[FFmpeg-user] What does 'i 0x0069' after mp3 codec mean?
zhangweiwu at realss.com
Sun Jan 19 13:22:37 CET 2014
2014/1/19 Zhang Weiwu <zhangweiwu at realss.com>:
> Newbie. Using ffmpeg 1.2.4. Plenty of googling before asking in the list.
> Sometimes the codec mp3 is followed by
> U 0x0055
> And sometimes:
> i 0x0069
> What does that mean? I am guessing the U/i is an indicator whether or not
> the mp3 stereo is joint-stereo, but 0055 and 0069 is beyond me.
After more study of mp3 joint stereo, it turns out there are 3
possible coding of stereo mp3:
1. Joint-stereo, Intensity stereo coding
2. Joint-stereo, M/S stereo coding
3. Not joint-stereo. Each channel is encoded seperately.
If you count mono in, there is a forth mode: no stereo.
A post, I found by googling, said 99.99% mp3 stereo are encoded in
Join-stereo. So, perhaps
menas "intensive stereo"
should mean "M/S stereo". Unless I happen to own a 0.01% mp3 that
really uses two seperate channels for left and and right, in which
case "U" means "Unique" for dual unique channels.
My guess so far. Perhaps totally wrong, but I prooved that I worked
hard trying to help myself before asking everyone.
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