Question

In my application for recording and playing audio using AVAudioRecorder and AVAudioPlayer I came across a scenario in the case of incoming phone call.While the recording is in progress and if the phone call comes,the audio recorded after the phone call is only recorded.I want the recording recorded after the phone call to be the continuation of the audio recorded before the phone call.

I track the interruption occuring in audio recorder using the AVAudioRecorderDelegate methods

• (void)audioRecorderBeginInterruption:(AVAudioRecorder *)avRecorder
  and
• (void)audioRecorderEndInterruption:(AVAudioRecorder *)avRecorder.

In my EndInterruption method I activates the audioSession.

Here is the recording code that I use

- (void)startRecordingProcess
{
    AVAudioSession *audioSession = [AVAudioSession sharedInstance];
    NSError *err = nil;
    [audioSession setCategory:AVAudioSessionCategoryPlayAndRecord error:&err];
    if(err)
    {
        DEBUG_LOG(@"audioSession: %@ %d %@", [err domain], [err code], [[err userInfo] description]);
        return;
    }
    [audioSession setActive:YES error:&err];
    err = nil;
    if(err)
    {
        DEBUG_LOG(@"audioSession: %@ %d %@", [err domain], [err code], [[err userInfo] description]);
        return;
    }
    // Record settings for recording the audio
    recordSetting = [[NSDictionary alloc] initWithObjectsAndKeys:
                     [NSNumber numberWithInt:kAudioFormatMPEG4AAC],AVFormatIDKey,
                     [NSNumber numberWithInt:44100],AVSampleRateKey,
                     [NSNumber numberWithInt: 2],AVNumberOfChannelsKey,
                     [NSNumber numberWithInt:16],AVLinearPCMBitDepthKey,
                     [NSNumber numberWithBool:NO],AVLinearPCMIsBigEndianKey,
                     [NSNumber numberWithBool:NO],AVLinearPCMIsFloatKey,
                     nil];
    BOOL fileExists = [[NSFileManager defaultManager] fileExistsAtPath:recorderFilePath];
    if (fileExists) 
    {        
        BOOL appendingFileExists = 
            [[NSFileManager defaultManager] fileExistsAtPath:appendingFilePath];
        if (appendingFileExists)
        {
            [[NSFileManager defaultManager]removeItemAtPath:appendingFilePath error:nil];
        }
        if (appendingFilePath) 
        {
            [appendingFilePath release];
            appendingFilePath = nil;
        }
        appendingFilePath = [[NSString alloc]initWithFormat:@"%@/AppendedAudio.m4a", DOCUMENTS_FOLDER];
        fileUrl = [NSURL fileURLWithPath:appendingFilePath]; 
    }
    else 
    {
        isFirstTime = YES;
        if (recorderFilePath) 
        {
            DEBUG_LOG(@"Testing 2");
            [recorderFilePath release];
            recorderFilePath = nil;
        }
        DEBUG_LOG(@"Testing 3");
        recorderFilePath = [[NSString alloc]initWithFormat:@"%@/RecordedAudio.m4a", DOCUMENTS_FOLDER];
        fileUrl = [NSURL fileURLWithPath:recorderFilePath];
    }
    err = nil;
    recorder = [[recorder initWithURL:fileUrl settings:recordSetting error:&err]retain];
    if(!recorder)
    {
        DEBUG_LOG(@"recorder: %@ %d %@", [err domain], [err code], [[err userInfo] description]);
        [[AlertFunctions sharedInstance] showMessageWithTitle:kAppName 
                                                      message:[err localizedDescription] 
                                                     delegate:nil
                                            cancelButtonTitle:@"Ok"];
        return;
    }
    //prepare to record
    [recorder setDelegate:self];
    [recorder prepareToRecord];
    recorder.meteringEnabled = YES;
    [recorder record];

}

While searching for a solution to this issue I came across another link
how to resume recording after interruption occured in iphone? and http://www.iphonedevsdk.com/forum/iphone-sdk-development/31268-avaudiorecorderdelegate-interruption.html which speaks of the same issue.
I tried the suggestions that were given in those links but were not successful.
I hope to make it work with AVAudioRecorder itself.
Is there any way I could find a solution to this issue?
All valuable suggestions are appreciated.

Answer 1

After several research I was notified by Apple that it’s an issue with the current API. So I managed to find a workaround for the issue by saving the previous audio file just after interruption and joining it with the resumed audio file. Hope it helps someone out there who may face the same issue.