在iOS中使用AVPlayer播放加密视频

Question

So, I'm trying to play an encrypted video using AVplayer, and nothing shows up in the player.

So my progress towards that project is as follows:

1.Implemented an AVPlayer that will have a UIView which is going to play the AV content (this is working fine for playing non encrypted files.)

AVURLAsset *asset = [[AVURLAsset alloc] initWithURL:fileURL options:nil]; //local file url with custom scheme         
AVAssetResourceLoader *loader = [asset resourceLoader];
[loader setDelegate:self queue:dispatch_get_main_queue()];
self.playerItem = [AVPlayerItem playerItemWithAsset:asset];
self.player = [AVPlayer playerWithPlayerItem:self.playerItem];
[self.playerView setPlayer:self.player];

From the above code, I know that my following resource loader method is being called:

2.Implemented the AVAssetResourceLoaderDelegate protocol, and I've implemented the resource loader method as follows.

- (BOOL) resourceLoader:(AVAssetResourceLoader *)resourceLoader shouldWaitForLoadingOfRequestedResource:(AVAssetResourceLoadingRequest *)loadingRequest 
{
    NSURLRequest* request = loadingRequest.request;
    AVAssetResourceLoadingDataRequest* dataRequest = loadingRequest.dataRequest;
    AVAssetResourceLoadingContentInformationRequest* contentRequest = loadingRequest.contentInformationRequest;
    NSMutableData *data;
    //handle content request
    if (contentRequest)
    {
        contentRequest.contentType = @"mov";
        contentRequest.contentLength = movieFileLengthInBytes
        contentRequest.byteRangeAccessSupported = YES;
    }
    if (dataRequest)
    {
        DecryptedStream* readStream = [FS getReadStream:filename error:nil];
        if (readStream)
        {
            while ([readStream hasBytesAvailable])
            {
                NSInteger nRead;
                uint8_t buffer[kBufferReadSize];
                nRead = [readStream read:buffer maxLength:kBufferReadSize];
                NSMutableData *data = [NSMutableData data];
                [data appendBytes:buffer length:nRead];
                [dataRequest respondWithData:data];
            }
        }
        [loadingRequest finishLoading];
    }
    return YES;
}

Based on the above code, and from other further reading in apple documents for resourceloader: "During loading, the resource loader object may be asked to assist in the loading of a resource. For example, a resource that requires decryption might result in the resource loader being asked to provide the appropriate decryption keys. You can assign a delegate object to the resource loader object and use your delegate to intercept these requests and provide an appropriate response" which is basically what I'm doing. However, I can't get my video to play. I made sure data that I've decrypted is correct (ie, I can write it to a tmp file and can play my mov).

Answer 1

I am also stuck on this task for several day. It is not difficult, but there isn't enough information (or clearly information) of how to use AVAssetResourceLoader and AVAssetResourceLoaderDelegate . Here is something I get when doing this task:

1. If you are loading a local video file, you must provide a custom scheme for your fileURL in order to be able to use AVAssetResourceLoaderDelegate .

    let urlComponents = NSURLComponents(URL: fileURL, resolvingAgainstBaseURL: false) urlComponents?.scheme = "enc" let asset = AVURLAsset(URL: urlComponents!.URL!, options: nil) 

   Simple use let asset = AVURLAsset(URL: fileURL, options: nil) won't trigger any of AVAssetResourceLoaderDelegate

2. In use of resourceLoader:(AVAssetResourceLoader *)resourceLoader shouldWaitForLoadingOfRequestedResource:(AVAssetResourceLoadingRequest *)loadingRequest you must provide the contentInformationRequest for loadingRequest . You can find the list of video format AV Foundation Constants Reference . And another thing is contentLength . It must be set to the size of the decrypted file, not the file you are using to decrypt.
3. The loadingRequest can request overlap data or request same data many times. So that you can't simply decode and paste data to the dataRequest . You will need to have another buffer for decoding data. And in resourceLoader:(AVAssetResourceLoader *)resourceLoader shouldWaitForLoadingOfRequestedResource:(AVAssetResourceLoadingRequest *)loadingRequest , check if you have enough data to return or you need to decode more. When you decode for more data, you can clean up previous buffer to keep memory low but remember to copy any unused data in the previous buffer.

And, I suggest you try to play a non-encrypted file first. Make sure your method to loading data for loadingRequest works properly before jumping into encrypted file. At the end you will find it is very fun and interesting in doing task like this. Happy coding :)

Answer 2

in the line

contentRequest.contentType = @"mov";

you have to set valid UTI of decrypted content like

contentRequest.contentType = @"public.mpeg-4";