CODEWITHSUNDEEP
androidaudiovideoandroid-mediaplayer
GGizmos
GGizmos

Reputation: 3773

MediaPlayer -- how to separate a narration track?

I'm working on an android app that plays video (using video view). the video is meant to have both music (left and right) and narration, but I want to selectively be able to turn off the narration track in the MediaPlayer.

Is the way to do this correctly to encode by mp4 video file with 3 audio tracks (right left and narration) and then turn off the naration audio track with deselectTrack()?

Not clear to me from the documentation that MediaPlayer can handle more than 2 audio tracks.

If the audio tracks are limited to 2, would it make sense to run two media player simultaneously (synching them up with seekTo())when I want the narration track to play?

Thanks.

Upvotes: 1

Views: 718

Answers (1)

Dave
Dave

Reputation: 4291

Sorry to burst your bubble, but...

1) You have a misunderstanding about what a "track" denotes. A track can have multiple channels (e.g., a stereo track has left and right channels). As I understand it, stereo is the extent of the Android AudioTrack implementation at present. I haven't yet checked if the OpenSL implementation is more extensive than the Java API.

2) Only 1 audio track can be selected at a time, so you wouldn't be able to have background and narration simultaneously in the way you were thinking.

3) Audio tracks can only be selected in the prepared state (i.e., not after playback has started). The documentation mentions this limitation is not ideal, so it will probably change in the future. If not for this problem, your goal could be accomplished with two audio tracks encoded in the stream, one with both background & narration, the other just background.

You will probably find it difficult to synchronize two MediaPlayers, but I haven't tried. Maybe this approach would be acceptable for your situation, although be forewarned the seekTo method isn't accurate. It depends on the encoding of the files.

Something I would try if I were you is to have two complete encoded videos, one with narration, the other without. Use two MediaPlayers and keep them both prepared. When you want to switch use seekTo to put the correct one at (or near) the desired location. That way you don't have to worry about synchronization. If the video is large, this method could use significantly more resources, though.

Upvotes: 1

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