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Brooke Vibber 2023-04-04 09:57:12 -07:00
parent 1603c45b7a
commit c3751acb49
7 changed files with 712 additions and 3 deletions
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405
HLS/MP3Segmenter.php Normal file
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<?php
/**
* .m3u8 playlist generation for HLS (HTTP Live Streaming)
*
* @file
* @ingroup HLS
*/
namespace MediaWiki\TimedMediaHandler\HLS;
use Exception;
class MP3Segmenter extends Segmenter {
// http://www.mp3-tech.org/programmer/frame_header.html
/**
* Internal layout of MP3 frame header bitfield
* @var array
*/
private static $bits = [
'sync' => [ 21, 11 ],
'mpeg' => [ 19, 2 ],
'layer' => [ 17, 2 ],
'protection' => [ 16, 1 ],
'bitrate' => [ 12, 4 ],
'sampleRate' => [ 10, 2 ],
'padding' => [ 9, 1 ],
// below this not needed at present
'private' => [ 8, 1 ],
'channelMode' => [ 6, 2 ],
'modeExt' => [ 4, 2 ],
'copyright' => [ 3, 1 ],
'original' => [ 2, 1 ],
'emphasis' => [ 0, 2 ],
];
/**
* 11-bit sync mask for MP3 frame header
* @var int
*/
private const SYNC_MASK = 0x7ff;
/**
* Map of sample count per frame based on version/mode
* This is just in case we need to measure non-default sample rates!
* @var array
*/
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 ],
];
/**
* Map of sample rates based on version/mode
* @var array
*/
private static $sampleRates = [
// MPEG-2.5
[ 11025, 12000, 8000, 1 ],
// Reserved
[ 1, 1, 1, 1 ],
// MPEG-2
[ 22050, 24000, 16000, 1 ],
// MPEG-1
[ 44100, 48000, 32000, 1 ],
];
/**
* Map of bit rates based on version/mode/code
* @var array
*/
private static $bitrates = [
// MPEG-2
[
// 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 ],
// layer 2
[ 0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160, 0 ],
// layer 1
[ 0, 32, 48, 56, 64, 80, 96, 112, 128, 144, 160, 176, 192, 224, 256, 0 ],
],
// MPEG-1
[
// 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 ],
// layer 2
[ 0, 32, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320, 384, 0 ],
// layer 1
[ 0, 32, 64, 96, 128, 160, 192, 224, 256, 288, 320, 352, 384, 316, 448, 0 ],
]
];
/**
* Timestamp resolution for HLS ID3 timestamp tags
*/
private const KHZ_90 = 90000;
/**
* Decode a binary field from the MP3 frame header
*/
private static function field( string $name, int $header ): int {
[ $shift, $bits ] = self::$bits[$name];
$mask = ( 1 << $bits ) - 1;
return ( $header >> $shift ) & $mask;
}
/**
* Decode an MP3 header bitfield
*/
private static function frameHeader( string $bytes ): ?array {
if ( strlen( $bytes ) < 4 ) {
return null;
}
$data = unpack( "Nval", $bytes );
$header = $data['val'];
// This includes "MPEG 2.5" support, so checks for 11 set bits
// not 12 set bits as per original MPEG 1/2
$sync = self::field( 'sync', $header );
if ( $sync !== self::SYNC_MASK ) {
return null;
}
$mpeg = self::field( 'mpeg', $header );
$layer = self::field( 'layer', $header );
$protection = self::field( 'protection', $header );
$br = self::field( 'bitrate', $header );
$bitrate = 1000 * self::$bitrates[$mpeg & 1][$layer][$br];
if ( $bitrate == 0 ) {
return null;
}
$sr = self::field( 'sampleRate', $header );
$sampleRate = self::$sampleRates[$mpeg][$sr];
if ( $sampleRate == 1 ) {
return null;
}
$padding = self::field( 'padding', $header );
$samples = self::$samplesPerFrame[$mpeg][$layer];
$duration = $samples / $sampleRate;
$nbits = $duration * $bitrate;
$nbytes = $nbits / 8;
$size = intval( $nbytes );
if ( $protection == 0 ) {
$size += 2;
}
if ( $padding == 1 ) {
$size++;
}
return [
'samples' => $samples,
'sampleRate' => $sampleRate,
'size' => $size,
'duration' => $duration,
];
}
private static function id3Header( string $bytes ): ?array {
// 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
$headerLen = 10;
if ( strlen( $bytes ) < $headerLen ) {
return null;
}
$data = unpack( "a3tag/nversion/Cflags/C4size", $bytes );
if ( $data['tag'] !== 'ID3' ) {
return null;
}
$size = $headerLen +
( $data['size4'] |
( $data['size3'] << 7 ) |
( $data['size2'] << 14 ) |
( $data['size1'] << 21 ) );
return [
'size' => $size,
];
}
protected function parse(): void {
$file = fopen( $this->filename, 'rb' );
$stream = new OwningStreamReader( $file );
$timestamp = 0.0;
while ( true ) {
$start = $stream->pos();
$lookahead = 10;
$bytes = $stream->read( $lookahead );
if ( $bytes === null ) {
// end of file
break;
}
// Check for MP3 frame header sync pattern
$header = self::frameHeader( $bytes );
if ( $header ) {
// Note we don't need the data at this time.
$stream->seek( $start + $header['size'] );
$timestamp += $header['duration'];
$this->segments[] = [
'start' => $start,
'size' => $header['size'],
'timestamp' => $timestamp,
'duration' => $header['duration'],
];
continue;
}
// Check for ID3v2 tag
$id3 = self::id3Header( $bytes );
if ( $id3 ) {
// For byte range purposes; count as zero duration
$stream->seek( $start + $id3['size'] );
$this->segments[] = [
'start' => $start,
'size' => $id3['size'],
'timestamp' => $timestamp,
'duration' => 0.0,
];
continue;
}
throw new Exception( "Not a valid MP3 or ID3 frame at $start" );
}
}
/**
* Rewrite the file to include ID3 private tags with timestamp
* data for HLS at segment boundaries. This will modify the file
* in-place and change the segment offsets and sizes in the object.
*/
public function rewrite(): void {
$offset = 0;
$id3s = [];
$segments = [];
foreach ( $this->segments as $i => $orig ) {
$id3 = self::timestampTag( $orig['timestamp'] );
$delta = strlen( $id3 );
$id3s[$i] = $id3;
$segments[$i] = [
'start' => $orig['start'] + $offset,
'size' => $orig['size'] + $delta,
'timestamp' => $orig['timestamp'],
'duration' => $orig['duration'],
];
$offset += $delta;
}
$file = fopen( $this->filename, 'rw+b' );
$stream = new OwningStreamReader( $file );
echo "old: ";
var_dump( $this->segments );
echo "new: ";
var_dump( $segments );
// Move each segment forward, starting at the lastmost to work in-place.
$preserveKeys = true;
foreach ( array_reverse( $this->segments, $preserveKeys ) as $i => $orig ) {
$stream->seek( $orig['start'] );
$bytes = $stream->readExactly( $orig['size'] );
$stream->seek( $segments[$i]['start'] );
$stream->write( $id3s[$i] );
$stream->write( $bytes );
}
$this->segments = $segments;
}
/**
* Generate an ID3 private tag with a timestamp for use in HLS
* streams of raw media data such as MP3 or AAC.
*/
protected static function timestampTag( float $timestamp ): string {
/*
PRIV frame type
should contain:
The ID3 PRIV owner identifier MUST be
"com.apple.streaming.transportStreamTimestamp". The ID3 payload MUST
be a 33-bit MPEG-2 Program Elementary Stream timestamp expressed as a
big-endian eight-octet number, with the upper 31 bits set to zero.
Clients SHOULD NOT play Packed Audio Segments without this ID3 tag.
https://id3.org/id3v2.4.0-frames
https://id3.org/id3v2.4.0-structure
bit order is MSB first, big-endian
header 10 bytes
extended header (var, optional)
frames (variable)
pading (variable, optional)
footer (10 bytes, optional)
header:
"ID3"
version: 16 bits $04 00
flags: 32 bits
idv2 size: 32 bits (in chunks of 4 bytes, not counting header or footer)
flags:
bit 7 - unsyncrhonization (??)
bit 6 - extended header
bit 5 - experimental indicator
bit 4 - footer present
frame:
id - 32 bits (four chars)
size - 32 bits (in chunks of 4 bytes, excluding frame header)
flags - 16 bits
(frame data)
priv payload:
owner text string followed by \x00
(binary data)
The timestamps... I think... have 90 kHz integer resolution
so convert from the decimal seconds in the HLS
*/
$owner = "com.apple.streaming.transportStreamTimestamp\x00";
$pts = round( $timestamp * self::KHZ_90 );
$thirtyThreeBits = pow( 2, 33 );
$thirtyOneBits = pow( 2, 31 );
if ( $pts >= $thirtyThreeBits ) {
// make sure they won't get too big for 33 bits
// this allows about a 24 hour media length
throw new Exception( "Timestamp overflow in MP3 output stream: $pts >= $thirtyThreeBits" );
}
$pts_high = intval( floor( $pts / $thirtyOneBits ) );
$pts_low = intval( $pts - ( $pts_high * $thirtyOneBits ) );
// Private frame payload
$frame_data = pack(
'a*NN',
$owner,
$pts_high,
$pts_low,
);
// Private frame header
$frame_type = 'PRIV';
$frame_flags = 0;
$frame_length = strlen( $frame_data );
if ( $frame_length > 127 ) {
throw new Error( "Should never happen: too large ID3 frame data" );
}
$frame = pack(
'a4Nna*',
$frame_type,
$frame_length,
$frame_flags,
$frame_data
);
// ID3 tag
$tag_type = 'ID3';
$tag_version = 0x0400;
$tag_flags = 0;
// if >127 bytes may need to adjust
$tag_length = strlen( $frame );
if ( $tag_length > 127 ) {
throw new Error( "Should never happen: too large ID3 tag" );
}
$tag = pack(
'a3nCNa*',
$tag_type,
$tag_version,
$tag_flags,
$tag_length,
$frame
);
return $tag;
}
}

21
HLS/OwningStreamReader.php Normal file
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<?php
/**
* Base class for streaming media segment readers
*
* @file
* @ingroup HLS
*/
namespace MediaWiki\TimedMediaHandler\HLS;
/**
* Base file class that fcloses on destruct.
*/
class OwningStreamReader extends StreamReader {
public function __destruct() {
if ( $this->file ) {
fclose( $this->file );
$this->file = null;
}
}
}

155
HLS/Segmenter.php Normal file
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<?php
/**
* Base class for streaming segment readers
*
* @file
* @ingroup HLS
*/
namespace MediaWiki\TimedMediaHandler\HLS;
use Exception;
/**
* Base class for reading a media file and segmenting it.
*/
abstract class Segmenter {
protected string $filename;
protected array $segments;
public function __construct( string $filename, ?array $segments = null ) {
$this->filename = $filename;
if ( $segments ) {
$this->segments = $segments;
} else {
$this->segments = [];
$this->parse();
}
}
/**
* Fill the segments from the underlying file
*/
abstract protected function parse(): void;
/**
* Consolidate adjacent segments to approach the target segment length.
*/
public function consolidate( float $target ): void {
$out = [];
$n = count( $this->segments );
$init = $this->segments['init'] ?? false;
if ( $init ) {
$n--;
$out['init'] = $init;
}
if ( $n < 2 ) {
return;
}
$first = $this->segments[0];
$start = $first['start'];
$size = $first['size'];
$timestamp = $first['timestamp'];
$duration = $first['duration'];
$i = 1;
while ( $i < $n ) {
// Append segments until we get close
while ( $i < $n - 1 && $duration < $target ) {
$segment = $this->segments[$i];
$total = $duration + $segment['duration'];
if ( $total >= $target ) {
$after = $total - $target;
$before = $target - $duration;
if ( $before < $after ) {
// Break segment early
break;
}
}
$duration += $segment['duration'];
$size += $segment['size'];
$i++;
}
// Save out a segment
$out[] = [
'start' => $start,
'size' => $size,
'timestamp' => $timestamp,
'duration' => $duration,
];
if ( $i < $n ) {
$segment = $this->segments[$i];
$start = $segment['start'];
$size = $segment['size'];
$timestamp = $segment['timestamp'];
$duration = $segment['duration'];
$i++;
}
}
$out[] = [
'start' => $start,
'size' => $size,
'timestamp' => $timestamp,
'duration' => $duration,
];
$this->segments = $out;
}
/**
* Modify the media file and segments in-place to insert any
* tweaks needed for the file to stream correctly.
*
* This is used by MP3Segmenter to insert ID3 timestamps.
*/
public function rewrite(): void {
// no-op in default; fragmented .mp4 can be left as-is
}
public function playlist( float $target, string $filename ): string {
$lines = [];
$lines[] = "#EXTM3U";
$lines[] = "#EXT-X-VERSION:7";
$lines[] = "#EXT-X-TARGETDURATION:$target";
$lines[] = "#EXT-MEDIA-SEQUENCE:0";
$lines[] = "#EXT-PLAYLIST-TYPE:VOD";
$url = urlencode( $filename );
$init = $this->segments['init'] ?? false;
if ( $init ) {
$lines[] = "#EXT-X-MAP:URI=\"{$url}\",BYTERANGE=\"{$init['size']}@{$init['start']}\"";
}
$n = count( $this->segments ) - 1;
for ( $i = 0; $i < $n; $i++ ) {
$segment = $this->segments[$i];
$lines[] = "#EXTINF:{$segment['duration']},";
$lines[] = "#EXT-X-BYTERANGE:{$segment['size']}@{$segment['start']}";
$lines[] = "{$url}";
}
$lines[] = "#EXT-X-ENDLIST";
return implode( "\n", $lines );
}
public static function segment( string $filename ): Segmenter {
$ext = strtolower( substr( $filename, strrpos( $filename, '.' ) ) );
switch ( $ext ) {
case '.mp3':
return new MP3Segmenter( $filename );
case '.mp4':
case '.m4v':
case '.m4a':
case '.mov':
case '.3gp':
return new MP4Segmenter( $filename );
default:
throw new Exception( "Unexpected streaming file extension $ext" );
}
}
}

104
HLS/StreamReader.php Normal file
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<?php
/**
* Base class for streaming media segment readers
*
* @file
* @ingroup HLS
*/
namespace MediaWiki\TimedMediaHandler\HLS;
use Exception;
/**
* Base class for reading/writing a media file with wrappers
* for exception handling and possible multi usage.
*/
class StreamReader {
/**
* @var resource
*/
protected $file;
protected int $pos;
/**
* @param resource $file
*/
public function __construct( $file ) {
if ( get_resource_type( $file ) !== 'stream' ) {
throw new Exception( 'Invalid file stream' );
}
$this->file = $file;
$this->pos = $this->tell();
}
private function tell(): int {
return ftell( $this->file );
}
public function pos(): int {
return $this->pos;
}
/**
* Seek to given absolute file position.
* @throws Exception on error
*/
public function seek( int $pos ): void {
$this->pos = intval( $pos );
if ( $this->pos === $this->tell() ) {
return;
}
$retval = fseek( $this->file, $this->pos, SEEK_SET );
if ( $retval < 0 ) {
throw new Exception( "Failed to seek to $this->pos bytes" );
}
}
/**
* Read $len bytes or return null on EOF/short read.
* @throws Exception on error
*/
public function read( int $len ): ?string {
$this->seek( $this->pos );
$bytes = fread( $this->file, $len );
if ( $bytes === false ) {
throw new Exception( "Read error for $len bytes at $this->pos" );
}
if ( strlen( $bytes ) < $len ) {
return null;
}
$this->pos += strlen( $bytes );
return $bytes;
}
/**
* Read exactly $len bytes
* @throws Exception on error or short read
*/
public function readExactly( int $len ): string {
$bytes = $this->read( $len );
if ( $bytes === null ) {
throw new Exception( "Short read for $len bytes at $this->pos" );
}
return $bytes;
}
/**
* Write the given data and return number of bytes written.
* Short writes are possible on network connections, in theory.
* @throws Exception on error
*/
public function write( string $bytes ): int {
$this->seek( $this->pos );
$len = strlen( $bytes );
$nbytes = fwrite( $this->file, $bytes );
if ( $nbytes === false ) {
throw new Exception( "Write error for $len bytes at $this->pos" );
}
return $nbytes;
}
}

20
HLS/rewrite-mp3.php Normal file
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<?php
require( __DIR__ . '/StreamReader.php' );
require( __DIR__ . '/OwningStreamReader.php' );
require( __DIR__ . '/Segmenter.php' );
require( __DIR__ . '/MP3Segmenter.php' );
use MediaWiki\TimedMediaHandler\HLS\MP3Segmenter;
$argv = $_SERVER['argv'];
$self = array_shift( $argv );
$filename = array_shift( $argv );
$target = 10;
$segmenter = new MP3Segmenter( $filename );
$segmenter->consolidate( $target );
$segmenter->rewrite();
$m3u8 = $segmenter->playlist( $target, $filename );
print $m3u8 . "\n";

8
make-fmp4.sh
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@ -23,12 +23,13 @@ INFILE=caminandes-llamigos.webm
set -e
# Audio for HLS
#ffmpeg -i $INFILE -vn $AUDIO_MP3 -y fmp4.audio.mpeg.mp3
# note - must make the MP3 because we have to reprocess it!
ffmpeg -i $INFILE -vn $AUDIO_MP3 -y fmp4.audio.mpeg.mp3
#ffmpeg -i $INFILE -vn $AUDIO_MP3 $AUDFLAGS -y fmp4.audio.mpeg.mp4
#ffmpeg -i $INFILE -vn $AUDIO_MP3 $AUDFLAGS -y fmp4.audio.mpeg.mov
#ffmpeg -i $INFILE -vn $AUDIO_AAC $AUDFLAGS -y fmp4.audio.aac.mp4
#ffmpeg -i $INFILE -vn $AUDIO_OPUS $AUDFLAGS -y fmp4.audio.opus.mp4
ffmpeg -i $INFILE -vn $AUDIO_OPUS $AUDFLAGS -y fmp4.audio.alac.mp4
# Video for HLS
@ -50,7 +51,8 @@ ffmpeg -i $INFILE -vn $AUDIO_OPUS $AUDFLAGS -y fmp4.audio.alac.mp4
# Playlist processing
php extract-playlist.php fmp4.audio.mpeg.mp3 > fmp4.audio.mpeg.mp3.m3u8
php HLS/rewrite-mp3.php fmp4.audio.mpeg.mp3 > fmp4.audio.mpeg.mp3.m3u8
#php extract-playlist.php fmp4.audio.mpeg.mp3 > fmp4.audio.mpeg.mp3.m3u8
php extract-playlist.php fmp4.audio.mpeg.mp4 > fmp4.audio.mpeg.mp4.m3u8
php extract-playlist.php fmp4.audio.mpeg.mov > fmp4.audio.mpeg.mov.m3u8
php extract-playlist.php fmp4.audio.aac.mp4 > fmp4.audio.aac.mp4.m3u8

2
test-rewrite.sh Normal file
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cp fmp4.audio.mpeg.mp3 rewrite.audio.mpeg.mp3
php HLS/rewrite-mp3.php rewrite.audio.mpeg.mp3