CODEWITHSUNDEEP
iphoneobjective-cioscocoa-touchavfoundation
devinross
devinross

Reputation: 2816

Basic AVAssetReader problems reading video samples

I'm looking to read video samples via AVAssetReader and I'm running into all kinds of road blocks. Can some one post code that sets up an AVAsset from a video named 'Movie.m4v' from the application bundle and uses AVAssetReader to loop through the video frames (CMSampleBufferRef).

Here's some of the code I'm using now that doesn't work:

NSString *path = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"Movie.m4v"];
AVAsset *avAsset = [[AVURLAsset alloc] initWithURL:[NSURL URLWithString:path] options:nil];
NSError *error = nil;
AVAssetReader *reader = [[AVAssetReader alloc] initWithAsset:avAsset error:&error]; // crashing right around here!

// I've gotten avassetreader to not crash upon initialization by grabbing an asset from the ALAssetsLibrary but it says it has 0 tracks!

NSArray *videoTracks = [avAsset tracksWithMediaType:AVMediaTypeVideo]; 
AVAssetTrack *videoTrack = [videoTracks objectAtIndex:0];
NSDictionary *options = [NSDictionary dictionaryWithObject:[NSNumber numberWithInt:kCVPixelFormatType_32BGRA] forKey:(id)kCVPixelBufferPixelFormatTypeKey];
AVAssetReaderTrackOutput *asset_reader_output = [[AVAssetReaderTrackOutput alloc] initWithTrack:videoTrack outputSettings:options];
[reader addOutput:asset_reader_output];
[reader startReading];

CMSampleBufferRef buffer;
while ( [reader status]==AVAssetReaderStatusReading ){

    buffer = [asset_reader_output copyNextSampleBuffer];
    NSLog(@"READING");



}

Upvotes: 6

Views: 5526

Answers (2)

bogardon
bogardon

Reputation: 915

you need to ask your AVAsset to asynchronously load its tracks property before you may use the tracks.

Upvotes: 0

Alex Chugunov
Alex Chugunov

Reputation: 748

Most likely crashes because of the [NSURL URLWithString:path]. You should use [NSURL fileURLWithPath:path] instead.

Upvotes: 11

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