AVAssetWriter codec type hevc

Question

I a trying to transcode an H264 video to HEVC using AVAssetWriter and it fails on iPhone 6s. Supposedly, the iPhone 6s supports HEVC for transcoding, not real-time video encoding. The same code works on iPhone 7 and above. If the iPhone 6s doesn't support the HEVC codec, how do we programmatically determine supported codecs at runtime?

let bitrate = trackBitrate / 5 
let trackDimensions = trackSize
let compressionSettings: [String: Any] = [
    AVVideoAverageBitRateKey: bitrate,
    AVVideoMaxKeyFrameIntervalKey: 30,
    AVVideoProfileLevelKey: kVTProfileLevel_HEVC_Main_AutoLevel
]
var videoSettings: [String : Any] = [
    AVVideoWidthKey: trackDimensions.width,
    AVVideoHeightKey: trackDimensions.height,
    AVVideoCompressionPropertiesKey: compressionSettings
]

videoSettings[AVVideoCodecKey] =  AVVideoCodecType.hevc

score 2 · Answer 1 · edited Mar 15 '21 at 10:48

2

I ended up doing it this way

if #available(iOS 11.0, *),  AVCaptureVideoDataOutput().availableVideoCodecTypes.contains(.hevc) {
    // use .hevc settings here
} else {
    // use .h264 settings here
}

The #available check is needed to make the compiler happy if your app is targeting < iOS 11

edited Mar 15 '21 at 10:48

Vukašin Manojlović

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answered Jan 03 '19 at 11:54

Ehab Amer

392
1
9

It would still fail on iPhone6 – bojan Nov 19 '21 at 16:54
This would give an empty array in some cases and so always fail – Glaphi Feb 22 '22 at 13:58

score 0 · Answer 2 · edited Mar 15 '21 at 10:49

0

You can get the iPhone model by the following code:

+ (NSString *) deviceModel {
    struct utsname systemInfo;
    uname(&systemInfo);

    return [NSString stringWithCString: systemInfo.machine encoding: NSUTF8StringEncoding];
}

and determine if iPhone 6S disable H265 encode and iPhone7 above enable H265 encode.

edited Mar 15 '21 at 10:49

Vukašin Manojlović

3,717
3
19
31

answered Sep 06 '19 at 23:27

hzhou

9
4

AVAssetWriter codec type hevc

2 Answers2