[opus] Antw: Re: Possible bug in Opus 1.3
Jan Stary
hans at stare.cz
Sun Nov 4 17:22:31 UTC 2018
(Please wrap your lines.)
> >>> Jan Stary <hans at stare.cz> 01.11.18 9.06 Uhr >>>
> (Please wrap your lines.)
On Nov 02 22:00:47, Ulrich.Windl at rz.uni-regensburg.de wrote:
> The FLAC version of the original is almost 6MB and it can be downloaded slowly from this time-limited link:
> https://sbr5vjid0jgmce4q.myfritz.net:40262/nas/filelink.lua?id=0ba5a10529a6fe7b
Thanks.
I saved that as file.flac, uncompressed to file.wav,
and compressed that as ogg and opus as follows:
$ sox file.flac file.wav
$ opusenc file.wav file.opus
$ oggenc file.wav
$ soxi file.*
Input File : 'file.flac'
Channels : 1
Sample Rate : 96000
Precision : 24-bit
Duration : 00:01:00.00 = 5760000 samples ~ 4500 CDDA sectors
File Size : 5.95M
Bit Rate : 793k
Sample Encoding: 24-bit FLAC
Comments :
ALBUM=Test-Sweeps
ARTIST=Audacity
COMMENT=60s logarithmic sweep (0-20kHz): 5s=10Hz, 10s=20Hz, 15s=39Hz, 20s=78Hz, 25s=156Hz, 30s=312Hz, 35s=625Hz, 40s=1.25kHz, 45s=2.5kHz, 50s=5kHz, 55s=10kHz, 60s=20kHz
COMMENTS=60s logarithmisch
DATE=2016
TITLE=Sweep (0-20kHz at 96kHz) log
TRACKNUMBER=2
Input File : 'file.ogg'
Channels : 1
Sample Rate : 96000
Precision : 16-bit
Duration : 00:01:00.00 = 5760000 samples ~ 4500 CDDA sectors
File Size : 218k
Bit Rate : 29.1k
Sample Encoding: Vorbis
Input File : 'file.opus'
Channels : 1
Sample Rate : 48000
Precision : 16-bit
Duration : 00:01:00.00 = 2880000 samples ~ 4500 CDDA sectors
File Size : 842k
Bit Rate : 112k
Sample Encoding: Opus
Comment : 'ENCODER=opusenc from opus-tools 0.2'
Input File : 'file.wav'
Channels : 1
Sample Rate : 96000
Precision : 24-bit
Duration : 00:01:00.00 = 5760000 samples ~ 4500 CDDA sectors
File Size : 17.3M
Bit Rate : 2.30M
Sample Encoding: 24-bit Signed Integer PCM
Total Duration of 4 files: 00:04:00.00
$ ll file.*
-rw-r--r-- 1 hans wheel 5947093 Nov 4 17:17 file.flac
-rw-r--r-- 1 hans wheel 218397 Nov 4 17:23 file.ogg
-rw-r--r-- 1 hans wheel 842170 Nov 4 17:24 file.opus
-rw-r--r-- 1 hans wheel 17280080 Nov 4 17:18 file.wav
So for me the opus file is four times the size of the ogg file.
Is that expected, for a frequency sweep?
> On 48kHz on Opus: I'm unsure. I thought Opus can't handle 96kHz
> and it downsamples automatically.
Apparently it did (and also reduced the 24bit to 16bit).
> Why using 96kHz in the original: AFAIK Vorbis and Opus both use
> frequency components to encode the file.
What frequency components are those,
in a sweep from 0 to 20kHz?
> With higher sampling frequencies in the original,
> I was expecting to reduce the aliasing effects for higher frequencies.
What higher frequencies?
Jan
> On Oct 26 01:38:34, Ulrich.Windl at rz.uni-regensburg.de wrote:
> > Playing with Opus 1.3 I converted a tone sweep with a sample rate of 96kHz (just for fun). Before I had converted that from WAV to FLAC, and to Vorbis without problems.
>
> 30s=312Hz, 35s=625Hz, 40s=1.25kHz, 45s=2.5kHz, 50s=5kHz, 55s=10kHz, 60s=20kHz
> so it seems the frequency rises logarithmically.)
>
> $ sox -c 1 -r 96k -b 16 -n /tmp/sweep.wav synth 60 sin create 1-20 gain -3
>
> > With Opus I noticed that the file size for 48kHz and 48 kbps
> > compared to 96kHz Vorbis at 31kbps is about double the size
>
> Your opusenc line says "--bitrate 56 --vbr",
> so where does the 48 come from?
>
> Anyway:
>
> $ flac sweep.wav
> $ oggenc sweep.wav
> $ opusenc sweep.wav sweep.opus
> $ ls -l sweep.*
> -rw-r--r-- 1 hans wheel 2635692 Nov 1 08:49 sweep.flac
> -rw-r--r-- 1 hans wheel 215185 Nov 1 08:49 sweep.ogg
> -rw-r--r-- 1 hans wheel 660815 Nov 1 08:49 sweep.opus
> -rw-r--r-- 1 hans wheel 11520044 Nov 1 08:49 sweep.wav
>
> So for me it is actualy about three times the size of an ogg
> (and about 6% the size of the original wav).
>
> I am not sure why you are using 96kHz in the original,
> but doing the same with a 48kHz original wav results in
>
> -rw-r--r-- 1 hans wheel 1468106 Nov 1 08:51 sweep.flac
> -rw-r--r-- 1 hans wheel 113787 Nov 1 08:51 sweep.ogg
> -rw-r--r-- 1 hans wheel 611386 Nov 1 08:51 sweep.opus
> -rw-r--r-- 1 hans wheel 5760044 Nov 1 08:51 sweep.wav
>
> All of them approximately halve, but opus does not.
> Is that expected?
>
> > and it sounds even worse (than Vorbis)
> > (there is a lot of noise in the lower frequencies
> > when a low frequency tone is being played).
>
> Are you sure your speakers/headphones can even reproduce
> such low frequencies accurately? I doubt it.
>
> > Here is what opusinfo outputs:
> >
> > Processing file "D:\Work\Ulrich\Musik\Vega\Opus\Audacity\Test-Sweeps\02 Sweep (0
> > -20kHz at 96kHz) log.opus"...
> >
> > New logical stream (#1, serial: 000028fd): type opus
> > Encoded with libopus 1.3, libopusenc 0.2.1
> > User comments section follows...
> > ENCODER=opusenc from opus-tools 0.2-3-gf5f571b
> > ENCODER_OPTIONS=--bitrate 56 --vbr --comp 5
> > ALBUM=Test-Sweeps
> > ARTIST=Audacity
> > COMMENT=60s logarithmic sweep (0-20kHz): 5s=10Hz, 10s=20Hz, 15s=39Hz, 20
> > s=78Hz, 25s=156Hz, 30s=312Hz, 35s=625Hz, 40s=1.25kHz, 45s=2.5kHz, 50s=5kHz, 55s=
> > 10kHz, 60s=20kHz
> > COMMENTS=60s logarithmisch
> > DATE=2016
> > TITLE=Sweep (0-20kHz at 96kHz) log
> > TRACKNUMBER=2
> > Opus stream 1:
> > Pre-skip: 312
> > Playback gain: 0 dB
> > Channels: 1
> > Original sample rate: 96000 Hz
> > Packet duration: 20.0ms (max), 20.0ms (avg), 20.0ms (min)
> > Page duration: 1000.0ms (max), 983.9ms (avg), 20.0ms (min)
> > Total data length: 637535 bytes (overhead: 1.07%)
> > Playback length: 1m:00.000s
> > Average bitrate: 85 kbit/s, w/o overhead: 84.09 kbit/s
> > Logical stream 1 ended
> >
> >
> > Here is the encoding output for a manual test:
>
> Wait, so there are two opus files at play here?
> How exactly did you create each? Is this the 48kHz one?
> Post the files you are describing.
>
> Jan
>
>
> > C:\Program Files (x86)\foobar2000\codecs\opus-tools-0.2-opus-1.3>opusenc.exe --b
> > itrate 56 --vbr "D:\Work\Ulrich\Musik\Vega\FLAC\Audacity\Test-Sweeps\02 Sweep (0
> > -20kHz at 96kHz) log.flac" "D:\Work\Ulrich\Musik\test.opus"
> > Encoding using libopus 1.3 (audio)
> > -----------------------------------------------------
> > Input: 96 kHz, 1 channel
> > Output: 1 channel (1 uncoupled)
> > 20ms packets, 56 kbit/s VBR
> > Preskip: 312
> >
> > Encoding complete
> > -----------------------------------------------------
> > Encoded: 1 minute and 0.02 seconds
> > Runtime: 1 second
> > (60.02x realtime)
> > Wrote: 749625 bytes, 3001 packets, 63 pages
> > Bitrate: 98.9456 kbit/s (without overhead)
> > Instant rates: 44 to 122.4 kbit/s
> > (110 to 306 bytes per packet)
> > Overhead: 0.972% (container+metadata)
> >
>
> _______________________________________________
> opus mailing list
> opus at xiph.org
> http://lists.xiph.org/mailman/listinfo/opus
>
More information about the opus
mailing list