Binding MediaPlayer to be played at a specific time

问题

When using MediaPlayer, I noticed that whenever my phone stucks, the MediaPlayer glitches and then continues playing from the position in the audio it glitched.
This is bad for my implementation since I want the audio to be played at a specific time.

If I have a song of 1000 millisecond length, I want is the ability to set MediaPlayer to start playing at some specific time t, and then exactly stop at at time t+1000.

This means that I actually need two things:
1) Start MediaPlayer at a specific time with a very small delay.
2) Making MediaPlayer glitches ignore the audio they glitched on and continue playing in order to finish the song on time.

The delay of the functions is very important to me and I need the audio to be played exactly(~) at the time it was supposed to be played.

Thanks!

回答1:

You will need to use possibly mp.getDuration(); and/or mp.getCurrentPosition(); although it's impossible to know exactly what you mean by "I need the audio to be played exactly(~) at the time it was supposed to be played."

Something like this should get you started:

 int a = (mp.getCurrentPosition() + b);

回答2:

Thanks for the answer Mike. but unfortunately this won't help me.

Let's say that I asked MediaPlayer to start playing a song of length 3:45 at 00:00.
At 01:00 I started using the phone's resources, due to the heavy usage my phone glitched making MediaPlayer pause for 2 seconds.

Time:

00:00-01:00 - I heard the audio at 00:00-01:00
01:00-01:02 - I heard silence because the phone glitched
01:02-03:47 - I heard the audio at 01:00-03:45 with 2 second time skew

Now from what I understood MediaPlayer is a bad choice of usage on this problem domain, since MediaPlayer provides a high level API.
I am currently experimenting with the AudioTrack class which should provide me with what I need:

//Creating a new audio track
AudioTrack audioTrack = new AudioTrack(...)

//Get start time
long start = System.currentTimeMillis();

// loop until finished
for (...) {
    // Get time in song
    long now = System.currentTimeMillis();
    long nowInSong = now - start;
    // get a buffer from the song at time nowInSong with a length of 1 second
    byte[] b = getAudioBuffer(nowInSong);
    // play 1 second of music
    audioTrack.write(b, 0, b.length);
    // remove any unplayed data
    audioTrack.flush();
}

Now if I glitch I only glitch for 1 second and then I correct myself by playing the right audio at the right time!

NOTE

I haven't tested this code but it seems like the right way to do it. If it will actually work I will update this post again.

P.S. seeking in MediaPlayer is: 1. A heavy operation that will surely delay my music (every millisecond counts here) 2. Is not thread safe and cannot be used from multiple threads (seeks, starts etc...)

来源：https://stackoverflow.com/questions/14001664/binding-mediaplayer-to-be-played-at-a-specific-time

标签

android

android-mediaplayer

timing