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/*
This file is part of libextractor.
Copyright (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., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, 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 */
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