Transcode Media

Media files can also be transcoded without using UI.

This example stitches two AVAssets named “test.mov” and “test2.mp4” into a single 60 fps mp4 file with H.264 video encoding and stereo AAC audio encoding.

Additionally, a Saturation filter is applied to the first segment (asset), and a Pixellate filter is applied to the second segment.

import PixelSDK
import AVFoundation

let asset1 = AVAsset(url: Bundle.main.url(forResource: "test", withExtension: "mov")!)
let asset2 = AVAsset(url: Bundle.main.url(forResource: "test2", withExtension: "mp4")!)

let _ = Session(assets: [asset1, asset2], sessionReady: { (session, error) in
    guard let session = session,
        let video = session.video else {
        print("Unable to create session: \(error!)")
        return
    }

    // Mark the session as transient so it does not persist on disk/appear in the users drafts
    session.isTransient = true

    // Set the video frame rate to 60 fps
    video.frameDuration = CMTime(value: 1, timescale: 60)

    // Apply a Saturation filter to the first segment
    let saturationFilter = SessionFilterSaturation()
    saturationFilter.normalizedIntensity = 0.2
    video.videoSegments[0].filters = [saturationFilter]

    // Apply a Pixellate filter to the second segment
    let pixellateFilter = SessionFilterPixellate()
    video.videoSegments[1].filters = [pixellateFilter]

    // Write to an MP4 file with H.264 video encoding and stereo AAC audio encoding

    var acl = AudioChannelLayout()
    memset(&acl, 0, MemoryLayout<AudioChannelLayout>.size)
    acl.mChannelLayoutTag = kAudioChannelLayoutTag_Stereo

    let audioEncodingSettings: [String: Any] = [
        AVFormatIDKey: kAudioFormatMPEG4AAC,
        AVNumberOfChannelsKey: 2,
        AVSampleRateKey: AVAudioSession.sharedInstance().sampleRate,
        AVChannelLayoutKey: NSData(bytes:&acl, length:MemoryLayout<AudioChannelLayout>.size),
        AVEncoderBitRateKey: 96000
    ]

    let videoEncodingSettings: [String: Any] = [
        AVVideoCompressionPropertiesKey: [
            AVVideoProfileLevelKey: AVVideoProfileLevelH264HighAutoLevel,
            AVVideoH264EntropyModeKey: AVVideoH264EntropyModeCABAC],
        AVVideoCodecKey: AVVideoCodecType.h264
    ]

    VideoExporter.shared.export(video: video,
                                fileType: .mp4,
                                videoEncodingSettings: videoEncodingSettings,
                                audioEncodingSettings: audioEncodingSettings,
                                progress: { (progress) in
        print("Transcode progress: \(progress)")
    }, completion: { (error) in
        if let error = error {
            print("Unable to transcode video: \(error)")
            return
        }

        print("Finished video transcode at URL: \(video.exportedVideoURL)")
    })
})

After your transcode has completed, you may move, copy or delete the file found at the video.exportedVideoURL.

There are many combinations of encoding settings you can provide. They must conform to the specifications set forth in AVFoundations AVVideoSettings.h and AVAudioSettings.h headers. There is also a list of available codecs. Keep in mind each codec may have different requirements for the settings you provide.