On Mar 25, 2004, at 5:21 AM, Erik Jälevik wrote:

Is the number of channels an MP3 file is encoded in always constant? Or can it change from stereo to mono somewhere in the middle?

Or to phrase it differently: Can I always assume that pcm->channels has the same value within the output callback as long as I'm working on the same file?

In theory, the number of channels could change at any time. Each frame independently encodes either one or two channels of audio.

In practice, the number of channels rarely changes within a single file because generally the file was encoded from a single source. It is possible though for a file to contain audio from multiple sources, as a concatenation of streams, so the number of channels could change.