Hello. Me again. Have you tried to encode piano solo? Noticed high bitrate Opus gave? And there's also artefact at 15kHz which wasn't in the original audio. Visible with Spek program. Download FLAC and Opus both files, new link: http://www.filedropper.com/example_3 FLAC full: 1084 kbps; FLAC solo: 465 kbps. with --bitrate 160: Opus full: 158 kbps; Opus solo: 190 kbps. Included also Spek spectrogram PNG file for Opus solo to see the artefacts. Music is copyrighted but we using it for testing purposes, ok? -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.xiph.org/pipermail/opus/attachments/20181117/17cea3d4/attachment.html>
On Nov 17 20:37:21, sergeinakamoto at gmail.com wrote:> Hello. Me again. > Have you tried to encode piano solo? > Noticed high bitrate Opus gave? > Download FLAC and Opus both files, > new link: > http://www.filedropper.com/example_3 > FLAC full: 1084 kbps; > FLAC solo: 465 kbps. > with --bitrate 160: > Opus full: 158 kbps; > Opus solo: 190 kbps.The two recordings are totaly unrelated. The fact that it's the same song has nothing to do with it. Why would a recording of a solo piano necessarily use a smaller bitrate than a recording of a band?> And there's also artefact at 15kHz > which wasn't in the original audio. > Visible with Spek program. > Included also Spek spectrogram PNG file > for Opus solo to see the artefacts.It is already present in the FLAC file (see attached spectrogram, obtained with SoX). -------------- next part -------------- A non-text attachment was scrubbed... Name: spectrogram.png Type: image/png Size: 365525 bytes Desc: not available URL: <http://lists.xiph.org/pipermail/opus/attachments/20181117/cc242ccd/attachment-0001.png>
On Fri, Nov 16, 2018 at 7:40 PM ongaku zettai <sergeinakamoto at gmail.com> wrote:> Hello. > i have over 30GB of Opus music and noticed that > solo instrumentals and solo vocals uses more bitrate > than full-mixes. > Here's example where Opus 1.3 used 190 kbps for > piano solo and 159 kbps for full-mix. > (--bitrate 160 --music) > Download example piano solo 15MB: > https://mega.nz/#!wLBz3AZT!YmqQMkAGqc4kGHumNWZAfB7Cmcf4vFlHpT6IiiAVCNA > FLAC uses 2 times less bitrate for solo than full-mix because > it contain less data, naturally. > Hence i think it's a bug in Opus. >Why would you expect FLAC's and Opus's wildly different methods of compression to be comparable? You won't understand anything about a lossy codec by comparing it to FLAC. Whether a piece has "more data" or not only depends on what measure of entropy you use; in Opus's case, the encoder believes the solo has less entropy because it can't throw as much away while maintaining quality, even though the full mix has less entropy if you retain every bit. On Sat, Nov 17, 2018 at 5:37 AM ongaku zettai <sergeinakamoto at gmail.com> wrote:> Hello. Me again. > Have you tried to encode piano solo? > Noticed high bitrate Opus gave? > And there's also artefact at 15kHz > which wasn't in the original audio. > Visible with Spek program. > Download FLAC and Opus both files, > new link: > http://www.filedropper.com/example_3 > FLAC full: 1084 kbps; > FLAC solo: 465 kbps. > with --bitrate 160: > Opus full: 158 kbps; > Opus solo: 190 kbps. > Included also Spek spectrogram PNG file > for Opus solo to see the artefacts. > Music is copyrighted but we using it > for testing purposes, ok? >There's no point in even looking at it. A spectrogram isn't going to tell you anything useful about whether an audible artifact exists, and is mostly useless except in lossless codecs, unless you're just plain curious about what gets masked to give you the end result. The whole point of psychoacoustic masking is to remove frequencies that can't be heard, please don't call it a bug. If there's an audible artifact, that's much more interesting. Is this your first foray into lossy codecs? You might want to familiarize yourself with the behavior of the other modern standards, like MP3, AAC, and Vorbis, as well, instead of singling out Opus without understanding its peers. (MP3 in particular is much simpler to understand, if you want to follow the details, or even MP2, since there's no spectral replication or noise or anything like that.) hydrogenaudio.io is a good place to start. Em -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.xiph.org/pipermail/opus/attachments/20181117/ee33698e/attachment.html>
tracked down the spectogram atrefact source; it comes from the resampler. so it's not really a bug, just a nuisance. let's hope in the future Opus will be able to save bitrate on simple audio parts as all other lossy and lossless codecs do. i think opus decreasing bitrate only when it thinks that audio is too complex for human to hear difference. that's a bad attitude.
>>> Jan Stary <hans at stare.cz> schrieb am 17.11.2018 um 17:03 in Nachricht<20181117160308.GA83156 at www.stare.cz>:> On Nov 17 20:37:21, sergeinakamoto at gmail.com wrote: >> Hello. Me again. >> Have you tried to encode piano solo? >> Noticed high bitrate Opus gave? >> Download FLAC and Opus both files, >> new link: >> http://www.filedropper.com/example_3 >> FLAC full: 1084 kbps; >> FLAC solo: 465 kbps. >> with ‑‑bitrate 160: >> Opus full: 158 kbps; >> Opus solo: 190 kbps. > > The two recordings are totaly unrelated. > The fact that it's the same song has nothing to do with it. > > Why would a recording of a solo piano necessarily use > a smaller bitrate than a recording of a band?Less music to be heard? ;-)> >> And there's also artefact at 15kHz >> which wasn't in the original audio. >> Visible with Spek program. >> Included also Spek spectrogram PNG file >> for Opus solo to see the artefacts. > > It is already present in the FLAC file > (see attached spectrogram, obtained with SoX).