Audio pitch during playback appears to be inconsistent
This bug occurs when either playing MP3 or M4A audio formats, or playing MP4 video that has audio. In my testing I found this issue did not occur with FLAC files.
When you start playing one of the formats I listed, the start of the audio sounds like the pitch is wrong by ±1% and for me is noticeable. Sometimes after 30 seconds of playback, it "evens out" and plays correctly, but sometimes it continues to have an unstable pitch.
When tested side by side with another audio player app, I could notice VLC was playing the pitch slightly wrong.
I have tested another Another device with VLC with other MP3 files and it still occurs.
While trying other formats, I tried the ADX file format (CRI Middleware ADPCM) with some ADX files extracted from a game that used this format and the bug became very noticeable with the pitch bending up and down by itself.
I tried another player for Android that supports all the formats I listed and the same bug did not occur.
VLC for Windows did not seem to have this issue when I tested.
The effect is less noticeable when I change the output format from "AudioTrack" to "OpenSL ES". Changing the hardware acceleration setting made no difference.
I tried the latest stable 3.2.10 and the the 13th April 3.3.0 nightly and both had the bug
The app to play audio files and videos with audio with the correct pitch and to not vary in pitch.
Audio files play with the pitch very slightly too high or too low and it varies during playback.
Steps to reproduce
- Get an MP3, M4A or MP4 video (or alternatively an ADX audio file)
- Play the file in the VLC Android App
- Listen closely for incorrect pitch. You can compare with another audio player app side by side to notice this bug.
Screenshot / video
I have video recording of the app playing an ADX file seems to be the best way to demonstrate the bug.
The pitch issue occurs at the start of playback where it starts too slow and then becomes too fast (to catch up?)