[vorbis] Mono wavs with b4

[Craig Dickson]

When I encode a monophonic wav file, I would expect the resulting ogg file
to be at about half the bit rate specified on the command line, as stated in
the "oggenc -h" help text: "The 6 modes are approximately 112, 128, 160,
192, 256, and 350 kbps (for stereo 44.1kHz input. Halve these numbers for
mono input).".

This doesn't seem to be happening, though. I took a 16-bit, 44.1 khz mono
wav file, 2:38 long (about 12MB in size -- an old pop song), and encoded it
with "oggenc -b 160 file.wav". Oggenc reported an average bit rate of
150k-plus. The resulting ogg file is about 2.7 MB. When I play it in Winamp,
the on-screen display shows that it is mono, and the bit rate varies in the
range of roughly 140-170k. From the help text, and my experience with MP3
encoders, I expected to see bit rates of about 70-90k, and a file size of
under 2 MB.

Unless I'm simply misunderstanding what appears to be reasonably plain
English, it would appear that the help text and the actual behavior of the
code are out of sync.

Other than this fairly minor point, so far b4 is doing very nicely.

Craig


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