【发布时间】：2014-06-30 23:06:05
【问题描述】：
我正在尝试将 1s 音轨（“dummy_recording.m4a”）添加到我的 3s 视频的开头。但我现在得到的是一个 6 秒长的视频。它以黑色背景的录制开始，然后仅显示黑色背景，然后在最后显示视频。我在这里做错了什么？我只希望音频从头开始与我的视频重叠。
-(void) addAudioToFileAtPath:(NSString *) filePath toPath:(NSString *)outFilePath completion:( void ( ^ ) () )completion
{
NSString *audioFilePath = [[NSBundle mainBundle] pathForResource:@"dummy_recording"
ofType:@"m4a"];
NSDictionary *audioInfoDictionary = @{@"audioFilePath": audioFilePath, @"audioDuration": [NSNumber numberWithFloat:1.0]};
NSArray *audioInfoArray = @[audioInfoDictionary];
NSError * error = nil;
AVMutableComposition * composition = [AVMutableComposition composition];
AVURLAsset * videoAsset = [AVURLAsset URLAssetWithURL:[NSURL fileURLWithPath:filePath] options:nil];
AVAssetTrack * videoAssetTrack = [[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
AVMutableCompositionTrack *compositionVideoTrack = [composition addMutableTrackWithMediaType:AVMediaTypeVideo
preferredTrackID: kCMPersistentTrackID_Invalid];
NSLog(@"videoAsset.duration... value: %lld, timescale: %d, seconds: %lld", videoAsset.duration.value, videoAsset.duration.timescale, videoAsset.duration.value / videoAsset.duration.timescale);
[compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAsset.duration) ofTrack:videoAssetTrack atTime:kCMTimeZero
error:&error];
CMTime audioStartTime = kCMTimeZero;
for (NSDictionary * audioInfo in audioInfoArray)
{
NSString * pathString = [audioInfo objectForKey:@"audioFilePath"];
AVURLAsset * urlAsset = [AVURLAsset URLAssetWithURL:[NSURL fileURLWithPath:pathString] options:nil];
AVAssetTrack * audioAssetTrack = [[urlAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
AVMutableCompositionTrack *compositionAudioTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio
preferredTrackID: kCMPersistentTrackID_Invalid];
NSLog(@"urlAsset.duration... value: %lld, timescale: %d, seconds: %lld", urlAsset.duration.value, urlAsset.duration.timescale, urlAsset.duration.value / urlAsset.duration.timescale);
[compositionAudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero,urlAsset.duration) ofTrack:audioAssetTrack atTime:audioStartTime error:&error];
audioStartTime = CMTimeAdd(audioStartTime, CMTimeMake((int) (([[audioInfo objectForKey:@"audioDuration"] floatValue] * RECORDING_FPS) + 0.5), RECORDING_FPS));
}
NSLog(@"composition.duration... value: %lld, timescale: %d, seconds: %lld", composition.duration.value, composition.duration.timescale, composition.duration.value / composition.duration.timescale);
AVAssetExportSession* assetExport = [[AVAssetExportSession alloc] initWithAsset:composition presetName:AVAssetExportPresetHighestQuality];
assetExport.outputFileType = AVFileTypeMPEG4;
assetExport.outputURL = [NSURL fileURLWithPath:outFilePath];
[assetExport exportAsynchronouslyWithCompletionHandler:
^(void ) {
switch (assetExport.status)
{
case AVAssetExportSessionStatusCompleted:
// export complete
NSLog(@"Export Complete");
completion();
break;
case AVAssetExportSessionStatusFailed:
NSLog(@"Export Failed");
NSLog(@"ExportSessionError: %@", [assetExport.error localizedDescription]);
// export error (see exportSession.error)
break;
case AVAssetExportSessionStatusCancelled:
NSLog(@"Export Failed");
NSLog(@"ExportSessionError: %@", [assetExport.error localizedDescription]);
// export cancelled
break;
}
}];
}
这是记录持续时间的语句的结果。作品的长度是 3 秒，这正是我想要的，但它仍然错误地导出为 6 秒：
videoAsset.duration... value: 1840, timescale: 600, seconds: 3
urlAsset.duration... value: 87040, timescale: 44100, seconds: 1
composition.duration... value: 1840, timescale: 600, seconds: 3
我从静止图像创建了 3s 视频文件。代码如下：
NSString *documentsFolder = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)
objectAtIndex:0];
NSString *path = [documentsFolder stringByAppendingPathComponent:@"test_video.mp4"];
DDLogInfo(@"path: %@", path);
NSFileManager *fileManager = [NSFileManager defaultManager];
NSError *removeItemError;
BOOL success = [fileManager removeItemAtPath:path error:&removeItemError];
if (success) {
NSLog(@"removed file");
}
else
{
NSLog(@"Could not delete file -:%@ ",[removeItemError localizedDescription]);
}
NSString *path2 = [documentsFolder stringByAppendingPathComponent:@"test_video_with_audio.mp4"];
DDLogInfo(@"path2: %@", path);
NSError *removeItemError2;
BOOL success2 = [fileManager removeItemAtPath:path2 error:&removeItemError2];
if (success2) {
NSLog(@"removed file");
}
else
{
NSLog(@"Could not delete file -:%@ ",[removeItemError2 localizedDescription]);
}
//1. Wire the writer.
NSError *error = nil;
AVAssetWriter *videoWriter = [[AVAssetWriter alloc] initWithURL:
[NSURL fileURLWithPath:path] fileType:AVFileTypeMPEG4
error:&error];
NSParameterAssert(videoWriter);
self.videoWriter = videoWriter;
NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:
AVVideoCodecH264, AVVideoCodecKey,
[NSNumber numberWithInt:640], AVVideoWidthKey,
[NSNumber numberWithInt:640], AVVideoHeightKey,
nil];
AVAssetWriterInput* writerInput = [AVAssetWriterInput
assetWriterInputWithMediaType:AVMediaTypeVideo
outputSettings:videoSettings]; //retain should be removed if ARC
NSParameterAssert(writerInput);
NSParameterAssert([videoWriter canAddInput:writerInput]);
[videoWriter addInput:writerInput];
NSMutableDictionary *attributes = [[NSMutableDictionary alloc] init];
[attributes setObject:[NSNumber numberWithUnsignedInt:kCVPixelFormatType_32ARGB] forKey:(NSString*)kCVPixelBufferPixelFormatTypeKey];
[attributes setObject:[NSNumber numberWithUnsignedInt:640] forKey:(NSString*)kCVPixelBufferWidthKey];
[attributes setObject:[NSNumber numberWithUnsignedInt:640] forKey:(NSString*)kCVPixelBufferHeightKey];
AVAssetWriterInputPixelBufferAdaptor *adaptor = [AVAssetWriterInputPixelBufferAdaptor
assetWriterInputPixelBufferAdaptorWithAssetWriterInput:writerInput
sourcePixelBufferAttributes:attributes];
//2. Start a session
[videoWriter startWriting];
[videoWriter startSessionAtSourceTime:kCMTimeZero]; //use kCMTimeZero if unsure
UIImage *image = [UIImage imageNamed:@"dummy_square.jpg"];
CGImageRef cgImage = image.CGImage;
//3. Write some samples
//CVPixelBufferRef pixelBuffer = [self newPixelBufferFromCGImage:cgImage];
CVPixelBufferRef pixelBuffer = [self pixelBufferFromCGImage:cgImage];
BOOL result = [adaptor appendPixelBuffer:pixelBuffer withPresentationTime:CMTimeMakeWithSeconds(3.0, RECORDING_FPS)];
if (result == NO)
NSLog(@"failed to append buffer");
else
NSLog(@"appended buffer!");
if(pixelBuffer)
{
CVBufferRelease(pixelBuffer);
}
//4. Finish the session
[writerInput markAsFinished];
//[videoWriter endSessionAtSourceTime:…]; //optional can call finishWriting without specifiying endTime
self.library = [[ALAssetsLibrary alloc] init];
__weak ALAssetsLibrary *lib = self.library;
[videoWriter finishWritingWithCompletionHandler:^{
[self addAudioToFileAtPath:path toPath:path2 completion:^{
NSString *albumName = @"Test Album";
NSURL *pathUrl = [[NSURL alloc] initWithString:path2];
[lib addAssetsGroupAlbumWithName:albumName resultBlock:^(ALAssetsGroup *group) {
///checks if group previously created
if(group == nil){
//enumerate albums
[lib enumerateGroupsWithTypes:ALAssetsGroupAlbum
usingBlock:^(ALAssetsGroup *g, BOOL *stop)
{
//if the album is equal to our album
if ([[g valueForProperty:ALAssetsGroupPropertyName] isEqualToString:albumName]) {
[lib writeVideoAtPathToSavedPhotosAlbum:pathUrl completionBlock:^(NSURL *assetURL, NSError *error) {
//then get the image asseturl
[lib assetForURL:assetURL
resultBlock:^(ALAsset *asset) {
//put it into our album
[g addAsset:asset];
} failureBlock:^(NSError *error) {
}];
}];
}
}failureBlock:^(NSError *error){
}];
}else{
[lib writeVideoAtPathToSavedPhotosAlbum:pathUrl completionBlock:^(NSURL *assetURL, NSError *error) {
//then get the image asseturl
[lib assetForURL:assetURL
resultBlock:^(ALAsset *asset) {
//put it into our album
[group addAsset:asset];
} failureBlock:^(NSError *error) {
}];
}];
}
} failureBlock:^(NSError *error) {
}];
}];
}];
【问题讨论】：
-
我会看看你的源文件。我刚刚使用了您发布的带有 1s 音频和 3s 视频文件的确切代码，它运行良好。
-
@ChrisH 我正在从静止图像创建 3 秒视频。我刚刚将我用于此问题的代码添加到我的问题中。
-
@ChrisH 我非常坚持这一点，并且希望您能提供任何帮助。 :)
标签： ios avfoundation