Add TXTH mpeg bytes-to-samples and tweaks

src/coding/coding.h

@@ -353,8 +353,9 @@ int riff_get_fact_skip_samples(STREAMFILE * streamFile, off_t start_offset);
 
 size_t atrac3_bytes_to_samples(size_t bytes, int full_block_align);
 size_t atrac3plus_bytes_to_samples(size_t bytes, int full_block_align);
+size_t ac3_bytes_to_samples(size_t bytes, int full_block_align, int channels);
 size_t aac_get_samples(STREAMFILE *streamFile, off_t start_offset, size_t bytes);
-
+size_t mpeg_get_samples(STREAMFILE *streamFile, off_t start_offset, size_t bytes);
 
 
 /* An internal struct to pass around and simulate a bitstream. */

src/coding/coding_utils.c

@@ -1006,22 +1006,34 @@ fail:
 /* ******************************************** */
 
 size_t atrac3_bytes_to_samples(size_t bytes, int full_block_align) {
+    if (full_block_align <= 0) return 0;
     /* ATRAC3 expects full block align since as is can mix joint stereo with mono blocks;
      * so (full_block_align / channels) DOESN'T give the size of a single channel (uncommon in ATRAC3 though) */
     return (bytes / full_block_align) * 1024;
 }
 
 size_t atrac3plus_bytes_to_samples(size_t bytes, int full_block_align) {
+    if (full_block_align <= 0) return 0;
     /* ATRAC3plus expects full block align since as is can mix joint stereo with mono blocks;
      * so (full_block_align / channels) DOESN'T give the size of a single channel (common in ATRAC3plus) */
     return (bytes / full_block_align) * 2048;
 }
 
+size_t ac3_bytes_to_samples(size_t bytes, int full_block_align, int channels) {
+    if (full_block_align <= 0) return 0;
+    return (bytes / full_block_align) * 256 * channels;
+}
+
+
 size_t aac_get_samples(STREAMFILE *streamFile, off_t start_offset, size_t bytes) {
     const int samples_per_frame = 1024; /* theoretically 960 exists in .MP4 so may need a flag */
     int frames = 0;
     off_t offset = start_offset;
     off_t max_offset = start_offset + bytes;
+
+    if (!streamFile)
+        return 0;
+
     if (max_offset > get_streamfile_size(streamFile))
         max_offset = get_streamfile_size(streamFile);
 

src/coding/mpeg_custom_utils.c

@@ -302,5 +302,64 @@ fail:
     return 0;
 }
 
+size_t mpeg_get_samples(STREAMFILE *streamFile, off_t start_offset, size_t bytes) {
+    off_t offset = start_offset;
+    off_t max_offset = start_offset + bytes;
+    int samples = 0;
+    mpeg_frame_info info;
+    size_t prev_size = 0;
+    int cbr_count = 0;
+    int is_vbr = 0;
+
+    if (!streamFile)
+        return 0;
+
+    if (max_offset > get_streamfile_size(streamFile))
+        max_offset = get_streamfile_size(streamFile);
+
+    /* MPEG may use VBR so must read all frames */
+    while (offset < max_offset) {
+
+        /* skip ID3v2 */
+        if ((read_32bitBE(offset+0x00, streamFile) & 0xFFFFFF00) == 0x49443300) { /* "ID3\0" */
+            size_t frame_size = 0;
+            uint8_t flags = read_8bit(offset+0x05, streamFile);
+            /* this is how it's officially read :/ */
+            frame_size += read_8bit(offset+0x06, streamFile) << 21;
+            frame_size += read_8bit(offset+0x07, streamFile) << 14;
+            frame_size += read_8bit(offset+0x08, streamFile) << 7;
+            frame_size += read_8bit(offset+0x09, streamFile) << 0;
+            frame_size += 0x0a;
+            if (flags & 0x10) /* footer? */
+                frame_size += 0x0a;
+
+            offset += frame_size;
+            continue;
+        }
+
+        /* this may fail with unknown ID3 tags */
+        if (!mpeg_get_frame_info(streamFile, offset, &info))
+            break;
+
+        if (prev_size && prev_size != info.frame_size) {
+            is_vbr = 1;
+        }
+        else if (!is_vbr) {
+            cbr_count++;
+        }
+
+        if (cbr_count >= 10) {
+            /* must be CBR, don't bother counting */
+            samples = (bytes / info.frame_size) * info.frame_samples;
+            break;
+        }
+
+        offset += info.frame_size;
+        prev_size = info.frame_size;
+        samples += info.frame_samples; /* header frames may be 0? */
+    }
+
+    return samples;
+}
 
 #endif

src/meta/txth.c

@@ -1174,24 +1174,21 @@ static int get_bytes_to_samples(txth_header * txth, uint32_t bytes) {
             if (!txth->interleave) return 0;
             return msadpcm_bytes_to_samples(bytes, txth->interleave, txth->channels);
         case ATRAC3:
-            if (!txth->interleave) return 0;
             return atrac3_bytes_to_samples(bytes, txth->interleave);
         case ATRAC3PLUS:
-            if (!txth->interleave) return 0;
             return atrac3plus_bytes_to_samples(bytes, txth->interleave);
         case AAC:
-            if (!txth->streamBody) return 0;
             return aac_get_samples(txth->streamBody, txth->start_offset, bytes);
+        case MPEG:
+            return mpeg_get_samples(txth->streamBody, txth->start_offset, bytes);
+        case AC3:
+            return ac3_bytes_to_samples(bytes, txth->interleave, txth->channels);
 
         /* XMA bytes-to-samples is done at the end as the value meanings are a bit different */
         case XMA1:
         case XMA2:
             return bytes; /* preserve */
 
-        case AC3:
-            if (!txth->interleave) return 0;
-            return bytes / txth->interleave * 256 * txth->channels;
-
         case IMA:
         case DVI_IMA:
             return ima_bytes_to_samples(bytes, txth->channels);
@@ -1210,7 +1207,6 @@ static int get_bytes_to_samples(txth_header * txth, uint32_t bytes) {
             if (!txth->interleave) return 0;
             return (bytes / txth->interleave) * (txth->interleave - 2) * 2;
 
-        case MPEG: /* a bit complex */
         case FFMPEG: /* too complex, try after init */
         default:
             return 0;