使用 AVAssetExportSession 从 3gp 视频文件导出音频
我正在尝试从 3gpp 视频文件导出音频，但它不起作用...有人知道我可能做错了什么吗？这是我正在使用的代码：
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *filePath = [[paths objectAtIndex:0] stringByAppendingPathComponent:@"newFile.m4a"];
NSString *tempFile = [[paths objectAtIndex:0] stringByAppendingPathComponent:@"oldFile.3gp"];
AVURLAsset *asset = [AVURLAsset URLAssetWithURL:[NSURL URLWithString:tempFilePath] options:nil];
[asset loadValuesAsynchronouslyForKeys:[NSArray arrayWithObject:@"tracks"] completionHandler:^ {
//HERE IS THE PROBLEM. THE ARRAY OF TRACKS IS EMPTY FOR SOME REASON.
AVAssetTrack* audioTrack = [[asset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
AVMutableComposition* audioComposition = [AVMutableComposition composition];
AVMutableCompositionTrack* audioCompositionTrack = [audioComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
[audioCompositionTrack insertTimeRange:[audioTrack timeRange] ofTrack:audioTrack atTime:CMTimeMake(0, 1) error:nil];
AVAssetExportSession *exprortSession = [AVAssetExportSession exportSessionWithAsset:audioComposition presetName:AVAssetExportPresetAppleM4A];
NSURL *toFileURL = [NSURL URLWithString:filePath];
exprortSession.outputURL = toFileURL;
exprortSession.outputFileType = @"com.apple.m4a-audio";
NSLog(@"exportAsynchronouslyWithCompletionHandler will start");
[exprortSession exportAsynchronouslyWithCompletionHandler: ^(void) {
if (exprortSession.status == AVAssetExportSessionStatusCompleted) {
NSLog(@"Export success");
}
else {
NSLog(@"Export failed");
}
}];
}];
I am trying to export the audio from a 3gpp video file and it is not working... Does anyone know what I may be doing wrong? Here is the code I am using:
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *filePath = [[paths objectAtIndex:0] stringByAppendingPathComponent:@"newFile.m4a"];
NSString *tempFile = [[paths objectAtIndex:0] stringByAppendingPathComponent:@"oldFile.3gp"];
AVURLAsset *asset = [AVURLAsset URLAssetWithURL:[NSURL URLWithString:tempFilePath] options:nil];
[asset loadValuesAsynchronouslyForKeys:[NSArray arrayWithObject:@"tracks"] completionHandler:^ {
//HERE IS THE PROBLEM. THE ARRAY OF TRACKS IS EMPTY FOR SOME REASON.
AVAssetTrack* audioTrack = [[asset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
AVMutableComposition* audioComposition = [AVMutableComposition composition];
AVMutableCompositionTrack* audioCompositionTrack = [audioComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
[audioCompositionTrack insertTimeRange:[audioTrack timeRange] ofTrack:audioTrack atTime:CMTimeMake(0, 1) error:nil];
AVAssetExportSession *exprortSession = [AVAssetExportSession exportSessionWithAsset:audioComposition presetName:AVAssetExportPresetAppleM4A];
NSURL *toFileURL = [NSURL URLWithString:filePath];
exprortSession.outputURL = toFileURL;
exprortSession.outputFileType = @"com.apple.m4a-audio";
NSLog(@"exportAsynchronouslyWithCompletionHandler will start");
[exprortSession exportAsynchronouslyWithCompletionHandler: ^(void) {
if (exprortSession.status == AVAssetExportSessionStatusCompleted) {
NSLog(@"Export success");
}
else {
NSLog(@"Export failed");
}
}];
}];
如果你对这篇内容有疑问，欢迎到本站社区发帖提问 参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。
绑定邮箱获取回复消息
由于您还没有绑定你的真实邮箱，如果其他用户或者作者回复了您的评论，将不能在第一时间通知您！
发布评论
评论（2）
尝试加载资源
而不是
Try to load the asset with
instead of
由于您的任务将直接操作音频样本缓冲区，因此您应该使用 AVFoundation 为您提供的第二种变体：配对的 AVAssetReader 和 AVAssetWriter 设置。您将在 Apple 开发人员源的 AVReaderWriterOSX 中找到正确的示例代码。除了您可以使用不同的 I/O 格式设置之外，这也应该适用于 iOS。应提供将音频解压缩为 PCM 并写回未压缩的 .wav 或音频文件的可用性
As your task will be manipulating the audio sample buffers directly you should use the second variant that AVFoundation will give you: paired AVAssetReader and AVAssetWriter setup. You'll find proper sample code as in AVReaderWriterOSX from Apple developer source. This should also work with iOS besides you have different I/O format settings available. The availability to decompress audio as PCM and write back to uncompressed .wav or Audio file should be given