分析：
这是一个仿秒拍音视频合成的demo。打开秒拍并拍摄一段视频，然后进入编辑界面，给拍摄的视频添加背景音乐，可以选择任何你喜欢的音乐作为背景音乐，还可以调节背景音乐的音量和拍摄视频的原始音量，来进行合成，但是音视频的合成是需要时间的，而滑动调节音量和选择音乐没有卡顿，所以推测在这个编辑界面并没有进行合成操作，只是音视频一起循环播放；而合成操作是在点击发布按钮后才进行的。
分析完毕，实现功能：
1，根据拍摄视频的长短来剪辑音频的长度
2，实现音视频的同步循环播放
3，音视频合成
1、剪辑音频
根据时间生成输出路径
#pragma mark - 输出路径
+ (NSURL *)exporterPath {
NSInteger nowInter = (long)[[NSDate date] timeIntervalSince1970];
NSString *fileName = [NSString stringWithFormat:@"output%ld.mp4",(long)nowInter];
NSString *documentsDirectory = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES).lastObject;
NSString *outputFilePath =[documentsDirectory stringByAppendingPathComponent:fileName];
if([[NSFileManager defaultManager]fileExistsAtPath:outputFilePath]){
[[NSFileManager defaultManager]removeItemAtPath:outputFilePath error:nil];
}
return [NSURL fileURLWithPath:outputFilePath];
}
根据拍摄视频的长短，来剪辑音频的长度，从而实现音视频同步播放
#pragma mark - 音视频剪辑,如果是视频（mp4格式）剪辑把下面的两个地方类型换为AVFileTypeAppleM4V
/**
音视频剪辑
@param assetURL 音视频资源路径
@param startTime 开始剪辑的时间
@param endTime 结束剪辑的时间
@param completionHandle 剪辑完成后的回调
*/
+ (void)cutAudioVideoResourcePath:(NSURL *)assetURL startTime:(CGFloat)startTime endTime:(CGFloat)endTime complition:(void (^)(NSURL *outputPath,BOOL isSucceed)) completionHandle{
// 素材
AVAsset *asset = [AVAsset assetWithURL:assetURL];
// 导出素材
AVAssetExportSession *exporter = [[AVAssetExportSession alloc]initWithAsset:asset presetName:AVAssetExportPresetAppleM4A];
//剪辑(设置导出的时间段)
CMTime start = CMTimeMakeWithSeconds(startTime, asset.duration.timescale);
CMTime duration = CMTimeMakeWithSeconds(endTime - startTime,asset.duration.timescale);
exporter.timeRange = CMTimeRangeMake(start, duration);
// 输出路径
NSURL *outputPath = [self exporterPath];
exporter.outputURL = [self exporterPath];
// 输出格式
exporter.outputFileType = AVFileTypeAppleM4A;
exporter.shouldOptimizeForNetworkUse= YES;
// 合成后的回调
[exporter exportAsynchronouslyWithCompletionHandler:^{
switch ([exporter status]) {
case AVAssetExportSessionStatusFailed: {
NSLog(@"合成失败：%@",[[exporter error] description]);
completionHandle(outputPath,NO);
} break;
case AVAssetExportSessionStatusCancelled: {
completionHandle(outputPath,NO);
} break;
case AVAssetExportSessionStatusCompleted: {
completionHandle(outputPath,YES);
} break;
default: {
completionHandle(outputPath,NO);
} break;
}
}];
}
2、音视频的循环同步播放
下面注释已经很清楚了，不多说了
// 添加播放层
UIView *playView = [[UIView alloc]initWithFrame:CGRectMake(0, 0, self.view.bounds.size.width, 400)];
[self.view addSubview:playView];
// 将资源路径添加到AVPlayerItem上
AVPlayerItem *playItem = [[AVPlayerItem alloc]initWithURL:[self filePathName:@"abc.mp4"]];
// AVPlayer播放需要添加AVPlayerItem
self.player = [[AVPlayer alloc]initWithPlayerItem:playItem];
self.player.volume = 0.5;//默认音量设置为0.5，取值范围0-1
// 播放视频需要在AVPlayerLayer上进行显示
AVPlayerLayer *playerLayer = [AVPlayerLayer playerLayerWithPlayer:self.player];
playerLayer.frame = playView.frame;//必须要设置playerLayer的frame
[playView.layer addSublayer:playerLayer];//将AVPlayerLayer添加到播放层的layer上
// 添加一个循环播放的通知
[[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(repeatPlay) name:AVPlayerItemDidPlayToEndTimeNotification object:nil];
// 背景音乐剪辑播放
// 计算视频的长度，从而进行相应的音频剪辑
AVAsset *asset = [AVAsset assetWithURL:[self filePathName:@"abc.mp4"]];
CMTime duration = asset.duration;
CGFloat videoDuration = duration.value / (float)duration.timescale;
NSLog(@"%f",videoDuration);
// 音频剪辑，调用第一步的音频剪辑工具类
typeof(self) weakSelf = self;
[EditAudioVideo cutAudioVideoResourcePath:[self filePathName:@"123.mp3"] startTime:0 endTime:videoDuration complition:^(NSURL *outputPath, BOOL isSucceed) {
// 音频剪辑成功后，拿到剪辑后的音频路径
NSError *error;
weakSelf.BGMPlayer = [[AVAudioPlayer alloc]initWithContentsOfURL:outputPath error:&error];
if (error == nil) {
weakSelf.BGMPlayer.numberOfLoops = -1;//循环播放
weakSelf.BGMPlayer.volume = 0.5;
[weakSelf.BGMPlayer prepareToPlay];//预先加载音频到内存，播放更流畅
// 播放音频，同时调用视频播放，实现同步播放
[weakSelf.BGMPlayer play];
[weakSelf.player play];
}else{
NSLog(@"%@",error);
}
}];
3、音视频的合成
1、加载音频和视频资源
// 素材
AVAsset *asset = [AVAsset assetWithURL:assetURL];
AVAsset *audioAsset = [AVAsset assetWithURL:BGMPath];
2、分离素材
音频只有音频轨道，而我们录制的视频有两个轨道：音频轨道、视频轨道。需要把音视频资源分离成各个轨道来进行编辑。
// 分离素材
AVAssetTrack *videoAssetTrack = [[asset tracksWithMediaType:AVMediaTypeVideo]objectAtIndex:0];//视频素材
AVAssetTrack *audioAssetTrack = [[audioAsset tracksWithMediaType:AVMediaTypeAudio]objectAtIndex:0];//音频素材
3、编辑各个轨道需要在AVMutableComposition类的环境中进行
// 编辑视频环境
AVMutableComposition *composition = [[AVMutableComposition alloc]init];
视频素材加入视频轨道
AVMutableCompositionTrack *videoCompositionTrack = [composition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
将视频轨道插入到编辑环境中
[videoCompositionTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAssetTrack.timeRange.duration) ofTrack:videoAssetTrack atTime:kCMTimeZero error:nil];
背景音乐音频素材加入音频轨道
AVMutableCompositionTrack *audioCompositionTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
将背景音乐的音频轨道插入到编辑环境中
[audioCompositionTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAssetTrack.timeRange.duration) ofTrack:audioAssetTrack atTime:kCMTimeZero error:nil];
是否加入视频原声，根据需要选择添加，原理同上
AVMutableCompositionTrack *originalAudioCompositionTrack = nil;
if (needOriginalVoice) {
AVAssetTrack *originalAudioAssetTrack = [[asset tracksWithMediaType:AVMediaTypeAudio]objectAtIndex:0];
originalAudioCompositionTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
[originalAudioCompositionTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAssetTrack.timeRange.duration) ofTrack:originalAudioAssetTrack atTime:kCMTimeZero error:nil];
}
将配置好的AVMutableComposition环境添加到导出类
// 导出素材
AVAssetExportSession *exporter = [[AVAssetExportSession alloc]initWithAsset:composition presetName:AVAssetExportPresetMediumQuality];
这里有一个坑，AVMutableCompositionTrack轨道中控制音量preferredVolume属性不起作用，不知道为什么，知道的大神指正下。
所以只能用音频混合调节音量
#pragma mark - 调节合成的音量
+ (AVAudioMix *)buildAudioMixWithVideoTrack:(AVCompositionTrack *)videoTrack VideoVolume:(float)videoVolume BGMTrack:(AVCompositionTrack *)BGMTrack BGMVolume:(float)BGMVolume controlVolumeRange:(CMTime)volumeRange {
// 创建音频混合类
AVMutableAudioMix *audioMix = [AVMutableAudioMix audioMix];
// 拿到视频声音轨道设置音量
AVMutableAudioMixInputParameters *Videoparameters = [AVMutableAudioMixInputParameters audioMixInputParametersWithTrack:videoTrack];
[Videoparameters setVolume:videoVolume atTime:volumeRange];
// 设置背景音乐音量
AVMutableAudioMixInputParameters *BGMparameters = [AVMutableAudioMixInputParameters audioMixInputParametersWithTrack:BGMTrack];
[BGMparameters setVolume:BGMVolume atTime:volumeRange];
// 加入混合数组
audioMix.inputParameters = @[Videoparameters,BGMparameters];
return audioMix;
}
拿到视频、音频资源路径，取到设置的音视频对应音量，进行合成
完整合成代码如下
/**
音视频合成
@param assetURL 原始视频路径
@param BGMPath 背景音乐路径
@param needOriginalVoice 是否添加原视频的声音
@param videoVolume 视频音量
@param BGMVolume 背景音乐音量
@param completionHandle 合成后的回调
*/
+ (void)editVideoSynthesizeVieoPath:(NSURL *)assetURL BGMPath:(NSURL *)BGMPath needOriginalVoice:(BOOL)needOriginalVoice videoVolume:(CGFloat)videoVolume BGMVolume:(CGFloat)BGMVolume complition:(void (^)(NSURL *outputPath,BOOL isSucceed)) completionHandle{
// 素材
AVAsset *asset = [AVAsset assetWithURL:assetURL];
AVAsset *audioAsset = [AVAsset assetWithURL:BGMPath];
// 分离素材
AVAssetTrack *videoAssetTrack = [[asset tracksWithMediaType:AVMediaTypeVideo]objectAtIndex:0];//视频素材
AVAssetTrack *audioAssetTrack = [[audioAsset tracksWithMediaType:AVMediaTypeAudio]objectAtIndex:0];//音频素材
// 编辑视频环境
AVMutableComposition *composition = [[AVMutableComposition alloc]init];
// 视频素材加入视频轨道
AVMutableCompositionTrack *videoCompositionTrack = [composition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
[videoCompositionTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAssetTrack.timeRange.duration) ofTrack:videoAssetTrack atTime:kCMTimeZero error:nil];
// 音频素材加入音频轨道
AVMutableCompositionTrack *audioCompositionTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
[audioCompositionTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAssetTrack.timeRange.duration) ofTrack:audioAssetTrack atTime:kCMTimeZero error:nil];
// 是否加入视频原声
AVMutableCompositionTrack *originalAudioCompositionTrack = nil;
if (needOriginalVoice) {
AVAssetTrack *originalAudioAssetTrack = [[asset tracksWithMediaType:AVMediaTypeAudio]objectAtIndex:0];
originalAudioCompositionTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
[originalAudioCompositionTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAssetTrack.timeRange.duration) ofTrack:originalAudioAssetTrack atTime:kCMTimeZero error:nil];
}
// 导出素材
AVAssetExportSession *exporter = [[AVAssetExportSession alloc]initWithAsset:composition presetName:AVAssetExportPresetMediumQuality];
// 音量控制
exporter.audioMix = [self buildAudioMixWithVideoTrack:originalAudioCompositionTrack VideoVolume:videoVolume BGMTrack:audioCompositionTrack BGMVolume:BGMVolume controlVolumeRange:kCMTimeZero];
// 设置输出路径
NSURL *outputPath = [self exporterPath];
exporter.outputURL = [self exporterPath];
exporter.outputFileType = AVFileTypeMPEG4;//指定输出格式
[exporter exportAsynchronouslyWithCompletionHandler:^{
switch ([exporter status]) {
case AVAssetExportSessionStatusFailed: {
NSLog(@"合成失败：%@",[[exporter error] description]);
completionHandle(outputPath,NO);
} break;
case AVAssetExportSessionStatusCancelled: {
completionHandle(outputPath,NO);
} break;
case AVAssetExportSessionStatusCompleted: {
completionHandle(outputPath,YES);
} break;
default: {
completionHandle(outputPath,NO);
} break;
}
}];
GitHub代码下载https://github.com/D-james/AudioVideoEdit，文件比较大，因为把要合成的音频、视频也传上去了。
swift版https://github.com/D-james/EditAudioVideo-swift
参考资料：《AV Foundation开发秘籍:实践掌握iOS & OS X 应用的视听处理技术》
