : Test finished.
----------
Total: 10/16 (22.7%)