How to add playable(such as wav,wmv) header with PCM data/buffer in iOS?

audio, ios, objective-c, wav

Solution

OK, I am answering my own question if it helps someone else. After few days of tireless trying, at last i have got it working. Below is a complete Function written with Objective-C and C. It takes a file path as a parameter which contains RAW PCM data directly captured from microphone and returns a file path which contains PCM data followed by appropriate wav header info. Then you can play that file with AVAudioPlayer or AVPlayer. Here is the code...

- (NSURL *) getAndCreatePlayableFileFromPcmData:(NSString *)filePath
{
    NSString *wavFileName = [[filePath lastPathComponent] stringByDeletingPathExtension];
    NSString *wavFileFullName = [NSString stringWithFormat:@"%@.wav",wavFileName];

    [self createFileWithName:wavFileFullName];
    NSArray *dirPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *docsDir = [dirPaths objectAtIndex:0];
    NSString *wavFilePath = [docsDir stringByAppendingPathComponent:wavFileFullName];

    NSLog(@"PCM file path : %@",filePath);

    FILE *fout;

    short NumChannels = AUDIO_CHANNELS_PER_FRAME;
    short BitsPerSample = AUDIO_BITS_PER_CHANNEL;
    int SamplingRate = AUDIO_SAMPLE_RATE;
    int numOfSamples = [[NSData dataWithContentsOfFile:filePath] length];

    int ByteRate = NumChannels*BitsPerSample*SamplingRate/8;
    short BlockAlign = NumChannels*BitsPerSample/8;
    int DataSize = NumChannels*numOfSamples*BitsPerSample/8;
    int chunkSize = 16;
    int totalSize = 46 + DataSize;
    short audioFormat = 1;

    if((fout = fopen([wavFilePath cStringUsingEncoding:1], "w")) == NULL)
    {
        printf("Error opening out file ");
    }

    fwrite("RIFF", sizeof(char), 4,fout);
    fwrite(&totalSize, sizeof(int), 1, fout);
    fwrite("WAVE", sizeof(char), 4, fout);
    fwrite("fmt ", sizeof(char), 4, fout);
    fwrite(&chunkSize, sizeof(int),1,fout);
    fwrite(&audioFormat, sizeof(short), 1, fout);
    fwrite(&NumChannels, sizeof(short),1,fout);
    fwrite(&SamplingRate, sizeof(int), 1, fout);
    fwrite(&ByteRate, sizeof(int), 1, fout);
    fwrite(&BlockAlign, sizeof(short), 1, fout);
    fwrite(&BitsPerSample, sizeof(short), 1, fout);
    fwrite("data", sizeof(char), 4, fout);
    fwrite(&DataSize, sizeof(int), 1, fout);

    fclose(fout);

    NSMutableData *pamdata = [NSMutableData dataWithContentsOfFile:filePath];
    NSFileHandle *handle;
    handle = [NSFileHandle fileHandleForUpdatingAtPath:wavFilePath];
    [handle seekToEndOfFile];
    [handle writeData:pamdata];
    [handle closeFile];

    return [NSURL URLWithString:wavFilePath];
}

But that function only works with the following audio settings.

// Audio settings.
#define AUDIO_SAMPLE_RATE 8000
#define AUDIO_FRAMES_PER_PACKET 1
#define AUDIO_CHANNELS_PER_FRAME 1
#define AUDIO_BITS_PER_CHANNEL 16
#define AUDIO_BYTES_PER_PACKET 2
#define AUDIO_BYTES_PER_FRAME 2

Problem

Original source