gistfile1.m

NSDictionary *videoCleanApertureSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                                                @480, AVVideoCleanApertureWidthKey,
                                                @480, AVVideoCleanApertureHeightKey,
                                                @0, AVVideoCleanApertureHorizontalOffsetKey,
                                                @0, AVVideoCleanApertureVerticalOffsetKey,
                                                nil];
    
    
    NSDictionary *videoAspectRatioSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                                              @1,AVVideoPixelAspectRatioHorizontalSpacingKey,
                                              @1,AVVideoPixelAspectRatioVerticalSpacingKey,
                                              nil];
    
   // NSNumber* bitsPerSecond = [NSNumber numberWithDouble:1024.0*1024.0];
    NSNumber* bitsPerSecond = [NSNumber numberWithDouble:1024*256];
   // NSNumber* bitsPerSecond = [NSNumber numberWithDouble:1024*178];
    
    NSDictionary *codecSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                                   bitsPerSecond, AVVideoAverageBitRateKey,
                                   //@1,AVVideoMaxKeyFrameIntervalKey,
                                   videoCleanApertureSettings, AVVideoCleanApertureKey,
                                   videoAspectRatioSettings, AVVideoPixelAspectRatioKey,
                                   nil];
    
    NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                                   AVVideoCodecH264, AVVideoCodecKey,
                                   codecSettings,AVVideoCompressionPropertiesKey,
                                   AVVideoScalingModeResizeAspectFill,AVVideoScalingModeKey,  // this is the key to getting square video out
                                   @480, AVVideoWidthKey,
                                   @480, AVVideoHeightKey,
                                   nil];
    
    
    
    videoWriterInput = [AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeVideo outputSettings:videoSettings];
    NSParameterAssert(videoWriterInput);
    videoWriterInput.expectsMediaDataInRealTime = YES;
    
    // Add the audio input
    AudioChannelLayout acl;
    bzero( &acl, sizeof(acl));
    acl.mChannelLayoutTag = kAudioChannelLayoutTag_Mono;
    
    NSDictionary* audioOutputSettings = nil;
    // Both type of audio inputs causes output video file to be corrupted.
    audioOutputSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                           [NSNumber numberWithInt: kAudioFormatMPEG4AAC ], AVFormatIDKey,
                           [NSNumber numberWithFloat: 44100.0 ], AVSampleRateKey,
                           [NSNumber numberWithInt: 1 ], AVNumberOfChannelsKey,
                           [NSData dataWithBytes: &acl length: sizeof( acl ) ], AVChannelLayoutKey,nil];
    
    audioWriterInput = [AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeAudio outputSettings:audioOutputSettings];
    audioWriterInput.expectsMediaDataInRealTime = YES;
    
    // add input
    [videoWriter addInput:videoWriterInput];
    [videoWriter addInput:audioWriterInput];
    

    self.swapCameraButton.enabled = NO;