我如何使用 AVCaptureSession 和 swift (IOS 8) 在 mpeg4 容器中录制 mp4 视频
How can i record an mp4 video in mpeg4 container with AVCaptureSession with swift (IOS 8)
我会回答我自己的问题来分享我的经验，因为互联网上没有完整的工作代码。
IOS 设备通常将视频录制为 .mov 格式的 quicktime 文件。即使输出视频有 AVC 基线视频编解码器和 AAC 音频编解码器，生成的文件也会在 quicktime 容器中。这些视频可能无法在 android 台设备上播放。 Apple 有 Avfoundation 类，如 AvCaptureSession 和 AVCaptureMovieFileOutput，但它们不直接支持 mp4 文件输出。我如何在支持 swift 和 IOS 8 的 mpeg4 容器中录制实际的 mp4 视频？
首先要做的是：这可能不是最好的解决方案，但这是一个完整的解决方案。
下面的代码使用 AvCaptureSession 捕获视频和音频，并使用 AvExportSession 将其转换为 mpeg4。还有放大、缩小和切换相机功能以及权限检查。您可以录制 480p 或 720p。您还可以设置最小和最大帧速率以创建较小的视频。希望这有助于作为一个完整的指南。
注意：info.plist 中有一些键可以请求相机和照片库权限：
<key>NSCameraUsageDescription</key>
<string>Yo, this is a cam app.</string>
<key>NSPhotoLibraryUsageDescription</key>
<string>Yo, i need to access your photos.</string>
<key>NSMicrophoneUsageDescription</key>
<string>Yo, i can't hear you</string>
代码：
import UIKit
import Photos
import AVFoundation
class VideoAct: UIViewController, AVCaptureFileOutputRecordingDelegate
{
let captureSession : AVCaptureSession = AVCaptureSession()
var captureDevice : AVCaptureDevice!
var microphone : AVCaptureDevice!
var previewLayer : AVCaptureVideoPreviewLayer!
let videoFileOutput : AVCaptureMovieFileOutput = AVCaptureMovieFileOutput()
var duration : Int = 30
var v_path : URL = URL(fileURLWithPath: "")
var my_timer : Timer = Timer()
var cameraFront : Bool = false
var cameras_number : Int = 0
var max_zoom : CGFloat = 76
var devices : [AVCaptureDevice] = []
var captureInput : AVCaptureDeviceInput = AVCaptureDeviceInput()
var micInput : AVCaptureDeviceInput = AVCaptureDeviceInput()
@IBOutlet weak var cameraView: UIView!
override func viewDidLoad()
{
super.viewDidLoad()
if (check_permissions())
{
initialize()
}
else
{
AVCaptureDevice.requestAccess(forMediaType: AVMediaTypeVideo, completionHandler: { (granted) in
if (granted)
{
self.initialize()
}
else
{
self.dismiss(animated: true, completion: nil)
}
})
}
}
func check_permissions() -> Bool
{
return AVCaptureDevice.authorizationStatus(forMediaType: AVMediaTypeVideo) == AVAuthorizationStatus.authorized
}
@available(iOS 4.0, *)
func capture(_ captureOutput: AVCaptureFileOutput!, didFinishRecordingToOutputFileAt outputFileURL: URL!, fromConnections connections: [Any]!, error: Error!)
{
//you can implement stopvideoaction here if you want
}
func initialize()
{
let directory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0]
v_path = directory.appendingPathComponent("temp_video.mp4")
// we just set the extension .mp4 but
// actually it is a mov file with QT container !! May not play in Android devices.
// it will be ceonverted
self.duration = 30
devices = AVCaptureDevice.devices() as! [AVCaptureDevice]
for device in devices
{
if (device.hasMediaType(AVMediaTypeVideo))
{
if (device.position == AVCaptureDevicePosition.back)
{
captureDevice = device as AVCaptureDevice
}
if (device.position == AVCaptureDevicePosition.front)
{
cameras_number = 2
}
}
if (device.hasMediaType(AVMediaTypeAudio))
{
microphone = device as AVCaptureDevice
}
}
if (cameras_number == 1)
{
//only 1 camera available
btnSwitchCamera.isHidden = true
}
if captureDevice != nil
{
beginSession()
}
max_zoom = captureDevice.activeFormat.videoMaxZoomFactor
}
func beginSession()
{
if (captureSession.isRunning)
{
captureSession.stopRunning()
}
do
{
try captureInput = AVCaptureDeviceInput(device: captureDevice)
try micInput = AVCaptureDeviceInput(device: microphone)
try captureDevice.lockForConfiguration()
}
catch
{
print("errorrrrrrrrrrr \(error)")
}
// beginconfig before adding input and setting settings
captureSession.beginConfiguration()
captureSession.addInput(captureInput)
captureSession.addInput(micInput)
previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
previewLayer.connection.videoOrientation = AVCaptureVideoOrientation.init(rawValue: UIDevice.current.orientation.rawValue)!
if (previewLayer.connection.isVideoStabilizationSupported)
{
previewLayer.connection.preferredVideoStabilizationMode = AVCaptureVideoStabilizationMode.auto
}
if (captureDevice.isSmoothAutoFocusSupported)
{
captureDevice.isSmoothAutoFocusEnabled = false
}
if (captureDevice.isFocusModeSupported(AVCaptureFocusMode.continuousAutoFocus))
{
captureDevice.focusMode = .continuousAutoFocus
}
set_preview_size_thing()
set_quality_thing()
if (captureDevice.isLowLightBoostSupported)
{
captureDevice.automaticallyEnablesLowLightBoostWhenAvailable = true
}
if (cameraView.layer.sublayers?[0] is AVCaptureVideoPreviewLayer)
{
//to prevent previewlayers stacking on every camera switch
cameraView.layer.sublayers?.remove(at: 0)
}
cameraView.layer.insertSublayer(previewLayer, at: 0)
previewLayer?.frame = cameraView.layer.frame
captureSession.commitConfiguration()
captureSession.startRunning()
}
func duration_thing()
{
// there is a textview to write remaining time left
self.duration = self.duration - 1
timerTextView.text = "remaining seconds: \(self.duration)"
timerTextView.sizeToFit()
if (self.duration == 0)
{
my_timer.invalidate()
stopVideoAction()
}
}
func switch_cam()
{
captureSession.removeInput(captureInput)
captureSession.removeInput(micInput)
cameraFront = !cameraFront
// capturedevice will be locked again
captureDevice.unlockForConfiguration()
for device in devices
{
if (device.hasMediaType(AVMediaTypeVideo))
{
if (device.position == AVCaptureDevicePosition.back && !cameraFront)
{
captureDevice = device as AVCaptureDevice
}
else if (device.position == AVCaptureDevicePosition.front && cameraFront)
{
captureDevice = device as AVCaptureDevice
}
}
}
beginSession()
}
func zoom_in()
{
// 10x zoom would be enough
if (captureDevice.videoZoomFactor * 1.5 < 10)
{
captureDevice.videoZoomFactor = captureDevice.videoZoomFactor * 1.5
}
else
{
captureDevice.videoZoomFactor = 10
}
}
func zoom_out()
{
if (captureDevice.videoZoomFactor * 0.67 > 1)
{
captureDevice.videoZoomFactor = captureDevice.videoZoomFactor * 0.67
}
else
{
captureDevice.videoZoomFactor = 1
}
}
func set_quality_thing()
{
// there is a switch in the screen (30-30 fps high quality or 15-23 fps normal quality)
// you may not have to do this because export session also has some presets and a property called “optimizefornetwork” or something. But it would be better to make sure the output file is not huge with unnecessary 90 fps video
captureDevice.activeVideoMinFrameDuration = CMTimeMake(1, switch_quality.isOn ? 30 : 15)
captureDevice.activeVideoMaxFrameDuration = CMTimeMake(1, switch_quality.isOn ? 30 : 23)
}
func set_preview_size_thing()
{
//there is a switch for resolution (720p or 480p)
captureSession.sessionPreset = switch_res.isOn ? AVCaptureSessionPreset1280x720 : AVCaptureSessionPreset640x480
//this for loop is probably unnecessary and ridiculous but you can make sure you are using the right format
for some_format in captureDevice.formats as! [AVCaptureDeviceFormat]
{
let some_desc : String = String(describing: some_format)
if (switch_res.isOn)
{
if (some_desc.contains("1280x") && some_desc.contains("720") && some_desc.contains("420v") && some_desc.contains("30 fps"))
{
captureDevice.activeFormat = some_format
break
}
}
else
{
if (some_desc.contains("640x") && some_desc.contains("480") && some_desc.contains("420v"))
{
captureDevice.activeFormat = some_format
break
}
}
}
}
func takeVideoAction()
{
// movieFragmentInterval is important !! or you may end up with a video without audio
videoFileOutput.movieFragmentInterval = kCMTimeInvalid
captureSession.addOutput(videoFileOutput)
(videoFileOutput.connections.first as! AVCaptureConnection).videoOrientation = returnedOrientation()
videoFileOutput.maxRecordedDuration = CMTime(seconds: Double(self.duration), preferredTimescale: 1)
videoFileOutput.startRecording(toOutputFileURL: v_path, recordingDelegate: self)
//timer will tell the remaining time
my_timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(duration_thing), userInfo: nil, repeats: true)
}
func stopVideoAction()
{
captureDevice.unlockForConfiguration()
videoFileOutput.stopRecording()
captureSession.stopRunning()
// turn temp_video into an .mpeg4 (mp4) video
let directory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0]
let avAsset = AVURLAsset(url: v_path, options: nil)
// there are other presets than AVAssetExportPresetPassthrough
let exportSession = AVAssetExportSession(asset: avAsset, presetName: AVAssetExportPresetPassthrough)!
exportSession.outputURL = directory.appendingPathComponent("main_video.mp4")
// now it is actually in an mpeg4 container
exportSession.outputFileType = AVFileTypeMPEG4
let start = CMTimeMakeWithSeconds(0.0, 0)
let range = CMTimeRangeMake(start, avAsset.duration)
exportSession.timeRange = range
exportSession.exportAsynchronously(completionHandler: {
if (exportSession.status == AVAssetExportSessionStatus.completed)
{
// you don’t need temp video after exporting main_video
do
{
try FileManager.default.removeItem(atPath: self.v_path.path)
}
catch
{
}
// v_path is now points to mp4 main_video
self.v_path = directory.appendingPathComponent("main_video.mp4")
self.performSegue(withIdentifier: "ShareVideoController", sender: nil)
}
})
}
func btn_capture_click_listener()
{
if (videoFileOutput.isRecording)
{
stopVideoAction()
}
else
{
takeVideoAction()
}
}
func returnedOrientation() -> AVCaptureVideoOrientation
{
var videoOrientation: AVCaptureVideoOrientation!
let orientation = UIDevice.current.orientation
switch orientation
{
case .landscapeLeft:
videoOrientation = .landscapeRight
case .landscapeRight:
videoOrientation = .landscapeLeft
default:
videoOrientation = .landscapeLeft
}
return videoOrientation
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?)
{
if (segue.identifier == "ShareVideoController")
{
//to make it visible in the camera roll (main_video.mp4)
PHPhotoLibrary.shared().performChanges({PHAssetChangeRequest.creationRequestForAssetFromVideo(atFileURL: self.v_path)}) { completed, error in}
let destVC : ShareVideoController = segue.destination as! ShareVideoController
// use the path in other screen to upload it or whatever
destVC.videoFilePath = v_path
// bla bla
}
}
override var supportedInterfaceOrientations: UIInterfaceOrientationMask
{
// screen will always be in landscape (remove this override if you want)
return .landscape
}
}
我会回答我自己的问题来分享我的经验，因为互联网上没有完整的工作代码。
IOS 设备通常将视频录制为 .mov 格式的 quicktime 文件。即使输出视频有 AVC 基线视频编解码器和 AAC 音频编解码器，生成的文件也会在 quicktime 容器中。这些视频可能无法在 android 台设备上播放。 Apple 有 Avfoundation 类，如 AvCaptureSession 和 AVCaptureMovieFileOutput，但它们不直接支持 mp4 文件输出。我如何在支持 swift 和 IOS 8 的 mpeg4 容器中录制实际的 mp4 视频？
首先要做的是：这可能不是最好的解决方案，但这是一个完整的解决方案。
下面的代码使用 AvCaptureSession 捕获视频和音频，并使用 AvExportSession 将其转换为 mpeg4。还有放大、缩小和切换相机功能以及权限检查。您可以录制 480p 或 720p。您还可以设置最小和最大帧速率以创建较小的视频。希望这有助于作为一个完整的指南。
注意：info.plist 中有一些键可以请求相机和照片库权限：
<key>NSCameraUsageDescription</key>
<string>Yo, this is a cam app.</string>
<key>NSPhotoLibraryUsageDescription</key>
<string>Yo, i need to access your photos.</string>
<key>NSMicrophoneUsageDescription</key>
<string>Yo, i can't hear you</string>
代码：
import UIKit
import Photos
import AVFoundation
class VideoAct: UIViewController, AVCaptureFileOutputRecordingDelegate
{
let captureSession : AVCaptureSession = AVCaptureSession()
var captureDevice : AVCaptureDevice!
var microphone : AVCaptureDevice!
var previewLayer : AVCaptureVideoPreviewLayer!
let videoFileOutput : AVCaptureMovieFileOutput = AVCaptureMovieFileOutput()
var duration : Int = 30
var v_path : URL = URL(fileURLWithPath: "")
var my_timer : Timer = Timer()
var cameraFront : Bool = false
var cameras_number : Int = 0
var max_zoom : CGFloat = 76
var devices : [AVCaptureDevice] = []
var captureInput : AVCaptureDeviceInput = AVCaptureDeviceInput()
var micInput : AVCaptureDeviceInput = AVCaptureDeviceInput()
@IBOutlet weak var cameraView: UIView!
override func viewDidLoad()
{
super.viewDidLoad()
if (check_permissions())
{
initialize()
}
else
{
AVCaptureDevice.requestAccess(forMediaType: AVMediaTypeVideo, completionHandler: { (granted) in
if (granted)
{
self.initialize()
}
else
{
self.dismiss(animated: true, completion: nil)
}
})
}
}
func check_permissions() -> Bool
{
return AVCaptureDevice.authorizationStatus(forMediaType: AVMediaTypeVideo) == AVAuthorizationStatus.authorized
}
@available(iOS 4.0, *)
func capture(_ captureOutput: AVCaptureFileOutput!, didFinishRecordingToOutputFileAt outputFileURL: URL!, fromConnections connections: [Any]!, error: Error!)
{
//you can implement stopvideoaction here if you want
}
func initialize()
{
let directory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0]
v_path = directory.appendingPathComponent("temp_video.mp4")
// we just set the extension .mp4 but
// actually it is a mov file with QT container !! May not play in Android devices.
// it will be ceonverted
self.duration = 30
devices = AVCaptureDevice.devices() as! [AVCaptureDevice]
for device in devices
{
if (device.hasMediaType(AVMediaTypeVideo))
{
if (device.position == AVCaptureDevicePosition.back)
{
captureDevice = device as AVCaptureDevice
}
if (device.position == AVCaptureDevicePosition.front)
{
cameras_number = 2
}
}
if (device.hasMediaType(AVMediaTypeAudio))
{
microphone = device as AVCaptureDevice
}
}
if (cameras_number == 1)
{
//only 1 camera available
btnSwitchCamera.isHidden = true
}
if captureDevice != nil
{
beginSession()
}
max_zoom = captureDevice.activeFormat.videoMaxZoomFactor
}
func beginSession()
{
if (captureSession.isRunning)
{
captureSession.stopRunning()
}
do
{
try captureInput = AVCaptureDeviceInput(device: captureDevice)
try micInput = AVCaptureDeviceInput(device: microphone)
try captureDevice.lockForConfiguration()
}
catch
{
print("errorrrrrrrrrrr \(error)")
}
// beginconfig before adding input and setting settings
captureSession.beginConfiguration()
captureSession.addInput(captureInput)
captureSession.addInput(micInput)
previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
previewLayer.connection.videoOrientation = AVCaptureVideoOrientation.init(rawValue: UIDevice.current.orientation.rawValue)!
if (previewLayer.connection.isVideoStabilizationSupported)
{
previewLayer.connection.preferredVideoStabilizationMode = AVCaptureVideoStabilizationMode.auto
}
if (captureDevice.isSmoothAutoFocusSupported)
{
captureDevice.isSmoothAutoFocusEnabled = false
}
if (captureDevice.isFocusModeSupported(AVCaptureFocusMode.continuousAutoFocus))
{
captureDevice.focusMode = .continuousAutoFocus
}
set_preview_size_thing()
set_quality_thing()
if (captureDevice.isLowLightBoostSupported)
{
captureDevice.automaticallyEnablesLowLightBoostWhenAvailable = true
}
if (cameraView.layer.sublayers?[0] is AVCaptureVideoPreviewLayer)
{
//to prevent previewlayers stacking on every camera switch
cameraView.layer.sublayers?.remove(at: 0)
}
cameraView.layer.insertSublayer(previewLayer, at: 0)
previewLayer?.frame = cameraView.layer.frame
captureSession.commitConfiguration()
captureSession.startRunning()
}
func duration_thing()
{
// there is a textview to write remaining time left
self.duration = self.duration - 1
timerTextView.text = "remaining seconds: \(self.duration)"
timerTextView.sizeToFit()
if (self.duration == 0)
{
my_timer.invalidate()
stopVideoAction()
}
}
func switch_cam()
{
captureSession.removeInput(captureInput)
captureSession.removeInput(micInput)
cameraFront = !cameraFront
// capturedevice will be locked again
captureDevice.unlockForConfiguration()
for device in devices
{
if (device.hasMediaType(AVMediaTypeVideo))
{
if (device.position == AVCaptureDevicePosition.back && !cameraFront)
{
captureDevice = device as AVCaptureDevice
}
else if (device.position == AVCaptureDevicePosition.front && cameraFront)
{
captureDevice = device as AVCaptureDevice
}
}
}
beginSession()
}
func zoom_in()
{
// 10x zoom would be enough
if (captureDevice.videoZoomFactor * 1.5 < 10)
{
captureDevice.videoZoomFactor = captureDevice.videoZoomFactor * 1.5
}
else
{
captureDevice.videoZoomFactor = 10
}
}
func zoom_out()
{
if (captureDevice.videoZoomFactor * 0.67 > 1)
{
captureDevice.videoZoomFactor = captureDevice.videoZoomFactor * 0.67
}
else
{
captureDevice.videoZoomFactor = 1
}
}
func set_quality_thing()
{
// there is a switch in the screen (30-30 fps high quality or 15-23 fps normal quality)
// you may not have to do this because export session also has some presets and a property called “optimizefornetwork” or something. But it would be better to make sure the output file is not huge with unnecessary 90 fps video
captureDevice.activeVideoMinFrameDuration = CMTimeMake(1, switch_quality.isOn ? 30 : 15)
captureDevice.activeVideoMaxFrameDuration = CMTimeMake(1, switch_quality.isOn ? 30 : 23)
}
func set_preview_size_thing()
{
//there is a switch for resolution (720p or 480p)
captureSession.sessionPreset = switch_res.isOn ? AVCaptureSessionPreset1280x720 : AVCaptureSessionPreset640x480
//this for loop is probably unnecessary and ridiculous but you can make sure you are using the right format
for some_format in captureDevice.formats as! [AVCaptureDeviceFormat]
{
let some_desc : String = String(describing: some_format)
if (switch_res.isOn)
{
if (some_desc.contains("1280x") && some_desc.contains("720") && some_desc.contains("420v") && some_desc.contains("30 fps"))
{
captureDevice.activeFormat = some_format
break
}
}
else
{
if (some_desc.contains("640x") && some_desc.contains("480") && some_desc.contains("420v"))
{
captureDevice.activeFormat = some_format
break
}
}
}
}
func takeVideoAction()
{
// movieFragmentInterval is important !! or you may end up with a video without audio
videoFileOutput.movieFragmentInterval = kCMTimeInvalid
captureSession.addOutput(videoFileOutput)
(videoFileOutput.connections.first as! AVCaptureConnection).videoOrientation = returnedOrientation()
videoFileOutput.maxRecordedDuration = CMTime(seconds: Double(self.duration), preferredTimescale: 1)
videoFileOutput.startRecording(toOutputFileURL: v_path, recordingDelegate: self)
//timer will tell the remaining time
my_timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(duration_thing), userInfo: nil, repeats: true)
}
func stopVideoAction()
{
captureDevice.unlockForConfiguration()
videoFileOutput.stopRecording()
captureSession.stopRunning()
// turn temp_video into an .mpeg4 (mp4) video
let directory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0]
let avAsset = AVURLAsset(url: v_path, options: nil)
// there are other presets than AVAssetExportPresetPassthrough
let exportSession = AVAssetExportSession(asset: avAsset, presetName: AVAssetExportPresetPassthrough)!
exportSession.outputURL = directory.appendingPathComponent("main_video.mp4")
// now it is actually in an mpeg4 container
exportSession.outputFileType = AVFileTypeMPEG4
let start = CMTimeMakeWithSeconds(0.0, 0)
let range = CMTimeRangeMake(start, avAsset.duration)
exportSession.timeRange = range
exportSession.exportAsynchronously(completionHandler: {
if (exportSession.status == AVAssetExportSessionStatus.completed)
{
// you don’t need temp video after exporting main_video
do
{
try FileManager.default.removeItem(atPath: self.v_path.path)
}
catch
{
}
// v_path is now points to mp4 main_video
self.v_path = directory.appendingPathComponent("main_video.mp4")
self.performSegue(withIdentifier: "ShareVideoController", sender: nil)
}
})
}
func btn_capture_click_listener()
{
if (videoFileOutput.isRecording)
{
stopVideoAction()
}
else
{
takeVideoAction()
}
}
func returnedOrientation() -> AVCaptureVideoOrientation
{
var videoOrientation: AVCaptureVideoOrientation!
let orientation = UIDevice.current.orientation
switch orientation
{
case .landscapeLeft:
videoOrientation = .landscapeRight
case .landscapeRight:
videoOrientation = .landscapeLeft
default:
videoOrientation = .landscapeLeft
}
return videoOrientation
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?)
{
if (segue.identifier == "ShareVideoController")
{
//to make it visible in the camera roll (main_video.mp4)
PHPhotoLibrary.shared().performChanges({PHAssetChangeRequest.creationRequestForAssetFromVideo(atFileURL: self.v_path)}) { completed, error in}
let destVC : ShareVideoController = segue.destination as! ShareVideoController
// use the path in other screen to upload it or whatever
destVC.videoFilePath = v_path
// bla bla
}
}
override var supportedInterfaceOrientations: UIInterfaceOrientationMask
{
// screen will always be in landscape (remove this override if you want)
return .landscape
}
}