CODEWITHSUNDEEP
androidaudiofrequency
Neigyl R. Noval
Neigyl R. Noval

Reputation: 6038

Play stereo tone in android

Similar topics on this question include only playing tone in mono where the left and right frequencies are the same.

My question is: how to generate a stereo tone such that the left channel has a different frequency than the right channel?

I thought of pre-recording .wav files but recording many .wav files and putting it on res folder is not a good idea.

i come across the SoundPool and AudioTrack class but I need a snippet showing the different frequencies of the left and right channel stored as buffer before playing the tone.

Or is there other ways? Please provide the desired snippet.

Upvotes: 6

Views: 2910

Answers (4)

Pedro Gonzalez
Pedro Gonzalez

Reputation: 1459

I would use other software to generate an .ogg stereo file (don't use WAV files, they weight too much), wich is a very lightweight audio format wich works well in Android. I use the free Reaper, Audacity is easier, anyone would do. Just create two mono audio tracks, set their pan to full right and full left. Load your samples, and apply a pitch-change plugin to alter the frequency of one of the tracks. You can also generate them with a sintesizer. Then render all to a tone.ogg file. Tone

Upvotes: 0

MusiGenesis
MusiGenesis

Reputation: 75376

Instead of prerecording WAV files and embedding them in your application, you can instead generate the split-channel WAV audio in memory from code, and then either save it as a WAV file that you would play with SoundPool, or play the audio directly using AudioTrack (I'd recommend the latter).

The audio itself is just an array of (usually) 2-byte integers. With stereo, the left and right samples are interleaved throughout the array (so sample[0] is the first L sample, sample[1] is the first R sample, sample[2] is the second L sample etc.). So when your app starts up, you would create an array however long you need (with CD-quality audio, your array will need 88200 elements for each second of audio) then fill the samples with calculated values for your tone, then pass the array to AudioTrack for playing.

Or you would save the audio as a WAV file and play it with SoundPool (which might actually be better from a memory footprint standpoint). The WAV format is very simple to write (reading is more complicated): just a 44-byte header with various properties, and then the audio data itself.

I think I've answered a similar android question before, so I'm going to go see if I have some basic code for doing this.

Not me, but some good code for reading and writing WAV files in java:

http://computermusicblog.com/blog/2008/08/29/reading-and-writing-wav-files-in-java

Upvotes: 1

Wookie1120
Wookie1120

Reputation: 194

From my understanding, if you use SoundPool it will play in stereo without any special configuration. From the documentation: "The SoundPool library uses the MediaPlayer service to decode the audio into a raw 16-bit PCM mono or stereo stream" so as long as the file you play is in Stereo to begin with, it should play that way.

Upvotes: 3

Sherif elKhatib
Sherif elKhatib

Reputation: 45942

I have never tried this:

  1. Initialize your left and right frequencies
    //playback rate (1.0 = normal playback, range 0.5 to 2.0)
    float lFrequency = 1.0;
    float rFrequency = 1.0;

  2. Initialize a SoundPool object
    SoundPool sp = SoundPool(2, AudioManager.STREAM_MUSIC, 0);

  3. Load your track twice (load function)
    int sLeft = sp.load(mContext, R.raw.yourAudioFileId, 1);
    int sRight = sp.load(mContext, R.raw.yourAudioFileId, 1);

  4. Play the 2 sounds (one on Left and one on Right) using different rates (play function)
    sp.play (sLeft, 1.0, 0.0, 0, 0, lFrequency);
    sp.play (sRight, 0.0, 1.0, 0, 0, rFrequency);

Upvotes: 5

Related Questions