释放 AVAudioRecorder 会话后恢复录制

Question

我正在使用 AVAudioRecorder 类来录制声音。可以在一个 AVAudioRecorder 会话中开始、暂停、恢复、停止录制声音。如果应用程序关闭并重新启动，则无法恢复对已存在的音频文件的录制。

Issues with recording and playing .wav files IOS

请参考我的问题（以前在这里问过）来看看我的代码来初始化录音机。

有可能吗？请帮忙！谢谢！

Answer 1

我认为您必须在每次应用关闭时将录音文件单独保存到文档目录中，并且在应用启动后混合所有可用的录音。

这里是混合音频文件的代码，在你的情况下，你只需要混合两个文件，因此需要相应地使用代码。

-(void)mixAudios
{
//mix all audio files
AVMutableComposition* mixComposition = [AVMutableComposition composition];
AVMutableCompositionTrack *compositionCommentaryTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio  preferredTrackID:kCMPersistentTrackID_Invalid];

for (number of your recordings)
{

    AVURLAsset* audioAsset = [[AVURLAsset alloc]initWithURL:[NSURL URLWithString:@"** Recording file Path **"] options:nil];

    if(![compositionCommentaryTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, audioAsset.duration) ofTrack:[[audioAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0] atTime:CMTimeMake(Start time in seconds for each Recoring,1) error:nil])
    {
         NSLog(@" error: %@"error);
    }

}


//save mixed composition as file
AVAssetExportSession* _assetExport = [[AVAssetExportSession alloc] initWithAsset:mixComposition
                                                                      presetName:AVAssetExportPresetPassthrough];

NSString* videoName = @".mov";
NSString* videoPath = [[NSString alloc] initWithFormat:@"%@/%@", [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0], videoName];
NSString *exportPath = [NSTemporaryDirectory() stringByAppendingPathComponent:videoName];
if([[NSFileManager defaultManager] fileExistsAtPath:exportPath])
{
    [[NSFileManager defaultManager] removeItemAtPath:exportPath error:nil];
}
NSURL *exportUrl = [NSURL fileURLWithPath:exportPath];
_assetExport.outputFileType = @"com.apple.quicktime-movie";
_assetExport.outputURL = exportUrl;
_assetExport.shouldOptimizeForNetworkUse = YES;
[_assetExport exportAsynchronouslyWithCompletionHandler:
 ^(void )
 {
     [_assetExport release];
     NSString *path = [NSString stringWithString:[exportUrl path]];
     if (UIVideoAtPathIsCompatibleWithSavedPhotosAlbum (path)) {
         UISaveVideoAtPathToSavedPhotosAlbum (path, nil, nil, nil);
     }

 }

 ];
}