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avfoundation 是apple ios和os x系统中用于处理基于时间的媒体数据的高级框架，通过开发所需的工具提供了强大的功能集，让开发者能够基于苹果平台创建当下最先进的媒体应用程序，其针对64位处理器设计，充分利用了多核硬件优势，会自动提供硬件加速操作，确保大部分设备能以最佳性能运行，是ios开发接触音视频开发必学的框架之一。
参与掘金日新计划，持续记录avfoundation学习，demo学习地址，里面封装了一些工具类，可以直接使用，这篇文章主要讲述avfoundation中的avcapturesession等类实现媒体捕捉功能，其他类的相关用法可查看我的其他文章。
捕捉媒体
媒体捕捉是avfoundation的核心功能之一，也是开发音视频app必不可少的功能。捕捉用到的类如图所示
- avcapturesession是avfoundation捕捉栈的核心类，捕捉会话用于连接输入和输出资源，管理从物理设备得到的输入流，例如从摄像头得到的视频从麦克风得到的音频，以不同的方式输出给一个或多个输出，可以动态配置输入和输出线路，让开发者能够在会话中按需重新配置捕捉环境。
- avcapturedevice为摄像头麦克风等物理设备定义了一个接口，在ios10以后，使用avcapturedevicediscoverysession获取设备。
- 将avcapturedevice包装成avcapturedeviceinput才能添加到捕捉回话中。
- avfoundation定义了avcaptureoutput的许多扩展类，avcaptureoutput是一个抽象基类，用于从捕捉回话中得到数据，框架定义了这个抽象类的高级扩展类，常用的有avcapturestillimageoutput静态图片输出、avcapturemoviefileoutput视频文件输出、avcapturevideodataoutput视频流数据输出、avcaptureaudiodataoutput音频流数据输出、avcapturemetadataoutput元数据输出。注意，不能同时配置avcapturevideodataoutput和avcapturemoviefileoutput，二者无法同时启用。
- avcapturevideopreviewlayer是coreanimation框架中calayer的一个子类，对捕捉视频数据实时预览。当然也可以使用glkview、uiimageview预览实时视频流的buffer。
具体代码可以看demo中的cqcapturemanager类对捕捉工具的封装
1.创建会话
创建会话并配置分辨率
- 配置分辨率注意要判断下能否支持，例如老机型前置摄像头配置4k是不支持的。
- 不同分辨率的缩放倍数也是不同的
self.capturesession = [[avcapturesession alloc] init];
- (void)configsessionpreset:(avcapturesessionpreset)sessionpreset {
[self.capturesession beginconfiguration];
if ([self.capturesession cansetsessionpreset:sessionpreset]) {
self.capturesession.sessionpreset = sessionpreset;
} else {
self.capturesession.sessionpreset = avcapturesessionpresethigh;
}
[self.capturesession commitconfiguration];
self.isconfigsessionpreset = yes;
}
2.配置视频输入
/// 配置视频输入
- (bool)configvideoinput:(nserror * _nullable *)error {
// 添加视频捕捉设备
// 拿到默认视频捕捉设备 ios默认后置摄像头
// avcapturedevice *videodevice = [avcapturedevice defaultdevicewithmediatype:avmediatypevideo];
avcapturedevice *videodevice = [self getcamerawithposition:avcapturedevicepositionback];
// 将捕捉设备转化为avcapturedeviceinput
// 注意：会话不能直接使用avcapturedevice，必须将avcapturedevice封装成avcapturedeviceinput对象
avcapturedeviceinput *videoinput = [avcapturedeviceinput deviceinputwithdevice:videodevice error:error];
// 将捕捉设备添加给会话
// 使用前判断videoinput是否有效以及能否添加，因为摄像头是一个公共设备，不属于任何app，有可能别的app在使用，添加前应该先进行判断是否可以添加
if (videoinput && [self.capturesession canaddinput:videoinput]) {
// 将videoinput 添加到 capturesession中
[self.capturesession beginconfiguration];
[self.capturesession addinput:videoinput];
[self.capturesession commitconfiguration];
self.videodeviceinput = videoinput;
return yes;
}else {
return no;
}
}
/// 移除视频输入设备
- (void)removevideodeviceinput {
if (self.videodeviceinput) [self.capturesession removeinput:self.videodeviceinput];
self.videodeviceinput = nil;
}
- 获取摄像头，ios10之后使用avcapturedevicediscoverysession获取
- 长焦超广或者双摄三摄必须使用avcapturedevicediscoverysession获取，[avcapturedevice deviceswithmediatype:avmediatypevideo]无法获取
/// 根据position拿到摄像头
- (avcapturedevice *)getcamerawithposition:(avcapturedeviceposition)position {
/**
avcapturedevicetypebuiltinwideanglecamera 广角(默认设备，28mm左右焦段)
avcapturedevicetypebuiltintelephotocamera 长焦(默认设备的2x或3x,只能使用avcapturedevicediscoverysession获取)
avcapturedevicetypebuiltinultrawidecamera 超广角(默认设备的0.5x，只能使用avcapturedevicediscoverysession获取)
avcapturedevicetypebuiltindualcamera (一个广角一个长焦(iphone7p,iphonex)，可以自动切换摄像头,只能使用avcapturedevicediscoverysession获取)
avcapturedevicetypebuiltindualwidecamera (一个超广一个广角(iphone12 iphone13)，可以自动切换摄像头,只能使用avcapturedevicediscoverysession获取)
avcapturedevicetypebuiltintriplecamera (超广，广角，长焦三摄像头，iphone11promax iphone12promax iphone13promax，可以自动切换摄像头,只能使用avcapturedevicediscoverysession获取)
avcapturedevicetypebuiltintruedepthcamera (红外和摄像头， iphone12promax iphone13promax )
*/
nsarray *devicetypes;
if (position == avcapturedevicepositionback) {
devicetypes = @[avcapturedevicetypebuiltindualcamera,
avcapturedevicetypebuiltindualwidecamera,
avcapturedevicetypebuiltintriplecamera, ];
} else {
devicetypes = @[avcapturedevicetypebuiltinwideanglecamera];
}
avcapturedevicediscoverysession *devicesession = [avcapturedevicediscoverysession discoverysessionwithdevicetypes:devicetypes mediatype:avmediatypevideo position:position];
if (devicesession.devices.count) return devicesession.devices.firstobject;
if (position == avcapturedevicepositionback) {
// 非多摄手机
devicetypes = @[avcapturedevicetypebuiltinwideanglecamera];
avcapturedevicediscoverysession *devicesession = [avcapturedevicediscoverysession discoverysessionwithdevicetypes:devicetypes mediatype:avmediatypevideo position:position];
if (devicesession.devices.count) return devicesession.devices.firstobject;
}
return nil;
}
3.配置音频输入
/// 配置音频输入
- (bool)configaudioinput:(nserror * _nullable *)error {
// 添加音频捕捉设备 ，如果只是拍摄静态图片，可以不用设置
// 选择默认音频捕捉设备 即返回一个内置麦克风
avcapturedevice *audiodevice = [avcapturedevice defaultdevicewithmediatype:avmediatypeaudio];
self.audiodeviceinput = [avcapturedeviceinput deviceinputwithdevice:audiodevice error:error];
if (self.audiodeviceinput && [self.capturesession canaddinput:self.audiodeviceinput]) {
[self.capturesession beginconfiguration];
[self.capturesession addinput:self.audiodeviceinput];
[self.capturesession commitconfiguration];
return yes;
}else {
return no;
}
}
/// 移除音频输入设备
- (void)removeaudiodeviceinput {
if (self.audiodeviceinput) [self.capturesession removeinput:self.audiodeviceinput];
}
5.配置输出
#pragma mark - func 静态图片输出配置
/// 配置静态图片输出
- (void)configstillimageoutput {
// avcapturestillimageoutput 从摄像头捕捉静态图片
self.stillimageoutput = [[avcapturestillimageoutput alloc] init];
// 配置字典：希望捕捉到jpeg格式的图片
self.stillimageoutput.outputsettings = @{avvideocodeckey:avvideocodecjpeg};
// 输出连接 判断是否可用，可用则添加到输出连接中去
[self.capturesession beginconfiguration];
if ([self.capturesession canaddoutput:self.stillimageoutput]) {
[self.capturesession addoutput:self.stillimageoutput];
}
[self.capturesession commitconfiguration];
}
/// 移除静态图片输出
- (void)removestillimageoutput {
if (self.stillimageoutput) [self.capturesession removeoutput:self.stillimageoutput];
}
#pragma mark - func 电影文件输出配置
/// 配置电影文件输出
- (void)configmoviefileoutput {
// avcapturemoviefileoutput，将quicktime视频录制到文件系统
self.moviefileoutput = [[avcapturemoviefileoutput alloc] init];
[self.capturesession beginconfiguration];
if ([self.capturesession canaddoutput:self.moviefileoutput]) {
[self.capturesession addoutput:self.moviefileoutput];
}
[self.capturesession commitconfiguration];
}
/// 移除电影文件输出
- (void)removemoviefileoutput {
if (self.moviefileoutput) [self.capturesession removeoutput:self.moviefileoutput];
}
6.开始会话\结束会话
// 异步开始会话
- (void)startsessionasync {
// 检查是否处于运行状态
if (![self.capturesession isrunning]) {
// 使用同步调用会损耗一定的时间，则用异步的方式处理
dispatch_async(self.capturevideoqueue, ^{
[self.capturesession startrunning];
});
}
}
// 异步停止会话
- (void)stopsessionasync {
// 检查是否处于运行状态
if ([self.capturesession isrunning]) {
dispatch_async(self.capturevideoqueue, ^{
[self.capturesession stoprunning];
});
}
}
7.捕捉静态图片
#pragma mark - 静态图片捕捉
#pragma mark public func 静态图片捕捉
// 捕捉静态图片
- (void)capturestillimage {
if (!self.isconfigsessionpreset) [self configsessionpreset:avcapturesessionpresetmedium];
if (!self.videodeviceinput) {
nserror *configerror;
bool configresult = [self configvideoinput:&configerror];
if (!configresult) return;
}
if (!self.stillimageoutput) [self configstillimageoutput];
[self startsessionsync];
// 获取图片输出连接
avcaptureconnection *connection = [self.stillimageoutput connectionwithmediatype:avmediatypevideo];
// 即使程序只支持纵向，但是如果用户横向拍照时，需要调整结果照片的方向
// 判断是否支持设置视频方向， 支持则根据设备方向设置输出方向值
if (connection.isvideoorientationsupported) {
connection.videoorientation = [self getcurrentvideoorientation];
}
[self.stillimageoutput capturestillimageasynchronouslyfromconnection:connection completionhandler:^(cmsamplebufferref _nullable imagedatasamplebuffer, nserror * _nullable error) { if (imagedatasamplebuffer != null) { dispatch_async(dispatch_get_main_queue(), ^{ if (self.delegate && [self.delegate respondstoselector:@selector(mediacaptureimagefilesuccess)]) {
[self.delegate mediacaptureimagefilesuccess];
}
});
// cmsamplebufferref转uiimage 并写入相册
nsdata *imagedata = [avcapturestillimageoutput jpegstillimagensdatarepresentation:imagedatasamplebuffer];
uiimage *image = [[uiimage alloc] initwithdata:imagedata];
[self writeimagetoassetslibrary:image];
} else {
dispatch_async(dispatch_get_main_queue(), ^{
if (self.delegate && [self.delegate respondstoselector:@selector(mediacaptureimagefailedwitherror:)]) {
[self.delegate mediacaptureimagefailedwitherror:error];
}
});
nslog(@"null samplebuffer:%@",[error localizeddescription]);
}
}];
}
#pragma mark private func 静态图片捕捉
/**
assets library 框架
用来让开发者通过代码方式访问ios photo
注意：会访问到相册，需要修改plist 权限。否则会导致项目崩溃
*/
/// 将uiimage写入到用户相册
- (void)writeimagetoassetslibrary:(uiimage *)image {
alassetslibrary *library = [[alassetslibrary alloc] init];
// 参数1 图片， 参数2 方向， 参数3 回调
[library writeimagetosavedphotosalbum:image.cgimage orientation:(nsuinteger)image.imageorientation completionblock:^(nsurl *asseturl, nserror *error) { if (!error) { dispatch_async(dispatch_get_main_queue(), ^{ if (self.delegate && [self.delegate respondstoselector:@selector(assetlibrarywriteimagesuccesswithimage:)]) {
[self.delegate assetlibrarywriteimagesuccesswithimage:image];
}
});
} else {
dispatch_async(dispatch_get_main_queue(), ^{
if (self.delegate && [self.delegate respondstoselector:@selector(assetlibrarywriteimagefailedwitherror:)]) {
[self.delegate assetlibrarywriteimagefailedwitherror:error];
}
});
}
}];
}
8.捕捉视频文件
#pragma mark - 电影文件捕捉
#pragma mark public func 电影文件捕捉
// 开始录制电影文件
- (void)startrecordingmoviefile {
if (!self.isconfigsessionpreset) [self configsessionpreset:avcapturesessionpresetmedium];
if (!self.videodeviceinput) {
nserror *configerror;
bool configresult = [self configvideoinput:&configerror];
if (!configresult) return;
}
if (!self.moviefileoutput) [self configmoviefileoutput];
[self startsessionsync];
if ([self isrecordingmoviefile]) return;
avcaptureconnection *videoconnection = [self.moviefileoutput connectionwithmediatype:avmediatypevideo];
// 设置输出方向
// 即使程序只支持纵向，但是如果用户横向拍照时，需要调整结果照片的方向
// 判断是否支持设置视频方向， 支持则根据设备方向设置输出方向值
if (videoconnection.isvideoorientationsupported) {
videoconnection.videoorientation = [self getcurrentvideoorientation];
}
// 设置视频帧稳定
// 判断是否支持视频稳定 可以显著提高视频的质量。只会在录制视频文件涉及
// if (videoconnection.isvideostabilizationsupported) {
// videoconnection.enablesvideostabilizationwhenavailable = yes;
// }
videoconnection.preferredvideostabilizationmode = avcapturevideostabilizationmodeauto;
// 设置对焦
avcapturedevice *device = [self getactivecamera];
// 摄像头可以进行平滑对焦模式操作。即减慢摄像头镜头对焦速度。当用户移动拍摄时摄像头会尝试快速自动对焦。
if (device.issmoothautofocusenabled) {
nserror *error;
if ([device lockforconfiguration:&error]) {
device.smoothautofocusenabled = yes;
[device unlockforconfiguration];
} else {
dispatch_async(dispatch_get_main_queue(), ^{
if (self.delegate && [self.delegate respondstoselector:@selector(deviceconfigurationfailedwitherror:)]) {
[self.delegate deviceconfigurationfailedwitherror:error];
}
});
}
}
self.moviefileoutputurl = [self getvideotemppathurl];
// 开始录制 参数1:录制保存路径 参数2:代理
[self.moviefileoutput startrecordingtooutputfileurl:self.moviefileoutputurl recordingdelegate:self];
}
// 停止录制电影文件
- (void)stoprecordingmoviefile {
if ([self isrecordingmoviefile]) {
[self.moviefileoutput stoprecording];
}
}
// 是否在录制电影文件
- (bool)isrecordingmoviefile {
return self.moviefileoutput.isrecording;
}
// 录制电影文件的时间
- (cmtime)moviefilerecordedduration {
return self.moviefileoutput.recordedduration;
}
#pragma mark avcapturefileoutputrecordingdelegate
/// 捕捉电影文件成功的回调
- (void)captureoutput:(avcapturefileoutput *)output didfinishrecordingtooutputfileaturl:(nsurl *)outputfileurl fromconnections:(nsarray<avcaptureconnection *> *)connections error:(nserror *)error {
if (error) {
dispatch_async(dispatch_get_main_queue(), ^{
if (self.delegate && [self.delegate respondstoselector:@selector(mediacapturemoviefilefailedwitherror:)]) {
[self.delegate mediacapturemoviefilefailedwitherror:error];
}
});
} else {
dispatch_async(dispatch_get_main_queue(), ^{
if (self.delegate && [self.delegate respondstoselector:@selector(mediacapturemoviefilesuccess)]) {
[self.delegate mediacapturemoviefilesuccess];
}
});
// copy一个副本再置为nil
// 将文件写入相册
[self writevideotoassetslibrary:self.moviefileoutputurl.copy];
self.moviefileoutputurl = nil;
}
}
#pragma mark private func 电影文件捕捉
/// 创建视频文件临时路径url
- (nsurl *)getvideotemppathurl {
nsfilemanager *filemanager = [nsfilemanager defaultmanager];
nsstring *temppath = [filemanager temporarydirectorywithtemplatestring:@"video.xxxxxx"];
if (temppath) {
nsstring *filepath = [temppath stringbyappendingpathcomponent:@"temp_video.mov"];
return [nsurl fileurlwithpath:filepath];
}
return nil;
}
/// 将视频文件写入到用户相册
- (void)writevideotoassetslibrary:(nsurl *)videourl {
alassetslibrary *library = [[alassetslibrary alloc] init];
// 和图片不同，视频的写入更耗时，所以写入之前应该判断是否能写入
if (![library videoatpathiscompatiblewithsavedphotosalbum:videourl]) return;
[library writevideoatpathtosavedphotosalbum:videourl completionblock:^(nsurl *asseturl, nserror *error) {
if (error) {
dispatch_async(dispatch_get_main_queue(), ^{
if (self.delegate && [self.delegate respondstoselector:@selector(assetlibrarywritemoviefilefailedwitherror:)]) {
[self.delegate assetlibrarywritemoviefilefailedwitherror:error];
}
});
} else {
// 写入成功 回调封面图
[self getvideocoverimagewithvideourl:videourl callblock:^(uiimage *coverimage) {
dispatch_async(dispatch_get_main_queue(), ^{
if (self.delegate && [self.delegate respondstoselector:@selector(assetlibrarywritemoviefilesuccesswithcoverimage:)]) {
[self.delegate assetlibrarywritemoviefilesuccesswithcoverimage:coverimage];
}
});
}];
}
}];
}
/// 获取视频文件封面图
- (void)getvideocoverimagewithvideourl:(nsurl *)videourl callblock:(void(^)(uiimage *))callblock {
dispatch_async(self.capturevideoqueue, ^{
avasset *asset = [avasset assetwithurl:videourl];
avassetimagegenerator *imagegenerator = [avassetimagegenerator assetimagegeneratorwithasset:asset];
// 设置maximumsize 宽为100，高为0 根据视频的宽高比来计算图片的高度
imagegenerator.maximumsize = cgsizemake(100.0f, 0.0f);
// 捕捉视频缩略图会考虑视频的变化（如视频的方向变化），如果不设置，缩略图的方向可能出错
imagegenerator.appliespreferredtracktransform = yes;
cgimageref imageref = [imagegenerator copycgimageattime:kcmtimezero actualtime:null error:nil];
uiimage *image = [uiimage imagewithcgimage:imageref];
cgimagerelease(imageref);
dispatch_async(dispatch_get_main_queue(), ^{
!callblock ?: callblock(image);
});
});
}
9.预览视频
previewview.session = capturemanager.capturesession
以上就是avfoundation avcapturesession媒体捕捉的详细内容，更多关于avfoundation avcapturesession的资料请关注代码网其它相关文章！
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