在ios中解碼h264

Question

我是AVFoundation和解碼過程的新手。我需要解碼h264視頻文件並在iphone中播放...任何人都可以給我指導。

我不想使用ffmpeg或任何第三方庫來做到這一點。 據我所知使用Avfoundation編碼是可能的...這里是我認為用於編碼但完全不確定的代碼...

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;

我對此完全天真，請幫助......從哪里開始///

謝謝

Answer 1

您可以參考並構建官方示例代碼： AVPlayerDemo以查看其工作原理。 它使用AV Foundation框架，主要是AVPlayer API來播放視頻文件而且性能非常出色。 要通過AVPlayerDemo播放視頻文件，您應該通過itunes將視頻文件復制到iOS設備，並在AVPlayerDemo應用程序上選擇iPod庫。

Answer 2

更簡單的解決方案是使用MPMoviePlayerController。 它接收輸入mov或mv4文件（來自本地文件系統或通過URL）。

另一種選擇是使用AVPlayer類。

希望能幫助到你，

大衛