簡(jiǎn)介

??? 基于wav音頻文件太大,因項(xiàng)目上傳作業(yè)錄音,可能一次上傳幾十上百個(gè)wav 文件,就產(chǎn)生了將wav格式的錄音轉(zhuǎn)換成wav轉(zhuǎn)換成輕量級(jí)的mp3上傳的需求.

?實(shí)現(xiàn)

???? 實(shí)現(xiàn)是基于lame庫的. 至于lame庫的下載導(dǎo)入自己Google吧.

-(NSString *)changeWavToMp3WithOriginalPath:(NSString*)originalPath{

???????????? NSString * mp3Path = [[originalPath stringByDeletingLastPathComponent]stringByAppendingPathComponent:@"sentenceRecoder.mp3"];

????????? @try {

????????????? int read, write;

????????????? FILE *pcm = fopen([originalPath cStringUsingEncoding:1], "rb");? //source 被轉(zhuǎn)換的音頻文件位置

???????????? fseek(pcm, 4*1024, SEEK_CUR);? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? //skip file header

???????????? FILE *mp3 = fopen([mp3Path cStringUsingEncoding:1], "wb");? //output 輸出生成的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,8000);

???????????? lame_set_VBR(lame, vbr_default);

???????????? lame_init_params(lame);

???????????? lame_set_brate (lame, 128 );

???????????? lame_set_quality(lame,2);

????? ? ??? 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 {

??????? }

???????? [[NSFileManager defaultManager] removeItemAtPath:originalPath error:NULL];

????????? return mp3Path;

}

一些音頻格式Mark

1.aac格式 標(biāo)準(zhǔn)配置

@{AVFormatIDKey: @(kAudioFormatMPEG4AAC),

AVEncoderAudioQualityKey:@(AVAudioQualityMax),

AVSampleRateKey: @11025.0f,

AVNumberOfChannelsKey: @2,

AVLinearPCMBitDepthKey: @16};

2. wav 格式 標(biāo)準(zhǔn)配置

@{AVFormatIDKey: @(kAudioFormatLinearPCM),

AVSampleRateKey: @8000.00f,

AVNumberOfChannelsKey: @1,

AVLinearPCMBitDepthKey: @16,

AVLinearPCMIsNonInterleaved: @NO,

AVLinearPCMIsFloatKey: @NO,

AVLinearPCMIsBigEndianKey: @NO};