我要评论一、前言
avcapturesession 是 avfoundation 的核心类，用于管理捕获对象 avcaptureinput 的视频和音频的输入，协调捕获的输出 avcaptureoutput。
avcaptureoutput 的输出有两种方法：
- 一种是直接以 moviefileurl 方式输出；
- 一种是以原始数据流 data 的方式输出
流程对比图如下：
下面详细讲解录制视频的方案：
二、avcapturesession + avcapturemoviefileoutput
1.创建avcapturesession
//导入 avfoundation.framework
#import <avfoundation/avfoundation.h>
//声明属性
@property (nonatomic, strong) avcapturesession *capturesession;
//懒加载 avcapturesession
- (avcapturesession *)capturesession {
if (!_capturesession) {
_capturesession = [[avcapturesession alloc] init];
//设置分辨率
if ([_capturesession cansetsessionpreset:avcapturesessionpresethigh]) {
[_capturesession setsessionpreset:avcapturesessionpresethigh];
}
}
return _capturesession;
}注意：avcapturesession 的调用是会阻塞线程的，建议单独开辟子线程处理。2.设置音频、视频输入
//声明属性
@property (nonatomic, strong) avcapturedeviceinput *videoinput;
@property (nonatomic, strong) avcapturedeviceinput *audioinput;
//设置视频，音频输入源
- (void)setcapturedeviceinput {
//1. 视频输入源
//获取视频输入设备， 默认后置摄像头
avcapturedevice *videocapturedevice = [avcapturedevice defaultdevicewithmediatype:avmediatypevideo];
nserror *error = nil;
self.videoinput = [avcapturedeviceinput deviceinputwithdevice:videocapturedevice error:&error];
if ([self.capturesession canaddinput:self.videoinput]) {
[self.capturesession addinput:self.videoinput];
}
//2. 音频输入源
avcapturedevice *audiocapturedevice = [[avcapturedevice deviceswithmediatype:avmediatypeaudio] firstobject];
self.audioinput = [avcapturedeviceinput deviceinputwithdevice:audiocapturedevice error:&error];
if ([self.capturesession canaddinput:self.audioinput]) {
[self.capturesession addinput:self.audioinput];
}
}3.设置文件输出源
//声明属性
@property (nonatomic, strong) avcapturemoviefileoutput *moviefileoutput;
@property (nonatomic, strong) avcapturevideopreviewlayer *previewlayer;
//设置文件输出源
- (void)setdevicefileoutput {
//初始化文件输出对象
self.moviefileoutput = [[avcapturemoviefileoutput alloc] init];
//捕获会话中特定捕获输入对象和捕获输出对象之间的连接
avcaptureconnection *captureconnection = [self.moviefileoutput connectionwithmediatype:avmediatypevideo];
//设置防抖
if ([captureconnection isvideostabilizationsupported]) {
captureconnection.preferredvideostabilizationmode = avcapturevideostabilizationmodeauto;
}
//预览图层和视频方向保持一致
captureconnection.videoorientation = [self.previewlayer connection].videoorientation;
//添加文件输出源
if ([self.capturesession canaddoutput:self.moviefileoutput]) {
[self.capturesession addoutput:self.moviefileoutput];
}
}4.添加视频预览层
- (void)setvideopreviewlayer {
self.previewlayer.frame = [uiscreen mainscreen].bounds;
[self.superview.layer addsublayer:self.previewlayer];
}
- (avcapturevideopreviewlayer *)previewlayer {
if (!_previewlayer) {
_previewlayer = [avcapturevideopreviewlayer layerwithsession:self.capturesession];
_previewlayer.maskstobounds = yes;
_previewlayer.videogravity = avlayervideogravityresizeaspectfill;//填充模式
}
return _previewlayer;
}5. 开始采集
//声明属性
@property (nonatomic, strong) dispatch_queue_t sessionqueue;
//开始采集
- (void)startcapture {
self.sessionqueue = dispatch_queue_create("com.capturesession.queue", dispatch_queue_concurrent);
if (![self.capturesession isrunning]) {
__weak __typeof(self) weakself = self;
dispatch_async(self.sessionqueue, ^{
[weakself.capturesession startrunning];
});
}
}6. 开始录制
//开始录制
- (void)startrecord {
[self.moviefileoutput startrecordingtooutputfileurl:[self createvideopath] recordingdelegate:self];
}当实际的录制开始或停止时，系统会有代理回调。当开始录制之后，这时可能还没有真正写入，真正开始写入会回调下面代理，停止录制也是如此，所以如果你需要对录制视频起始点操作，建议通过系统的回调代理：
//实现协议 <avcapturefileoutputrecordingdelegate>中的方法
#pragma mark _ avcapturefileoutputrecordingdelegate
//起始点 - 开始录制
- (void)captureoutput:(avcapturefileoutput *)output didstartrecordingtooutputfileaturl:(nsurl *)fileurl fromconnections:(nsarray<avcaptureconnection *> *)connections {
}
//结束录制
-(void)captureoutput:(avcapturefileoutput *)captureoutput didfinishrecordingtooutputfileaturl:(nsurl *)outputfileurl fromconnections:(nsarray *)connections error:(nserror *)error
{
nslog(@"视频录制完成. 文件路径：%@",[outputfileurl absolutestring]);
}7.停止录制
//停止录制
- (void)stoprecord {
if ([self.moviefileoutput isrecording]) {
[self.moviefileoutput stoprecording];
}
}8.停止采集
//停止采集
- (void)stopcapture {
if ([self.capturesession isrunning]) {
__weak __typeof(self) weakself = self;
dispatch_async(self.sessionqueue, ^{
[weakself.capturesession stoprunning];
weakself.capturesession = nil;
});
}
}
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