IOS开发中视频编辑、裁剪、拼接、处理教程
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2022-03-08 15:17:10
IOS开发中视频编辑、裁剪、拼接、处理教程。用代码在简单视频编辑中，主要就是加美颜、水印（贴图）、视频截取、视频拼接、音视频的处理，在美颜中，使用GPUImage即可实现多种滤镜、...
IOS开发中视频编辑、裁剪、拼接、处理教程。用代码在简单视频编辑中，主要就是加美颜、水印（贴图）、视频截取、视频拼接、音视频的处理，在美颜中，使用GPUImage即可实现多种滤镜、磨皮美颜的功能，并且可以脸部识别实时美颜等功能，这个有很多成熟的处理方案，所以现在主要说后面的水印（贴图）、视频截取、视频拼接、音视频的处理，在文章结尾会给出一个完整的测试demo，该demo可以操作视频之后保存到系统相册，文章主要说明下注意的点。
原理正如上篇提到的，因为GPUImage只是对视频进行滤镜处理，并没有涉及到视频轨和音轨的处理，所以在视频的处理裁剪等编辑上面主要还是使用的AVFoundation对视频轨和音轨进行处理。
一、视频裁剪完整源码：
//使用gpuimage重新录制一次
-(void)saveVedioPath:(NSURL*)vedioPath WithFileName:(NSString*)fileName andCallBack:(JLXCommonToolVedioCompletionHandler)competion
{
self.completionHandler = competion;
// 滤镜
filter = [[GPUImageAlphaBlendFilter alloc] init];
// //mix即为叠加后的透明度,这里就直接写1.0了
[(GPUImageDissolveBlendFilter *)filter setMix:1.0f];
// 播放
NSURL *sampleURL = vedioPath;
AVAsset *asset = [AVAsset assetWithURL:sampleURL];
movieFile = [[GPUImageMovie alloc] initWithAsset:asset];
movieFile.runBenchmark = YES;
movieFile.playAtActualSpeed = NO;
AVAssetTrack *videoAssetTrack = [[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
UIImageOrientation videoAssetOrientation_ = UIImageOrientationUp;
//拍摄的时候视频是否是竖屏拍的
BOOL isVideoAssetvertical = NO;
CGAffineTransform videoTransform = videoAssetTrack.preferredTransform;
if (videoTransform.a == 0 && videoTransform.b == 1.0 && videoTransform.c == -1.0 && videoTransform.d == 0) {
isVideoAssetvertical = YES;
videoAssetOrientation_ = UIImageOrientationUp;//正着拍
}
if (videoTransform.a == 0 && videoTransform.b == -1.0 && videoTransform.c == 1.0 && videoTransform.d == 0) {
// videoAssetOrientation_ = UIImageOrientationLeft;
isVideoAssetvertical = YES;
videoAssetOrientation_ = UIImageOrientationDown;//倒着拍
}
if (videoTransform.a == 1.0 && videoTransform.b == 0 && videoTransform.c == 0 && videoTransform.d == 1.0) {
isVideoAssetvertical = NO;
videoAssetOrientation_ = UIImageOrientationLeft;//左边拍的
}
if (videoTransform.a == -1.0 && videoTransform.b == 0 && videoTransform.c == 0 && videoTransform.d == -1.0) {
isVideoAssetvertical = NO;
videoAssetOrientation_ = UIImageOrientationRight;//右边拍
}
GPUImageView *filterView = [[GPUImageView alloc] initWithFrame:CGRectMake(0, 0, asset.naturalSize.width, asset.naturalSize.height)];
[filterView setTransform:CGAffineTransformMakeRotation(M_PI_2)];
UIView *view = [[UIView alloc] initWithFrame:CGRectMake(0, 0, asset.naturalSize.width, asset.naturalSize.height)];
[view setBackgroundColor:[UIColor clearColor]];
GPUImageUIElement *uielement = [[GPUImageUIElement alloc] initWithView:view];
NSString *pathToMovie = [NSHomeDirectory() stringByAppendingPathComponent:[NSString stringWithFormat:@"Documents/%@.mp4",fileName]];
unlink([pathToMovie UTF8String]);
NSURL *movieURL = [NSURL fileURLWithPath:pathToMovie];
movieWriter = [[GPUImageMovieWriter alloc] initWithMovieURL:movieURL size:CGSizeMake(asset.naturalSize.width, asset.naturalSize.height)];
GPUImageFilter* progressFilter = [[GPUImageFilter alloc] init];
[movieFile addTarget:progressFilter];
[progressFilter addTarget:filter];
[uielement addTarget:filter];
movieWriter.shouldPassthroughAudio = YES;
if ([[asset tracksWithMediaType:AVMediaTypeAudio] count] > 0){
movieFile.audioEncodingTarget = movieWriter;
} else {//no audio
movieFile.audioEncodingTarget = nil;
}
[movieFile enableSynchronizedEncodingUsingMovieWriter:movieWriter];
// 显示到界面
[filter addTarget:filterView];
[filter addTarget:movieWriter];
[movieWriter startRecording];
[movieFile startProcessing];
__weak typeof(self) weakSelf = self;
[progressFilter setFrameProcessingCompletionBlock:^(GPUImageOutput *output, CMTime time) {
[uielement update];
}];
[movieWriter setCompletionBlock:^{
__strong typeof(self) strongSelf = weakSelf;
[strongSelf->filter removeTarget:strongSelf->movieWriter];
[strongSelf->movieWriter finishRecording];
if (strongSelf.completionHandler) {
strongSelf.completionHandler(movieURL,nil,isVideoAssetvertical);
}
}];
}
/**
裁剪视频
@param videoPath 视频的路径
@param startTime 截取视频开始时间
@param endTime 截取视频结束时间，如果为0则为整个视频
@param videoSize 视频截取的大小，如果为0则不裁剪视频大小
@param videoDealPoint Point(x,y):传zero则为裁剪从0,0开始
@param fileName 文件名字
@param shouldScale 是否拉伸，false的话不拉伸，裁剪黑背景
*/
- (void)saveVideoPath:(NSURL*)videoPath withStartTime:(float)startTime withEndTime:(float)endTime withSize:(CGSize)videoSize withVideoDealPoint:(CGPoint)videoDealPoint WithFileName:(NSString*)fileName shouldScale:(BOOL)shouldScale
{
if (!videoPath) {
[SVProgressHUD dismiss];
return;
}
[SVProgressHUD showWithStatus:@"裁剪视频到系统相册"];
//1 创建AVAsset实例 AVAsset包含了video的所有信息 self.videoUrl输入视频的路径
//封面图片
NSDictionary *opts = [NSDictionary dictionaryWithObject:@(YES) forKey:AVURLAssetPreferPreciseDurationAndTimingKey];
videoAsset = [AVURLAsset URLAssetWithURL:videoPath options:opts]; //初始化视频媒体文件
bool isWXVideo = false;
for (int i=0; i<videoasset.metadata.count; i++)="" {="" avmetadataitem="" *="" item="[videoAsset.metadata" objectatindex:i];="" nslog(@"="=====metadata:%@,%@,%@,%@",item.identifier,item.extraAttributes,item.value,item.dataType);" nsdictionary="" *dic="[self" strtoarrayornsdictionary:[nsstring="" stringwithformat:@"%@",item.value]];="" if="" ([[dic.allkeys="" objectatindex:0]="" isequaltostring:="" @"wxver"])="" iswxvideo="true;" [self="" savevediopath:videopath="" withfilename:@"wxvideo"="" andcallback:^(nsurl="" *asseturl,="" nserror="" *error,bool="" isvideoassetvertical)="" dispatch_after(dispatch_time(dispatch_time_now,="" (int64_t)(0="" nsec_per_sec)),="" dispatch_get_main_queue(),="" ^{="" nsstring="" *newvideopath="[NSHomeDirectory()" stringbyappendingpathcomponent:@"documents="" wxvideo.mp4"];="" gosavevideopath:[nsurl="" fileurlwithpath:newvideopath]="" withstarttime:starttime="" withendtime:endtime="" withsize:videosize="" withvideodealpoint:videodealpoint="" withfilename:filename="" shouldscale:shouldscale="" iswxvideoassetvertical:isvideoassetvertical];="" });="" }];="" break;="" }="" ([[videoasset="" trackswithmediatype:avmediatypeaudio]="" count]="=" 0){="" return;="" (!iswxvideo)="" gosavevideopath:videopath="" iswxvideoassetvertical:no];="" assetvertical="" gpuimage会把微信的竖屏渲染成横屏，横屏还是横屏="" -="" (void)gosavevideopath:(nsurl*)videopath="" withstarttime:(float)starttime="" withendtime:(float)endtime="" withsize:(cgsize)videosize="" withvideodealpoint:(cgpoint)videodealpoint="" withfilename:(nsstring*)filename="" shouldscale:(bool)shouldscale="" iswxvideoassetvertical:(bool)assetvertical{="" (!videopath)="" [svprogresshud="" dismiss];="" 1="" 创建avasset实例="" avasset包含了video的所有信息="" self.videourl输入视频的路径="" 封面图片="" *opts="[NSDictionary" dictionarywithobject:@(yes)="" forkey:avurlassetpreferprecisedurationandtimingkey];="" dictionarywithobjectsandkeys:@(yes),avurlassetpreferprecisedurationandtimingkey,avassetreferencerestrictionforbidnone,avurlassetreferencerestrictionskey,="" nil];="" videoasset="[AVURLAsset" urlassetwithurl:videopath="" options:opts];="" 初始化视频媒体文件="" 开始时间="" cmtime="" startcroptime="CMTimeMakeWithSeconds(startTime," 600);="" 结束时间="" endcroptime="CMTimeMakeWithSeconds(endTime," (endtime="=" 0)="" videoasset.duration.timescale);="" 2="" 创建avmutablecomposition实例.="" apple="" developer="" 里边的解释="" 【avmutablecomposition="" is="" a="" mutable="" subclass="" of="" avcomposition="" you="" use="" when="" want="" to="" create="" new="" composition="" from="" existing="" assets.="" can="" add="" and="" remove="" tracks,="" add,="" remove,="" scale="" time="" ranges.】="" avmutablecomposition="" *mixcomposition="[AVMutableComposition" composition];="" 有声音=""> 0){
//声音采集
AVURLAsset * audioAsset = [[AVURLAsset alloc] initWithURL:videoPath options:opts];
//音频通道
AVMutableCompositionTrack * audioTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
//音频采集通道
AVAssetTrack * audioAssetTrack = [[audioAsset tracksWithMediaType:AVMediaTypeAudio] lastObject];
[audioTrack insertTimeRange:CMTimeRangeMake(startCropTime, endCropTime) ofTrack:audioAssetTrack atTime:kCMTimeZero error:nil];
}
//3 视频通道 工程文件中的轨道，有音频轨、视频轨等，里面可以插入各种对应的素材
AVMutableCompositionTrack *videoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo
preferredTrackID:kCMPersistentTrackID_Invalid];
NSError *error;
//把视频轨道数据加入到可变轨道中 这部分可以做视频裁剪TimeRange
[videoTrack insertTimeRange:CMTimeRangeMake(startCropTime, endCropTime)
ofTrack:[[videoAsset tracksWithMediaType:AVMediaTypeVideo] lastObject]
atTime:kCMTimeZero error:&error];
//3.1 AVMutableVideoCompositionInstruction 视频轨道中的一个视频，可以缩放、旋转等
AVMutableVideoCompositionInstruction *mainInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
mainInstruction.timeRange = CMTimeRangeMake(kCMTimeZero, videoTrack.timeRange.duration);
// 3.2 AVMutableVideoCompositionLayerInstruction 一个视频轨道，包含了这个轨道上的所有视频素材
AVMutableVideoCompositionLayerInstruction *videolayerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:videoTrack];
AVAssetTrack *videoAssetTrack = [[videoAsset tracksWithMediaType:AVMediaTypeVideo] lastObject];
UIImageOrientation videoAssetOrientation_ = UIImageOrientationUp;
//拍摄的时候视频是否是竖屏拍的
BOOL isVideoAssetvertical = NO;
CGAffineTransform videoTransform = videoAssetTrack.preferredTransform;
if (videoTransform.a == 0 && videoTransform.b == 1.0 && videoTransform.c == -1.0 && videoTransform.d == 0) {
isVideoAssetvertical = YES;
videoAssetOrientation_ = UIImageOrientationUp;//正着拍
}
if (videoTransform.a == 0 && videoTransform.b == -1.0 && videoTransform.c == 1.0 && videoTransform.d == 0) {
// videoAssetOrientation_ = UIImageOrientationLeft;
isVideoAssetvertical = YES;
videoAssetOrientation_ = UIImageOrientationDown;//倒着拍
}
if (videoTransform.a == 1.0 && videoTransform.b == 0 && videoTransform.c == 0 && videoTransform.d == 1.0) {
isVideoAssetvertical = NO;
videoAssetOrientation_ = UIImageOrientationLeft;//左边拍的
}
if (videoTransform.a == -1.0 && videoTransform.b == 0 && videoTransform.c == 0 && videoTransform.d == -1.0) {
isVideoAssetvertical = NO;
videoAssetOrientation_ = UIImageOrientationRight;//右边拍
}
float scaleX = 1.0,scaleY = 1.0,scale = 1.0;
CGSize originVideoSize;
if (isVideoAssetvertical || Assetvertical) {
originVideoSize = CGSizeMake([[[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] naturalSize].height, [[[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] naturalSize].width);
}
else{
originVideoSize = CGSizeMake([[[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] naturalSize].width, [[[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] naturalSize].height);
}
float x = videoDealPoint.x;
float y = videoDealPoint.y;
if (shouldScale) {
scaleX = videoSize.width/originVideoSize.width;
scaleY = videoSize.height/originVideoSize.height;
scale = MAX(scaleX, scaleY);
if (scaleX>scaleY) {
NSLog(@"竖屏");
}
else{
NSLog(@"横屏");
}
}
else{
scaleX = 1.0;
scaleY = 1.0;
scale = 1.0;
}
if (Assetvertical) {
CGAffineTransform trans = CGAffineTransformMake(videoAssetTrack.preferredTransform.a*scale, videoAssetTrack.preferredTransform.b*scale, videoAssetTrack.preferredTransform.c*scale, videoAssetTrack.preferredTransform.d*scale, videoAssetTrack.preferredTransform.tx*scale-x+720, videoAssetTrack.preferredTransform.ty*scale-y);
// [videolayerInstruction setTransform:trans atTime:kCMTimeZero];
CGAffineTransform trans2 = CGAffineTransformRotate(trans, M_PI_2);
[videolayerInstruction setTransform:trans2 atTime:kCMTimeZero];
}
else{
CGAffineTransform trans = CGAffineTransformMake(videoAssetTrack.preferredTransform.a*scale, videoAssetTrack.preferredTransform.b*scale, videoAssetTrack.preferredTransform.c*scale, videoAssetTrack.preferredTransform.d*scale, videoAssetTrack.preferredTransform.tx*scale-x, videoAssetTrack.preferredTransform.ty*scale-y);
[videolayerInstruction setTransform:trans atTime:kCMTimeZero];
}
//裁剪区域
// [videolayerInstruction setCropRectangle:CGRectMake(0, 0, 720, 720) atTime:kCMTimeZero];
// 3.3 - Add instructions
mainInstruction.layerInstructions = [NSArray arrayWithObjects:videolayerInstruction,nil];
//AVMutableVideoComposition：管理所有视频轨道，可以决定最终视频的尺寸，裁剪需要在这里进行
AVMutableVideoComposition *mainCompositionInst = [AVMutableVideoComposition videoComposition];
CGSize naturalSize;
// if(isVideoAssetvertical){
// naturalSize = CGSizeMake(videoAssetTrack.naturalSize.height, videoAssetTrack.naturalSize.width);
// } else {
// naturalSize = videoAssetTrack.naturalSize;
// }
naturalSize = originVideoSize;
int64_t renderWidth = 0, renderHeight = 0;
if (videoSize.height ==0.0 || videoSize.width == 0.0) {
renderWidth = naturalSize.width;
renderHeight = naturalSize.height;
}
else{
renderWidth = ceil(videoSize.width);
renderHeight = ceil(videoSize.height);
}
mainCompositionInst.renderSize = CGSizeMake(renderWidth, renderHeight);
mainCompositionInst.instructions = [NSArray arrayWithObject:mainInstruction];
mainCompositionInst.frameDuration = CMTimeMake(1, 30);
// 4 - 输出路径
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *myPathDocs = [documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.mp4",fileName]];
unlink([myPathDocs UTF8String]);
NSURL* videoUrl = [NSURL fileURLWithPath:myPathDocs];
// dlink = [CADisplayLink displayLinkWithTarget:self selector:@selector(updateProgress)];
// [dlink setFrameInterval:15];
// [dlink addToRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
// [dlink setPaused:NO];
// 5 - 视频文件输出
exporter = [[AVAssetExportSession alloc] initWithAsset:mixComposition
presetName:AVAssetExportPresetHighestQuality];
exporter.outputURL=videoUrl;
exporter.outputFileType = AVFileTypeMPEG4;
exporter.shouldOptimizeForNetworkUse = YES;
exporter.videoComposition = mainCompositionInst;
[exporter exportAsynchronouslyWithCompletionHandler:^{
dispatch_async(dispatch_get_main_queue(), ^{
//这里是输出视频之后的操作，做你想做的
[self cropExportDidFinish:exporter];
});
}];
}
- (void)cropExportDidFinish:(AVAssetExportSession*)session {
if (session.status == AVAssetExportSessionStatusCompleted) {
NSURL *outputURL = session.outputURL;
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.2 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
[SVProgressHUD dismiss];
__block PHObjectPlaceholder *placeholder;
if (UIVideoAtPathIsCompatibleWithSavedPhotosAlbum(outputURL.path)) {
NSError *error;
[[PHPhotoLibrary sharedPhotoLibrary] performChangesAndWait:^{
PHAssetChangeRequest* createAssetRequest = [PHAssetChangeRequest creationRequestForAssetFromVideoAtFileURL:outputURL];
placeholder = [createAssetRequest placeholderForCreatedAsset];
} error:&error];
if (error) {
[SVProgressHUD showErrorWithStatus:[NSString stringWithFormat:@"%@",error]];
}
else{
[SVProgressHUD showSuccessWithStatus:@"视频已经保存到相册"];
}
}else {
[SVProgressHUD showErrorWithStatus:NSLocalizedString(@"视频保存相册失败，请设置软件读取相册权限", nil)];
}
});
}
else{
NSLog(@"%@",session.error);
[SVProgressHUD showErrorWithStatus:NSLocalizedString(@"裁剪失败", nil)];
}
}
// 将JSONDATA转化为字典或者数组
- (id)DataToArrayOrNSDictionary:(NSData *)jsonData{
NSError *error = nil;
id jsonObject = [NSJSONSerialization JSONObjectWithData:jsonData options:NSJSONReadingAllowFragments error:&error];
if (jsonObject != nil && error == nil){
return jsonObject;
}else{
// 解析错误
return nil;
}
}
// 将JSON串转化为字典或者数组
- (id)StrToArrayOrNSDictionary:(NSString *)jsonStr {
NSData *jsonData = [jsonStr dataUsingEncoding:NSUTF8StringEncoding];
return [self DataToArrayOrNSDictionary:jsonData];
}
调用的时候，直接使用
-(void)cropImage{
NSURL *videoPath = [NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"selfS" ofType:@"MOV"]];
[self saveVideoPath:videoPath withStartTime:0.1 withEndTime:0 withSize:CGSizeMake(300, 300) withVideoDealPoint:CGPointMake(50, 50) WithFileName:@"cropVideo" shouldScale:YES];
}
其实对于一般的视频裁剪，只需要使用下面这个函数即可
- (void)goSaveVideoPath:(NSURL*)videoPath withStartTime:(float)startTime withEndTime:(float)endTime withSize:(CGSize)videoSize withVideoDealPoint:(CGPoint)videoDealPoint WithFileName:(NSString*)fileName shouldScale:(BOOL)shouldScale isWxVideoAssetvertical:(BOOL)Assetvertical
1.1、微信的处理
但是在实际使用过程中发现，单独使用这个函数中的AVFoundation处理裁剪视频的时候，对微信的支持并不好，如果使用微信自带的相机拍摄那个十秒视频虽然可以裁剪成功，但是是蓝屏的，只有声音没有画面，在打印的metadata信息中对比发现
WX拍摄
2017-05-11 19:35:58.529751+0800 JianLiXiu[9592:2774766] ======metadata:uiso/dscp,{
dataType = 2;
dataTypeNamespace = "com.apple.quicktime.udta";
},{"WXVer":369428256},com.apple.metadata.datatype.UTF-8
2017-05-11 19:35:58.531034+0800 JianLiXiu[9592:2774766] ======commonMetadata:uiso/dscp,{
dataType = 2;
dataTypeNamespace = "com.apple.quicktime.udta";
},{"WXVer":369428256},com.apple.metadata.datatype.UTF-8
WX下载
======metadata:uiso/dscp,{
dataType = 2;
dataTypeNamespace = "com.apple.quicktime.udta";
},{"WXVer":369428256},com.apple.metadata.datatype.UTF-8
======commonMetadata:uiso/dscp,{
dataType = 2;
dataTypeNamespace = "com.apple.quicktime.udta";
},{"WXVer":369428256},com.apple.metadata.datatype.UTF-8
自带拍摄
2017-05-11 19:35:09.708010+0800 JianLiXiu[9592:2774253] ======metadata:uiso/loci,{
dataType = 2;
dataTypeNamespace = "com.apple.quicktime.udta";
},+31.1711+121.3836+045.636/,com.apple.metadata.datatype.UTF-8
2017-05-11 19:35:09.710245+0800 JianLiXiu[9592:2774253] ======metadata:uiso/date,{
dataType = 0;
dataTypeNamespace = "com.apple.quicktime.udta";
},2017-05-11T17:40:41+0800,com.apple.metadata.datatype.raw-data
2017-05-11 19:35:09.712193+0800 JianLiXiu[9592:2774253] ======commonMetadata:uiso/date,{
dataType = 0;
dataTypeNamespace = "com.apple.quicktime.udta";
},2017-05-11T17:40:41+0800,com.apple.metadata.datatype.raw-data
2017-05-11 19:35:09.712746+0800 JianLiXiu[9592:2774253] ======commonMetadata:uiso/loci,{
dataType = 2;
dataTypeNamespace = "com.apple.quicktime.udta";
},+31.1711+121.3836+045.636/,com.apple.metadata.datatype.UTF-8
所以通过视频的metadata信息来判断是不是微信的视频，通过metadata是否含有{"WXVer":369428256}这个来判断是不是微信处理过的视频，如果是微信的视频先使用GPUImage重新渲染编码一次然后再处理。
代码中的
CGAffineTransform videoTransform = videoAssetTrack.preferredTransform;
是代表的视频的拍摄方向，在正常拍摄的时候打印如下
自带竖 0,1,-1,0 自带横 1,0,0,1 qq竖 1,0,0,1 qq横 0,-1,1,0 微信竖 0,1,-1,0 微信横 1,0,0,1
但微信的视频在GPUImage重新录制之后，拍摄方向变成了
微信竖 1,0,0,1 微信横 1,0,0,1
也就是说不管横竖，全部变成了一样的，这样就导致横屏拍摄的时候裁剪正常，竖屏拍摄的时候，裁剪之后出来的视频时错误的，所以要先判断原视频是什么方向，之后在裁剪处理的时候去处理。
1.2、裁剪位置的选择
int64_t renderWidth = 0, renderHeight = 0;
是要渲染输出的视频大小是多少，所以如果想设置指定大小，那就在这个设置，输出的大小就可以了，但是这个裁剪是默认从(0,0)开始的，如果是从中间开始的就需要设置videolayerInstruction这个的移动了。
videolayerInstruction是这个视频轨的动画等移动效果，视频的移动，翻转，缩小等都在这个上面进行操作。通过设置CGAffineTransform来达到裁剪位置
x会跟着c的值进行拉伸(View的宽度是跟着改变)，y会跟着b的值进行拉伸（View的高度跟着改变），要注意到的是c和b的值改变不会影响到View的point（center中心点）的改变。这是个很有意思的两个参数。
x会跟着t.x进行x做表平移，y会跟着t.y进行平移。这里的point（center）是跟着变换的。
下面是Apple整合的transform
平移 ：
①根据本身的transform进行平移 CGAffineTransformMakeTranslation(CGFloat tx,CGFloat ty)
②根据本身的transform后者另外的transform进行平移CGAffineTransformTranslate(CGAffineTransform t,CGFloat tx,CGFloat ty)
缩放 ：
①根据本身的transform进行缩放
CGAffineTransformMakeScale(CGFloat sx,CGFloat sy)
②根据本身的transform后者另外的transform进行缩放
CGAffineTransformScale(CGAffineTransform t,CGFloat sx,CGFloat sy)
旋转 ：
① 根据本身的transform进行旋转
CGAffineTransformMakeRotation(CGFloat angle) （angle 旋转的角度）
②根据本身的transform后者另外的transform进行旋转
CGAffineTransformRotate(CGAffineTransform t,CGFloat angle)
所以结合渲染的大小和要移动的效果，就可以知道是从哪个点开始裁剪，裁剪多大的视频了。
1.3、裁剪时间的选择
裁剪时间主要是在视频轨和音轨编辑的时候，设置插入的时长，从而控制裁剪时间。
//把视频轨道数据加入到可变轨道中 这部分可以做视频裁剪TimeRange
[videoTrack insertTimeRange:CMTimeRangeMake(startCropTime, endCropTime)
ofTrack:[[videoAsset tracksWithMediaType:AVMediaTypeVideo] lastObject]
atTime:kCMTimeZero error:&error];
1.4、对没有声音视频的处理，比如延时视频
上篇说了如果没有声音的视频在处理的时候会错误，所以在裁剪的时候也要注意是否含有声音，如果没有声音就不要添加音轨了
//有声音
if ([[videoAsset tracksWithMediaType:AVMediaTypeAudio] count] > 0){
//声音采集
AVURLAsset * audioAsset = [[AVURLAsset alloc] initWithURL:videoPath options:opts];
//音频通道
AVMutableCompositionTrack * audioTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
//音频采集通道
AVAssetTrack * audioAssetTrack = [[audioAsset tracksWithMediaType:AVMediaTypeAudio] lastObject];
[audioTrack insertTimeRange:CMTimeRangeMake(startCropTime, endCropTime) ofTrack:audioAssetTrack atTime:kCMTimeZero error:nil];
}
1.5、原视频大小的处理
如果不裁剪视频的大小，只是默认大小裁剪时间的时候，发现获取的naturalSize在竖屏的时候是错误的，比如一个视频720*1280，结果获得的naturalSize是1280*720，横竖刚好相反，所以需要对竖屏的大小进行处理一下，这样就是正确的了
if (isVideoAssetvertical || Assetvertical) {
originVideoSize = CGSizeMake([[[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] naturalSize].height, [[[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] naturalSize].width);
}
else{
originVideoSize = CGSizeMake([[[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] naturalSize].width, [[[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] naturalSize].height);
}
二、视频拼接、音视频的处理
视频的拼接和音视频的拼接是一样的，都是处理视频轨和音轨的开始时间，如果第二个视频的开始时间是第一个视频的结束时间，那么就是两段视频的拼接，如果开始时间相同，那么就是两个视频在混合了。
下面给出一个两个视频拼接，再加上一个背景音乐的例子。
-(void)addFirstVideo:(NSURL*)firstVideoPath andSecondVideo:(NSURL*)secondVideo withMusic:(NSURL*)musicPath{
[SVProgressHUD showWithStatus:@"正在合成到系统相册中"];
AVAsset *firstAsset = [AVAsset assetWithURL:firstVideoPath];
AVAsset *secondAsset = [AVAsset assetWithURL:secondVideo];
AVAsset *musciAsset = [AVAsset assetWithURL:musicPath];
// 1 - Create AVMutableComposition object. This object will hold your AVMutableCompositionTrack instances.
AVMutableComposition *mixComposition = [[AVMutableComposition alloc] init];
// 2 - Video track
AVMutableCompositionTrack *firstTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo
preferredTrackID:kCMPersistentTrackID_Invalid];
[firstTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, firstAsset.duration)
ofTrack:[[firstAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] atTime:kCMTimeZero error:nil];
[firstTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, secondAsset.duration)
ofTrack:[[secondAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] atTime:firstAsset.duration error:nil];
if (musciAsset!=nil){
AVMutableCompositionTrack *AudioTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio
preferredTrackID:kCMPersistentTrackID_Invalid];
[AudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, CMTimeAdd(firstAsset.duration, secondAsset.duration))
ofTrack:[[musciAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0] atTime:kCMTimeZero error:nil];
}
// 4 - Get path
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *myPathDocs = [documentsDirectory stringByAppendingPathComponent:
[NSString stringWithFormat:@"mergeVideo-%d.mov",arc4random() % 1000]];
NSURL *url = [NSURL fileURLWithPath:myPathDocs];
// 5 - Create exporter
exporter = [[AVAssetExportSession alloc] initWithAsset:mixComposition
presetName:AVAssetExportPresetHighestQuality];
exporter.outputURL=url;
exporter.outputFileType = AVFileTypeQuickTimeMovie;
exporter.shouldOptimizeForNetworkUse = YES;
[exporter exportAsynchronouslyWithCompletionHandler:^{
dispatch_async(dispatch_get_main_queue(), ^{
[self exportDidFinish:exporter];
});
}];
}
- (void)exportDidFinish:(AVAssetExportSession*)session {
if (session.status == AVAssetExportSessionStatusCompleted) {
NSURL *outputURL = session.outputURL;
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.2 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
[SVProgressHUD dismiss];
__block PHObjectPlaceholder *placeholder;
if (UIVideoAtPathIsCompatibleWithSavedPhotosAlbum(outputURL.path)) {
NSError *error;
[[PHPhotoLibrary sharedPhotoLibrary] performChangesAndWait:^{
PHAssetChangeRequest* createAssetRequest = [PHAssetChangeRequest creationRequestForAssetFromVideoAtFileURL:outputURL];
placeholder = [createAssetRequest placeholderForCreatedAsset];
} error:&error];
if (error) {
[SVProgressHUD showErrorWithStatus:[NSString stringWithFormat:@"%@",error]];
}
else{
[SVProgressHUD showSuccessWithStatus:@"视频已经保存到相册"];
}
}else {
[SVProgressHUD showErrorWithStatus:NSLocalizedString(@"视频保存相册失败，请设置软件读取相册权限", nil)];
}
});
}
}
调用的时候
-(void)addMusic{
NSURL *videoPath1 = [NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"selfS" ofType:@"MOV"]];
NSURL *videoPath2 = [NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"selfH" ofType:@"MOV"]];
NSURL *music = [NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"music" ofType:@"mp3"]];
[self addFirstVideo:videoPath1 andSecondVideo:videoPath2 withMusic:music];
}
这样就是videopath1和videopath2拼接，然后加上一个背景音乐music，之后生成一个视频保存到相册。
(2017-08-14)2.1、音频音量的调节
最近需要把背景音乐的音量调小，当然背景音乐文件音量调小即可，但是毕竟每个文件处理都不太方便，所以还是用代码把指定音轨的音量减小，这里只减小背景音乐的音量，不减小其他的音量，所以用到了AVMutableAudioMix这个。
在原工程增加以下代码即可
//修改背景音乐的音量start
AVMutableAudioMix *videoAudioMixTools = [AVMutableAudioMix audioMix];
if (musciAsset) {
//调节音量
//获取音频轨道
AVMutableAudioMixInputParameters *firstAudioParam = [AVMutableAudioMixInputParameters audioMixInputParametersWithTrack:AudioTrack];
//设置音轨音量,可以设置渐变,设置为1.0就是全音量
[firstAudioParam setVolumeRampFromStartVolume:1.0 toEndVolume:1.0 timeRange:CMTimeRangeMake(kCMTimeZero, CMTimeAdd(firstAsset.duration, secondAsset.duration))];
[firstAudioParam setTrackID:AudioTrack.trackID];
videoAudioMixTools.inputParameters = [NSArray arrayWithObject:firstAudioParam];
}
//end
exporter.audioMix = videoAudioMixTools;