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我是 ios 开发新手。我在 AudioToolBox 框架的帮助下使用音频队列服务从https://github.com/vecter/Audio-Queue-Services-Example下载了示例录音机项目。在该示例项目中录制了音频格式是.aif。同时运行下载的示例项目工作正常。在示例示例项目中使用如何录制音频，如 .mp3 格式。我该怎么做？

只是我已将kAudioFileAIFFType更改为kAudioFileMP3Type我从 nslog 收到消息

   //---------nslog message--------------
      Not recording, returning
      Writing buffer 0 
   //------------------

- (void)startRecording
{
[self setupAudioFormat:&recordState.dataFormat];

recordState.currentPacket = 0;

OSStatus status;
status = AudioQueueNewInput(&recordState.dataFormat,
                            AudioInputCallback,
                            &recordState,
                            CFRunLoopGetCurrent(),
                            kCFRunLoopCommonModes,
                            0,
                            &recordState.queue);

if (status == 0)
{
    // Prime recording buffers with empty data
    for (int i = 0; i < NUM_BUFFERS; i++)
    {
        AudioQueueAllocateBuffer(recordState.queue, 16000, &recordState.buffers[i]);
        AudioQueueEnqueueBuffer (recordState.queue, recordState.buffers[i], 0, NULL);
    }

    status = AudioFileCreateWithURL(fileURL,
                                    kAudioFileMP3Type,
                                    &recordState.dataFormat,
                                    kAudioFileFlags_EraseFile,
                                    &recordState.audioFile);
    if (status == 0)
    {
        recordState.recording = true;        
        status = AudioQueueStart(recordState.queue, NULL);
        if (status == 0)
        {
            labelStatus.text = @"Recording";
        }
    }
}

if (status != 0)
{
    [self stopRecording];
    labelStatus.text = @"Record Failed";
}
}

//------------------------------------------------ --------------------------

- (void)startPlayback
{
playState.currentPacket = 0;

[self setupAudioFormat:&playState.dataFormat];

OSStatus status;
status = AudioFileOpenURL(fileURL, kAudioFileReadPermission, kAudioFileMP3Type, &playState.audioFile);
if (status == 0)
{
    status = AudioQueueNewOutput(&playState.dataFormat,
                                 AudioOutputCallback,
                                 &playState,
                                 CFRunLoopGetCurrent(),
                                 kCFRunLoopCommonModes,
                                 0,
                                 &playState.queue);

    if (status == 0)
    {
        // Allocate and prime playback buffers
        playState.playing = true;
        for (int i = 0; i < NUM_BUFFERS && playState.playing; i++)
        {
            AudioQueueAllocateBuffer(playState.queue, 16000, &playState.buffers[i]);
            AudioOutputCallback(&playState, playState.queue, playState.buffers[i]);
        }

        status = AudioQueueStart(playState.queue, NULL);
        if (status == 0)
        {
            labelStatus.text = @"Playing";
        }
    }        
}

if (status != 0)
{
    [self stopPlayback];
    labelStatus.text = @"Play failed";
}
}
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1 回答 1

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No you cannot record to MP3. The reason behind this is clearly explained in core audio documentation (page no 51 of core audio pdf).

In their own words->
iOS contains the recording codecs listed in Table 2-5. As you can see, neither MP3 nor AAC recording is available. This is due to the high CPU overhead, and consequent battery drain, of these formats.

iOS: recording audio formats

  • Apple Lossless
  • iLBC (internet Low Bitrate Codec, a speech codec)
  • IMA/ADPCM (also known as IMA-4)
  • Linear PCM
  • µμLaw and aLaw
于 2014-05-14T08:48:08.757 回答