Question

It looks like no matter what AVVideoWidthKey, AVVideoHeightKey, AVVideoCleanApertureWidthKey, AVVideoCleanApertureHeightKey I choose, my video resolution will be either 320×240 or 480×360.

I’m trying to save a video at 480p and all my buffers are 640×480, my session is at AVCaptureSessionPreset640x480, everything is at 640×480 but still my output video is scaled down.

I’m using AVAssetWriterInputPixelBufferAdaptor and the CMSampleBufferRef that I’ve pass into it it’s at 640×480.

I’ve looked all over Stack Overflow but I haven’t found this issue yet being reported. :/

Answer 1

I use this setting all the time and it works. Here is a code sample.

self.compressionProperties = [[[NSMutableDictionary alloc] initWithObjectsAndKeys:
                               [NSNumber numberWithInt:params.bps], AVVideoAverageBitRateKey,
                               [NSNumber numberWithInt:params.keyFrameInterval],AVVideoMaxKeyFrameIntervalKey,
                               //videoCleanApertureSettings, AVVideoCleanApertureKey,
                               params.videoProfileLevel, AVVideoProfileLevelKey,
                               nil ] autorelease];

self.videoSettings = [[[NSMutableDictionary alloc] initWithObjectsAndKeys:AVVideoCodecH264, AVVideoCodecKey,
                       [NSNumber numberWithInt:params.outWidth], AVVideoWidthKey,
                       [NSNumber numberWithInt:params.outHeight], AVVideoHeightKey, 
                       self.compressionProperties, AVVideoCompressionPropertiesKey,
                       nil] autorelease];

...

wobj.writerInput = [[[AVAssetWriterInput alloc] initWithMediaType:AVMediaTypeVideo outputSettings:self.videoSettings] autorelease];