switch between speech and music encoding rather quickly.
I wanted to try that for a CD track that has a vocal (talk) introduction
followed by music (just two instruments).
Using foobar2000 with some custom setup for Opus, I tried VBR encoding with a
256kbps setting (opus-tools-0.1.9-win32). My expectation was that the bitrate
would be significantly lower than 256kbps while speech is encoded, while it
would go up for the music part. However during playback I could not see a
significant difference in foobar's (version 1.3.2 before you ask) display.
Is this the way things should be? The other thing that confused me is that
foobar displays 48kHz for the sampling rate in file properties (a bug?).
Opusinfo displays "Original sample rate: 44100Hz".
Here are the essential data of my sample:
User comments section follows...
ENCODER=3Dopusenc from opus-tools 0.1.9
ENCODER_OPTIONS=3D--bitrate 256 --vbr --comp 10 --ignorelength
title=3DCD Track 04
tracknumber=3D4
TRACKTOTAL=3D16
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), 999.3ms (avg), 880.0ms (min)
Total data length: 5392233 bytes (overhead: 0.556%)
Playback length: 2m:41.866s
Average bitrate: 266.5 kb/s, w/o overhead: 265 kb/s
Logical stream 1 ended
I tired 56kbps with complexity 5, and I was amazed how good it still sounded.
Then I got mad trying 6kbps with complexity 10; well, you could still hear what
is was all about ;-) Just one question on that last setting: I had the
subjective feeling that volume of speech was much lower than for the other
bitrates. I guess that's due to the cut of higher frequencies and the
non-linearity of my ears ;-) Is that a known artefact and should that effect be
corrected?
Just in case a foobar2000 developer reads this: I'd like to see a
visualization with spectrum and bitrate (maybe volume (level) would be nice
also)...
Regards,
Ulrich
