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Is there a way to convert the iphone record .caf files to .mp3 or amr files? Because the caf file need to upload, and server part can't use this format. I am not familiar with audio processing. Here is my conclude :

  1. The iphone sdk don't have a direct api to do this. We can only change the encoding format (AAC, IMA, iLBC, ALAC), see ACAudioFileConvert Demo. But it's still a caf file, I want to know if I can convert to mp3 by this.

  2. Some guys suggest to use "LAME" api. Is anyone successful to use it in ios? Can anyone share a simple demo ? Someone said it may cause a licence issue ?

Can anyone give me any advice ? Sincere thanks!!!

TK189
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1 Answers1

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It's quite simple: int read, write;

FILE *pcm = fopen("file.caf", "rb");
FILE *mp3 = fopen("file.mp3", "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_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);
Ken
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