我想實現一項功能,讓用戶修剪他先前錄製的音頻文件(.caf)。錄音部分已經可以工作了,但是我如何添加類似於Voicememos應用程序中的修剪功能。蘋果公司使用的音頻微調器有api嗎? 任何幫助將是偉大的...使用iOS修剪音頻
8
A
回答
20
如何使用AVFoundation?將音頻文件導入到AVAsset(合成等)中,然後可以將它導出(將首選時間+持續時間)設置爲文件。
我之前寫過一個股票函數,用於將資產導出到文件中,您還可以指定一個audiomix。如下所示,它會導出所有文件,但是您可以將NSTimeRange添加到exporter.timeRange,然後您可以繼續。我還沒有測試,但應該工作(?)。另一種方法是在創建AVAsset +音軌時調整時間範圍。當然,出口商只處理m4a(AAC)。對不起,如果這不是你想要的。
-(void)exportAsset:(AVAsset*)asset toFile:(NSString*)filename overwrite:(BOOL)overwrite withMix:(AVAudioMix*)mix {
//NSArray* availablePresets = [AVAssetExportSession exportPresetsCompatibleWithAsset:asset];
AVAssetExportSession* exporter = [AVAssetExportSession exportSessionWithAsset:asset presetName:AVAssetExportPresetAppleM4A];
if (exporter == nil) {
DLog(@"Failed creating exporter!");
return;
}
DLog(@"Created exporter! %@", exporter);
// Set output file type
DLog(@"Supported file types: %@", exporter.supportedFileTypes);
for (NSString* filetype in exporter.supportedFileTypes) {
if ([filetype isEqualToString:AVFileTypeAppleM4A]) {
exporter.outputFileType = AVFileTypeAppleM4A;
break;
}
}
if (exporter.outputFileType == nil) {
DLog(@"Needed output file type not found? (%@)", AVFileTypeAppleM4A);
return;
}
// Set outputURL
NSArray* paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString* parentDir = [NSString stringWithFormat:@"%@/", [paths objectAtIndex:0]];
NSString* outPath = [NSString stringWithFormat:@"%@%@", parentDir, filename];
NSFileManager* manager = [NSFileManager defaultManager];
if ([manager fileExistsAtPath:outPath]) {
DLog(@"%@ already exists!", outPath);
if (!overwrite) {
DLog(@"Not overwriting, uh oh!");
return;
}
else {
// Overwrite
DLog(@"Overwrite! (delete first)");
NSError* error = nil;
if (![manager removeItemAtPath:outPath error:&error]) {
DLog(@"Failed removing %@, error: %@", outPath, error.description);
return;
}
else {
DLog(@"Removed %@", outPath);
}
}
}
NSURL* const outUrl = [NSURL fileURLWithPath:outPath];
exporter.outputURL = outUrl;
// Specify a time range in case only part of file should be exported
//exporter.timeRange =
if (mix != nil)
exporter.audioMix = mix; // important
DLog(@"Starting export! (%@)", exporter.outputURL);
[exporter exportAsynchronouslyWithCompletionHandler:^(void) {
// Export ended for some reason. Check in status
NSString* message;
switch (exporter.status) {
case AVAssetExportSessionStatusFailed:
message = [NSString stringWithFormat:@"Export failed. Error: %@", exporter.error.description];
DLog(@"%@", message);
[self showAlert:message];
break;
case AVAssetExportSessionStatusCompleted: {
/*if (playfileWhenExportFinished) {
DLog(@"playfileWhenExportFinished!");
[self playfileAfterExport:exporter.outputURL];
playfileWhenExportFinished = NO;
}*/
message = [NSString stringWithFormat:@"Export completed: %@", filename];
DLog(@"%@", message);
[self showAlert:message];
break;
}
case AVAssetExportSessionStatusCancelled:
message = [NSString stringWithFormat:@"Export cancelled!"];
DLog(@"%@", message);
[self showAlert:message];
break;
default:
DLog(@"Export unhandled status: %d", exporter.status);
break;
}
}];
}
1
@Jonny的上面的答案是正確的。這裏是我添加AudioMixer的使用,以添加音頻修整時的淡入效果。
輸出:音頻資產修剪至20秒,在10秒的褪色 被設置裝飾了在代碼段發生在30秒 標記資產的,因此,軌道持續時間應在至少 50秒。
- (BOOL)exportAssettoFilePath:(NSString *)filePath {
NSString *inputFilePath = <inputFilePath>;
NSURL *videoToTrimURL = [NSURL fileURLWithPath:inputFilePath];
AVAsset *avAsset = [AVAsset assetWithURL:videoToTrimURL];
// we need the audio asset to be at least 50 seconds long for this snippet
CMTime assetTime = [avAsset duration];
Float64 duration = CMTimeGetSeconds(assetTime);
if (duration < 50.0) return NO;
// get the first audio track
NSArray *tracks = [avAsset tracksWithMediaType:AVMediaTypeAudio];
if ([tracks count] == 0) return NO;
AVAssetTrack *track = [tracks objectAtIndex:0];
// create the export session
// no need for a retain here, the session will be retained by the
// completion handler since it is referenced there
AVAssetExportSession *exportSession = [AVAssetExportSession
exportSessionWithAsset:avAsset
presetName:AVAssetExportPresetAppleM4A];
if (nil == exportSession) return NO;
// create trim time range - 20 seconds starting from 30 seconds into the asset
CMTime startTime = CMTimeMake(30, 1);
CMTime stopTime = CMTimeMake(50, 1);
CMTimeRange exportTimeRange = CMTimeRangeFromTimeToTime(startTime, stopTime);
// create fade in time range - 10 seconds starting at the beginning of trimmed asset
CMTime startFadeInTime = startTime;
CMTime endFadeInTime = CMTimeMake(40, 1);
CMTimeRange fadeInTimeRange = CMTimeRangeFromTimeToTime(startFadeInTime,
endFadeInTime);
// setup audio mix
AVMutableAudioMix *exportAudioMix = [AVMutableAudioMix audioMix];
AVMutableAudioMixInputParameters *exportAudioMixInputParameters =
[AVMutableAudioMixInputParameters audioMixInputParametersWithTrack:track];
[exportAudioMixInputParameters setVolumeRampFromStartVolume:0.0 toEndVolume:1.0
timeRange:fadeInTimeRange];
exportAudioMix.inputParameters = [NSArray
arrayWithObject:exportAudioMixInputParameters];
// configure export session output with all our parameters
exportSession.outputURL = [NSURL fileURLWithPath:filePath]; // output path
exportSession.outputFileType = AVFileTypeAppleM4A; // output file type
exportSession.timeRange = exportTimeRange; // trim time range
//exportSession.audioMix = exportAudioMix; // fade in audio mix
// perform the export
[exportSession exportAsynchronouslyWithCompletionHandler:^{
if (AVAssetExportSessionStatusCompleted == exportSession.status) {
NSLog(@"AVAssetExportSessionStatusCompleted");
} else if (AVAssetExportSessionStatusFailed == exportSession.status) {
// a failure may happen because of an event out of your control
// for example, an interruption like a phone call comming in
// make sure and handle this case appropriately
NSLog(@"AVAssetExportSessionStatusFailed");
} else {
NSLog(@"Export Session Status: %ld", (long)exportSession.status);
}
}];
return YES;}
感謝
瞭解更多詳情:
https://developer.apple.com/library/ios/qa/qa1730/_index.html
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但這種方法只允許聲音保存在M4A格式,是什麼如果你喜歡修剪一個MP3或一個caf文件並保持fo RMAT? – tommys 2012-02-24 20:38:57
修剪MP3也工作,輸出存儲在m4a格式 2年後,你仍然救我的生命:) – 2013-11-29 09:36:11