Opus files are encoded in hard-CBR

[qduaty]

Opusinfo tool shows that OPUS files produced by soundconverter use hard-CBR mode (instead of VBR).

[GautierPortet (kassoulet)]

So I have to add cbr=false to opusenc. But there is a big problem here. It crashes GStreamer...

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Lem (lem-jjr)]

Soundconverter 2.1.2, in gstreamer.py, line 668 and 669:

def add_opus_encoder(self):
        return 'opusenc bitrate=%s cbr=false ! oggmux' % (self.opus_quality * 1000)

Adding cbr=false seemed to result in a different output.

Encoded on Ubuntu 13.10 (unsure whether soundconverter 2.1.2 from source is using gstreamer 0.10 or 1.0), before adding cbr=false:
$ opusinfo 03\ -\ North\ Bound\ \(1\).opus
Processing file "03 - North Bound (1).opus"...

New logical stream (#1, serial: 7dc771f2): type opus
WARNING: Implausibly low preskip in Opus stream (1)
Encoded with Encoded with GStreamer Opusenc
User comments section follows...
 TITLE=North Bound
 ARTIST=Tony O'Connor
 ALBUM=Seashore Sunrise
 DISCNUMBER=1
 DATE=1991-01-01
 TRACKNUMBER=3
 TRACKTOTAL=6
 GENRE=New Age
 DESCRIPTION=EAC FLAC -8
 COMMENT=EAC FLAC -8
Opus stream 1:
 Pre-skip: 0
 Playback gain: 0 dB
 Channels: 2
 Original sample rate: 48000Hz
 Packet duration: 20.0ms (max), 20.0ms (avg), 20.0ms (min)
 Page duration: 260.0ms (max), 259.9ms (avg), 120.0ms (min)
 Total data length: 5129508 bytes (overhead: 1.26%)
 Playback length: 5m:16.539s
 Average bitrate: 129.6 kb/s, w/o overhead: 128 kb/s (hard-CBR)
Logical stream 1 ended

After adding cbr=false:

$ opusinfo 03\ -\ North\ Bound\ \(2\).opus
Processing file "03 - North Bound (2).opus"...

New logical stream (#1, serial: 658e5e51): type opus
WARNING: Implausibly low preskip in Opus stream (1)
Encoded with Encoded with GStreamer Opusenc
User comments section follows...
 TITLE=North Bound
 ARTIST=Tony O'Connor
 ALBUM=Seashore Sunrise
 DISCNUMBER=1
 DATE=1991
 TRACKNUMBER=3
 TRACKTOTAL=6
 GENRE=New Age
 DESCRIPTION=EAC FLAC -8
 COMMENT=EAC FLAC -8
Opus stream 1:
 Pre-skip: 0
 Playback gain: 0 dB
 Channels: 2
 Original sample rate: 48000Hz
 Packet duration: 20.0ms (max), 20.0ms (avg), 20.0ms (min)
 Page duration: 280.0ms (max), 261.2ms (avg), 220.0ms (min)
 Total data length: 5145176 bytes (overhead: 1.26%)
 Playback length: 5m:16.539s
 Average bitrate: 130 kb/s, w/o overhead: 128.4 kb/s
Logical stream 1 ended

However using opusenc (opus-tools 0.1.8) with --bitrate=128, I get a different file again:
$ opusinfo 03\ -\ North\ Bound.flac.opus
Processing file "03 - North Bound.flac.opus"...

New logical stream (#1, serial: 126ed0e5): type opus
Encoded with libopus 1.1
User comments section follows...
 ENCODER=opusenc from opus-tools 0.1.8
 ENCODER_OPTIONS=--bitrate 128
 TITLE=North Bound
 ARTIST=Tony O'Connor
 ALBUM=Seashore Sunrise
 DISCNUMBER=1
 DATE=1991
 TRACKNUMBER=03
 TRACKTOTAL=06
 GENRE=New Age
 DESCRIPTION=EAC FLAC -8
 COMMENT=EAC FLAC -8
Opus stream 1:
 Pre-skip: 356
 Playback gain: 0 dB
 Channels: 2
 Original sample rate: 44100Hz
 Packet duration: 20.0ms (max), 20.0ms (avg), 20.0ms (min)
 Page duration: 1000.0ms (max), 998.6ms (avg), 560.0ms (min)
 Total data length: 5431593 bytes (overhead: 0.763%)
 Playback length: 5m:16.533s
 Average bitrate: 137.3 kb/s, w/o overhead: 136.2 kb/s
Logical stream 1 ended

Anyway, the different size/bitrate files might be due to opus version. But, was it really that simple to just add cbr=false?

[Lem (lem-jjr)]

Oops, I forgot that adding cbr=false crashes Soundconverter. From the debug log:

launching: 'giosrc location="file:///media/Arch/Audio/FLAC/New_Age/Tony_O'Connor/Tony%20O'Connor%20-%20Seashore%20Sunrise%20(1991)%20%5BFLAC%5D/03%20-%20North%20Bound.flac" name=src ! decodebin name=decoder ! audiorate ! audioconvert ! audioresample ! opusenc bitrate=128000 cbr=false ! oggmux ! giosink location="file:///media/Space/Audio/Opus_Transcodes/1/Unknown%20Artist-Unknown%20Album/03%20-%20North%20Bound.opus.opus~SC~"'
Segmentation fault (core dumped)

I actually then launched the above command with gst-launch-1.0, that worked.

One more thing about the output from opusdec above, I noticed that the files were 48kHz (the source is definitely 44.1kHz), but I didn't have resampling enabled. opusenc itself didn't resample the FLAC to 48kHz.

[GautierPortet (kassoulet)]

So hopefully this will be solved by using gstreamer 1.0...

[wayne (mathwhiz1212)]

I can't use soundconverter for conversion if this is the case. Wouldn't opusenc --vbr work?

[Alexander Schlarb (alexander255)]

Just wanted to chime in. I needed to convert some music today and your tool worked almost perfectly for me. :+1:

Regarding this issue: I'm using `soundconverter` 3.0.0~alpha1+git20151209-1 with GStreamer 1.0 from Debian Multimedia and tried to convert some 320 MP3s into Opus. However I got an error message when I tried to do so:

    GStreamer error when creating pipeline
    gst_parse_error: no property "cbr" in element "opusenc3" (2)

After finding this issue, I did a short investigation and it turns out that the `cbr` option does not exist in GStreamer 1.0; instead the `bitrate-type` option was introduced:

    bitrate-type : Bitrate type
                         flags: readable, writable, changeable in NULL, READY, PAUSED or PLAYING state
                          Enum "GstOpusEncBitrateType" Default: 0, "cbr"
                             (0): cbr - CBR
                             (1): vbr - VBR
                             (2): constrained-vbr - Constrained VBR

Replacing `cbr=false` with `bitrate-type=vbr` resulted in a proper VBR Opus being generated:

    Processing file "10 Running In Place.opus"...

    New logical stream (#1, serial: 30e48d71): type opus
    Encoded with Encoded with GStreamer opusenc
    User comments section follows...
            ALBUM=Feeding The Wolves (Deluxe Edition)
            ALBUMARTIST=10 Years
            ARTIST=10 Years
            COMMENT=0
            DATE=2010
            DISCNUMBER=1
            DISCTOTAL=1
            GENRE=Rock
            METADATA_BLOCK_PICTURE=3|image/jpeg||0x0x0|<20581 bytes of image data>
            TITLE=Running In Place
            TRACKNUMBER=10
    Opus stream 1:
            Pre-skip: 312
            Playback gain: 0 dB
            Channels: 2
            Original sample rate: 48000Hz
            Packet duration: 20.0ms (max), 20.0ms (avg), 20.0ms (min)
            Page duration: 520.0ms (max), 185.3ms (avg), 120.0ms (min)
            Total data length: 5144236 bytes (overhead: 1.6%)
            Playback length: 3m:35.875s
            Average bitrate: 190.6 kb/s, w/o overhead: 187.6 kb/s
    Logical stream 1 ended

[GautierPortet (kassoulet)]

Fix: https://github.com/kassoulet/soundconverter/commit/b65d4f0bde2439e48dc4ee2021cb22675fc8ce1f

Thanks Alexander !

[Sebastian Ramacher (s-ramacher)]

Fixed in 3.0.0~beta1-1.