I'd like to see variable-tempo playback (where you can slow down playback for understandability or speedup / time-compress podcasts) in Rockbox on my DAP (a H300). However, CPU is very limited on most current DAPs, so I'm wondering if keeping some of the temporary data used during FLAC compression might allow a flac playback routine to use that data on a low-CPU system to more easily vary the tempo (freq domain data?).
For me, the use case would be:
-download mp3 podcast
-convert the mp3 to flac, using "--keep-freq-data"
-use that flac instead of the mp3 on my DAP
Of course, this wouldn't be useful until the playback software supports it, but if this approach is to work it would have to start with the encoder.
I've tried various tempo-adjusting software in Linux, and so far the resulting audio sounded terrible to me, so I am looking for better solutions.