This commit is contained in:
Brooke Vibber 2023-03-07 14:34:57 -08:00
parent 194b0fc284
commit cbae496cf8

View file

@ -401,6 +401,8 @@ class MP3FrameHeader {
public $valid = false;
public $size = 0;
public $samples = 0;
public $duration = 0.0;
public $sync;
public $mpeg;
@ -428,6 +430,33 @@ class MP3FrameHeader {
private const SYNC_MASK = 0x7ff;
private static $versions = [
'MPEG-2.5',
'reserved',
'MPEG-2',
'MPEG-1',
];
private static $layers = [
'reserved',
'III',
'II',
'I',
];
private static $samplesPerFrame = [
// invalid / layer 3 / 2 / 1
// MPEG-2.5
[ 0, 576, 1152, 384 ],
// Reserved
[ 0, 0, 0, 0 ],
// MPEG-2
[ 0, 576, 1152, 384 ],
// MPEG-1
[ 0, 1152, 384, 384 ],
];
// 1s used for reserved slots to avoid exploding
// in case of invalid input
private static $sampleRates = [
@ -442,9 +471,9 @@ class MP3FrameHeader {
];
private static $bitrates = [
// MPEG-2
[
// MPEG-2
// invalid
// invalid layer
[ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, ],
// layer 3
[ 0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160, 0 ],
@ -453,9 +482,9 @@ class MP3FrameHeader {
// layer 1
[ 0, 32, 48, 56, 64, 80, 96, 112, 128, 144, 160, 176, 192, 224, 256, 0 ],
],
// MPEG-1
[
// MPEG-1
// invalid
// invalid layer
[ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, ],
// layer 3
[ 0, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160, 192, 224, 256, 320, 0 ],
@ -475,31 +504,47 @@ class MP3FrameHeader {
public function __construct( $header ) {
$this->header = $header;
$this->sync = $this->field( 'sync' ) == self::SYNC_MASK;
$sync = $this->field( 'sync' );
$this->sync = $sync == self::SYNC_MASK;
if ( $this->sync ) {
$this->mpeg = $this->field( 'mpeg' );
$this->layer = $this->field( 'layer' );
$this->protection = $this->field( 'protection' );
$mpeg = $this->field( 'mpeg' );
$this->mpeg = self::$versions[$mpeg];
$layer = $this->field( 'layer' );
$this->layer = self::$layers[$layer];
$protection = $this->field( 'protection' );
$this->protection = !$protection;
$br = $this->field( 'bitrate' );
$this->bitrate = 1000 * self::$bitrates[$this->mpeg & 1][$this->layer][$br];
$this->bitrate = 1000 * self::$bitrates[$mpeg & 1][$layer][$br];
$sr = $this->field( 'sampleRate' );
$this->sampleRate = self::$sampleRates[$this->mpeg][$sr];
$this->sampleRate = self::$sampleRates[$mpeg][$sr];
$this->padding = $this->field( 'padding' );
$this->valid = $this->sync;
if ( $this->bitrate == 0 ) {
var_dump( $this );
echo "br: $br\n";
//throw new Exception( "Invalid bitrate" );
$this->valid = false;
if ( $this->sync ) {
if ( $this->bitrate == 0 ) {
$this->valid = false;
var_dump( $this );
echo "br: $br\n";
throw new Exception( "Invalid bitrate" );
}
if ( $this->sampleRate == 1 ) {
$this->valid = false;
var_dump( $this );
echo "sr: $sr\n";
throw new Exception( "Invalid sample rate" );
}
$this->valid = true;
}
if ( $this->sampleRate == 1 ) {
var_dump( $this );
echo "sr: $sr\n";
//throw new Exception( "Invalid sample rate" );
$this->valid = false;
}
$this->size = intval( 144.0 * $this->bitrate / $this->sampleRate );
$this->samples = self::$samplesPerFrame[$mpeg][$layer];
$this->duration = $this->samples / $this->sampleRate;
$nbits = $this->duration * $this->bitrate;
$nbytes = $nbits / 8;
$this->size = intval( $nbytes );
if ( $this->protection ) {
$this->size += 2;
}
@ -513,6 +558,7 @@ class MP3FrameHeader {
class MP3Reader {
private $file;
private $timestamp = 0.0;
public function __construct( $file ) {
$this->file = $file;
@ -524,33 +570,60 @@ class MP3Reader {
public function readFrame() {
while ( true ) {
// Look for the sync pattern
$start = $this->pos();
$bytes = fread( $this->file, 4 );
if ( $bytes === false || strlen( $bytes ) < 4 ) {
$lookahead = 10;
$bytes = fread( $this->file, $lookahead );
if ( $bytes === false || strlen( $bytes ) < $lookahead ) {
// end of file
return false;
}
// Check for MP3 frame header sync pattern
$data = unpack( "Nval", $bytes );
$header = new MP3FrameHeader( $data['val'] );
if ( $header->valid ) {
if ( $header->sync ) {
$segments[] = [
'start' => $start,
'size' => $header->size,
'timestamp' => $this->timestamp,
'duration' => $header->duration,
];
$this->timestamp += $header->duration;
// Note we don't need the data at this time.
//fseek( $this->file, $start + $header->size, SEEK_SET );
var_dump ( $header );
fread( $this->file, $header->size - 4 );
return $header;
fseek( $this->file, $start + $header->size, SEEK_SET );
continue;
}
$x = hexdump( $bytes );
print "BACKUP $x\n";
if ( $header->sync && !$header->valid ) {
$x = hexdump( $bytes );
die('xxx ' . $x);
// ID3v2.3
// https://web.archive.org/web/20081008034714/http://www.id3.org/id3v2.3.0
// ID3v2/file identifier "ID3"
// ID3v2 version $03 00
// ID3v2 flags %abc00000
// ID3v2 size 4 * %0xxxxxxx
$id3 = unpack( "a3tag/nversion/Cflags/C4size", $bytes );
if ( $id3['tag'] === 'ID3' ) {
$size = $lookahead +
( $id3['size4'] |
( $id3['size3'] << 7) |
( $id3['size2'] << 14) |
( $id3['size1'] << 21) );
// For byte range purposes; count as zero duration
$segments[] = [
'start' => $start,
'size' => $size,
'timestamp' => $this->timestamp,
'duration' => 0.0,
];
fseek( $this->file, $start + $size, SEEK_SET );
continue;
}
// back up 3 bytes and try again
$hex = hexdump( $bytes );
$safe = safestr ( $bytes );
var_dump($segments);
throw new Exception("Invalid packet at $start? $hex $safe");
// back up and try again
fseek( $this->file, $start + 1, SEEK_SET );
}
}
@ -567,19 +640,13 @@ function extractMP3( $filename ) {
$timestamp = 0.0;
while ( true ) {
$start = $reader->pos();
$frame = $reader->readFrame();
if ( !$frame ) {
$segment = $reader->readFrame();
if ( !$segment ) {
return $segments;
}
$duration = 144.0 / $frame->sampleRate;
$segments[] = [
'start' => $start,
'size' => $frame->size,
'timestamp' => $timestamp,
'duration' => $duration,
];
$timestamp += $duration;
$segments[] = $segment;
}
return $segments;
} finally {
fclose( $file );
}
@ -590,6 +657,9 @@ function consolidate( $target, $segments ) {
if ( isset( $segments['init'] ) ) {
$out['init'] = $segments['init'];
}
if ( count( $segments ) < 2 ) {
return $segments;
}
$n = count( $segments ) - 1;
$start = $segments[0]['start'];