iOS 音频转码.mp4转.m4a、.m4a转.caf、.caf和.m4a转mp3

前言

iOS 有固有的音频格式，不支持mp3，转码借助三方lame库，

.mp4转.m4a 视频分类音频

+(void)accessAudioFromVideo:(NSURL *)videoPath completion:(void (^)(NSURL *outputPath,BOOL isSucceed)) completionHandle{
     AVAsset *videoAsset = [AVAsset assetWithURL:videoPath];
    //1创建一个AVMutableComposition
    AVMutableComposition *mixComposition = [[AVMutableComposition alloc]init];
    //2 创建一个轨道,类型为AVMediaTypeAudio
    AVMutableCompositionTrack *audioTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
    
    //获取videoPath的音频插入轨道
    [audioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAsset.duration) ofTrack:[[videoAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0] atTime:kCMTimeZero error:nil];
    
    //4创建输出路径
    NSString *path = [self getPathm4a];
    
    NSURL *outputURL = [NSURL fileURLWithPath:path];
    
    //5创建输出对象
    AVAssetExportSession *exporter = [[AVAssetExportSession alloc]initWithAsset:mixComposition presetName:AVAssetExportPresetAppleM4A];
    exporter.outputURL = outputURL ;
    exporter.outputFileType = AVFileTypeAppleM4A;
    exporter.shouldOptimizeForNetworkUse = YES;
    [exporter exportAsynchronouslyWithCompletionHandler:^{
        if (exporter.status == AVAssetExportSessionStatusCompleted) {
            NSURL *outputURL = exporter.outputURL;
            completionHandle(outputURL,YES);

        }else {
            NSLog(@"失败%@",exporter.error.description);
            completionHandle(outputURL,NO);
        }
    }];
    
}

+ (NSString *)getPathm4a{
    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
    [formatter setDateFormat:@"YYYYMMdd"];
    NSString *dateStr = [formatter stringFromDate:[NSDate date]];
    NSString *path = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.m4a", dateStr]];
    
    if ([[NSFileManager defaultManager] fileExistsAtPath:path]) {
        NSError *error;
        if ([[NSFileManager defaultManager] removeItemAtPath:path error:&error] == NO) {
            
        }
    }
    return path;
}

m4a 转 caf 音频间转码

/**
 把.m4a转为.caf格式
 @param originalUrlStr .m4a文件路径
 @param destUrlStr .caf文件路径
 @param completed 转化完成的block
 */
+ (void)convetM4aToWav:(NSString *)originalUrlStr
               destUrl:(NSString *)destUrlStr
             completed:(void (^)(NSError *error)) completed {
    
    if ([[NSFileManager defaultManager] fileExistsAtPath:destUrlStr]) {
        [[NSFileManager defaultManager] removeItemAtPath:destUrlStr error:nil];
    }
    NSURL *originalUrl = [NSURL fileURLWithPath:originalUrlStr];
    NSURL *destUrl     = [NSURL fileURLWithPath:destUrlStr];
    AVURLAsset *songAsset = [AVURLAsset URLAssetWithURL:originalUrl options:nil];
    
    //读取原始文件信息
    NSError *error = nil;
    AVAssetReader *assetReader = [AVAssetReader assetReaderWithAsset:songAsset error:&error];
    if (error) {
        NSLog (@"error: %@", error);
        completed(error);
        return;
    }
    AVAssetReaderOutput *assetReaderOutput = [AVAssetReaderAudioMixOutput
                                              assetReaderAudioMixOutputWithAudioTracks:songAsset.tracks
                                              audioSettings: nil];
    if (![assetReader canAddOutput:assetReaderOutput]) {
        NSLog (@"can't add reader output... die!");
        completed(error);
        return;
    }
    [assetReader addOutput:assetReaderOutput];
    
    AVAssetWriter *assetWriter = [AVAssetWriter assetWriterWithURL:destUrl
                                                          fileType:AVFileTypeCoreAudioFormat
                                                             error:&error];
    if (error) {
        NSLog(@"error: %@", error);
        completed(error);
        return;
    }
    AudioChannelLayout channelLayout;
    memset(&channelLayout, 0, sizeof(AudioChannelLayout));
    channelLayout.mChannelLayoutTag = kAudioChannelLayoutTag_Stereo;
    NSDictionary *outputSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                                    [NSNumber numberWithInt:kAudioFormatLinearPCM], AVFormatIDKey,
                                    [NSNumber numberWithFloat:11025.0], AVSampleRateKey,
                                    [NSNumber numberWithInt:2], AVNumberOfChannelsKey,
                                    [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!");
        completed(error);
        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: ^
     {
         while (assetWriterInput.readyForMoreMediaData) {
             CMSampleBufferRef nextBuffer = [assetReaderOutput copyNextSampleBuffer];
             if (nextBuffer) {
                 // append buffer
                 [assetWriterInput appendSampleBuffer: nextBuffer];
                 NSLog (@"appended a buffer (%zu bytes)",
                        CMSampleBufferGetTotalSampleSize (nextBuffer));
                 convertedByteCount += CMSampleBufferGetTotalSampleSize (nextBuffer);
                 
                 
             } else {
                 [assetWriterInput markAsFinished];
                 [assetWriter finishWritingWithCompletionHandler:^{
                     
                 }];
                 [assetReader cancelReading];
                 NSDictionary *outputFileAttributes = [[NSFileManager defaultManager]
                                                       attributesOfItemAtPath:[destUrl path]
                                                       error:nil];
                 NSLog (@"FlyElephant %lld",[outputFileAttributes fileSize]);
                 break;
             }
         }
         NSLog(@"转换结束");
         // 删除临时temprecordAudio.m4a文件
         NSError *removeError = nil;
         if ([[NSFileManager defaultManager] fileExistsAtPath:originalUrlStr]) {
             BOOL success = [[NSFileManager defaultManager] removeItemAtPath:originalUrlStr error:&removeError];
             if (!success) {
                 NSLog(@"删除临时temprecordAudio.m4a文件失败:%@",removeError);
                 completed(removeError);
             }else{
                 NSLog(@"删除临时temprecordAudio.m4a文件:%@成功",originalUrlStr);
                 completed(removeError);
             }
         }
         
     }];
}

苹果的各种音频格式转mp3 包括各种音频格式互转

GZZAudioConverter *converter = [[GZZAudioConverter alloc] init];
        converter.inputFile = m4pPath;
        converter.outputFile = mp3Path;
        converter.outputFileType = kAudioFileMP3Type;
        converter.outputFormatID = kAudioFormatMPEGLayer3;
        BOOL success = [converter convert];
        dispatch_async(dispatch_get_main_queue(), ^ {
            if (success) {
                NSLog(@"转换成功");
            } else {
                NSLog(@"转换失败");
            }
        });

等空了做成pod 私有库，太累了先不弄了
demo下载地址
 https://gitee.com/zbc101/recorder-audio-or-video.git