我正在尝试从.m4v视频中提取音频文件.它显示错误,如,
Error Domain=AVFoundationErrorDomain Code=-11800 "The operation could not be completed" UserInfo=0x15e350d0 {NSLocalizedDescription=The operation could not be completed, NSUnderlyingError=0x15d1c6b0 "The operation couldn’t be completed. (OSStatus error -12124.)", NSLocalizedFailureReason=An unknown error occurred (-12124)}
这是我的代码:
-(void)extractAudioFromVideo{
//Create a audia composition and add audio track
AVMutableComposition *newAudioAsset = [AVMutableComposition composition];
AVMutableCompositionTrack *dstCompositionTrack = [newAudioAsset addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
//Get video asset from which the audio should be extracted
NSURL *url = [[NSBundle mainBundle] URLForResource:@"sample_iPod" withExtension:@"m4v"];
AVAsset *srcAsset = [AVAsset assetWithURL:url];
NSArray *trackArray = [srcAsset tracksWithMediaType:AVMediaTypeAudio];
if(!trackArray.count){
NSLog(@"Track returns empty array for mediatype AVMediaTypeAudio");
return;
}
AVAssetTrack *srcAssetTrack = [trackArray objectAtIndex:0];
//Extract time range
CMTimeRange timeRange = srcAssetTrack.timeRange;
//Insert audio from the video to mutable avcomposition track
NSError *err = nil;
if(NO == [dstCompositionTrack insertTimeRange:timeRange ofTrack:srcAssetTrack atTime:kCMTimeZero error:&err]){
NSLog(@"Failed to insert audio from the video to mutable avcomposition track");
return;
}
//Export the avcompostion track to destination path
NSString *documentsDirectory = [NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex: 0];
NSString *dstPath = [documentsDirectory stringByAppendingString:@"sample_audio.mp4"];
NSURL *dstURL = [NSURL fileURLWithPath:dstPath];
//Remove if any file already exists
[[NSFileManager defaultManager] removeItemAtURL:dstURL error:nil];
AVAssetExportSession *exportSession = [[AVAssetExportSession alloc]initWithAsset:newAudioAsset presetName:AVAssetExportPresetPassthrough];
NSLog(@"support file types= %@", [exportSession supportedFileTypes]);
exportSession.outputFileType = @"public.mpeg-4";
exportSession.outputURL = dstURL;
[exportSession exportAsynchronouslyWithCompletionHandler:^{
AVAssetExportSessionStatus status = exportSession.status;
if(AVAssetExportSessionStatusCompleted != status){
NSLog(@"Export status not yet completed. Error: %@", exportSession.error.description);
}
}];
}
我该如何解决这个错误?
最佳答案 我已经在模拟器中测试了你的代码.它在模拟器(IOS7)中运行良好.但是当我在iPodTouch-5上运行时,它会像你提到的那样显示错误.花了超过15分钟,发现和愚蠢的错误.
我在Device中运行时获取如下路径(Documentssample_audio.mp4)
@"file:///var/mobile/Applications/A1E1D85F-0198-4A0C-80F8-222F0DA1C31A/Documentssample_audio.mp4"
所以我修改了路径…
NSString *documentsDirectory = [NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex: 0];
NSString *dstPath = [documentsDirectory stringByAppendingString:@"/sample_audio.mp4"];
现在我得到如下路径(/Documents/sample_audio.mp4)并正常工作.但我不知道,它是如何发生的
@"file:///var/mobile/Applications/A1E1D85F-0198-4A0C-80F8-222F0DA1C31A/Documents/sample_audio.mp4"