简短问题：
尝试以59fps录制时获取异常。如何解决？
2014-09-16 15：16：27.740 RosyWriter [2294：60b] **终止app到期 未被捕获的异常'NSInvalidArgumentException'，原因：' 接收方不支持传递的activeVideoMaxFrameDuration 活动格式。使用-activeFormat.videoSupportedFrameRateRanges 发现有效范围。
我的问题详情：
我想做什么？
尝试以 30+ fps（60 fps或更高fps ）录制视频。
到目前为止我尝试了什么？
AVCaptureConnection *conn = [output connectionWithMediaType:AVMediaTypeVideo];
CMTimeShow(conn.videoMinFrameDuration);
CMTimeShow(conn.videoMaxFrameDuration);
if (conn.isVideoMinFrameDurationSupported)
conn.videoMinFrameDuration = CMTimeMake(1, CAPTURE_FRAMES_PER_SECOND);
if (conn.isVideoMaxFrameDurationSupported)
conn.videoMaxFrameDuration = CMTimeMake(1, CAPTURE_FRAMES_PER_SECOND);
参考： 根据头文件（AVCaptureSession.h），
iOS上不推荐使用此属性，其中使用activeVideoMinFrameDuration和activeVideoMaxFrameDuration属性在AVCaptureDevice上专门应用最小和最大帧速率调整。
然后，我尝试使用“AVCaptureDevice”，如下所示：
-(void)setupCaptureSession
{
if ( _captureSession ) {
return;
}
_captureSession = [[AVCaptureSession alloc] init];
AVCaptureDevice *videoDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
....................................
....................................
_videoConnection = [videoOut connectionWithMediaType:AVMediaTypeVideo];
int frameRate;
NSString *sessionPreset = AVCaptureSessionPreset640x480;
CMTime frameDuration = kCMTimeInvalid;
// For single core systems like iPhone 4 and iPod Touch 4th Generation wI
//use a lower resolution and framerate to maintain real-time performance.
if ( [[NSProcessInfo processInfo] processorCount] == 1 )
{
if ( [_captureSession canSetSessionPreset:AVCaptureSessionPreset1280x720] ) {
sessionPreset = AVCaptureSessionPreset1280x720;
}
frameRate = 59;
}
else
{
// USE_GPU_RENDERER is set in the project's build settings
#if ! use_gpu_renderer
// When using the CPU renderer we lower the resolution to 720p so that all devices can maintain real-time performance (this is primarily for A5 based devices like iPhone 4s and iPod Touch 5th Generation).
if ( [_captureSession canSetSessionPreset:AVCaptureSessionPreset640x480] ) {
sessionPreset = AVCaptureSessionPreset640x480;
}
#endif // ! use_gpu_renderer
frameRate = 59;
}
_captureSession.sessionPreset = sessionPreset;
frameDuration = CMTimeMake( 1, frameRate );
NSError *error = nil;
if ( [videoDevice lockForConfiguration:&error] ) {
videoDevice.activeFormat = bestFormat;
[**videoDevice setActiveVideoMaxFrameDuration:frameDuration];
[videoDevice setActiveVideoMinFrameDuration:frameDuration**];
[videoDevice unlockForConfiguration];
}
else {
NSLog(@"videoDevice lockForConfiguration returned error %@", error);
}
self.videoOrientation = [_videoConnection videoOrientation];
[videoOut release];
return;
}
我的问题：
2014-09-16 15:16:27.740 RosyWriter[2294:60b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'The activeVideoMaxFrameDuration passed is not supported by the receiver's active format. Use -activeFormat.videoSupportedFrameRateRanges to discover valid ranges.'
*** First throw call stack:
(0x2da2ff83 0x385d2ccf 0x2c919e4f 0xb4c7d 0xb4317 0x38aba81f 0x38ac07cb 0xb42b1 0xb2539 0x302676df 0x30258e89 0x3025864d 0x302584bf 0x30257fe5 0x30255827 0x302bf33d 0x302bbfad 0x302b656b 0x302526e9 0x30251851 0x302b5ca9 0x3288baed 0x3288b6d7 0x2d9faa67 0x2d9faa03 0x2d9f91d7 0x2d963ebf 0x2d963ca3 0x302b4ed1 0x302b014d 0xb1b4d 0x38adfab7)
libc++abi.dylib: terminating with uncaught exception of type NSException
我在这里做错了吗？
稍后，我将代码更改为
AVCaptureDeviceFormat *bestFormat = nil;
AVFrameRateRange *bestFrameRateRange = nil;
for ( AVCaptureDeviceFormat *format in [videoDevice formats] ) {
for ( AVFrameRateRange *range in format.videoSupportedFrameRateRanges ) {
if ( range.maxFrameRate > bestFrameRateRange.maxFrameRate ) {
bestFormat = format;
bestFrameRateRange = range;
}
}
}
NSError *error = nil;
if ( bestFormat ) {
if ( [videoDevice lockForConfiguration:&error] ) {
videoDevice.activeFormat = bestFormat;
videoDevice.activeVideoMinFrameDuration = bestFrameRateRange.minFrameDuration;
videoDevice.activeVideoMaxFrameDuration = bestFrameRateRange.maxFrameDuration;
[videoDevice unlockForConfiguration];
}}
但我得到的视频以30fps的速度使用bestFrameRateRange录制，但不是以59fps录制..
答案 0 :(得分：0)
以下是如何使用更高帧速率的工作示例：
查找并设置活动模式以使用可用的最大帧速率。
float maxFrameRate = 0.0;
int maxIndex = 0;
for(int i=0;i<_videoCaptureDevice.formats.count;i++) {
AVCaptureDeviceFormat *format = [_videoCaptureDevice.formats objectAtIndex:i];
AVFrameRateRange *frameRateRange = [format.videoSupportedFrameRateRanges firstObject];
//You can add hard coded checking for specific format like if(frameRateRange.maxFrameRate == 240) etc I am using the max one
if(maxFrameRate<frameRateRange.maxFrameRate) {
maxFrameRate = frameRateRange.maxFrameRate;
maxIndex = i;
}
}
AVCaptureDeviceFormat *format = [_videoCaptureDevice.formats objectAtIndex:maxIndex];
AVFrameRateRange *frameRateRange = [format.videoSupportedFrameRateRanges firstObject];
[self.videoCaptureDevice lockForConfiguration:nil];
self.videoCaptureDevice.activeFormat = format;
self.videoCaptureDevice.activeVideoMinFrameDuration = frameRateRange.minFrameDuration;
self.videoCaptureDevice.activeVideoMaxFrameDuration = frameRateRange.maxFrameDuration;
[self.videoCaptureDevice unlockForConfiguration];
之后改变帧速率
if(YourFrameRate<=frameRateRange.maxFrameRate && YourFrameRate>=frameRateRange.minFrameRate) {
if([device lockForConfiguration:&error]) {
[device setActiveVideoMinFrameDuration:CMTimeMake(1, YourFrameRate)];
[device setActiveVideoMaxFrameDuration:CMTimeMake(1, YourFrameRate)];
[device unlockForConfiguration];
} else {
[self passError:error];
}
}
从here
得到答案答案 1 :(得分：0)
您应将有效格式设置为AVCaptureDevice。
您可以做到
// get device what you like
let device = xxxxx
// list all default formats for this device
for format in device.formats {
var founded = false
// check what you want and pick a perfect format.
let formatDesc = format.formatDescription
// mediaType / SubType
let mediaType = format.mediaSubType
// if your target is above(equal) iOS 13. use formatDesc.mediaSubType
let mediaSubType = CMFormatDescriptionGetMediaSubType(formatDesc)
// dimensions
// if your target is above(equal) iOS 13. use formatDesc.dimensions
let dimensions = CMVideoFormatDescriptionGetDimensions(formatDesc)
// fps
let ranges = format.videoSupportedFrameRateRanges.first
for supportedFPSRange in ranges {
if supportedFPSRange.maxFrameRate == 60 {
founded = true
}
}
// support Multi cam
let isMultiCamSupported = format.isMultiCamSupported
....
if founded {
// Set activeFormat for device! Your capture device is up and loaded.
do {
try device.lockForConfiguration()
device.activeFormat = format
device.unlockForConfiguration()
} catch {
// catch some locking error
}
// Don't forget break the loop.:p
break
}
}