From 5915736dd5f88ba644189b4f25df56c7c3cb855d Mon Sep 17 00:00:00 2001
From: Thom Johansen <thomj@rockbox.org>
Date: Tue, 4 Dec 2007 20:48:40 +0000
Subject: Put A52/AC3 metadata parser in its own file. Cosmetic changes in
 metadata.c. Remove some unneeded headers from MPC metadata parser.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@15874 a1c6a512-1295-4272-9138-f99709370657
---
 apps/metadata/a52.c | 98 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 98 insertions(+)
 create mode 100644 apps/metadata/a52.c

(limited to 'apps/metadata/a52.c')

diff --git a/apps/metadata/a52.c b/apps/metadata/a52.c
new file mode 100644
index 0000000000..0ed85d37ed
--- /dev/null
+++ b/apps/metadata/a52.c
@@ -0,0 +1,98 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id: metadata.c 15859 2007-11-30 18:48:07Z lostlogic $
+ *
+ * Copyright (C) 2005 Magnus Holmgren
+ *
+ * All files in this archive are subject to the GNU General Public License.
+ * See the file COPYING in the source tree root for full license agreement.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+
+#include "id3.h"
+#include "logf.h"
+
+static const unsigned short a52_bitrates[] =
+{
+     32,  40,  48,  56,  64,  80,  96, 112, 128, 160, 
+    192, 224, 256, 320, 384, 448, 512, 576, 640
+};
+
+/* Only store frame sizes for 44.1KHz - others are simply multiples 
+   of the bitrate */
+static const unsigned short a52_441framesizes[] =
+{
+      69 * 2,   70 * 2,   87 * 2,   88 * 2,  104 * 2,  105 * 2,  121 * 2, 
+     122 * 2,  139 * 2,  140 * 2,  174 * 2,  175 * 2,  208 * 2,  209 * 2,
+     243 * 2,  244 * 2,  278 * 2,  279 * 2,  348 * 2,  349 * 2,  417 * 2,
+     418 * 2,  487 * 2,  488 * 2,  557 * 2,  558 * 2,  696 * 2,  697 * 2,  
+     835 * 2,  836 * 2,  975 * 2,  976 * 2, 1114 * 2, 1115 * 2, 1253 * 2, 
+    1254 * 2, 1393 * 2, 1394 * 2
+};
+
+bool get_a52_metadata(int fd, struct mp3entry *id3)
+{        
+    /* Use the trackname part of the id3 structure as a temporary buffer */
+    unsigned char* buf = (unsigned char *)id3->path;
+    unsigned long totalsamples;
+    int i;
+
+    if ((lseek(fd, 0, SEEK_SET) < 0) || (read(fd, buf, 5) < 5))
+    {
+        return false;
+    }
+
+    if ((buf[0] != 0x0b) || (buf[1] != 0x77)) 
+    { 
+        logf("%s is not an A52/AC3 file\n",trackname);
+        return false;
+    }
+
+    i = buf[4] & 0x3e;
+  
+    if (i > 36) 
+    {
+        logf("A52: Invalid frmsizecod: %d\n",i);
+        return false;
+    }
+  
+    id3->bitrate = a52_bitrates[i >> 1];
+    id3->vbr = false;
+    id3->filesize = filesize(fd);
+
+    switch (buf[4] & 0xc0) 
+    {
+    case 0x00: 
+        id3->frequency = 48000;
+        id3->bytesperframe=id3->bitrate * 2 * 2;
+        break;
+        
+    case 0x40: 
+        id3->frequency = 44100;
+        id3->bytesperframe = a52_441framesizes[i];
+        break;
+    
+    case 0x80: 
+        id3->frequency = 32000;
+        id3->bytesperframe = id3->bitrate * 3 * 2;
+        break;
+    
+    default: 
+        logf("A52: Invalid samplerate code: 0x%02x\n", buf[4] & 0xc0);
+        return false;
+        break;
+    }
+
+    /* One A52 frame contains 6 blocks, each containing 256 samples */
+    totalsamples = id3->filesize / id3->bytesperframe * 6 * 256;
+    id3->length = totalsamples / id3->frequency * 1000;
+    return true;
+}
-- 
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