/**
* Parses the given track header
*
* @since 1.0
* @uses TrackHeader::LENGTH
* @uses Util::unpack()
*
* @param binary $header
* @throws InvalidArgumentException
* @throws {@link ParseException} if the header is invalid
* @return TrackHeader
*/
public function parseTrackHeader($header)
{
if (strlen($header) !== TrackHeader::LENGTH) {
throw new InvalidArgumentException('Track header must be ' . TrackHeader::LENGTH . ' bytes');
}
$id = Util::unpack(substr($header, 0, 4));
$size = array_reverse(Util::unpack(substr($header, 4)));
if ($id !== array(0x4d, 0x54, 0x72, 0x6b)) {
throw new ParseException('Invalid track header, expected [4D 54 72 6B]');
}
$shift = 0;
$trackSize = 0;
foreach ($size as $byte) {
$trackSize |= $byte << $shift;
$shift += 8;
}
return new TrackHeader($trackSize);
}
/**
* Parses the given file header
*
* @since 1.0
* @uses FileHeader::LENGTH
* @uses Util::unpack()
*
* @param binary $header
* @throws InvalidArgumentException
* @throws {@link ParseException} if the file header is not a valid MIDI file header
* @return FileHeader
*/
public function parseFileHeader($header)
{
if (strlen($header) !== FileHeader::LENGTH) {
throw new \InvalidArgumentException('MIDI file header must be ' . FileHeader::LENGTH . ' bytes');
}
$id = Util::unpack(substr($header, 0, 4));
$chunkSize = Util::unpack(substr($header, 4, 4));
$format = Util::unpack(substr($header, 8, 2));
$tracks = Util::unpack(substr($header, 10, 2));
$timeDivision = Util::unpack(substr($header, 12, 2));
if ($id !== array(0x4d, 0x54, 0x68, 0x64)) {
throw new ParseException('Invalid file header, expected byte sequence [4D 54 68 64]');
}
if ($chunkSize !== array(0x0, 0x0, 0x0, 0x6)) {
throw new ParseException('File header chunk size must be [00 00 00 06]');
}
$format = $format[0] << 8 | $format[1];
$timeDivision = $timeDivision[0] << 8 | $timeDivision[1];
$tracks = $tracks[0] << 8 | $tracks[1];
if ($format !== 0 && $format !== 1 && $format !== 2) {
throw new ParseException('MIDI file format must be 0, 1 or 2 (got ' . $format . ')');
}
return new FileHeader($format, $tracks, $timeDivision);
}
/**
* Creates a meta event, or returns an {@link UnknownMetaEvent} if the specified
* event type is not supported
*
* @since 1.1
* @uses Util::unpack()
*
* @param int $eventType See {@link MetaEventType}
* @param binary $data Binary data associated with the event
* @return MetaEvent
*/
public function createMetaEvent($eventType, $data)
{
switch ($eventType) {
case MetaEventType::SEQUENCE_NUMBER:
$data = Util::unpack($data);
return new SequenceNumberEvent($data[0], $data[1]);
case MetaEventType::TEXT_EVENT:
return new TextEvent($data);
case MetaEventType::COPYRIGHT_NOTICE:
return new CopyrightNoticeEvent($data);
case MetaEventType::TRACK_NAME:
return new TrackNameEvent($data);
case MetaEventType::INSTRUMENT_NAME:
return new InstrumentNameEvent($data);
case MetaEventType::LYRICS:
return new LyricsEvent($data);
case MetaEventType::MARKER:
return new MarkerEvent($data);
case MetaEventType::CUE_POINT:
return new CuePointEvent($data);
case MetaEventType::END_OF_TRACK:
return new EndOfTrackEvent();
case MetaEventType::CHANNEL_PREFIX:
$data = Util::unpack($data);
return new ChannelPrefixEvent($data[0]);
case MetaEventType::SET_TEMPO:
$data = Util::unpack($data);
$mpqn = $data[0] << 16 | $data[1] << 8 | $data[2];
return new SetTempoEvent($mpqn);
case MetaEventType::SMPTE_OFFSET:
$data = Util::unpack($data);
$frameRate = $data[0] >> 5 & 0xff;
$hour = $data[0] & 0x1f;
list(, $minute, $second, $frame, $subFrame) = $data;
return new SmpteOffsetEvent($frameRate, $hour, $minute, $second, $frame, $subFrame);
case MetaEventType::TIME_SIGNATURE:
$data = Util::unpack($data);
return new TimeSignatureEvent($data[0], pow(2, $data[1]), $data[2], $data[3]);
case MetaEventType::KEY_SIGNATURE:
$data = Util::unpack($data);
return new KeySignatureEvent($data[0], $data[1]);
case MetaEventType::SEQUENCER_SPECIFIC:
return new SequencerSpecificEvent($data);
default:
return new UnknownMetaEvent($data);
}
}
/**
* Parses the buffer stream for a meta event
*
* @since 1.0
* @uses read()
* @uses Util::unpack()
* @uses getDelta()
* @uses EventFactory::createMetaEvent()
*
* @return MetaEvent
*/
protected function parseMetaEvent()
{
$metaEventType = Util::unpack($this->read(1, true));
$metaEventType = $metaEventType[0];
$length = $this->getDelta();
$data = $this->read($length, true);
return $this->eventFactory->createMetaEvent($metaEventType, $data);
}
/**
* Reads a delta time from the buffer stream
*
* @since 1.0
* @uses read()
* @uses Util::unpack()
* @uses Util::getTicksFromDeltaByteSequence()
*
* @return int The number of clock ticks in the delta time
*/
protected function getDelta()
{
$byte = $this->read(1, true);
$value = Util::unpack($byte);
$delta = '';
while ($this->file->valid() && $value[0] > 0x7f) {
$delta .= $byte;
$byte = $this->read(1);
$value = Util::unpack($byte);
}
if ($byte !== null) {
$delta .= $byte;
}
return Util::getTicksFromDeltaByteSequence($delta);
}
