导入lame
gitbub地址：
https://github.com/hedgehogIda/caf-mp3
在录制caf文件时，需要使用双通道，否则在转换为MP3格式时，声音不对。caf录制端的设置为：
NSMutableDictionary * recordSetting = [NSMutableDictionary dictionary];
[recordSetting setValue :[NSNumber numberWithInt:kAudioFormatLinearPCM] forKey:AVFormatIDKey];//
[recordSetting setValue:[NSNumber numberWithFloat:8000.0] forKey:AVSampleRateKey];//采样率
[recordSetting setValue:[NSNumber numberWithInt: 2] forKey:AVNumberOfChannelsKey];//声音通道，这里必须为双通道
[recordSetting setValue:[NSNumber numberWithInt:AVAudioQualityLow] forKey:AVEncoderAudioQualityKey];//音频质量
在转换mp3端的代码为:
NSString *cafFilePath = destPath; //caf文件路径
NSString *mp3FilePath = mp3FilePath;//存储mp3文件的路径
@try {
int read, write;
FILE *pcm = fopen([destPath cStringUsingEncoding:1], "rb"); //source 被转换的音频文件位置
fseek(pcm, 4*1024, SEEK_CUR); //skip file header
FILE *mp3 = fopen([mp3FilePath cStringUsingEncoding:1], "wb"); //output 输出生成的Mp3文件位置
const int PCM_SIZE = 8192;
const int MP3_SIZE = 8192;
short int pcm_buffer[PCM_SIZE*2];
unsigned char mp3_buffer[MP3_SIZE];
lame_t lame = lame_init();
lame_set_in_samplerate(lame, 11025.0);
lame_set_VBR(lame, vbr_default);
lame_init_params(lame);
do {
read = fread(pcm_buffer, 2*sizeof(short int), PCM_SIZE, pcm);
if (read == 0)
write = lame_encode_flush(lame, mp3_buffer, MP3_SIZE);
else
write = lame_encode_buffer_interleaved(lame, pcm_buffer, read, mp3_buffer, MP3_SIZE);
fwrite(mp3_buffer, write, 1, mp3);
} while (read != 0);
lame_close(lame);
fclose(mp3);
fclose(pcm);
}
@catch (NSException *exception) {
NSLog(@"%@",[exception description]);
}
@finally {
}
补充
先说明一点，默认AVAudioRecorder录制后的格式是.caf，而大部分的播放器都是不支持这个格式的，下面一段设置是可以让录制格式是wav的格式kAudioFormatLinearPCM],AVFormatIDKey
#录制
NSDictionary *recordSetting = [[NSDictionary alloc] initWithObjectsAndKeys:
[NSNumber numberWithFloat: 44100.0],AVSampleRateKey, //采样率
[NSNumber numberWithInt: kAudioFormatLinearPCM],AVFormatIDKey,
[NSNumber numberWithInt:16],AVLinearPCMBitDepthKey,//采样位数
默认 16
[NSNumber numberWithInt: 2], AVNumberOfChannelsKey,//通道的数目
[NSNumber numberWithBool:NO],AVLinearPCMIsBigEndianKey,//大端还是小端
是内存的组织方式
[NSNumber numberWithBool:NO],AVLinearPCMIsFloatKey,nil];//采样信号是整数还是浮点数
_recordedFile = [NSURL fileURLWithPath:[NSTemporaryDirectory() stringByAppendingString:@"RecordedFile"]];//文件存储位置
NSError* error;
_recorder = [[AVAudioRecorder alloc] initWithURL:_recordedFile settings:settings error:&error];//设置AVAudioRecorder
#转为Mp3
- (void) toMp3
{
NSString *cafFilePath =[NSTemporaryDirectory() stringByAppendingString:@"RecordedFile"];
NSString *mp3FileName = @"Mp3File";
mp3FileName = [mp3FileName stringByAppendingString:@".mp3"];
NSString *mp3FilePath = [[NSHomeDirectory() stringByAppendingFormat:@"/Documents/"] stringByAppendingPathComponent:mp3FileName];
@try {
int read, write;
FILE *pcm = fopen([cafFilePath cStringUsingEncoding:1], "rb"); //source
fseek(pcm, 4*1024, SEEK_CUR); //skip file header
FILE *mp3 = fopen([mp3FilePath cStringUsingEncoding:1], "wb"); //output
const int PCM_SIZE = 8192;
const int MP3_SIZE = 8192;
short int pcm_buffer[PCM_SIZE*2];
unsigned char mp3_buffer[MP3_SIZE];
lame_t lame = lame_init();
lame_set_in_samplerate(lame, _sampleRate);
lame_set_VBR(lame, vbr_default);
lame_init_params(lame);
do {
read = fread(pcm_buffer, 2*sizeof(short int), PCM_SIZE, pcm);
if (read == 0)
write = lame_encode_flush(lame, mp3_buffer, MP3_SIZE);
else
write = lame_encode_buffer_interleaved(lame, pcm_buffer, read, mp3_buffer, MP3_SIZE);
fwrite(mp3_buffer, write, 1, mp3);
} while (read != 0);
lame_close(lame);
fclose(mp3);
fclose(pcm);
}
@catch (NSException *exception) {
NSLog(@"%@",[exception description]);
}
@finally {
[self performSelectorOnMainThread:@selector(convertMp3Finish)
withObject:nil
waitUntilDone:YES];
}
}
