decoding h264 in ios

Question

I am a newbie in AVFoundation and decoding process.I need to decode a h264 video file and play it in iphone...can anyone give me guideline to do it.

I dont want to use ffmpeg or any third party library to do that. As far as I know using Avfoundation encoding is possible...here is the code which I thought is used for encoding but not sure at all...

float bitsPerPixel;
CMVideoDimensions dimensions = CMVideoFormatDescriptionGetDimensions(currentFormatDescription);
int numPixels = dimensions.width * dimensions.height;
int bitsPerSecond;

// Assume that lower-than-SD resolutions are intended for streaming, and use a lower bitrate
if ( numPixels < (640 * 480) )
    bitsPerPixel = 4.05; // This bitrate matches the quality produced by AVCaptureSessionPresetMedium or Low.
else
    bitsPerPixel = 11.4; // This bitrate matches the quality produced by AVCaptureSessionPresetHigh.

bitsPerSecond = numPixels * bitsPerPixel;

NSDictionary *videoCompressionSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                                          AVVideoCodecH264, AVVideoCodecKey,
                                          [NSNumber numberWithInteger:dimensions.width], AVVideoWidthKey,
                                          [NSNumber numberWithInteger:dimensions.height], AVVideoHeightKey,
                                          [NSDictionary dictionaryWithObjectsAndKeys:
                                           [NSNumber numberWithInteger:bitsPerSecond], AVVideoAverageBitRateKey,
                                           [NSNumber numberWithInteger:30], AVVideoMaxKeyFrameIntervalKey,
                                           nil], AVVideoCompressionPropertiesKey,
                                          nil];
if ([assetWriter canApplyOutputSettings:videoCompressionSettings forMediaType:AVMediaTypeVideo]) {
    assetWriterVideoIn = [[AVAssetWriterInput alloc] initWithMediaType:AVMediaTypeVideo outputSettings:videoCompressionSettings];
    assetWriterVideoIn.expectsMediaDataInRealTime = YES;
    assetWriterVideoIn.transform = [self transformFromCurrentVideoOrientationToOrientation:self.referenceOrientation];
    if ([assetWriter canAddInput:assetWriterVideoIn])
        [assetWriter addInput:assetWriterVideoIn];
    else {
        NSLog(@"Couldn't add asset writer video input.");
        return NO;
    }
}
else {
    NSLog(@"Couldn't apply video output settings.");
    return NO;
}

return YES;

I am completely naive about this, please help...from where to start///

thanks

Answer 1

You can refer and build the official sample code: AVPlayerDemo to see how it works. It uses AV Foundation framework, mainly the AVPlayer APIs to play video files and the performance is excellent. To play a video file by AVPlayerDemo you should copy the video files to your iOS device by itunes and select iPod library on the AVPlayerDemo App.

Answer 2

The simpler solution is to use MPMoviePlayerController. It takes in input a mov or mv4 file (from local file system or through an URL).

The another option is to use AVPlayer class.

Hope it helps,

David