1 files changed, 187 insertions, 0 deletions

diff --git a/src/plugins/midi_extractor.c b/src/plugins/midi_extractor.c
new file mode 100644
index 0000000..d35b435
--- /dev/null
+++ b/src/plugins/midi_extractor.c
@@ -0,0 +1,187 @@
+/*
+     This file is part of libextractor.
+     (C) 2012 Christian Grothoff
+
+     libextractor is free software; you can redistribute it and/or modify
+     it under the terms of the GNU General Public License as published
+     by the Free Software Foundation; either version 3, or (at your
+     option) any later version.
+
+     libextractor is distributed in the hope that it will be useful, but
+     WITHOUT ANY WARRANTY; without even the implied warranty of
+     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+     General Public License for more details.
+
+     You should have received a copy of the GNU General Public License
+     along with libextractor; see the file COPYING.  If not, write to the
+     Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+     Boston, MA 02111-1307, USA.
+ */
+/**
+ * @file plugins/midi_extractor.c
+ * @brief plugin to support MIDI files
+ * @author Christian Grothoff
+ */
+#include "platform.h"
+#include "extractor.h"
+#include <smf.h>
+
+
+/**
+ * Types of events in MIDI.
+ */
+enum EventType
+  {
+    ET_SEQUENCE_NUMBER = 0,
+    ET_TEXT_EVENT = 1,
+    ET_COPYRIGHT_NOTICE = 2,
+    ET_TRACK_NAME = 3,
+    ET_INSTRUMENT_NAME = 4,
+    ET_LYRIC_TEXT = 5,
+    ET_MARKER_TEXT = 6,
+    ET_CUE_POINT = 7,
+    ET_CHANNEL_PREFIX_ASSIGNMENT = 0x20,
+    ET_END_OF_TRACK = 0x2F,
+    ET_TEMPO_SETTING = 0x51,
+    ET_SMPTE_OFFSET = 0x54,
+    ET_TIME_SIGNATURE = 0x58,
+    ET_KEY_SIGNATURE = 0x59,
+    ET_SEQUENCE_SPECIRFIC_EVENT = 0x7F
+  };
+
+
+/**
+ * Main entry method for the 'audio/midi' extraction plugin.  
+ *
+ * @param ec extraction context provided to the plugin
+ */
+void
+EXTRACTOR_midi_extract_method (struct EXTRACTOR_ExtractContext *ec)
+{
+  void *buf;
+  unsigned char *data;
+  uint64_t size;
+  uint64_t off;
+  ssize_t iret;
+  smf_t *m = NULL;
+  smf_event_t *event;
+  uint8_t len;
+  
+  if (4 >= (iret = ec->read (ec->cls, &buf, 1024)))
+    return;
+  data = buf;
+  if ( (data[0] != 0x4D) || (data[1] != 0x54) ||
+       (data[2] != 0x68) || (data[3] != 0x64) )
+    return;                /* cannot be MIDI */
+  size = ec->get_size (ec->cls);
+  if (size > 16 * 1024 * 1024)
+    return; /* too large */
+  if (NULL == (data = malloc ((size_t) size)))
+    return; /* out of memory */
+  memcpy (data, buf, iret);
+  off = iret;
+  while (off < size)
+    {
+      if (0 >= (iret = ec->read (ec->cls, &buf, 16 * 1024)))
+        {
+          free (data);
+          return;
+        }
+      memcpy (&data[off], buf, iret);
+      off += iret;
+    } 
+  if (0 != ec->proc (ec->cls, 
+                     "midi",
+                     EXTRACTOR_METATYPE_MIMETYPE,
+                     EXTRACTOR_METAFORMAT_UTF8,
+                     "text/plain",
+                     "audio/midi",
+                     strlen ("audio/midi") + 1))
+    goto CLEANUP;
+  if (NULL == (m = smf_load_from_memory (data, size)))
+    goto CLEANUP;
+  while (NULL != (event = smf_get_next_event (m)))
+    {
+      if (! smf_event_is_metadata (event))
+        break;
+      len = event->midi_buffer[2];
+      if ( (len > 0) &&
+           isspace (event->midi_buffer[2 + len]))
+        len--;
+#if 0
+      fprintf (stderr, 
+               "type: %d, len: %d value: %.*s\n",
+               event->midi_buffer[1],
+               event->midi_buffer[2],
+               (int) event->midi_buffer_length - 3,
+               (char *) &event->midi_buffer[3]);
+#endif
+      if (1 != event->track_number)
+        continue; /* heuristic to not get instruments */
+      if (0 == len)
+        continue;
+      switch (event->midi_buffer[1])
+        {
+        case ET_TEXT_EVENT:
+          if (0 != ec->proc (ec->cls, 
+                             "midi",
+                             EXTRACTOR_METATYPE_COMMENT,
+                             EXTRACTOR_METAFORMAT_UTF8,
+                             "text/plain",
+                             (void*) &event->midi_buffer[3],
+                             len))
+            goto CLEANUP;
+          break;
+        case ET_COPYRIGHT_NOTICE:
+          if (0 != ec->proc (ec->cls, 
+                             "midi",
+                             EXTRACTOR_METATYPE_COPYRIGHT,
+                             EXTRACTOR_METAFORMAT_UTF8,
+                             "text/plain",
+                             (void*) &event->midi_buffer[3],
+                             len))
+            goto CLEANUP;       
+          break;
+        case ET_TRACK_NAME:
+          if (0 != ec->proc (ec->cls, 
+                             "midi",
+                             EXTRACTOR_METATYPE_TITLE,
+                             EXTRACTOR_METAFORMAT_UTF8,
+                             "text/plain",
+                             (void*) &event->midi_buffer[3],
+                             len))
+            goto CLEANUP;
+          break;
+        case ET_INSTRUMENT_NAME:
+          if (0 != ec->proc (ec->cls, 
+                             "midi",
+                             EXTRACTOR_METATYPE_SOURCE_DEVICE,
+                             EXTRACTOR_METAFORMAT_UTF8,
+                             "text/plain",
+                             (void*) &event->midi_buffer[3],
+                             len))
+            goto CLEANUP;
+          break;
+        case ET_LYRIC_TEXT:
+          if (0 != ec->proc (ec->cls, 
+                             "midi",
+                             EXTRACTOR_METATYPE_LYRICS,
+                             EXTRACTOR_METAFORMAT_UTF8,
+                             "text/plain",
+                             (void*) &event->midi_buffer[3],
+                             len))
+            goto CLEANUP;
+          break;
+        default:
+          break;
+        }
+    }
+  
+ CLEANUP:
+  if (NULL != m)
+    smf_delete (m);
+  free (data);
+}
+
+
+/* end of midi_extractor.c */