using iTunes i've noticed that AAC is very good at re-encoding own lossy sound. let's test Opus! neroaacenc.exe -q 0.75 -if 000.wav -of 001.m4a neroaacdec.exe -if 001.m4a -of aac001.wav wavdiff.exe 000.wav aac001.wav Comparing 000.wav - aac001.wav... Max diff: -17.3867dB RMS diff: -33.0851dB Mean diff: -32.4582dB opusenc.exe --bitrate 512 "000.wav" 001.opus opusdec.exe 001.opus opus001.wav wavdiff 000.wav opus001.wav Comparing 000.wav - opus001.wav... Max diff: -22.5646dB RMS diff: -39.0425dB Mean diff: -38.7372dB Opus @482kbps is much better than AAC @288kbps. now let's see what happens after 10 passes Comparing 000.wav - aac010.wav... Max diff: -16.1286dB RMS diff: -32.3361dB Mean diff: -31.715dB AAC stepped back just a little Comparing 000.wav - opus010.wav... Max diff: -7.61385dB RMS diff: -20.3666dB Mean diff: -20.1286dB Opus made complete disaster, but HF looks good (so it isn't an error in frames synchronisation of wavdiff program). And no, i'm not going to do ABX test at high bitrates because i'm not wavdiff.exe, and i'm not going to do ABX tests at low bitrates because i don not use them. FLAC is good, but MIDI is better. Lossy codecs "reverse-engeneering" audio back to MIDI, that's what they do :) <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail> Virus-free. www.avast.com <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.xiph.org/pipermail/opus/attachments/20171117/e1fc23fc/attachment.html>
Opus is specifically designed to survive tandeming but you need to keep the frames aligned and not mess with the gain, which your tools probably do not do. On Thu, Nov 16, 2017 at 10:58 PM, encrupted anonymous < sergeinakamoto at gmail.com> wrote:> using iTunes i've noticed that AAC is > very good at re-encoding own lossy sound. > let's test Opus! > > neroaacenc.exe -q 0.75 -if 000.wav -of 001.m4a > neroaacdec.exe -if 001.m4a -of aac001.wav > wavdiff.exe 000.wav aac001.wav > Comparing 000.wav - aac001.wav... > Max diff: -17.3867dB > RMS diff: -33.0851dB > Mean diff: -32.4582dB > > opusenc.exe --bitrate 512 "000.wav" 001.opus > opusdec.exe 001.opus opus001.wav > wavdiff 000.wav opus001.wav > Comparing 000.wav - opus001.wav... > Max diff: -22.5646dB > RMS diff: -39.0425dB > Mean diff: -38.7372dB > > Opus @482kbps is much better than AAC @288kbps. > now let's see what happens after 10 passes > > Comparing 000.wav - aac010.wav... > Max diff: -16.1286dB > RMS diff: -32.3361dB > Mean diff: -31.715dB > > AAC stepped back just a little > > Comparing 000.wav - opus010.wav... > Max diff: -7.61385dB > RMS diff: -20.3666dB > Mean diff: -20.1286dB > > Opus made complete disaster, but HF looks > good (so it isn't an error in frames > synchronisation of wavdiff program). > > And no, i'm not going to do ABX test at high > bitrates because i'm not wavdiff.exe, and i'm > not going to do ABX tests at low bitrates > because i don not use them. > > FLAC is good, but MIDI is better. Lossy codecs > "reverse-engeneering" audio back to MIDI, that's > what they do :) > > > > <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail> Virus-free. > www.avast.com > <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail> > <#m_1631935980190637709_DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> > > _______________________________________________ > opus mailing list > opus at xiph.org > http://lists.xiph.org/mailman/listinfo/opus > >-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.xiph.org/pipermail/opus/attachments/20171116/119b047d/attachment.html>
On 11/16/2017 06:55 PM, Gregory Maxwell wrote:> > Opus is specifically designed to survive tandeming but you need to keep > the frames aligned and not mess with the gain, which your tools probably > do not do.Actually, what happens is that if you use 44.1 kHz, the resampling in the decoder causes a fractional-sample delay in opusdec. There's a fix in master, but I'm not sure it's been committed. I actually ran the test a while ago and that delay makes a huge difference in the cascading performance because of the alignment. Jean-Marc> On Thu, Nov 16, 2017 at 10:58 PM, encrupted anonymous > <sergeinakamoto at gmail.com <mailto:sergeinakamoto at gmail.com>> wrote: > > using iTunes i've noticed that AAC is > very good at re-encoding own lossy sound. > let's test Opus! > > neroaacenc.exe -q 0.75 -if 000.wav -of 001.m4a > neroaacdec.exe -if 001.m4a -of aac001.wav > wavdiff.exe 000.wav aac001.wav > Comparing 000.wav - aac001.wav... > Max diff: -17.3867dB > RMS diff: -33.0851dB > Mean diff: -32.4582dB > > opusenc.exe --bitrate 512 "000.wav" 001.opus > opusdec.exe 001.opus opus001.wav > wavdiff 000.wav opus001.wav > Comparing 000.wav - opus001.wav... > Max diff: -22.5646dB > RMS diff: -39.0425dB > Mean diff: -38.7372dB > > Opus @482kbps is much better than AAC @288kbps. > now let's see what happens after 10 passes > > Comparing 000.wav - aac010.wav... > Max diff: -16.1286dB > RMS diff: -32.3361dB > Mean diff: -31.715dB > > AAC stepped back just a little > > Comparing 000.wav - opus010.wav... > Max diff: -7.61385dB > RMS diff: -20.3666dB > Mean diff: -20.1286dB > > Opus made complete disaster, but HF looks > good (so it isn't an error in frames > synchronisation of wavdiff program). > > And no, i'm not going to do ABX test at high > bitrates because i'm not wavdiff.exe, and i'm > not going to do ABX tests at low bitrates > because i don not use them. > > FLAC is good, but MIDI is better. Lossy codecs > "reverse-engeneering" audio back to MIDI, that's > what they do :) > > > <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail> > Virus-free. www.avast.com > <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail> > > > <#m_1631935980190637709_DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> > > _______________________________________________ > opus mailing list > opus at xiph.org <mailto:opus at xiph.org> > http://lists.xiph.org/mailman/listinfo/opus > <http://lists.xiph.org/mailman/listinfo/opus> > > > > > _______________________________________________ > opus mailing list > opus at xiph.org > http://lists.xiph.org/mailman/listinfo/opus >