/**
* Parses the buffer stream for a meta event
*
* @since 1.0
* @uses read()
* @uses Util::unpack()
* @uses getDelta()
* @uses getMetaEvent()
*
* @return MetaEvent
*/
protected function parseMetaEvent()
{
$metaEventType = Util::unpack($this->read(1, true));
$metaEventType = $metaEventType[0];
$length = $this->getDelta();
$data = $this->read($length, true);
return $this->getMetaEvent($metaEventType, $data);
}
/**
* 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 ' . \Midi\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);
}
/**
* 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);
}
/**
* 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);
}
