[TOS #9] Opus 96 kbps vs. FLAC sources

2015-05-24 13:26:44

Hello from 4chan.org. Today a user on /g/, the technology board, bet me 3.22 bitcoins that I couldn't tell the difference in ABX testing between 96 kbps Opus and FLAC sources.

The posts in question:
MODERATION: Links removed due to TOS #9 violation.

Well, he was wrong. Below is a .zip file containing the files I used and the ABX logs. Tests 1 and 2 were 16/16, the third was 15/16.

MODERATION: Link removed due to TOS #9 violation.

Files were encoded using opus-tools 0.1.9 on Foobar2000 1.3.8. Listening was done using my well-worn Monoprice 8223s on my laptop's built-in sound.

There you are, Anon. Feel free to send the bitcoins to ganonymous@420blaze.it

[TOS #9] Opus 96 kbps vs. FLAC sources

Reply #1 – 2015-05-25 01:49:28

Well, several points:

A) I'd never bet money that any lossy codec couldn't be ABXed at any bitrate. There are killer samples for every codec. Opus at 96kbps is amazing, but even our own listening tests have shown that it can be ABXed.

B) ABX logs are so easily forged as to be useless as proof of anything.

The test at these bitrates isn't perfect transparency, it's how close to transpareny it can get with the least annoying artifacts if and when they are perceptible.

[TOS #9] Opus 96 kbps vs. FLAC sources

Reply #2 – 2015-05-25 05:44:12

That's a considerable bet

[TOS #9] Opus 96 kbps vs. FLAC sources

Reply #3 – 2015-05-25 19:13:17

Like yourlord said, it's not very hard to beat any codec if you know the right samples, not to mention at bitrates as low as 96 kb/s. Another aspect is the audio output of your OS: if you use Direct Sound from Windows this might become audible too, because it applies a limiter that tends to be more aggressive on lossy files, due the higher peaks, especially at low bitrates. So if you want to have the full potential of the codec you would have to use some sort of bit-perfect output, which would be only practicable on mobile players, since those don't need to mix several signals.
For me personally I would like to switch to Vorbis or AAC, since those are the only codecs of which I don't know any major killers samples from 224 kb/s upwards, but they're not very widely supported e.g. for gapless playback, so I'm stuck with 320 kb/s mp3's right now.

[TOS #9] Opus 96 kbps vs. FLAC sources

Reply #4 – 2015-05-25 19:42:58

Can the OP please supply a link to a maximum 30 second sample. Link above is whole track, see TOS #9.

Also, I'd be interested to read a description of the problem / what you focused on.