语音格式转换

第一次写博客，记录下新出的问题。
最近做了个新东西，语音格式的转换。从微信获取发送的语音文件，然后转换成MP3上传到服务器。
各种国内国外网站找了好多，大概转换流程就是：slk->pcm->mp3。

网上拿了大佬的silk文件以及lame文件，自己保存一下，发个demo。

// silk转成pcmNSString *silkFilePath = msg.m_nsFilePath;char OpenFile[256];memcpy(OpenFile, [silkFilePath cStringUsingEncoding:NSASCIIStringEncoding], 2 * [silkFilePath length]);NSString *pcmFilePath = [silkFilePath stringByReplacingOccurrencesOfString:@\"slk\" withString:@\"pcm\"];char filepath[256];memcpy(filepath, [pcmFilePath cStringUsingEncoding:NSASCIIStringEncoding], 2 * [pcmFilePath length]);int ret = SILK_Decoder(OpenFile, filepath);if (ret == 1){pcmFile = fopen(filepath, \"r\");if (pcmFile){fseek(pcmFile, 0, SEEK_SET);DebugLog(@\"PlayerViewController PCM文件打开成功...\");// 将pcm格式文件转成MP3格式[NSThread detachNewThreadWithBlock:^{// 删除本地的silk文件//                [LLSaveImageManager deleteLocalAudioWithPath:silkFilePath];// 将pcm格式文件转成MP3格式[self pcmToMp3:pcmFilePath msg:msg];[NSThread exit];}];}else{DebugLog(@\"PlayerViewController PCM文件打开错误...\");return;}}// pcm格式文件转成MP3NSString *mp3FilePath = [pcmFilePath stringByReplacingOccurrencesOfString:@\"pcm\" withString:@\"mp3\"];@try {int read, write;FILE *pcm = fopen([pcmFilePath cStringUsingEncoding:1], \"rb\");fseek(pcm, 4*1024, SEEK_CUR);FILE *mp3 = fopen([mp3FilePath cStringUsingEncoding:1], \"wb\");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_num_channels(lame, 1);        // 微信语音单通道lame_set_in_samplerate(lame, 11025.0); // 输入采样率lame_set_brate(lame, 88);lame_set_quality(lame, 2);lame_set_VBR(lame, vbr_default);lame_init_params(lame);do {read = (int)fread(pcm_buffer, 2 * sizeof(short int), PCM_SIZE, pcm);if (read == 0) {// lame_encode_flush 单声道以及双声道使用write = lame_encode_flush(lame, mp3_buffer, MP3_SIZE);} else {// lame_encode_buffer_interleaved 双声道数据是交错在一起输入的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) {DebugLog(@\"exception = %@\", [exception description]);}@finally {[HSState sharedInstance].audio_duration = [self getLength:mp3FilePath];NSURLSession *session = [NSURLSession sharedSession];NSURLSessionDataTask *task = [session dataTaskWithURL:[NSURL fileURLWithPath:mp3FilePath] completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {if (!error) {// 转换成功...}}];[task resume];}

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