Join the social network of Tech Nerds, increase skill rank, get work, manage projects...
 
  • How to clip an audio file in iPhone?

    • 0
    • 0
    • 0
    • 0
    • 0
    • 0
    • 0
    • 0
    • 638
    Comment on it

    Here is the method in ios that can clip an audio file(i.e MPMediaItem) with the time interval.

    In below mentioned method, For time interval we are sending two parameter first is startinterval which is the interval form where we wanted to start clipping the audio file and another parameter is totalTimeInterval which is for the duration till where we need the audio to be clipped and the url path of the audio clipped will be retrieved in the block.

    -(void)convertAudioFileWithFile:(MPMediaItem *)song startInterval:(NSTimeInterval)startinterval
                      totalTimeInterval:(NSTimeInterval)totalTimeInterval
                         completion:(void(^)(NSString *urlString))callback{
        // set up an AVAssetReader to read from the iPod Library
        NSURL *assetURL = [song valueForProperty:MPMediaItemPropertyAssetURL];
        AVURLAsset *songAsset = [AVURLAsset URLAssetWithURL:assetURL options:nil];
    
        NSError *assetError = nil;
        AVAssetReader *assetReader = [AVAssetReader assetReaderWithAsset:songAsset
                                                                    error:&assetError]
                                      ;
        // set the interval
        CMTime start = songAsset.duration;
        CMTime end = songAsset.duration;
        start.value = start.timescale*startinterval;
        end.value = end.timescale*totalTimeInterval;
    
        [assetReader setTimeRange:CMTimeRangeMake(start, end)];
       ///////
    
    
        if (assetError) {
            NSLog (@"error: %@", assetError);
            return;
        }
    
        AVAssetReaderOutput *assetReaderOutput = [AVAssetReaderAudioMixOutput
                                                   assetReaderAudioMixOutputWithAudioTracks:songAsset.tracks
                                                   audioSettings: nil]
                                                  ;
    
    
        if (! [assetReader canAddOutput: assetReaderOutput]) {
            NSLog (@"can't add reader output... die!");
            return;
        }
        [assetReader addOutput: assetReaderOutput];
    
        NSArray *dirs = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
        NSString *documentsDirectoryPath = [dirs objectAtIndex:0];
        NSString *exportPath = [documentsDirectoryPath stringByAppendingPathComponent:EXPORT_NAME];
        if ([[NSFileManager defaultManager] fileExistsAtPath:exportPath]) {
            [[NSFileManager defaultManager] removeItemAtPath:exportPath error:nil];
        }
        NSURL *exportURL = [NSURL fileURLWithPath:exportPath];
        AVAssetWriter *assetWriter = [AVAssetWriter assetWriterWithURL:exportURL
                                                               fileType:AVFileTypeCoreAudioFormat
                                                                 error:&assetError];
        if (assetError) {
            NSLog (@"error: %@", assetError);
            return;
        }
    
        NSNumber *sampleRate = [NSNumber numberWithInt:12000.0];//[NSNumber numberWithFloat:44100.0]
    
        AudioChannelLayout channelLayout;
        memset(&channelLayout, 0, sizeof(AudioChannelLayout));
        channelLayout.mChannelLayoutTag = kAudioChannelLayoutTag_Mono;
        NSDictionary *outputSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                                        [NSNumber numberWithInt:kAudioFormatLinearPCM], AVFormatIDKey,
                                        sampleRate, AVSampleRateKey,
                                        [NSNumber numberWithInt:1], AVNumberOfChannelsKey,
                                        [NSData dataWithBytes:&channelLayout length:sizeof(AudioChannelLayout)], AVChannelLayoutKey,
                                        [NSNumber numberWithInt:16], AVLinearPCMBitDepthKey,
                                        [NSNumber numberWithBool:NO], AVLinearPCMIsNonInterleaved,
                                        [NSNumber numberWithBool:NO],AVLinearPCMIsFloatKey,
                                        [NSNumber numberWithBool:NO], AVLinearPCMIsBigEndianKey,
                                        nil];
        AVAssetWriterInput *assetWriterInput = [AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeAudio
                                                                                   outputSettings:outputSettings]
                                                ;
        if ([assetWriter canAddInput:assetWriterInput]) {
            [assetWriter addInput:assetWriterInput];
        } else {
            NSLog (@"can't add asset writer input... die!");
            return;
        }
    
    
        assetWriterInput.expectsMediaDataInRealTime = NO;
    
    
    
        [assetWriter startWriting];
        [assetReader startReading];
    
        AVAssetTrack *soundTrack = [songAsset.tracks objectAtIndex:0];
        CMTime startTime = CMTimeMake (0, soundTrack.naturalTimeScale);
        [assetWriter startSessionAtSourceTime: startTime];
    
    
    
        __block UInt64 convertedByteCount = 0;
    
        dispatch_queue_t mediaInputQueue = dispatch_queue_create("mediaInputQueue", NULL);
        [assetWriterInput requestMediaDataWhenReadyOnQueue:mediaInputQueue
                                                usingBlock: ^
         {
             // NSLog (@"top of block");
             while (assetWriterInput.readyForMoreMediaData) {
                 CMSampleBufferRef nextBuffer = [assetReaderOutput copyNextSampleBuffer];
                 if (nextBuffer) {
                     // append buffer
                     [assetWriterInput appendSampleBuffer: nextBuffer];
                     //                NSLog (@"appended a buffer (%d bytes)",
                     //                       CMSampleBufferGetTotalSampleSize (nextBuffer));
                     convertedByteCount += CMSampleBufferGetTotalSampleSize (nextBuffer);
                     // oops, no
                     // sizeLabel.text = [NSString stringWithFormat: @"%ld bytes converted", convertedByteCount];
    
    //                 NSNumber *convertedByteCountNumber = [NSNumber numberWithLong:convertedByteCount];
    //                 [self performSelectorOnMainThread:@selector(updateSizeLabel:)
    //                                        withObject:convertedByteCountNumber
    //                                     waitUntilDone:NO];
                 } else {
                     // done!
                     [assetWriterInput markAsFinished];
                     [assetWriter finishWritingWithCompletionHandler:^{
    //                     callback(exportPath);
                     }];
                     callback(exportPath);
    
                     [assetReader cancelReading];
                     NSDictionary *outputFileAttributes = [[NSFileManager defaultManager]
                                                           attributesOfItemAtPath:exportPath
                                                           error:nil];
                     NSLog (@"done. file size is %llu",
                            [outputFileAttributes fileSize]);
    
    
    // release a lot of stuff
    
    
    
                     [assetReader release];
                     [assetReaderOutput release];
                     [assetWriter release];
                     [assetWriterInput release];
                     [exportPath release];
                     break;
                 }
             }
    
         }];
        NSLog (@"bottom of convertTapped:");
    }
    

 0 Comment(s)

Sign In
                           OR                           
                           OR                           
Register

Sign up using

                           OR                           
Forgot Password
Fill out the form below and instructions to reset your password will be emailed to you:
Reset Password
Fill out the form below and reset your password: