将CAF转换为WAV，渠道布局iOS

Question

我正在使用录音机以caf格式录制iPhone中的声音。然后，我希望它是wav格式。所以我用网上的一个代码进行转换：

AudioChannelLayout channelLayout;
memset(&channelLayout, 0, sizeof(AudioChannelLayout));
channelLayout.mChannelLayoutTag = kAudioChannelLayoutTag_Mono;
NSMutableDictionary *outputSettings = [NSMutableDictionary dictionaryWithObjectsAndKeys:
                                       [NSNumber numberWithInt:audioFormat], AVFormatIDKey,
                                       [NSNumber numberWithFloat:16000.0], AVSampleRateKey,
                                       [NSNumber numberWithInt:1], AVNumberOfChannelsKey,
                                       [NSData dataWithBytes:&channelLayout length:sizeof(AudioChannelLayout)], AVChannelLayoutKey,
                                       nil];

但问题是文件get是这样的：（afinfo）

File type ID:   WAVE
Num Tracks:     1
----
Data format:     1 ch,  16000 Hz, 'lpcm' (0x0000000C) 16-bit little-endian signed integer
Channel layout: Mono
estimated duration: 2.229125 sec
audio bytes: 71332
audio packets: 35666
bit rate: 256000 bits per second
packet size upper bound: 2
maximum packet size: 2
audio data file offset: 4096
optimized
source bit depth: I16

我需要一个这样的文件：

File type ID:   WAVE
Num Tracks:     1
----
Data format:     1 ch,  16000 Hz, 'lpcm' (0x0000000C) 16-bit little-endian signed integer
           no channel layout.
estimated duration: 2.229125 sec
audio bytes: 71332
audio packets: 35666
bit rate: 256000 bits per second
packet size upper bound: 2
maximum packet size: 2
audio data file offset: 44
optimized
source bit depth: I16

正如你所看到的，主要的区别是一个是"音频数据文件偏移量：44"，另一个是"音频数据文件偏置量：4096"还有信道布局，一个单声道（错误）和另一个"没有信道布局"

请帮帮我，我真的很失望。。就频道布局而言，我怎么可能没有频道？

Answer 1

我使用了[NSData dataWithBytes:nil length:0]而不是[NSData data WithBytes:&channelLayout length:sizeof（AudioChannelLayout）]，这导致了没有频道布局。

NSMutableDictionary *outputSettings = [NSMutableDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithInt:audioFormat], AVFormatIDKey,
[NSNumber numberWithFloat:16000.0], AVSampleRateKey,
[NSNumber numberWithInt:1], AVNumberOfChannelsKey,
[NSData dataWithBytes:nil length:0], AVChannelLayoutKey,
                                   nil];