I am able to query and find formats for slo-mo at 240FPS. There are two, with 420v
and 420f
each, at Full HD (correct me if I'm wrong that they only differ in the pixel value range). I was wondering if I could distinguish them at runtime.
print(format.formatDescription.mediaSubType) // this prints "420v" and "420f" each
This does not work, however:
// always false
if format.formatDescription.mediaSubType == .init(string: "420f") {
// ...
}
A workaround I have been adapting is to rely on the for-loop to always find v
first then f
for my device, but I am not sure if this is guaranteed for all devices.
Here are some of discovered slow motion formats on this iPad: (other slo-mo formats are for 1280x720 dimension, etc.)
<AVCaptureDeviceFormat: 0x280b58ec0 'vide'/'420v' 1920x1080, { 2-240 fps}, fov:64.717, binned, supports vis, max zoom:67.50 (upscales @1.00), AF System:1, ISO:18.0-720.0, SS:0.000016-0.500000> <CMVideoFormatDescription 0x2807d95c0 [0x1ff615860]> {
mediaType:'vide'
mediaSubType:'420v'
mediaSpecific: {
codecType: '420v' dimensions: 1920 x 1080
}
extensions: {(null)}
}
<AVCaptureDeviceFormat: 0x280b58eb0 'vide'/'420f' 1920x1080, { 2-240 fps}, fov:64.717, binned, supports vis, max zoom:67.50 (upscales @1.00), AF System:1, ISO:18.0-720.0, SS:0.000016-0.500000, supports wide color> <CMVideoFormatDescription 0x280731770 [0x1ff615860]> {
mediaType:'vide'
mediaSubType:'420f'
mediaSpecific: {
codecType: '420f' dimensions: 1920 x 1080
}
extensions: {(null)}
}
There are already some pixel type constants defined on MediaSubType
, like CMFormatDescription.MediaSubType.pixelFormat_422YpCbCr8_yuvs
, but sadly no 4:2:0 variants.
You can symbolically check for 420f and 420v with
format.formatDescription.mediaSubType == .init(rawValue: kCVPixelFormatType_420YpCbCr8BiPlanarFullRange)
and
format.formatDescription.mediaSubType == .init(rawValue: kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange)
The strange thing is your .init(string:"420f")
works for me.