ios – 以编程方式将.m4a转换为.mp3文件

这里我有m4a格式的audio，我需要转换成mp3格式。

为此，我使用了代码

- (void) toMp3{ NSString *m4aFilePath = pathToSave; NSString *mp3FileName = [NSString stringWithFormat:@"Audio%d",[audioArr count]]; mp3FileName = [mp3FileName stringByAppendingString:@".mp3"]; pathToSave = [NSString stringWithFormat:@"%@/%@", DOCUMENTS_FOLDER, mp3FileName]; NSLog(@"pathToSave :%@",pathToSave); @try { int read, write; FILE *pcm = fopen([cafFilePath cStringUsingEncoding:1], "rb"); //source fseek(pcm, 4*1024, SEEK_CUR); //skip file header FILE *mp3 = fopen([pathToSave 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, 44100); 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]; } } 

我怎么能从m4a转换成mp3格式。请帮助我

Answer 1

尝试这个，

 @try { int read, write; FILE *pcm = fopen([cafFilePath cStringUsingEncoding:1], "rb"); //source fseek(pcm, 4*1024, SEEK_CUR); //skip file header mp3 = fopen([mp3FilePath cStringUsingEncoding:1], "wb"); //output const int PCM_SIZE = 8192*3; const int MP3_SIZE = 8192*3; short int pcm_buffer[PCM_SIZE*2]; unsigned char mp3_buffer[MP3_SIZE]; lame_t lame = lame_init(); lame_set_in_samplerate(lame, 11025*2); lame_set_VBR(lame, vbr_default); lame_init_params(lame); int nTotalRead=0; do { read = fread(pcm_buffer, 2*sizeof(short int), PCM_SIZE, pcm); nTotalRead+=read*4; 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); // write = lame_encode_buffer(lame, pcm_buffer,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]); } 

Answer 2

一个iOS项目，可以将任何格式的audio转换成任何格式。 为此它易于使用ExtAudioConverter

Answer 3

你可以尝试使用CoreAudio

和LAME编解码器（由于许可原因，这不包括在iOS中）

一些通过CoreAudio转换audiotypes的例子： http : //developer.apple.com/library/mac/#samplecode/ConvertFile/Introduction/Intro.html

和CoreAudio文档： http : //developer.apple.com/library/mac/#documentation/MusicAudio/Conceptual/CoreAudioOverview/Introduction/Introduction.html

并支持CoreAudio的文件types： http : //developer.apple.com/library/mac/#documentation/MusicAudio/Conceptual/CoreAudioOverview/SupportedAudioConverterFormats/SupportedAudioConverterFormats.html#//apple_ref/doc/uid/TP40003577-CH7-SW1