I tracked a session today (48 kHz) where I ended up switching my sample rate half-way through down to 44.1 kHz (playing something on the internet that was playing back slow). I don't think I changed it back and continued the session. After bouncing, all vocals came out pitched up, but the speed/timing still matches perfectly with the session. Everything was playing back normally during the session and it wasn't until bounce that the pitch became altered on both the audio files and inside the project file.
I have tried to resample the audio in hex edit successfully. The pitch drops back down, but the speed/rate slows to be out of time.
I believe this may also but partly a Reaper issue where Reaper, say, have actively resampled my audio while this problem occurred and somehow preserved the timing but not the pitch?
I am desperate to fix this, and it is confusing because even though I made a mistake, the session was playing totally fine while continuing to track vocals. Somehow after that the audio files overwrote themselves.
Bless.
