iOS中音频合并是指将两个不同的声音文件合成一个声音文件进行输出，音视频合并适用于视频中没有声音，将声音合并到视频中，最好声音的时长和视频的时长是一致的，生成新的适配会更有效果一点，剪切是合并的逆向操作，对音视频可以进行更精细化的处理~
CMTime简介
音视频合并剪切需要更精确，所有中间时间的都是通过CMTime进行出来的，先来看一下结构:
typedef struct
{
CMTimeValue value; /*! @field value The value of the CMTime. value/timescale = seconds. */
CMTimeScale timescale; /*! @field timescale The timescale of the CMTime. value/timescale = seconds. */
CMTimeFlags flags; /*! @field flags The flags, eg. kCMTimeFlags_Valid, kCMTimeFlags_PositiveInfinity, etc. */
CMTimeEpoch epoch; /*! @field epoch Differentiates between equal timestamps that are actually different because
of looping, multi-item sequencing, etc.
Will be used during comparison: greater epochs happen after lesser ones.
Additions/subtraction is only possible within a single epoch,
however, since epoch length may be unknown/variable. */
} CMTime;
value是分子，timeScale是分母，下面是几种CMTime常用的方式，CMTimeShow进行输出，代码如下:
CMTime startTime = CMTimeMake(13, 100);
CMTimeShow(startTime);
CMTime endTime = CMTimeMake(40, 100);
CMTimeShow(endTime);
CMTime addTime = CMTimeAdd(startTime, endTime);
CMTimeShow(addTime);
CMTime subTime = CMTimeSubtract(startTime,endTime);
CMTimeShow(subTime);
CMTimeRange timeRange = CMTimeRangeMake(startTime, endTime);
CMTimeRangeShow(timeRange);
CMTimeRange fromRange = CMTimeRangeFromTimeToTime(startTime, endTime);
CMTimeRangeShow(fromRange);
//交集
CMTimeRange intersectionRange = CMTimeRangeGetIntersection(timeRange, fromRange);
CMTimeRangeShow(intersectionRange);
//合集
CMTimeRange unionRange = CMTimeRangeGetUnion(timeRange, fromRange);
CMTimeRangeShow(unionRange);
音频合并
音视频合并只需要AVFoundation头文件即可进行文件操作，不过有一个限制就是导出的文件都是m4a格式的：
音频合并操作:
NSString *wayPath = [[NSBundle mainBundle] pathForResource:@"MyWay" ofType:@"mp3"];
NSString *easyPath = [[NSBundle mainBundle] pathForResource:@"Easy" ofType:@"mp3"];
NSMutableArray *dataArr = [NSMutableArray array];
[dataArr addObject:[NSURL fileURLWithPath:wayPath]];
[dataArr addObject:[NSURL fileURLWithPath:easyPath]];
NSString *destPath = [[self composeDir] stringByAppendingString:@"FlyElephant.m4a"];
if ([[NSFileManager defaultManager] fileExistsAtPath:destPath]) {
[[NSFileManager defaultManager] removeItemAtPath:destPath error:nil];
}
[self audioMerge:dataArr destUrl:[NSURL fileURLWithPath:destPath]];
核心代码:
- (void)audioMerge:(NSMutableArray *)dataSource destUrl:(NSURL *)destUrl{
AVMutableComposition *mixComposition = [AVMutableComposition composition];
// 开始时间
CMTime beginTime = kCMTimeZero;
// 设置音频合并音轨
AVMutableCompositionTrack *compositionAudioTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
NSError *error = nil;
for (NSURL *sourceURL in dataSource) {
//音频文件资源
AVURLAsset *audioAsset = [[AVURLAsset alloc] initWithURL:sourceURL options:nil];
//需要合并的音频文件的区间
CMTimeRange audio_timeRange = CMTimeRangeMake(kCMTimeZero, audioAsset.duration);
// ofTrack 音频文件内容
BOOL success = [compositionAudioTrack insertTimeRange:audio_timeRange ofTrack:[[audioAsset tracksWithMediaType:AVMediaTypeAudio] firstObject] atTime:beginTime error:&error];
if (!success) {
NSLog(@"Error: %@",error);
}
beginTime = CMTimeAdd(beginTime, audioAsset.duration);
}
// presetName 与 outputFileType 要对应 导出合并的音频
AVAssetExportSession *assetExportSession = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPresetAppleM4A];
assetExportSession.outputURL = destUrl;
assetExportSession.outputFileType = @"com.apple.m4a-audio";
assetExportSession.shouldOptimizeForNetworkUse = YES;
[assetExportSession exportAsynchronouslyWithCompletionHandler:^{
dispatch_async(dispatch_get_main_queue(), ^{
NSLog(@"%@",assetExportSession.error);
});
}];
}
音视频合并
音视频和音频合并类似，合并操作:
NSString *wayPath = [[NSBundle mainBundle] pathForResource:@"MyWay" ofType:@"mp3"];
NSString *easyPath = [[NSBundle mainBundle] pathForResource:@"Way" ofType:@"mp4"];
NSString *destPath = [[self composeDir] stringByAppendingString:@"FlyElephant.mp4"];
if ([[NSFileManager defaultManager] fileExistsAtPath:destPath]) {
[[NSFileManager defaultManager] removeItemAtPath:destPath error:nil];
}
[self audioVedioMerge:[NSURL fileURLWithPath:wayPath] vedioUrl:[NSURL fileURLWithPath:easyPath] destUrl:[NSURL fileURLWithPath:destPath]];
核心代码:
- (void)audioVedioMerge:(NSURL *)audioUrl vedioUrl:(NSURL *)vedioUrl destUrl:(NSURL *)destUrl {
AVMutableComposition *mixComposition = [AVMutableComposition composition];
NSError *error;
AVMutableCompositionTrack *audioCompostionTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
//音频文件资源
AVURLAsset *audioAsset = [[AVURLAsset alloc] initWithURL:audioUrl options:nil];
CMTimeRange audio_timeRange = CMTimeRangeMake(kCMTimeZero, audioAsset.duration);
[audioCompostionTrack insertTimeRange:audio_timeRange ofTrack:[[audioAsset tracksWithMediaType:AVMediaTypeAudio] firstObject] atTime:kCMTimeZero error:&error];
//视频文件资源
AVMutableCompositionTrack *vedioCompostionTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
AVURLAsset *vedioAsset = [[AVURLAsset alloc] initWithURL:vedioUrl options:nil];
CMTimeRange vedio_timeRange = CMTimeRangeMake(kCMTimeZero, vedioAsset.duration);
[vedioCompostionTrack insertTimeRange:vedio_timeRange ofTrack:[[vedioAsset tracksWithMediaType:AVMediaTypeVideo] firstObject] atTime:kCMTimeZero error:&error];
// presetName 与 outputFileType 要对应 导出合并的音频
AVAssetExportSession* assetExportSession = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPresetMediumQuality];
assetExportSession.outputURL = destUrl;
assetExportSession.outputFileType = @"com.apple.quicktime-movie";
assetExportSession.shouldOptimizeForNetworkUse = YES;
[assetExportSession exportAsynchronouslyWithCompletionHandler:^{
dispatch_async(dispatch_get_main_queue(), ^{
NSLog(@"%@",assetExportSession.error);
});
}];
}
音频剪切
剪切比合并简单，只需要操作一个文件即可:
NSString *inputPath = [[self composeDir] stringByAppendingString:@"FlyElephant.m4a"];
[self audioCrop:[NSURL fileURLWithPath:inputPath] startTime:CMTimeMake(30, 1) endTime:CMTimeMake(48, 1)];
核心代码:
- (void)audioCrop:(NSURL *)url startTime:(CMTime)startTime endTime:(CMTime)endTime {
NSString *outPutPath = [[self composeDir] stringByAppendingPathComponent:@"Crop.m4a"];
NSURL *audioFileOutput = [NSURL fileURLWithPath:outPutPath];
[[NSFileManager defaultManager] removeItemAtURL:audioFileOutput error:NULL];
AVAsset *asset = [AVAsset assetWithURL:url];
AVAssetExportSession *exportSession = [AVAssetExportSession exportSessionWithAsset:asset
presetName:AVAssetExportPresetAppleM4A];
CMTimeRange exportTimeRange = CMTimeRangeFromTimeToTime(startTime, endTime);
exportSession.outputURL = audioFileOutput;
exportSession.outputFileType = AVFileTypeAppleM4A;
exportSession.timeRange = exportTimeRange;
[exportSession exportAsynchronouslyWithCompletionHandler:^{
if (AVAssetExportSessionStatusCompleted == exportSession.status) {
NSLog(@" FlyElephant \n %@", outPutPath);
} else if (AVAssetExportSessionStatusFailed == exportSession.status) {
NSLog(@"FlyElephant error: %@", exportSession.error.localizedDescription);
}
}];
}
文件路径:
- (NSString *)composeDir {
NSString *cacheDir = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) firstObject];
NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *compseDir = [NSString stringWithFormat:@"%@/AudioCompose/", cacheDir];
BOOL isDir = NO;
BOOL existed = [fileManager fileExistsAtPath:compseDir isDirectory:&isDir];
if ( !(isDir == YES && existed == YES) ) {
[fileManager createDirectoryAtPath:compseDir withIntermediateDirectories:YES attributes:nil error:nil];
}
return compseDir;
}
以上就是音频合并，剪切的基本操作，如有疑问，欢迎评论区探讨~