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