Audio Record & Convert Wav to m4a

最近都有點懶～寫的都很簡略 囧～

最近因為專業需要用到錄音的東西 所以直接想到了AVFoundation.framework

找了找似乎有AVAudioRecorder 這個

網上找了找一下sample code 都有點複雜 我打算自己改寫一下

首先可以再h檔中@property (retain, nonatomic) AVAudioRecorder *recorder;

然後可以寫個Method 以便於別的Class 調用，

  • (void) startRecordVoice :(NSString *)filename 之類的

之後 首先要給個輸出路徑 paht (假定已經設好在Document資料夾裡，這裡要注意如果要存到子資料夾需先建立 不然錄完不會存進去)

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
self.recordFileName = @"隨你叫什麼或是用時間給名(不帶副檔名)"
self.recordFilePath = [[path stringByAppendingPathComponent:self.recordFileName]stringByAppendingPathExtension:@"wav"];
record.delegate = self
record.meteringEnabled = YES; //如果你想取峰值的話
[record prepareToRecord];
 //開始錄音
    [[AVAudioSession sharedInstance] setCategory: AVAudioSessionCategoryPlayAndRecord error:nil];
    [[AVAudioSession sharedInstance] setActive:YES error:nil];
    [recorder record];
    
有三個Delegate 可以參考使用
- (void)audioRecorderDidFinishRecording:(AVAudioRecorder *)recorder successfully:(BOOL)flag;
<P>
- (void)audioRecorderBeginInterruption:(AVAudioRecorder *)recorder;
<p>
- (void)audioRecorderEndInterruption:(AVAudioRecorder *)recorder withOptions:(NSUInteger)flags;
<p>

開始轉檔

轉檔則是用到CoreMedia 得參數

使用的是 AVAssetRead 和AVAssetWirter 兩個方法

比較長 就直接上代碼了

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
+ (void)convertWavToM4a:(NSString *)_filePath fileName:(NSString *)_fileName{
        
    
    //這裡是我
        NSString *exportPath = @"輸出路徑副檔名要給m4a"
        
        
        AVAsset *asset = [AVAsset assetWithURL:[NSURL fileURLWithPath:_filePath]];
        
        NSURL *exportURL = [NSURL fileURLWithPath:exportPath];
        
        // reader
        NSError *readerError = nil;
        AVAssetReader *reader = [[AVAssetReader alloc] initWithAsset:asset
                                                               error:&readerError];
        
        AVAssetTrack *track = [[asset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
        AVAssetReaderTrackOutput *readerOutput = [[AVAssetReaderTrackOutput alloc] initWithTrack:track
                                                                                  outputSettings:nil];
        [reader addOutput:readerOutput];
        
        // writer
        NSError *writerError = nil;
        AVAssetWriter *writer = [[AVAssetWriter alloc] initWithURL:exportURL
                                                          fileType:AVFileTypeAppleM4A
                                                             error:&writerError];
        
        AudioChannelLayout channelLayout;
        memset(&channelLayout, 0, sizeof(AudioChannelLayout));
        channelLayout.mChannelLayoutTag = kAudioChannelLayoutTag_Stereo;
        
        // use different values to affect the downsampling/compression
        NSDictionary *outputSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                                        [NSNumber numberWithInt: kAudioFormatMPEG4AAC], AVFormatIDKey,
                                        [NSNumber numberWithFloat:44100.0], AVSampleRateKey,
                                        [NSNumber numberWithInt:2], AVNumberOfChannelsKey,
                                        [NSNumber numberWithInt:128000], AVEncoderBitRateKey,
                                        [NSData dataWithBytes:&channelLayout length:sizeof(AudioChannelLayout)], AVChannelLayoutKey,
                                        nil];
        
        AVAssetWriterInput *writerInput = [[AVAssetWriterInput alloc] initWithMediaType:AVMediaTypeAudio
                                                                         outputSettings:outputSettings];
        [writerInput setExpectsMediaDataInRealTime:NO];
        [writer addInput:writerInput];
        
        //////////
        [writer startWriting];
        [writer startSessionAtSourceTime:kCMTimeZero];
        
        [reader startReading];
        dispatch_queue_t mediaInputQueue = dispatch_queue_create("mediaInputQueue", NULL);
        [writerInput requestMediaDataWhenReadyOnQueue:mediaInputQueue usingBlock:^{
            
            NSLog(@"Asset Writer ready : %d", writerInput.readyForMoreMediaData);
            while (writerInput.readyForMoreMediaData) {
                CMSampleBufferRef nextBuffer;
                if ([reader status] == AVAssetReaderStatusReading && (nextBuffer = [readerOutput copyNextSampleBuffer])) {
                    if (nextBuffer) {
                        NSLog(@"Adding buffer");
                        [writerInput appendSampleBuffer:nextBuffer];
                    }
                } else {
                    [writerInput markAsFinished];
                    
                    switch ([reader status]) {
                        case AVAssetReaderStatusReading:
                            break;
                        case AVAssetReaderStatusFailed:
                            [writer cancelWriting];
                            break;
                        case AVAssetReaderStatusCompleted:
                            NSLog(@"Writer completed");
                            [writer endSessionAtSourceTime:asset.duration];
                            [writer finishWriting];
                            
//                     NSData *data = [NSData dataWithContentsOfFile:exportPath];
//                     NSLog(@"Data: %@", data);
                            
                            break;
                    }
                    break;
                }
            }
        }];
    [reader release];
    [readerOutput release];
    [writer release];
    [writerInput release];
}

壓完的檔案大小大概會比wav小8~10倍左右
中間的outputSettings 的參數會影響壓的質量 可以自己試試