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Another audiobook question

I've been using '--alt-preset medium -a --lowpass 10' and very satisfied with the size/performance output (averaging 53 kbps). Since some audiobooks have music at various points the VBR is especially useful.

Quick question-
I'm now encoding some mono audiobook files. Can I use a mono tag (and if so which?) with --apm or does it matter for joint stereo if its a mono file and thus when played back (in at least iTunes) has two identical channels compare?

Any help would be greatly appreciated.
Also I'm not looking to use any other codec for compatibility purposes.

Another audiobook question

Reply #1
Hate to sound impatient, but going to encode several books tomorrow (currently in AIFF) and curious if anyone has an answer?

Thanks.

Another audiobook question

Reply #2
If you have a mono or near mono sound file AND this file has two channels (identical or nearly identical), then you would better add -m m to  Lame.
If your input file has only 1 channel, then you do not need -m m (but it doesn't harm).

Another audiobook question

Reply #3
Just wondering... I converted a stereo PCM file to mono and then to stereo again (so both channels had the same information). The source stereo file had an average bitrate of 202 kbps with APS while the mono file had all frames set to 128 kbps. Why is that so? In the source file, were the extra bits needed for stereo separation only?

Another audiobook question

Reply #4
Quote
Why is that so?

Don't know. This is not an expected behavior. You should expect a "twice mono" file to have an higher bitrate than a normal mono file, but the difference should not be that huge.

Another audiobook question

Reply #5
Quote
Quote
Why is that so?

Don't know. This is not an expected behavior. You should expect a "twice mono" file to have an higher bitrate than a normal mono file, but the difference should not be that huge.
[a href="index.php?act=findpost&pid=249461"][{POST_SNAPBACK}][/a]


Weird... There is no frame other than 128 kbps reported by EncSpot...

Another audiobook question

Reply #6
Quote
Just wondering... I converted a stereo PCM file to mono and then to stereo again (so both channels had the same information). The source stereo file had an average bitrate of 202 kbps with APS while the mono file had all frames set to 128 kbps. Why is that so? In the source file, were the extra bits needed for stereo separation only?
[a href="index.php?act=findpost&pid=249439"][{POST_SNAPBACK}][/a]


Actually that is expected behavior.  128 is the lowest setting for APS.  All of my mono recordings in APS are entirely 128.

Another audiobook question

Reply #7
yeah, i usually add -b64 when doing mono since it's half 128, if you wanted to be safer, try -b96 when using mono.  I've even used -b32 with mono sometimes, but -b96 sounds safe, right? perhaps -V's in newer lame shouldn't hold the same minimum bitrate when encoding mono mp3's.

Another audiobook question

Reply #8
I did a bunch of testing and found it hard if not impossible to beat
--preset voice
which is essentially abr 56k but with some magic in the background that makes it sound better than abr 56.  Not only does voice for ebooks sound great, music sounds superior to other low bitrate mono settings I tried.

the presets are good

 
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