Search code examples
web-audio-apiaudio-processingaudiocontext

Rendered audio plays in slow-mo

When decoding the audio data of an mp3 file I fetched, rendering it with my OfflineContext, and exporting it back to a .wav file, the sound is in slo-mo with a different pitch. Is it because the sample rates of my mp3 file and OfflineContext are different? If it is, how can I export the mp3 file in a different sample rate while not changing the pitch?

Edit:

I run decodeAudioData with the OfflineAudioContext that I use for the rendering: offlineContext.decodeAudioData(this.arrayBuffer). The sample rate of offlineContext is 48000, while the sample rate of my audioContext (used for normal playback, which works well) is 41000.

Solution

  • While creating the WAV file, the same sample rate than the offline context should be set in the WAV file header. For example, a WAV file with a sample rate of 44100 in the header that contains data chunks with a sample rate of 48000 will cause the playback to be in "slow motion" in iTunes.