I just recorded a Dj Mix at home and did record the whole mix in Audacity.
After 2 Hours and 3 minutes the Speed increases in the recording…
After 2 Hours and 56 min the Speed got back to normal
In this period the recording sounds distorted as well.
Before and after that pitch change the recording sounds perfect.
I do not remeber touching the Laptop in that time, luckily I was recording the set parallel with a tascam dr40 on Record-Out on my Mixer, so i have a working Mixfile, but i wonder what was the reason anyways.
Just saw that there is a newer version of audacity online, i will Update now from 2.2 to 2.4 and try again maybe another day.
Attached you see the waveform of the distorted time Area and a Soundfile which shows the beginning and the end of that strange behavior.
So I was thinking that perhaps the sample rate somehow got bumped around…
I measured and found that the before the jump, the rate was about 122 BPM, then right after the speed increase it went to 146 BPM, a ratio of 5:6. The 44100Hz to 48000 Hz is more like 10:11, so it does NOT look like this is what happened.
I am not sure I would want to hazard a guess as to what might cause this. Do you think it could be the USB interface on your mixer?