iOS视频录制(断点录制)的全过程
2017-03-03 本文已影响1025人
茄子_Apple
目前发送动态仅仅能发送图片已经满足不了用户的需求了,应产品的需求,还需要处理发送视频,即视频录制和断点录制.
由于之前对这块的内容还相对比较陌生,基于最近的临时学习和整理,目前已完成视频的断点录制和视频播放等相关功能,在这里总结一下.
同时也能给自己留个记忆...
下面介绍一下视频录制需要用到的类:
- AVCaptureSession -- 是AVFoundation捕捉视频类的中心枢纽
- AVCaptureVideoPreviewLayer -- 视频录制展示的layer层
- AVCaptureDeviceInput -- 视频的输入设备
- AVCaptureConnection -- 代表AVCaptureInputPort或端口之间的连接,和一个AVCaptureOutput或AVCaptureVideoPreviewLayer在AVCaptureSession中的呈现
- AVCaptureVideoDataOutput -- 视频输出设备
- AVCaptureAudioDataOutput -- 语音输出设备
- AVAssetWriter -- 写入媒体数据到一个新的文件提供服务
- AVAssetWriterInput 拼接一个多媒体样本类型为CMSampleBuffer的实例到AVAssetWriter对象输出文件,为断点录制的关键
AVCaptureMovieFileOutput 这个类要慎用,可以生成视频文件,但是不能断点录制,也不能自定义文件的类型,值得注意
以上的对象分别采用懒加载实现,在viewDidLoad里面将其装载,还可以切换前后摄像头,实现代理方法,录制的过程中回调代理
实例化AVCaptureVideoDataOutput和AVCaptureAudioDataOutput时,相应的要设置代理,遵守的协议为:
AVCaptureAudioDataOutputSampleBufferDelegate
AVCaptureAudioDataOutputSampleBufferDelegate
例如:
[_videoOutput setSampleBufferDelegate:self queue:self.captureQueue];
[_audioOutput setSampleBufferDelegate:self queue:self.captureQueue];
//视频输出
- (AVCaptureVideoDataOutput *)videoOutput {
if (!_videoOutput) {
_videoOutput = [[AVCaptureVideoDataOutput alloc] init];
[_videoOutput setSampleBufferDelegate:self queue:self.captureQueue];
NSDictionary* setcapSettings = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithInt:kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange], kCVPixelBufferPixelFormatTypeKey,
nil];
_videoOutput.videoSettings = setcapSettings;
}
return _videoOutput;
}
//音频输出
- (AVCaptureAudioDataOutput *)audioOutput {
if (!_audioOutput) {
_audioOutput = [[AVCaptureAudioDataOutput alloc] init];
[_audioOutput setSampleBufferDelegate:self queue:self.captureQueue];
}
return _audioOutput;
}
实现其代理方法,写入数据, 获取CMSampleBufferRef对象,写入数据
#pragma mark - 写入数据
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection {
BOOL isVideo = YES;
@synchronized(self) {
if (!self.isCapturing || self.isPaused) {
return;
}
if (captureOutput != self.videoOutput) {
isVideo = NO;
}
//初始化编码器，当有音频和视频参数时创建编码器
if ((self.recordEncoder == nil) && !isVideo) {
CMFormatDescriptionRef fmt = CMSampleBufferGetFormatDescription(sampleBuffer);
[self setAudioFormat:fmt];
NSString *videoName = [self getUploadFile_type:@"video" fileType:@"mp4"];
self.videoPath = [[self getVideoCachePath] stringByAppendingPathComponent:videoName];
self.recordEncoder = [WCLRecordEncoder encoderForPath:self.videoPath Height:_cy width:_cx channels:_channels samples:_samplerate];
}
//判断是否中断录制过
if (self.discont) {
if (isVideo) {
return;
}
self.discont = NO;
// 计算暂停的时间
CMTime pts = CMSampleBufferGetPresentationTimeStamp(sampleBuffer);
CMTime last = isVideo ? _lastVideo : _lastAudio;
if (last.flags & kCMTimeFlags_Valid) {
if (_timeOffset.flags & kCMTimeFlags_Valid) {
pts = CMTimeSubtract(pts, _timeOffset);
}
CMTime offset = CMTimeSubtract(pts, last);
if (_timeOffset.value == 0) {
_timeOffset = offset;
}else {
_timeOffset = CMTimeAdd(_timeOffset, offset);
}
}
_lastVideo.flags = 0;
_lastAudio.flags = 0;
}
// 增加sampleBuffer的引用计时,这样我们可以释放这个或修改这个数据，防止在修改时被释放
CFRetain(sampleBuffer);
if (_timeOffset.value > 0) {
CFRelease(sampleBuffer);
//根据得到的timeOffset调整
sampleBuffer = [self adjustTime:sampleBuffer by:_timeOffset];
}
// 记录暂停上一次录制的时间
CMTime pts = CMSampleBufferGetPresentationTimeStamp(sampleBuffer);
CMTime dur = CMSampleBufferGetDuration(sampleBuffer);
if (dur.value > 0) {
pts = CMTimeAdd(pts, dur);
}
if (isVideo) {
_lastVideo = pts;
}else {
_lastAudio = pts;
}
}
CMTime dur = CMSampleBufferGetPresentationTimeStamp(sampleBuffer);
if (self.startTime.value == 0) {
self.startTime = dur;
}
CMTime sub = CMTimeSubtract(dur, self.startTime);
self.currentRecordTime = CMTimeGetSeconds(sub);
if (self.currentRecordTime > self.maxRecordTime) {
if (self.currentRecordTime - self.maxRecordTime < 0.1) {
if ([self.delegate respondsToSelector:@selector(recordProgress:)]) {
dispatch_async(dispatch_get_main_queue(), ^{
[self.delegate recordProgress:self.currentRecordTime/self.maxRecordTime];
});
}
}
return;
}
if ([self.delegate respondsToSelector:@selector(recordProgress:)]) {
dispatch_async(dispatch_get_main_queue(), ^{
[self.delegate recordProgress:self.currentRecordTime/self.maxRecordTime];
});
}
// 进行数据编码
[self.recordEncoder encodeFrame:sampleBuffer isVideo:isVideo];
CFRelease(sampleBuffer);
}
//调整媒体数据的时间
- (CMSampleBufferRef)adjustTime:(CMSampleBufferRef)sample by:(CMTime)offset {
CMItemCount count;
CMSampleBufferGetSampleTimingInfoArray(sample, 0, nil, &count);
CMSampleTimingInfo* pInfo = malloc(sizeof(CMSampleTimingInfo) * count);
CMSampleBufferGetSampleTimingInfoArray(sample, count, pInfo, &count);
for (CMItemCount i = 0; i < count; i++) {
pInfo[i].decodeTimeStamp = CMTimeSubtract(pInfo[i].decodeTimeStamp, offset);
pInfo[i].presentationTimeStamp = CMTimeSubtract(pInfo[i].presentationTimeStamp, offset);
}
CMSampleBufferRef sout;
CMSampleBufferCreateCopyWithNewTiming(nil, sample, count, pInfo, &sout);
free(pInfo);
return sout;
}
相应的获取视频的第一帧图片的方法,利用AVAssetImageGenerator:
#pragma mark - Private Method
- (void)addVideoInfo:(CMAlbumVideoInfo *)videoInfo duration:(CMTime)duration asset:(AVAsset *)asset
{
AVAssetImageGenerator *generator = [[AVAssetImageGenerator alloc] initWithAsset:asset];
generator.appliesPreferredTrackTransform = TRUE;
generator.apertureMode = AVAssetImageGeneratorApertureModeEncodedPixels;
NSError *thumbnailImageGenerationError = nil;
CGImageRef thumbnailImageRef = [generator copyCGImageAtTime:duration actualTime:nil error:&thumbnailImageGenerationError];
if (!thumbnailImageRef) {
NSLog(@"thumbnailImageGenerationError %@",thumbnailImageGenerationError);
}
UIImage *thumbnailImage = thumbnailImageRef ? [[UIImage alloc]initWithCGImage:thumbnailImageRef] : nil;
}
相应的视频压缩函数:
#pragma mark - 视频压缩
- (void)compressVideoWithVideoURL:(NSURL *)videoURL savedName:(NSString *)savedName completion:(void (^)(NSString *savedPath))completion {
// Accessing video by URL
AVURLAsset *videoAsset = [[AVURLAsset alloc] initWithURL:videoURL options:nil];
// Find compatible presets by video asset.
NSArray *presets = [AVAssetExportSession exportPresetsCompatibleWithAsset:videoAsset];
// Begin to compress video
// Now we just compress to low resolution if it supports
// If you need to upload to the server, but server does't support to upload by streaming,
// You can compress the resolution to lower. Or you can support more higher resolution.
if ([presets containsObject:AVAssetExportPreset640x480]) {
AVAssetExportSession *session = [[AVAssetExportSession alloc] initWithAsset:videoAsset presetName:AVAssetExportPreset640x480];
NSString *doc = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents"];
NSString *folder = [doc stringByAppendingPathComponent:@"HYBVideos"];
BOOL isDir = NO;
BOOL isExist = [[NSFileManager defaultManager] fileExistsAtPath:folder isDirectory:&isDir];
if (!isExist || (isExist && !isDir)) {
NSError *error = nil;
[[NSFileManager defaultManager] createDirectoryAtPath:folder
withIntermediateDirectories:YES
attributes:nil
error:&error];
if (error == nil) {
NSLog(@"目录创建成功");
} else {
NSLog(@"目录创建失败");
}
}
NSString *outPutPath = [folder stringByAppendingPathComponent:savedName];
session.outputURL = [NSURL fileURLWithPath:outPutPath];
// Optimize for network use.
session.shouldOptimizeForNetworkUse = true;
NSArray *supportedTypeArray = session.supportedFileTypes;
if ([supportedTypeArray containsObject:AVFileTypeMPEG4]) {
session.outputFileType = AVFileTypeMPEG4;
} else if (supportedTypeArray.count == 0) {
NSLog(@"No supported file types");
return;
} else {
session.outputFileType = [supportedTypeArray objectAtIndex:0];
}
// Begin to export video to the output path asynchronously.
[session exportAsynchronouslyWithCompletionHandler:^{
if ([session status] == AVAssetExportSessionStatusCompleted) {
dispatch_async(dispatch_get_main_queue(), ^{
if (completion) {
completion([session.outputURL path]);
}
});
} else {
dispatch_async(dispatch_get_main_queue(), ^{
if (completion) {
completion(nil);
}
});
}
}];
}
}
如上我自己的一点小总结,只是贴出了一些相关的函数,都可以直接拷贝过去拿着用的.可能通过此文章,整个流程还不是很清晰.若有正常做相应功能的或想了解的朋友,大家可以共同交流!
在iOS的道路上,一起进步着!欢迎留下你的足迹!
