LAME encoding weirdness

[Big Wheel]

Here's a silly question: I'm ripping the Tristano/Konitz/Marsh Mosaic right now, on alt-preset-standard. The LAME window that pops up when encoding to mp3 starts shows a number of asterisks that change as encoding proceeds. These are labelled 128, 160, 192, and so forth, which I take to mean that they represent the proportion of the file that is being ripped at 128, 160, and 192 Kbps. Now, with most CDs, when LAME is set to encode at alt-preset-standard, the encoding is roughly centered around 192 Kbps--a small percentage will be at 128, a somewhat larger percentage at 160, the highest percentage at 192, a somewhat smaller percentage at 224, and even smaller percentages at 256 and 320. With this CD, however, almost everything is encoding at 128 Kbps, with very very small percentages at 160 and 192. Is this normal, and why does it happen?

Edited March 25, 2005 by Big Wheel

[Epithet]

Is it mono?

[Big Wheel]

Yes, this is disc 4, for which Mosaic used the mono masters.

(Should I be using a different setting to encode mono? I remember seeing a discussion of mono encoding somewhere.)

[Epithet]

Then what you're witnessing is the joint-stereo encoding going nuts.

http://www.organissimo.org/forum/index.php...ndpost&p=312110

[Big Wheel]

Aha--thanks for the tip, I knew I had seen that somewhere. Is the quality hurt any by not specially configuring mono encoding, or am I just wasting space?

[Epithet]

Not sure. I would've thought it'd be more than just a waste of space. But, as one of Daniel A's posts on the second page of that thread mentions, not all mono recordings have identical channels. I've encountered this myself, but when that happens the higher bitrates aren't in 'very very small' proportions. (To test for this I wrote a quick program a while ago that counts the number of non-identical samples across channels for WAVs.)

[Daniel A]

If the total bitrate drops as much as you're experiencing here, I'd bet that this recording is as mono as it gets (and probably a bit limited in dynamic range as well). My guess, based on what I've read here, is that the bitrate would average about 90-100 kbps if you'd used mono encoding. So re-do the ripping if you want 30 percent smaller files with the same quality. Quality is not affected by encoding this in joint stereo, as you've done here, there's only some waste of space since the files are bigger than necessary.