I'm trying to use Android's MediaPlayer to play a backing audio track to a music game which should stay in sync with other events.
However, I'm finding that on different devices the backing track seems out of sync.
After some frustration, I'm coming to the conclusion that the time it takes to start playing the audio is indeterminate.
Is there a way around this? Or some kind of callback from the MediaPlayer that represents "starting to play NOW"?
AFAICT I can't use the SoundPool for this backing track as the audio file is too long.
I am using Exoplayer2 to play an audio file in a loop. The audio file is 3600ms in length. However, different loops are played with slightly varied durations of 3811ms, 3611ms, 3589ms, 3605ms, 3602ms, 3595ms, etc. I want this to be precisely 3600ms. How do I achieve this?
I am recording the time durations in onPositionDiscontinuity with Player.DISCONTINUITY_REASON_PERIOD_TRANSITION.
I create Exoplayer MediaSource using SingleSampleMediaSource.Factory.
Could it be due to Exoplayer2's attempt to play gapless playback? If so, how do I turn gapless off.
Whenever I call setDisplay() on a MediaPlayer while it is playing (i.e. setDisplay(null) when backgrounding a video to play audio in the background) the media player stutters and rewinds for some small amount of time. Once I comment out these lines, essentially restricting the application to only play audio, these stutters and consequent rewinds no longer occur. Any ideas what the issue may be?
EDIT:
So I think the cause of the problem might be android media player choosing the closest keyframe to resume from on each display change because it can''t render inbetween keyframes. Any ideas?
Has anyone tried using ExoPlayer to achieve this?
I tried looking online with no success.
When I say gapless playback, I am referring to the problem of using the media player to play local videos back to back. After the first video is done playing, there is a noticeable delay of 1 second before the second video starts.
Hoping this question helps in understanding this issue further.
For reference please look at the following question:
Android: MediaPlayer gapless or seamless Video Playing
ExoPlayer 2, which is now officially released, seems to support gapless playback using the ConcatenatingMediaSource class. From its developer guide:
Transitions between sources are seamless. There is no requirement that the sources being concatenated are of the same format (e.g. it’s fine to concatenate a video file containing 480p H264 with one that contains 720p VP9). The sources may even be of different types (e.g. it’s fine to concatenate a video with an audio only stream).
And the example code:
MediaSource firstSource = new ExtractorMediaSource(firstVideoUri, ...);
MediaSource secondSource = new ExtractorMediaSource(secondVideoUri, ...);
// Plays the first video, then the second video.
ConcatenatingMediaSource concatenatedSource =
new ConcatenatingMediaSource(firstSource, secondSource);
EDIT: ExoPlayer 2 supports gapless playback, but as of the time of writing is still unreleased as a stable version.
You will most likely never be able to achieve perfect gapless playback of multiple tracks with ExoPlayer or Android Media Player. Neither have been written to support starting multiple tracks and I imagine it will stay out of scope for both of them.
You can achieve gapless playback by using 2 different player instances, once you have started and played the first, you can load the second and start playback once the first finishes. Using this method you could have a gapless solution, as long as you prepare the second video during playback of the first.
To take it further, you can also use 2 different surface textures for rendering the multiple videos, once the first video reaches the end you could fade out the texture and fade in the new one. Resulting in a nice seamless video effect.
Because of the nature of playing multiple videos at once you will most likely want to create your own timer for incrementing the time and deciding when to switch to the next video, rather than trying to use the callbacks from ExoPlayer or Android Media. This will allow you to keep track of the time in a more accurate fashion, without needing to keep talking to multiple video codecs.
I know this is not the answer you've been looking for, but it's the only reasonable answer. The sole way to ensure no gaps in playback is to download the entire file first and begin playback when it's done. Otherwise, in the event that you lose connectivity before the file is finished downloading, pausing is inescapable.
I just tried switching to ExoPlayer from the standard MediaPlayer implementation and the gap is the same if not worse. However I have used a very simple method of restarting the player when the status changes to ended. I don't know if there's a better proper way to do it, perhaps with 2 different ExoPlayers.
I have two media files located locally - mp4 video and m4a audio, which have to be played in sync. I use MediaPlayer objects for this purpose, all start/pause methods are called simultaneously.
Sometimes I see the difference between audio and video right after players start, sometimes after tapping on pause/resume.
I added logs, and see that after pausing media players, their position differs (e.g. MediaPlayer with audio file: 1820ms, MediaPlayer with video file: 1760ms).
One more interesting thing is that seekTo operation with audio file works good, while with video it's really unpredictable.
Please suggest what is the reason of such a behavior and which solutions are available in order to fix that?
I think that this effect with the video timing depends on how the " key frames", which contain a full frame of information have been encoded. It's only possible to locate to one of these keyframes.
Video editing software gets over this by rolling the deltas from intervening i-frames to the exact seek position.