Spence Pope
106 lines
3.6 KiB
Swift
106 lines
3.6 KiB
Swift
import AVFoundation
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import UniformTypeIdentifiers
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struct VideoProber {
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static func probe(url: URL) async throws -> [String: Any] {
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let asset = AVURLAsset(url: url)
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let duration = try await asset.load(.duration)
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let tracks = try await asset.loadTracks(withMediaType: .video)
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guard let videoTrack = tracks.first else {
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throw NSError(
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domain: "ExpoBlueskyVideoCompress",
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code: 1,
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userInfo: [NSLocalizedDescriptionKey: "No video track found"]
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)
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}
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let naturalSize = try await videoTrack.load(.naturalSize)
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let preferredTransform = try await videoTrack.load(.preferredTransform)
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let estimatedDataRate = try await videoTrack.load(.estimatedDataRate)
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let nominalFrameRate = try await videoTrack.load(.nominalFrameRate)
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let formatDescriptions = try await videoTrack.load(.formatDescriptions)
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var codec = "unknown"
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var isHDR = false
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if let formatDescription = formatDescriptions.first {
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let subType = CMFormatDescriptionGetMediaSubType(formatDescription)
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codec = fourCCToString(subType)
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// Dolby Vision codecs are HDR by definition.
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let dolbyVisionSubtypes: Set<String> = ["dvhe", "dvh1", "dvav", "dva1"]
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if dolbyVisionSubtypes.contains(codec) {
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isHDR = true
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} else if let extensions = CMFormatDescriptionGetExtensions(formatDescription)
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as? [String: Any]
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{
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let transferKey = kCMFormatDescriptionExtension_TransferFunction as String
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if let transfer = extensions[transferKey] as? String {
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let hlg = kCMFormatDescriptionTransferFunction_ITU_R_2100_HLG as String
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let pq = kCMFormatDescriptionTransferFunction_SMPTE_ST_2084_PQ as String
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isHDR = transfer == hlg || transfer == pq
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}
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}
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}
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let rotation = rotationFromTransform(preferredTransform)
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let isRotated = rotation == 90 || rotation == 270
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let width = isRotated ? Int(naturalSize.height) : Int(naturalSize.width)
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let height = isRotated ? Int(naturalSize.width) : Int(naturalSize.height)
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let audioTracks = try await asset.loadTracks(withMediaType: .audio)
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let hasAudio = !audioTracks.isEmpty
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let fileSize: Int
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if let attributes = try? FileManager.default.attributesOfItem(atPath: url.path),
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let size = attributes[.size] as? Int {
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fileSize = size
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} else {
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fileSize = 0
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}
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let mimeType: String
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if let utType = UTType(filenameExtension: url.pathExtension) {
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mimeType = utType.preferredMIMEType ?? "video/mp4"
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} else {
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mimeType = "video/mp4"
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}
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let durationSeconds = CMTimeGetSeconds(duration)
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var bitrate = Int(estimatedDataRate)
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if bitrate == 0 && durationSeconds > 0 {
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bitrate = Int(Double(fileSize * 8) / durationSeconds)
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}
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return [
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"width": width,
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"height": height,
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"duration": durationSeconds,
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"bitrate": bitrate,
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"fileSize": fileSize,
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"mimeType": mimeType,
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"codec": codec,
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"hasAudio": hasAudio,
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"frameRate": nominalFrameRate,
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"rotation": rotation,
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"isHDR": isHDR
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]
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}
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private static func rotationFromTransform(_ transform: CGAffineTransform) -> Int {
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let angle = atan2(transform.b, transform.a)
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let degrees = Int(round(angle * 180.0 / .pi))
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return ((degrees % 360) + 360) % 360
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}
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private static func fourCCToString(_ code: FourCharCode) -> String {
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let chars: [Character] = [
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Character(UnicodeScalar((code >> 24) & 0xFF)!),
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Character(UnicodeScalar((code >> 16) & 0xFF)!),
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Character(UnicodeScalar((code >> 8) & 0xFF)!),
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Character(UnicodeScalar(code & 0xFF)!)
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]
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return String(chars).trimmingCharacters(in: .whitespaces)
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}
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}
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