AVPlayerItemVideoOutput copyPixelBuffer always returns 1280x720

问题

Im instanciating the AVPlayerItemVideoOutput like so:

let videoOutput = AVPlayerItemVideoOutput(pixelBufferAttributes: [String(kCVPixelBufferPixelFormatTypeKey): NSNumber(value: kCVPixelFormatType_32BGRA)])

And retrieving the pixelBuffers like this:

@objc func displayLinkDidRefresh(link: CADisplayLink) {
        let itemTime = videoOutput.itemTime(forHostTime: CACurrentMediaTime())

        if videoOutput.hasNewPixelBuffer(forItemTime: itemTime) {
            if let pixelBuffer = videoOutput.copyPixelBuffer(forItemTime: itemTime, itemTimeForDisplay: nil) {

            }
        }
    }

But for some reason CVPixelBufferGetHeight(pixelBuffer) or Width. always return 1280x720 when the video was taken when the iPhone's camera (landscape or portrait) always height=1280 width=720. EVEN if the video is 4k. If I load a square video from instagram or any other video downloaded from the internet (not created directly with the camera app) the width and height are printed correctly when the resolution is less than 720p. But a different resolution, for ex. a 1008x1792 will throw CVPixelBufferGetHeight(pixelBuffer) = 1280

Videos taken with the camera... it always throws a lower res. I tried 4k and 1080 settings (you can change that in iOS Settings > Camera). still.. even in 1080, I get 1280x720 pixel buffers.

回答1:

I figured out that th UIPickerController I was using was set to default transcode the selected video from library to a Medium setting. in this case it was 1280x720

I ended up changing this properties of the picker

picker.videoQuality = .typeHigh 
picker.videoExportPreset =  AVAssetExportPresetHighestQuality

Altho the property that actually makes the change is the videoExportPreset the other one I dont know what it does, even tho the Documentation specifies it is for when you record a video OR you pick a video.

来源：https://stackoverflow.com/questions/53716000/avplayeritemvideooutput-copypixelbuffer-always-returns-1280x720

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swift

avfoundation