Hi! So here is what I got with different encoder settings; still not sure what the "best" setting is. 6kbps seems to add distortions, so I tried 12kbps. MP3-Original: LAME 3.99r, 120kbps, 44100Hz, Stereo, VBR V5 (22:23, 19.8MB) Opus (--raw-rate 44100 --bitrate 56 --vbr --comp 5): (44:45?, 23.4MB): Broken Opus (--bitrate 56 --vbr --comp 5 --ignorelength - %d): (22:23, 12.1 MB, 74kbps) Opus (--bitrate 6 --vbr --comp 10 --ignorelength - %d): (1MB, 6kbps) Opus (--speech --set-ctl-int 4008=1103 --bitrate 56 --vbr --comp 5 --ignorelength - %d): (22:23, 9.3 MB, 74kbps) Opus (--speech --set-ctl-int 4008=1103 --bitrate 6 --vbr --comp 5 --ignorelength - %d): (22:23, 1.1 MB, 74kbps) Opus (--bitrate 12 --vbr --comp 5 --ignorelength - %d): (2.1MB, 13kbps) Regards, Ulrich>>> Mathias Buhr 30.10.2019, 14:39 >>>Hi Ulrich, I assume you've been using opusenc to encode the files. If that is the case you can try giving the encoder some more hints about your files: opusenc --speech --set-ctl-int 4008=1103 ... The latter should tell the encoder that the signal bandwidth is 8kHz (OPUS_SET_BANDWIDTH). See opus_defines.h for all valid numbers. You can also experiment with the complexity settings. -Mathias _______________________________________________ opus mailing list opus at xiph.org http://lists.xiph.org/mailman/listinfo/opus
Hi Ulrich, Other than the bitrate, none of the discussed settings should have a significant impact on the file size as the encoder will always use the available bitrate to encode the input signal. The additional settings only configure where the encoder spends the bits and how much time it has to figure that out.>From my experience and as others noted, 15-32 kbps should yield verygood quality for wideband (8kHz acoustic bandwidth) speech. Less than 15kbps still yields good and intelligible speech but can also bring some noticeable artifacts (obviously depends on the input). The complexity setting basically configures the trade-off between runtime and encoding quality (whatever that is). As you probably don't care about runtime, you should set it to 10 as this should yield the best quality for a given bitrate (the default is 10). This should actually allow the encoder to perform a signal analysis (done for >= 8, if I remember correctly) and determine the "best" bit allocation. Now if the noise contained in your signal has some energy in the upper bands, the encoder might try to encode that as well (assuming 48kHz input). In order to avoid that, the codec control OPUS_SET_BANDWIDTH might have been helpful. -Mathias
>>> Mathias Buhr <napcode at apparatus.de> schrieb am 01.11.2019 um 10:28 in Nachricht<8c9ae155-c066-0a85-4a04-41a3d5cb14be at apparatus.de>:> Hi Ulrich, > > Other than the bitrate, none of the discussed settings should have a > significant impact on the file size as the encoder will always use the > available bitrate to encode the input signal. The additional settings > only configure where the encoder spends the bits and how much time it > has to figure that out. > > From my experience and as others noted, 15-32 kbps should yield very > good quality for wideband (8kHz acoustic bandwidth) speech. Less than > 15kbps still yields good and intelligible speech but can also bring some > noticeable artifacts (obviously depends on the input). The complexity > setting basically configures the trade-off between runtime and encoding > quality (whatever that is). As you probably don't care about runtime, > you should set it to 10 as this should yield the best quality for a > given bitrate (the default is 10). This should actually allow the > encoder to perform a signal analysis (done for >= 8, if I remember > correctly) and determine the "best" bit allocation. > Now if the noise contained in your signal has some energy in the upper > bands, the encoder might try to encode that as well (assuming 48kHz > input). In order to avoid that, the codec control OPUS_SET_BANDWIDTH > might have been helpful.Hi! The above is very helpful (for me who doesn't know all the details inside the black box). Maybe some of these "insights" could be added to the manual page for opusenc. Re-reading the manual, I also think that "--comp" that is said to default to 10 now, had had a different default in the past, but I may be wrong. Probably I thought "complexity" would affect the size of the resulting file... Regards, Ulrich> > -Mathias > > > _______________________________________________ > opus mailing list > opus at xiph.org > http://lists.xiph.org/mailman/listinfo/opus