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Topic: how to inspect if an mp3 uses simple stereo or joint stereo? (Read 8852 times) previous topic - next topic
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how to inspect if an mp3 uses simple stereo or joint stereo?

The title says it:
how to inspect if an mp3 uses simple stereo or joint stereo?

There are a lot of discussion of when or where to choose to generate simple stereo / joint stereo mp3, but none explains how to inspect whether or not an mp3 file / stream mostly contain simple stereo / joint stereo.

I've googled a lot without any luck.

It seems it is possible to mix the use of the two stereo encoding methods in a same stream, and swtich back and forth at the will of the encoder - this makes it not a file property. Perhaps this is the reason why none of the tools in my tool box (ffmpeg, sox, mplayer etc) says anything about what stereo is used, when displaying file properties.

how to inspect if an mp3 uses simple stereo or joint stereo?

Reply #2 –
The encoder is NOT switching back and forth between simple stereo and joint stereo. It either is allowed to switch back and forth between left/right and mid/side encoding (joint stereo), or else it is forced to use only left/right encoding (simple stereo) even when mid/side encoding would have been more efficient or better quality.

how to inspect if an mp3 uses simple stereo or joint stereo?

Reply #3 –
Quote from: Juha on
http://mpgedit.org/mpgedit/mpeg_format/MP3Format.html

You could make a script which checks the channel mode bits.


Thanks. That is a hard path. I had no other choice but to read the above mp3 spec, dump mp3 audio with xxd (linux command) and managed to reac the channel mode bits, in the end. So the problem is solved.

how to inspect if an mp3 uses simple stereo or joint stereo?

Reply #4 –
In case this thread comes up via search for someone in the future...

Mp3GuessEnc is a command line program for analysis of MP3 files. I've been using it for years, and was surprised to see it still updated.

For joint stereo it will count the number of simple and mid-side stereo frames:

Code: [Select]
Simple stereo                 : 1146 (33.3%)
Mid-side stereo               : 2299 (66.7%)
-----------------------------
sum                           : 3445


-m f or mono recordings might show 100% MS frames.

how to inspect if an mp3 uses simple stereo or joint stereo?

Reply #5 –
Wait, what is wrong with simply checking out file properties in foobar2k?

how to inspect if an mp3 uses simple stereo or joint stereo?

Reply #6 –
That would be an appropriate response if this question had been asked inside the foobar2000 subforum. However, since it was asked in a general MP3 subforum, it is also appropriate to suggest specific tools for the job.

how to inspect if an mp3 uses simple stereo or joint stereo?

Reply #7 –
Axone.jar will tell you if it's joint or simple. Also should be standard in anybody's mp3 toolbox