Implement auto_calc_flac() -- calculate granulepos for flac packets (if

granulepos is not given in Ogg framing). This tracks the current granulepos
and determines the block size by reading the FLAC frame header. Note that
this patch doesn't handle blocksize codes 0000, 0110 or 0111, which
require poking elsewhere to get the actual value. Nevertheless this patch
appears to handle the common case framing, and in any case it is very rare
for Ogg FLAC packets to not have a granulepos.
  * Handles both old-style Ogg Flac framing ("Flac0") and current framing
  * Tested on all flac-in-ogg files from MPlayer samples:
    http://www1.mplayerhq.hu/MPlayer/samples/ogg/flac-in-ogg/
  * Tested with valgrind --leakcheck=yes on src/examples/read-file (no leaks)


git-svn-id: http://svn.annodex.net/liboggz/trunk@2573 8158c8cd-e7e1-0310-9fa4-c5954c97daef

src/liboggz/oggz_auto.c

@@ -714,8 +714,8 @@ auto_calc_vorbis(ogg_int64_t now, oggz_stream_t *stream, ogg_packet *op) {
   
 }
 
-#if 0
-/*
+/**
+ * FLAC
  * Defined at: http://flac.sourceforge.net/ogg_mapping.html
  *   - Native FLAC audio frames appear as subsequent packets in the stream.
  *     Each packet corresponds to one FLAC audio frame.
@@ -729,11 +729,106 @@ auto_calc_vorbis(ogg_int64_t now, oggz_stream_t *stream, ogg_packet *op) {
  * http://rafb.net/paste/results/Pkib5w72.html
  */
 
+typedef struct {
+  ogg_int64_t previous_gp;
+  int encountered_first_data_packet;
+} auto_calc_flac_info_t;
+
 static ogg_int64_t 
 auto_calc_flac (ogg_int64_t now, oggz_stream_t *stream, ogg_packet *op)
 {
+  auto_calc_flac_info_t *info;
+
+  if (stream->calculate_data == NULL) {
+    stream->calculate_data = malloc(sizeof(auto_calc_flac_info_t));
+    info = (auto_calc_flac_info_t *)stream->calculate_data;
+    info->previous_gp = 0;
+    info->encountered_first_data_packet = 0;
+
+    /* this is a header packet */
+    goto out;
+  }
+
+  info = (auto_calc_flac_info_t *)stream->calculate_data;
+
+  /* FLAC audio frames begin with marker 0xFF */
+  if (op->packet[0] == 0xff)
+      info->encountered_first_data_packet = 1;
+
+  if (now == -1 && op->packet[0] == 0xff && op->bytes > 2) {
+    unsigned char bs;
+    int block_size;
+
+    bs = (op->packet[2] & 0xf0) >> 4;
+
+    switch (bs) {
+      case 0x0: /*   0000 : get from STREAMINFO metadata block */
+        block_size = -1;
+        break;
+      case 0x1: /* 0001 : 192 samples */
+        block_size = 192;
+        break;
+      /* 0010-0101 : 576 * (2^(n-2)) samples, i.e. 576/1152/2304/4608 */
+      case 0x2:
+        block_size = 576;
+        break;
+      case 0x3:
+        block_size = 1152;
+        break;
+      case 0x4:
+        block_size = 2304;
+        break;
+      case 0x5:
+        block_size = 4608;
+        break;
+      case 0x6: /* 0110 : get 8 bit (blocksize-1) from end of header */
+        block_size = -1;
+        break;
+      case 0x7: /* 0111 : get 16 bit (blocksize-1) from end of header */
+        block_size = -1;
+        break;
+      /* 1000-1111 : 256 * (2^(n-8)) samples, i.e. 256/512/1024/2048/4096/8192/16384/32768 */
+      case 0x8:
+        block_size = 256;
+        break;
+      case 0x9:
+        block_size = 512;
+        break;
+      case 0xa:
+        block_size = 1024;
+        break;
+      case 0xb:
+        block_size = 2048;
+        break;
+      case 0xc:
+        block_size = 4096;
+        break;
+      case 0xd:
+        block_size = 8192;
+        break;
+      case 0xe:
+        block_size = 16384;
+        break;
+      case 0xf:
+        block_size = 32768;
+        break;
+      default:
+        block_size = -1;
+        break;
+    }
+
+    if (block_size != -1) {
+      now = info->previous_gp + block_size;
+    }
+  } else if (now == -1 && info->encountered_first_data_packet == 0) {
+    /* this is a header packet */
+    now = 0;
+  }
+
+out:
+  info->previous_gp = now;
+  return now;
 }
-#endif
 
 const oggz_auto_contenttype_t oggz_auto_codec_ident[] = {
   {"\200theora", 7, "Theora", auto_theora, auto_calc_theora},
@@ -743,8 +838,8 @@ const oggz_auto_contenttype_t oggz_auto_codec_ident[] = {
   {"CMML\0\0\0\0", 8, "CMML", auto_cmml, NULL},
   {"Annodex", 8, "Annodex", auto_annodex, NULL},
   {"fishead", 7, "Skeleton", auto_fishead, NULL},
-  {"fLaC", 4, "Flac0", auto_flac0, NULL},
-  {"\177FLAC", 4, "Flac", auto_flac, NULL},
+  {"fLaC", 4, "Flac0", auto_flac0, auto_calc_flac},
+  {"\177FLAC", 4, "Flac", auto_flac, auto_calc_flac},
   {"AnxData", 7, "AnxData", auto_anxdata, NULL},
   {"", 0, "Unknown", NULL}
 };