[SOLVED] Opus too high bitrates

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pss
Posts: 3
Joined: Tue Apr 24, 2018 9:28 am

[SOLVED] Opus too high bitrates

Post by pss »

I started to encode my flac music library to opus for mobile phone use. I used VBR 128 in Xrecode3, latest version 1.77. Opusenc.exe is from this set.

Halfway throught my task I noticed that sometimes this setting produces opus files that have actually much higher bitrate, over 200 kbps.

I thought that well, maybe I've misunderstood opus settings and VBR 128 doesn't tell desired bitrate but desired quality – different sources require dirrefent bitrate to achieve similar quality, and opus adjusts bitrate accordingly?

However! For some reasons I happened to have two versions of exactly same album from two different sources on my HDD. This album is Katatonia's Last Fair Deal Gone Down, 2004 reissue version. I've probably ripped version 1 from my own CD and found version 2 somewhere in the internet.

Version 1 is 473 MB, version 2 is 441 MB (both flac). Only difference is in compression, audio content is 100 % identical. (I checked this with Audacity. When I invert a track from version 1 and play it simultaneously with same track from version 2, the result is silence = exactly same audio.)

And now to the encoding problem.

When I encode Last Fair Deal Gone Down version 1 to opus VBR 128 using Xrecode3, I get 102 MB of opus files. Average bitrate 203 kbps.

When I encode Last Fair Deal Gone Down version 2 to opus VBR 128 using Xrecode3, I get 61,4 MB of opus files. Average bitrate 129 kbps.

I tried to encode version 1 and version 2 using software called Xmedia Recode. Setting VBR 128 produces two identical sets of opus files (59,2 MB, avg bitrate 125 kbps). Encoded files are identical like they should, because source flac files contain identical audio.

What is going on here?

I won't link audio files here for copyright reasons but I can provide them for further analyse if asked.
admin
Site Admin
Posts: 964
Joined: Wed Nov 17, 2010 12:56 pm

Re: Opus too high bitrates

Post by admin »

Could you, please, send me (to xrecode@gmail.com) one or couple of flac files from each album, where got the the different output file sizes (you could use https://wetransfer.com). Also, please, send me the diagnostic information (it's under About/Diagnostic).
pss
Posts: 3
Joined: Tue Apr 24, 2018 9:28 am

Re: Opus too high bitrates

Post by pss »

Done. Takes some time, WeTransfer's processing.
admin
Site Admin
Posts: 964
Joined: Wed Nov 17, 2010 12:56 pm

Re: Opus too high bitrates

Post by admin »

Issue here is with the embedded Cover art. One album version does not have them (and resulting opus file is smaller), where the other havs 2MB covers in files and as a result the opus files are bigger. You can play with the Metadata settings, i.e. disable "Save covers in output file" and enable "Save front cover in file" or you could resize them to a smaller size. I tried with the 1st option and the output files were pretty much the same in size.
pss
Posts: 3
Joined: Tue Apr 24, 2018 9:28 am

[SOLVED] Re: Opus too high bitrates

Post by pss »

Thanks, this worked, you rock 8-)
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