如何写一个电影的视频和音频使用AVAssetWriter？ [英] How to write a movie with video AND audio using AVAssetWriter?
问题描述
我要导出电影 AVAssetWriter 和无法弄清楚如何将同步视频和音频轨道。仅导出视频工作正常，但是当我添加音频最终的影片看起来是这样的：
的首先，我看视频（无音频），那么视频冻结（显示最后一帧图像，直到结束），并在几秒钟后，我听到了声音。的
我尝试了一些事情 CMSampleBufferSetOutput presentationTimeStamp （减去第一个 CMSampleBufferGet presentationTimeStamp 从电流）音频，但是这一切都没有工作，我不认为这是正确的方向，因为视频和放大器;在源影片的音频应该是同步反正...
我在很短的设置：我创建一个 AVAssetReader 2 AVAssetReaderTrackOutput （一个用于视频，一个用于音频）并把它们添加到 AVAssetReader ，然后创建一个 AVAssetWriter 2 AVAssetWriterInput （视讯及音频），并将它们添加到 AVAssetWriter ...我开始这一切了：
[assetReader startReading]
[assetWriter startWriting]
[assetWriter startSessionAtSourceTime：kCMTimeZero];
然后我跑2队列做样品缓冲液的东西：
dispatch_queue_t queueVideo = dispatch_queue_create（assetVideoWriterQueue，NULL）;
[assetWriterVideoInput requestMediaDataWhenReadyOnQueue：queueVideo usingBlock：^
{
而（[assetWriterVideoInput isReadyForMoreMediaData]）
{
CMSampleBufferRef sampleBuffer = [assetReaderVideoOutput copyNextSampleBuffer]
如果（sampleBuffer）
{
[assetWriterVideoInput appendSampleBuffer：sampleBuffer];
CFRelease（sampleBuffer）;
}其他
{
[assetWriterVideoInput markAsFinished]
dispatch_release（queueVideo）;
videoFinished = YES;
打破;
}
}
}];dispatch_queue_t queueAudio = dispatch_queue_create（assetAudioWriterQueue，NULL）;
[assetWriterAudioInput requestMediaDataWhenReadyOnQueue：queueAudio usingBlock：^
{
而（[assetWriterAudioInput isReadyForMoreMediaData]）
{
CMSampleBufferRef sampleBuffer = [assetReaderAudioOutput copyNextSampleBuffer]
如果（sampleBuffer）
{
[assetWriterAudioInput appendSampleBuffer：sampleBuffer];
CFRelease（sampleBuffer）;
}其他
{
[assetWriterAudioInput markAsFinished]
dispatch_release（queueAudio）;
audioFinished = YES;
打破;
}
}
}];
在主循环我等两个队列，直到他们完成：
而（videoFinished＆安培;！＆安培;！audioFinished）
{
睡眠（1）;
}
[assetWriter finishWriting]
此外，我试图在库中生成的文件保存为以下code ...
NSURL * URL = [[NSURL页头] initFileURLWithPath：路径];
ALAssetsLibrary *库= [[ALAssetsLibrary的alloc]初始化];
如果（[库videoAtPathIsCompatibleWithSavedPhotosAlbum：URL]）
{
[库writeVideoAtPathToSavedPhotosAlbum：URL completionBlock：^（NSURL * assetURL，NSError *误差）
{
如果（错误）
的NSLog（@错误=％@，error.localizedDescription）;
其他
的NSLog（@已完成...）;
}];
}其他
的NSLog（@的错误，视频不保存...）;[库发布]
[URL发布]
...但我得到的错误：
视频/用户/ CB /库/应用程序支持/ iPhone模拟器/ 4.2 /应用/ E9865BF9-D190-4912-9248-66768B1AB635 /文件/ export.mp4
不能保存到存储的照片相册：错误
域名= NSOSStatusErrorDomain code = -12950电影无法播放。
的UserInfo = {0x5e4fb90 = NSLocalizedDescription电影不能
播放。}在code没有工作在另一个程序的问题。所以，什么是错的电影...？
解决方案- （无效）mergeAudioVideo
{ * NSString的= videoOutputPath [_ documentsDirectory stringByAppendingPathComponent：@dummy_video.mp4];
* NSString的outputFilePath = [_documentsDirectory stringByAppendingPathComponent：@final_video.mp4];
如果（[的NSFileManager defaultManager] fileExistsAtPath：outputFilePath]）
[的NSFileManager defaultManager] removeItemAtPath：outputFilePath错误：无];
NSURL * outputFileUrl = [NSURL fileURLWithPath：outputFilePath];
* NSString的文件路径= [_documentsDirectory stringByAppendingPathComponent：@newFile.m4a];
AVMutableComposition * mixComposition = [AVMutableComposition组成] NSURL * audio_inputFileUrl = [NSURL fileURLWithPath：文件路径]
NSURL * video_inputFileUrl = [NSURL fileURLWithPath：videoOutputPath]; CMTime nextClipStartTime = kCMTimeZero; AVURLAsset * videoAsset = [[AVURLAsset页头] initWithURL：video_inputFileUrl选项：无];
CMTimeRange video_timeRange = CMTimeRangeMake（kCMTimeZero，videoAsset.duration）; AVMutableCompositionTrack * a_compositionVideoTrack = [mixComposition addMutableTrackWithMediaType：AVMediaTypeVideo preferredTrackID：kCMPersistentTrackID_Invalid];
[a_compositionVideoTrack insertTimeRange：video_timeRange ofTrack：[videoAsset tracksWithMediaType：AVMediaTypeVideo] objectAtIndex：0] atTime：nextClipStartTime错误：无]; AVURLAsset * audioAsset = [[AVURLAsset页头] initWithURL：audio_inputFileUrl选项：无];
CMTimeRange audio_timeRange = CMTimeRangeMake（kCMTimeZero，audioAsset.duration）;
AVMutableCompositionTrack * b_compositionAudioTrack = [mixComposition addMutableTrackWithMediaType：AVMediaTypeAudio preferredTrackID：kCMPersistentTrackID_Invalid];
[b_compositionAudioTrack insertTimeRange：audio_timeRange ofTrack：[audioAsset tracksWithMediaType：AVMediaTypeAudio] objectAtIndex：0] atTime：nextClipStartTime错误：无]; AVAssetExportSession * _assetExport = [[AVAssetExportSession页头] initWithAsset：mixComposition presetName：AVAssetExport presetMediumQuality]。
_assetExport.outputFileType = @com.apple.quicktime-电影;
_assetExport.outputURL = outputFileUrl; [_assetExport exportAsynchronouslyWithCompletionHandler：
^（无效）{
如果（_assetExport.status == AVAssetExportSessionStatusCompleted）{ //将code此处继续
}
其他{
//在这里写下失败code
}
}
];}您可以使用此code合并音频和视频。
I want to export a movie with
AVAssetWriterand can't figure out how to include video and audio tracks in sync. Exporting only video works fine, but when I add audio the resulting movie looks like this:First I see the video (without audio), then the video freezes (showing the last image frame until the end) and after some seconds I hear the audio.
I tried some things with
CMSampleBufferSetOutputPresentationTimeStamp(subtracting the firstCMSampleBufferGetPresentationTimeStampfrom the current) for the audio, but it all didn't work and I don't think it is the right direction, since video & audio in the source movie should be in sync anyway...My setup in short: I create an
AVAssetReaderand 2AVAssetReaderTrackOutput(one for video, one for audio) and add them to theAVAssetReader, then I create anAVAssetWriterand 2AVAssetWriterInput(video & audio) and add them to theAVAssetWriter... I start it all up with:[assetReader startReading]; [assetWriter startWriting]; [assetWriter startSessionAtSourceTime:kCMTimeZero];Then I run 2 queues for doing the sample buffer stuff:
dispatch_queue_t queueVideo=dispatch_queue_create("assetVideoWriterQueue", NULL); [assetWriterVideoInput requestMediaDataWhenReadyOnQueue:queueVideo usingBlock:^ { while([assetWriterVideoInput isReadyForMoreMediaData]) { CMSampleBufferRef sampleBuffer=[assetReaderVideoOutput copyNextSampleBuffer]; if(sampleBuffer) { [assetWriterVideoInput appendSampleBuffer:sampleBuffer]; CFRelease(sampleBuffer); } else { [assetWriterVideoInput markAsFinished]; dispatch_release(queueVideo); videoFinished=YES; break; } } }]; dispatch_queue_t queueAudio=dispatch_queue_create("assetAudioWriterQueue", NULL); [assetWriterAudioInput requestMediaDataWhenReadyOnQueue:queueAudio usingBlock:^ { while([assetWriterAudioInput isReadyForMoreMediaData]) { CMSampleBufferRef sampleBuffer=[assetReaderAudioOutput copyNextSampleBuffer]; if(sampleBuffer) { [assetWriterAudioInput appendSampleBuffer:sampleBuffer]; CFRelease(sampleBuffer); } else { [assetWriterAudioInput markAsFinished]; dispatch_release(queueAudio); audioFinished=YES; break; } } }];In the main loop I wait for both queues until they finish:
while(!videoFinished && !audioFinished) { sleep(1); } [assetWriter finishWriting];Furthermore I try to save the resulting file in the library with the following code...
NSURL *url=[[NSURL alloc] initFileURLWithPath:path]; ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init]; if([library videoAtPathIsCompatibleWithSavedPhotosAlbum:url]) { [library writeVideoAtPathToSavedPhotosAlbum:url completionBlock:^(NSURL *assetURL, NSError *error) { if(error) NSLog(@"error=%@",error.localizedDescription); else NSLog(@"completed..."); }]; } else NSLog(@"error, video not saved..."); [library release]; [url release];...but I get the error:
Video /Users/cb/Library/Application Support/iPhone Simulator/4.2/Applications/E9865BF9-D190-4912-9248-66768B1AB635/Documents/export.mp4 cannot be saved to the saved photos album: Error Domain=NSOSStatusErrorDomain Code=-12950 "Movie could not be played." UserInfo=0x5e4fb90 {NSLocalizedDescription=Movie could not be played.}The code works without problems in another program. So something is wrong with the movie...?
解决方案-(void)mergeAudioVideo { NSString *videoOutputPath=[_documentsDirectory stringByAppendingPathComponent:@"dummy_video.mp4"]; NSString *outputFilePath = [_documentsDirectory stringByAppendingPathComponent:@"final_video.mp4"]; if ([[NSFileManager defaultManager]fileExistsAtPath:outputFilePath]) [[NSFileManager defaultManager]removeItemAtPath:outputFilePath error:nil]; NSURL *outputFileUrl = [NSURL fileURLWithPath:outputFilePath]; NSString *filePath = [_documentsDirectory stringByAppendingPathComponent:@"newFile.m4a"]; AVMutableComposition* mixComposition = [AVMutableComposition composition]; NSURL *audio_inputFileUrl = [NSURL fileURLWithPath:filePath]; NSURL *video_inputFileUrl = [NSURL fileURLWithPath:videoOutputPath]; CMTime nextClipStartTime = kCMTimeZero; AVURLAsset* videoAsset = [[AVURLAsset alloc]initWithURL:video_inputFileUrl options:nil]; CMTimeRange video_timeRange = CMTimeRangeMake(kCMTimeZero,videoAsset.duration); AVMutableCompositionTrack *a_compositionVideoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid]; [a_compositionVideoTrack insertTimeRange:video_timeRange ofTrack:[[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] atTime:nextClipStartTime error:nil]; AVURLAsset* audioAsset = [[AVURLAsset alloc]initWithURL:audio_inputFileUrl options:nil]; CMTimeRange audio_timeRange = CMTimeRangeMake(kCMTimeZero, audioAsset.duration); AVMutableCompositionTrack *b_compositionAudioTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid]; [b_compositionAudioTrack insertTimeRange:audio_timeRange ofTrack:[[audioAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0] atTime:nextClipStartTime error:nil]; AVAssetExportSession* _assetExport = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPresetMediumQuality]; _assetExport.outputFileType = @"com.apple.quicktime-movie"; _assetExport.outputURL = outputFileUrl; [_assetExport exportAsynchronouslyWithCompletionHandler: ^(void ) { if (_assetExport.status == AVAssetExportSessionStatusCompleted) { //Write Code Here to Continue } else { //Write Fail Code here } } ]; }You can use this code to merge audio and video.
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