I'm looking to implement an audio player with variable speed playback (1.0x, 1.25x, 1.5x) like typical audiobook players currently on the market do. I would like to use Google's Exoplayer library as my audioplayer library however they don't appear to support variable speed playback. Any ideas on how to implement this, or any extensions that do support this?
6 Answers
Kotlin Extension Solution
Make it easy to access and set this reliably across your app in Kotlin
// To set
player.playbackSpeed = 2f
var SimpleExoPlayer.playbackSpeed: Float
get() = playbackParameters?.speed ?: 1f
set(speed) {
val pitch = playbackParameters?.pitch ?: 1f
playbackParameters = PlaybackParameters(speed, pitch)
}
All you need is https://github.com/waywardgeek/sonic/blob/master/Sonic.java
If you look at MediaCodecAudioTrackRenderer.java, you can get the output buffer (decoded by MediaCodec) from ExoPlayer in method processOutputBuffer and process it through Sonic.java accordingly before sending it to AudioTrack.
Following document explains how to use libsonic https://github.com/waywardgeek/sonic/blob/master/doc/index.md
You should take a look this project, which was very useful for me: https://github.com/AmrMohammed89/exoplayer2.4.0_speedup
Inside SimpleExoPlayer, I implemented the next methods:
private final ExoPlayer player;
private float playbackSpeed;
float SPEED_NORMAL = 1f;
float SPEED_MEDIUM = 1.5f;
float SPEED_HIGH = 2f;
@Override
public float getPlaybackSpeed() {
return playbackSpeed;
}
@Override
public void setPlaybackSpeed(float speed) {
playbackSpeed = speed;
player.setPlaybackSpeed(speed);
}
@Override
public void changePlaybackSpeed() {
if (playbackSpeed == SPEED_MEDIUM) {
player.setPlaybackSpeed(SPEED_HIGH);
playbackSpeed = SPEED_HIGH;
} else if (playbackSpeed == SPEED_HIGH) {
player.setPlaybackSpeed(SPEED_NORMAL);
playbackSpeed = SPEED_NORMAL;
} else {
player.setPlaybackSpeed(SPEED_MEDIUM);
playbackSpeed = SPEED_MEDIUM;
}
}
I set and saved the speed that way due to there was a bug when I tried to get the last saved speed. So follow that mechanism and it will work perfectly.
Cheers