Changeset 196 for libmpc/branches/r2d/libmpcdec/mpc_demux.c

Timestamp:

12/30/06 17:49:40 (18 years ago)

Author:

r2d

Message:

• moved skip_id3v2 to demuxer and changed so it doesn't need seek (not tested with id3v2 tags)

File:

• libmpc/branches/r2d/libmpcdec/mpc_demux.c (modified) (4 diffs)

libmpc/branches/r2d/libmpcdec/mpc_demux.c

@@ -131 +131 @@
         mpc_demux_clear_buff(d);
         if (d->si.stream_version == 7)
-                mpc_demux_fill(d, (min_bytes + ((bit_offset + 7) >> 3) + 3) & (-1 << 2), MPC_BUFFER_SWAP);
+                mpc_demux_fill(d, (min_bytes + ((bit_offset + 7) >> 3) + 3) & (~3), MPC_BUFFER_SWAP);
         else
                 mpc_demux_fill(d, min_bytes + ((bit_offset + 7) >> 3), 0);
@@ -146 +146 @@
 {
         return ((d->r->tell(d->r) - d->bytes_total + d->bits_reader.buff - d->buffer) << 3) + 8 - d->bits_reader.count;
+}
+
+/**
+ * Searches for a ID3v2-tag and reads the length (in bytes) of it.
+ *
+ * @param d demuxer context
+ * @return size of tag, in bytes
+ * @return MPC_STATUS_FILE on errors of any kind
+ */
+mpc_int32_t mpc_demux_skip_id3v2(mpc_demux * d)
+{
+        mpc_uint8_t  tmp [4];
+        mpc_bool_t footerPresent;     // ID3v2.4-flag
+        mpc_int32_t size;
+
+    // we must be at the beginning of the stream
+        mpc_demux_fill(d, 3, 0);
+
+    // check id3-tag
+        if ( 0 != memcmp( d->bits_reader.buff, "ID3", 3 ) )
+                return 0;
+
+        mpc_demux_fill(d, 10, 0);
+
+        mpc_bits_read(&d->bits_reader, 24); // read ID3
+        mpc_bits_read(&d->bits_reader, 16); // read tag version
+
+        tmp[0] = mpc_bits_read(&d->bits_reader, 8); // read flags
+        footerPresent = tmp[0] & 0x10;
+        if ( tmp[0] & 0x0F )
+                return MPC_STATUS_FILE; // not (yet???) allowed
+
+        tmp[0] = mpc_bits_read(&d->bits_reader, 8); // read size
+        tmp[1] = mpc_bits_read(&d->bits_reader, 8); // read size
+        tmp[2] = mpc_bits_read(&d->bits_reader, 8); // read size
+        tmp[3] = mpc_bits_read(&d->bits_reader, 8); // read size
+
+        if ( (tmp[0] | tmp[1] | tmp[2] | tmp[3]) & 0x80 )
+                return MPC_STATUS_FILE; // not allowed
+
+    // read headerSize (syncsave: 4 * $0xxxxxxx = 28 significant bits)
+        size = tmp[0] << 21;
+        size |= tmp[1] << 14;
+        size |= tmp[2] << 7;
+        size |= tmp[3];
+
+        if ( footerPresent )
+                size += 10;
+
+        mpc_demux_fill(d, size, 0);
+        d->bits_reader.buff += size;
+
+        return size + 10;
 }
 
@@ -219 +272 @@
 {
         char magic[4];
-        int err;
 
         memset(&d->si, 0, sizeof d->si);
 
     // get header position
-        err = d->si.header_position = mpc_skip_id3v2(d->r);
-        if(err < 0) return MPC_STATUS_FILE;
-
-        // seek to first byte of mpc data
-        err = d->r->seek(d->r, d->si.header_position);
-        if(!err) return MPC_STATUS_FILE;
+        d->si.header_position = mpc_demux_skip_id3v2(d);
+        if(d->si.header_position < 0) return MPC_STATUS_FILE;
 
         d->si.tag_offset = d->si.total_file_length = d->r->get_size(d->r);
@@ -418 +466 @@
         return MPC_STATUS_OK;
 }
+