如何使用AVCaptureDeviceFormat从iPhone录制缩时视频? [英] How to record timelapse video from iPhone using AVCaptureDeviceFormat?
问题描述
我正在尝试通过iphone录制延时录像.我已经可以以120 fps的速度(通过捕获最大可能的帧数)来慢动作工作.
I am trying to record a timelapse video via iphone. I have already got it working for slow motion (by capturing maximum frames possible), with 120 fps.
现在，我正在尝试反转逻辑以捕获可能的最少帧，以实现延时功能.
Now I am trying to reverse the logic to capture least frames possible, to achieve timelapse functionality.
代码流是这样的:
-
从AVCaptureDevice的可用设备格式中查询所有受支持的帧范围.
Query all the supported frame range from the available device formats of the AVCaptureDevice.
检查帧频是否低于或等于所需的20 fps，尺寸是否等于或大于1920 * 1080.
Check if the frame rate is below or equal to the desired 20 fps and dimensions are equal to or greater than 1920*1080.
一切正常，除了当我按记录时，我得到"AVCaptureMovieFileOutput - no active/enabled connections"异常.我仅使用提供的帧频和范围之一，为什么会出现此异常?
All works fine except, when I press record, I get "AVCaptureMovieFileOutput - no active/enabled connections" exception. I am only using one of the provided frame rate and range, why am I getting this exception?
所有内容都能以30 fps的速度正常播放.
All works well for 30 fps.
#define kTimelapseRequiredFPS = 20
#define kMinRequiredDimensions (1920*1080)
- (void)configureCameraForSlowMoRecording:(AVCaptureDevice *)currentCaptureDevice
{
[_captureSession beginConfiguration];
AVCaptureDeviceFormat *bestFormat = nil;
AVFrameRateRange *bestFrameRateRange = nil;
for ( AVCaptureDeviceFormat *format in [currentCaptureDevice formats] )
{
//NSLog(@"Format: %@", format);
CMFormatDescriptionRef videoInfo = [format formatDescription];
double videoWidth = CMVideoFormatDescriptionGetDimensions(videoInfo).width;
double videoHeight = CMVideoFormatDescriptionGetDimensions(videoInfo).height;
double dimensions = videoWidth * videoHeight;
for ( AVFrameRateRange *range in format.videoSupportedFrameRateRanges )
{
//NSLog(@"Range: %@", range);
if ((range.maxFrameRate <= kTimelapseRequiredFPS) && (dimensions >= kMinRequiredDimensions))
{
bestFormat = format;
bestFrameRateRange = range;
}
}
}
if ( bestFormat )
{
NSLog(@"Final format: %@, Final range %@", bestFormat, bestFrameRateRange);
if ( [currentCaptureDevice lockForConfiguration:NULL] == YES )
{
currentCaptureDevice.activeFormat = bestFormat;
currentCaptureDevice.activeVideoMinFrameDuration = bestFrameRateRange.minFrameDuration;
currentCaptureDevice.activeVideoMaxFrameDuration = bestFrameRateRange.minFrameDuration;
[currentCaptureDevice unlockForConfiguration];
}
}
[_captureSession commitConfiguration];
}
以下是20 fps的帧率和范围的日志:
Here is the log of frame rate and range with 20 fps:
Format: <AVCaptureDeviceFormat: 0x1765f7a0 'vide'/'420v' 2592x1936, { 1- 20 fps}, fov:56.700, max zoom:153.00 (upscales @1.26), AF System:1, ISO:46.0-736.0, SS:0.000018-1.000000>
Range: <AVFrameRateRange: 0x176556d0 1 - 20>
Format: <AVCaptureDeviceFormat: 0x1765f750 'vide'/'420f' 2592x1936, { 1- 20 fps}, fov:56.700, max zoom:153.00 (upscales @1.26), AF System:1, ISO:46.0-736.0, SS:0.000018-1.000000>
Range: <AVFrameRateRange: 0x1750db10 1 - 20>
Format: <AVCaptureDeviceFormat: 0x1765f740 'vide'/'420v' 3264x2448, { 1- 20 fps}, fov:56.700, max zoom:153.00 (upscales @1.00), AF System:1, ISO:46.0-736.0, SS:0.000018-1.000000>
Range: <AVFrameRateRange: 0x1750dc80 1 - 20>
Format: <AVCaptureDeviceFormat: 0x1765f6f0 'vide'/'420f' 3264x2448, { 1- 20 fps}, fov:56.700, max zoom:153.00 (upscales @1.00), AF System:1, ISO:46.0-736.0, SS:0.000018-1.000000>
Range: <AVFrameRateRange: 0x1751a260 1 - 20>
推荐答案
不确定是否解决了这个问题，但是我一直在努力使慢动作开始起作用，并且也不断得到"AVCaptureMovieFileOutput - no active/enabled connections"(所以我真的很想知道你如何得到它可以工作:D).但是无论如何我都解决了它，以下是一些棘手的东西，我认为它们也可以解决您的问题:
Not sure if this is solved, but I was struggling in making slow motion to work, and kept getting "AVCaptureMovieFileOutput - no active/enabled connections" too (so I really wonder how you get it to work :D ). But anyways I solved it, and here are some tricky stuff that I think might as well solve your problem:
- 在设置
activeFormat之前，请确保已设置一些预设.事实证明，iOS不仅会自动处理其他内容.我所做的是先设置AVCaptureSession.Preset.hd1280x720，然后再设置activeFormat到具有120fps的帧. -
完成上述操作后，我开始获得
Error Domain=AVFoundationErrorDomain Code=-11803 "Cannot Record" UserInfo=0x152e60 {NSLocalizedRecoverySuggestion=Try recording again., AVErrorRecordingSuccessfullyFinishedKey=false, NSLocalizedDescription=Cannot Record}.我找不到任何可能的原因-连接正常，会话正在运行.因此，我再次按下了录制按钮，它开始录制(哇，真的吗?只是从字面上重试"?)我想iOS只是有些发脾气，还需要考虑更长的录制时间.因此，我添加了一个递归函数来给movieFileOutput一些记录时间. (很抱歉，它在Swift中)
- Make sure that you set some preset before setting
activeFormat. Turns out iOS won't just handle other stuff automatically. What I did is setAVCaptureSession.Preset.hd1280x720before setting theactiveFormatto the one with 120fps. After I did the above, I started to get
Error Domain=AVFoundationErrorDomain Code=-11803 "Cannot Record" UserInfo=0x152e60 {NSLocalizedRecoverySuggestion=Try recording again., AVErrorRecordingSuccessfullyFinishedKey=false, NSLocalizedDescription=Cannot Record}. I couldn't find any possible cause - the connection was fine, the session was running. So I pressed the record button again, and it starts to record (Wow, really? Just literally "try again"?) I guess iOS's just got some temper and has to think a little bit longer to record. So I added a recursive function to givemovieFileOutputsome time to record. (Sorry it's in Swift)
fileprivate func startRecording(to moviePath: URL) {
sessionQueue.async {
self.movieFileOutput.startRecording(to: moviePath, recordingDelegate: self)
if self.movieFileOutput.isRecording {
self.sessionQueue.asyncAfter(deadline: .now() + self.duration) {
self.stopRecording()
}
} else {
self.startRecording(to: moviePath)
}
}
}
希望它会有所帮助(或也许其他像我一样偶然发现此线程的人.)
Hope it'll help (or maybe others who just stumble on this thread just like I did.)
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