355 lines
10 KiB
PHP
Executable File
355 lines
10 KiB
PHP
Executable File
#!/usr/bin/env php
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<?php
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// Squishes given video input into sub-4000kb .mp4
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// Crops or pads to 16:9 (letterbox default; --crop to crop)
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// Includes stereo audio (to strip, pass --no-audio)
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// HDR to SDR tonemapping
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// Picks bitrate to match
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// Picks resolution based on bitrate target
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// 2-pass encoding with libx264 veryslow
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// fps limiter: warning requires newer ffmpeg than debian-buster
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$args = $_SERVER['argv'];
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$self = array_shift( $args );
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$maxBytes = 4000 * 1000; // fit in 4MB
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$maxBytes = $maxBytes * 15 / 16; // leave some headroom
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$options = [
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'crop' => false,
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'letterbox' => false,
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'no-audio' => false,
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'exposure' => '0', // stops
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'peak' => '1000', // '10000' is max
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'preset' => 'medium',
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'fps' => '60000/1001',
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'size' => $maxBytes,
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'quality' => 1.0,
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'hdr' => false,
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'dither' => false,
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];
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while ( count( $args ) > 0 && substr( $args[0], 0, 2 ) == '--' ) {
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$option = substr( array_shift( $args ), 2 );
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$parts = explode( '=', $option, 2 );
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if ( count( $parts ) == 2 ) {
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[ $key, $val ] = $parts;
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$options[$key] = $val;
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} else {
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$options[$option] = true;
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}
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}
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if ( count ( $args ) < 2 ) {
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die(
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"Usage: $self [options...] <srcfile.mp4> <destfile.mp4>\n" .
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"Options:\n" .
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" --crop crop to 16:9\n" .
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" --letterbox pad to 16:9\n" .
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" --no-audio strip audio\n" .
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" --exposure=n adjust exposure\n" .
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" --peak=n set HDR peak nits\n" .
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" --preset=key set h.264 encoding preset\n" .
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" --fps=n frame rate limit\n" .
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" --size=n target file size in bytes (default 3.5M)\n" .
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" --quality=n fraction of base bitrate to break on (deafult 0.75)\n" .
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" --hdr force HDR input processing on\n" .
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" --dither enable dithering in 8-bit downconversion\n"
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);
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}
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[ $src, $dest ] = $args;
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convert( $src, $dest, $options );
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exit(0);
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//
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function run( $cmd, $args ) {
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$commandLine = implode( ' ',
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array_merge(
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[ escapeshellcmd( $cmd ) ],
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array_map( 'escapeshellarg', $args )
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)
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);
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echo "$commandLine\n";
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$output = shell_exec( $commandLine );
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if ( $output === false ) {
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throw new Error( "Failed to run $cmd" );
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}
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return $output;
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}
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function ffprobe( $path ) {
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$output = run( 'ffprobe', [
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'-hide_banner',
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'-show_format',
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'-show_streams',
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'-print_format',
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'json',
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'--',
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$path
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] );
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$data = json_decode( $output );
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if ( $data === null ) {
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throw new Error( "Failed to read JSON from ffprobe: $output" );
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}
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return $data;
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}
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function evenize( $n ) {
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$n = round( $n );
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if ( $n & 1 ) {
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$n++;
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}
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return $n;
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}
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function sizify( $str ) {
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$matches = [];
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if ( preg_match( '/^(\d+(?:\.\d+)?)([kmgt]?)$/i', $str, $matches ) ) {
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[ , $digits, $suffix ] = $matches;
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$n = floatval( $digits );
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switch ( strtolower( $suffix ) ) {
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case 't': $n *= 1000; // fall through
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case 'g': $n *= 1000; // fall through
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case 'm': $n *= 1000; // fall through
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case 'k': $n *= 1000; // fall through
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default: return $n;
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}
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return $n;
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}
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die( "Unexpected size format '$str'\n" );
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}
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function extractTracks( $streams, $type ) {
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return array_values(
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array_filter( $streams, function ( $stream ) use ( $type ) {
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return $stream->codec_type === $type;
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} )
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);
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}
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function convert( $src, $dest, $options ) {
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$maxBits = 8 * sizify( $options['size'] );
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$probe = ffprobe( $src );
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$videoTracks = extractTracks( $probe->streams, 'video' );
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$audioTracks = extractTracks( $probe->streams, 'audio' );
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if ( count( $videoTracks ) == 0 ) {
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var_dump( $probe );
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die("oh no\n");
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}
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$track = $videoTracks[0];
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$duration = floatval( $track->duration );
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$width = $track->width;
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$height = $track->height;
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$hdr = $track->color_primaries === 'bt2020' || $options['hdr'];
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$keyframeInt = ceil( $duration * 60 );
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$bitrate = floor( $maxBits / $duration );
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if ( $options[ 'no-audio' ] || count( $audioTracks ) == 0 ) {
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$audio = [ '-an' ];
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} else {
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$audioBitrate = 96 * 1000;
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$audio = [
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'-ac', 2,
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'-b:a', $audioBitrate,
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];
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$bitrate -= $audioBitrate;
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}
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$bitrate = max( $bitrate, 16000 );
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$mbits = 1000 * 1000;
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$base = intval( $mbits * floatval( $options['quality'] ) );
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if ( $bitrate < 0.125 * $base || $height < 144 ) {
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$frameWidth = 256;
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$frameHeight = 144;
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$bitrate = min( $bitrate, $base * 0.25 );
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} elseif ( $bitrate < 0.25 * $base || $height < 180 ) {
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$frameWidth = 320;
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$frameHeight = 180;
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$bitrate = min( $bitrate, $base * 0.5 );
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} elseif ( $bitrate < 0.5 * $base || $height < 288 ) {
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$frameWidth = 512;
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$frameHeight = 288;
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$bitrate = min( $bitrate, $base * 0.5 );
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} elseif ( $bitrate < 1 * $base || $height < 480 ) {
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$frameWidth = 640;
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$frameHeight = 360;
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$bitrate = min( $bitrate, $base );
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} elseif ( $bitrate < 2 * $base || $height < 540) {
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$frameWidth = 854;
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$frameHeight = 480;
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$bitrate = min( $bitrate, $base * 2 );
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} elseif ( $bitrate < 2.5 * $base || $height < 720) {
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$frameWidth = 960;
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$frameHeight = 540;
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$bitrate = min( $bitrate, $base * 2.5 );
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} elseif ( $bitrate < 4 * $base || $height < 1080) {
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$frameWidth = 1280;
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$frameHeight = 720;
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$bitrate = min( $bitrate, $base * 4 );
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} else {
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$frameWidth = 1920;
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$frameHeight = 1080;
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$bitrate = min( $bitrate, $base * 8 );
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}
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$aspect = $width / $height;
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$pixels = $width * $height;
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// canonical base rate is 1 megabit at 480p
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$bitrate = min( $bitrate, 4 * $base );
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/*
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$minWidth = 640;
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$minHeight = 360;
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$baseWidth = 854;
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$baseHeight = 480;
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$pixelsPerBit = ( $baseWidth * $baseHeight ) / $base;
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$maxWidth = 1920;
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$maxHeight = 1080;
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$maxrate = $base * ( $maxWidth * $maxHeight ) / ( $baseWidth * $baseHeight );
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$pixels = $bitrate * $pixelsPerBit;
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$frameHeight = evenize( sqrt( $pixels / $aspect ) );
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$frameWidth = evenize( $frameHeight * $aspect );
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if ( $aspect > 16 / 9 ) {
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if ( $frameWidth < $minWidth ) {
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$frameWidth = $minWidth;
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$frameHeight = evenize( $frameWidth / $aspect );
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} elseif ( $frameWidth > $maxWidth ) {
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$frameWidth = $maxWidth;
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$frameHeight = evenize( $frameWidth / $aspect );
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$bitrate = min( $bitrate, $maxrate );
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}
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} else {
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if ( $frameHeight < $minHeight ) {
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$frameHeight = $minHeight;
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$frameWidth = evenize( $frameHeight * $aspect );
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} elseif ( $frameWidth > $maxWidth ) {
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$frameHeight = $maxHeight;
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$frameWidth = evenize( $frameHeight * $aspect );
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$bitrate = min( $bitrate, $maxrate );
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}
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}
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*/
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$wide = $aspect > ( $frameWidth / $frameHeight );
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$crop = boolval( $options['crop'] );
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$letterbox = boolval( $options['letterbox'] );
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if ( $crop ) {
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if ( $wide ) {
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$scaleHeight = $frameHeight;
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$scaleWidth = evenize( $frameHeight * $aspect );
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} else {
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$scaleWidth = $frameWidth;
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$scaleHeight = evenize( $frameWidth / $aspect );
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}
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} else {
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if ( $wide ) {
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$scaleWidth = $frameWidth;
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$scaleHeight = evenize( $frameWidth / $aspect );
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} else {
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$scaleHeight = $frameHeight;
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$scaleWidth = evenize( $frameHeight * $aspect );
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}
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}
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$exposure = floatval( $options['exposure'] );
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$peakNits = floatval( $options['peak'] );
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$sdrNits = 80;
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$peak = $peakNits / $sdrNits;
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$filters = [ "scale=w=$scaleWidth:h=$scaleHeight" ];
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if ( $hdr ) {
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$filters[] = "zscale=t=linear";
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if ( $exposure ) {
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$filters[] = "exposure=$exposure";
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}
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$filters[] = "tonemap=hable:peak=$peak:desat=0.0";
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if ( $options['dither'] ) {
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$dither = ":dither=ordered";
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} else {
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$dither = "";
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}
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$filters[] = "zscale=t=bt709:p=bt709:m=bt709:r=full$dither";
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$filters[] = "vibrance=0.2";
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}
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$filters[] = "format=yuv420p";
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if ( $crop ) {
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$filters[] = "crop=w=$frameWidth:h=$frameHeight";
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} elseif ( $letterbox ) {
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$offsetX = round( ( $frameWidth - $scaleWidth) / 2 );
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$offsetY = round( ( $frameHeight - $scaleHeight) / 2 );
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$filters[] = "pad=w=$frameWidth:h=$frameHeight:x=$offsetX:y=$offsetY";
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}
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$vf = implode( ',', $filters );
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$fps = $options['fps'];
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$preset = $options['preset'];
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$tempPrefix = 'pack-vid-passlog' . rand(0,1 << 31);
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$passlog = tempnam( '.', $tempPrefix );
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run( 'ffmpeg',
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array_merge( [
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'-i', $src,
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'-f', 'mp4',
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'-fpsmax', $fps,
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//'-r', $fps,
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'-vf', $vf,
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'-c:v', 'libx264',
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'-b:v', $bitrate,
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'-preset', $preset,
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'-pass', '1',
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'-passlogfile', $passlog,
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'-g', $keyframeInt,
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], $audio, [
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'-y', '/dev/null'
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] )
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);
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run( 'ffmpeg',
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array_merge( [
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'-i', $src,
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'-vf', $vf,
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'-fpsmax', $fps,
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//'-r', $fps,
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'-c:v', 'libx264',
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'-b:v', $bitrate,
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'-preset', $preset,
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'-pass', '2',
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'-passlogfile', $passlog,
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'-g', $keyframeInt,
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], $audio, [
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'-movflags', '+faststart',
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'-y', $dest
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] )
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);
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$len = strlen( $tempPrefix );
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if ( $len > 0 ) {
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$dir = dir( './' );
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for ( $entry = $dir->read(); $entry !== false; $entry = $dir->read() ) {
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if ( substr( $entry, 0, $len ) === $tempPrefix ) {
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print "...deleting temp file: $entry\n";
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unlink( $entry );
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}
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}
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$dir->close();
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}
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}
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