TOOLS/302m_convert.c

   1 /**
   2  * convert D-Cinema Audio (probably SMPTE 302M) to a
   3  * wav file that MPlayer can play.
   4  * Usage: 302m_convert <infile> <outfile>
   5  */
   6 #include <stdlib.h>
   7 #include <stdio.h>
   8 #include <inttypes.h>
   9 #include <byteswap.h>
  10 #define le2me_32(x) (x)
  11 #define le2me_16(x) (x)
  12 #define be2me_16(x) bswap_16(x)
  13
  14 // From MPlayer libao/ao_pcm.c
  15 #define WAV_ID_RIFF 0x46464952 /* "RIFF" */
  16 #define WAV_ID_WAVE 0x45564157 /* "WAVE" */
  17 #define WAV_ID_FMT  0x20746d66 /* "fmt " */
  18 #define WAV_ID_DATA 0x61746164 /* "data" */
  19 #define WAV_ID_PCM  0x0001
  20
  21 struct WaveHeader {
  22   uint32_t riff;
  23   uint32_t file_length;
  24   uint32_t wave;
  25   uint32_t fmt;
  26   uint32_t fmt_length;
  27   uint16_t fmt_tag;
  28   uint16_t channels;
  29   uint32_t sample_rate;
  30   uint32_t bytes_per_second;
  31   uint16_t block_align;
  32   uint16_t bits;
  33   uint32_t data;
  34   uint32_t data_length;
  35 };
  36
  37 static struct WaveHeader wavhdr = {
  38   le2me_32(WAV_ID_RIFF),
  39   le2me_32(0x7fffffff),
  40   le2me_32(WAV_ID_WAVE),
  41   le2me_32(WAV_ID_FMT),
  42   le2me_32(16),
  43   le2me_16(WAV_ID_PCM),
  44   le2me_16(6),
  45   le2me_32(96000),
  46   le2me_32(1728000),
  47   le2me_16(18),
  48   le2me_16(24),
  49   le2me_32(WAV_ID_DATA),
  50   le2me_32(0x7fffffff),
  51 };
  52
  53 // this format is completely braindead, and this bitorder
  54 // is the result of pure guesswork (counting how often
  55 // the bits flip), so it might be wrong.
  56 void fixup(unsigned char *in_, unsigned char *out) {
  57   int i;
  58   unsigned char in[3] = {in_[0], in_[1], in_[2]};
  59   unsigned char sync = in[2] & 0x0f; // sync flags
  60   in[2] >>= 4;
  61   out[2] = 0;
  62   for (i = 0; i < 4; i++) {
  63     out[2] <<= 1;
  64     out[2] |= in[2] & 1;
  65     in[2] >>= 1;
  66   }
  67   for (i = 0; i < 4; i++) {
  68     out[2] <<= 1;
  69     out[2] |= in[1] & 1;
  70     in[1] >>= 1;
  71   }
  72   out[1] = 0;
  73   for (i = 0; i < 4; i++) {
  74     out[1] <<= 1;
  75     out[1] |= in[1] & 1;
  76     in[1] >>= 1;
  77   }
  78   for (i = 0; i < 4; i++) {
  79     out[1] <<= 1;
  80     out[1] |= in[0] & 1;
  81     in[0] >>= 1;
  82   }
  83   out[0] = 0;
  84   for (i = 0; i < 4; i++) {
  85     out[0] <<= 1;
  86     out[0] |= in[0] & 1;
  87     in[0] >>= 1;
  88   }
  89   out[0] <<= 4;
  90   out[0] |= sync; // sync flags go into lowest bits
  91   // it seems those might also contain audio data,
  92   // don't know if this is the right order then
  93   // these might be also useful to detect the number
  94   // of channels in case there are files with != 6 channels
  95 }
  96
  97 int main(int argc, char *argv[]) {
  98   FILE *in = fopen(argv[1], "r");
  99   FILE *out = fopen(argv[2], "w");
 100   int i;
 101   uint16_t blocklen, unknown;
 102   unsigned char *block;
 103   if (!in) {
 104     printf("Could not open %s for reading\n", argv[1]);
 105     return EXIT_FAILURE;
 106   }
 107   if (!out) {
 108     printf("Could not open %s for writing\n", argv[2]);
 109     return EXIT_FAILURE;
 110   }
 111   fwrite(&wavhdr, 1, sizeof(wavhdr), out);
 112   do {
 113     fread(&blocklen, 2, 1, in);
 114     blocklen = be2me_16(blocklen);
 115     fread(&unknown, 2, 1, in);
 116     block = malloc(blocklen);
 117     blocklen = fread(block, 1, blocklen, in);
 118     for (i = 0; i < blocklen; i += 3)
 119       fixup(&block[i], &block[i]);
 120     fwrite(block, 1, blocklen, out);
 121     free(block);
 122   } while (!feof(in));
 123   return EXIT_SUCCESS;
 124 }
 125