#!/usr/bin/env php
<?php

// Squishes given video input into sub-4000kb .mp4
// Crops or pads to 16:9 (letterbox default; --crop to crop)
// Includes stereo audio (to strip, pass --no-audio)
// HDR to SDR tonemapping
// Picks bitrate to match
// Picks resolution based on bitrate target
// 2-pass encoding with libx264 veryslow
// fps limiter: warning requires newer ffmpeg than debian-buster

$args = $_SERVER['argv'];
$self = array_shift( $args );

$maxBytes = 4000 * 1000; // fit in 4MB
$maxBytes = $maxBytes * 15 / 16; // leave some headroom

$options = [
    'crop' => false,
    'letterbox' => false,
    'no-audio' => false,
    'audio-bitrate' => 96000,
    'audio-rate' => false,
    'audio-channels' => false,
    'exposure' => '0', // stops
    'peak' => '1000', // '10000' is max
    'preset' => false,
    'fps' => '60',
    'size' => $maxBytes,
    'quality' => 1.0,
    'bitrate' => 0,
    'hdr' => false,
    'dither' => false,
    'width' => false,
    'height' => false,
    'keyframe-int' => 0,
    'vibrance' => 0,
    'crop-width' => false,
    'crop-height' => false,
    'crop-left' => false,
    'crop-top' => false,
    'tonemap' => 'hable',
    'color-temperature' => false,
    'vcodec' => 'libx264',
    'stretch' => false,
];

while ( count( $args ) > 0 && substr( $args[0], 0, 2 ) == '--' ) {
    $option = substr( array_shift( $args ), 2 );
    $parts = explode( '=', $option, 2 );
    if ( count( $parts ) == 2 ) {
        [ $key, $val ] = $parts;
        $options[$key] = $val;
    } else {
        $options[$option] = true;
    }
}

if ( count ( $args ) < 2 ) {
    die(
        "Usage: $self [options...] <srcfile.mp4> <destfile.mp4>\n" .
        "Options:\n" .
        "  --crop           crop to 16:9\n" .
        "  --letterbox      pad to 16:9\n" .
        "  --no-audio       strip audio\n" .
        "  --exposure=n     adjust exposure\n" .
        "  --peak=n         set HDR peak nits\n" .
        "  --preset=key     set h.264 encoding preset\n" .
        "  --fps=n          frame rate limit\n" .
        "  --bitrate=n      target bitrate (exclusive with --size)\n" .
        "  --size=n         target file size in bytes (exclusive with --bitrate)\n" .
        "  --quality=n      fraction of base bitrate to break on (deafult 1.0)\n" .
        "  --hdr            force HDR input processing on\n" .
        "  --dither         enable dithering in 8-bit downconversion\n" .
        "  --width=n        override frame width in pixels\n" .
        "  --height=n       override frame height in pixels\n" .
        "  --keyframe-int=n set keyframe interval (default 0)\n" .
        "  --tonemap=mode   set HDR tone mapping mode (hable, clip, etc)\n" .
        "  --color-temperature=n adjust color temp va 6500K\n"
    );
}
[ $src, $dest ] = $args;
convert( $src, $dest, $options );
exit(0);

//

function run( $cmd, $args ) {
    $commandLine = implode( ' ',
        array_merge(
            [ escapeshellcmd( $cmd ) ],
            array_map( 'escapeshellarg', $args )
        )
    );

    echo "$commandLine\n";
    $output = shell_exec( $commandLine );
    if ( $output === false ) {
        throw new Error( "Failed to run $cmd" );
    }

    return $output;
}

function ffprobe( $path ) {
    $output = run( 'ffprobe', [
        '-hide_banner',
        '-show_format',
        '-show_streams',
        '-print_format',
        'json',
        '--',
        $path
    ] );

    $data = json_decode( $output );
    if ( $data === null ) {
        throw new Error( "Failed to read JSON from ffprobe: $output" );
    }

    return $data;
}

function evenize( $n ) {
    $n = round( $n );
    if ( $n & 1 ) {
        $n++;
    }
    return $n;
}

function sizify( $str ) {
    $matches = [];
    if ( preg_match( '/^(\d+(?:\.\d+)?)([kmgt]?)$/i', $str, $matches ) ) {
        [ , $digits, $suffix ] = $matches;
        $n = floatval( $digits );
        switch ( strtolower( $suffix ) ) {
            case 't': $n *= 1000; // fall through
            case 'g': $n *= 1000; // fall through
            case 'm': $n *= 1000; // fall through
            case 'k': $n *= 1000; // fall through
            default: return $n;
        }
        return $n;
    }
    die( "Unexpected size format '$str'\n" );
}

function extractTracks( $streams, $type ) {
    return array_values(
        array_filter( $streams, function ( $stream ) use ( $type ) {
            return $stream->codec_type === $type;
        } )
    );
}

function convert( $src, $dest, $options ) {
    $probe = ffprobe( $src );

    $videoTracks = extractTracks( $probe->streams, 'video' );
    $audioTracks = extractTracks( $probe->streams, 'audio' );
    
    if ( count( $videoTracks ) == 0 ) {
        var_dump( $probe );
        die("oh no\n");
    }
    $track = $videoTracks[0];

    $duration = floatval( $probe->format->duration );
    $width = $track->width;
    $height = $track->height;
    $cropLeft = 0;
    $cropTop = 0;

    if ( $options['crop-width'] ) {
        $cropWidth = intval( $options['crop-width'] );
        $cropLeft = intval( ( $width - $cropWidth ) / 2 );
        $width = $cropWidth;
    }
    if ( $options['crop-height'] ) {
        $cropHeight = intval( $options['crop-height'] );
        $cropTop = intval( ( $height - $cropHeight ) / 2 );
        $height = $cropHeight;
    }
    if ( $options['crop-top'] ) {
        $cropTop = intval( $options['crop-top'] );
    }
    if ( $options['crop-left'] ) {
        $cropLeft = intval( $options['crop-left'] );
    }
    // @fixme some files are missing this? trims from qt?
    //$hdr = $track->color_primaries === 'bt2020' || $options['hdr'];
    // pix_fmt: "yuv420p10le"
    $hdr = substr( $track->pix_fmt, -5 ) === 'p10le' || $options['hdr'];
    if ( $options['keyframe-int'] ) {
        $keyframeInt = intval( $options['keyframe-int'] );
    } else {
        $keyframeInt = intval( ceil( $duration * 60 ) );
    }

    if ( $options['bitrate'] ) {
        $bitrate = sizify( $options['bitrate'] );
    } else if ( $options[ 'size' ] ) {
        $maxBits = 8 * sizify( $options['size'] );
        $bitrate = floor( $maxBits / $duration );
    } else {
        // Calculate a target bitrate from the size later
        $bitrate = null;
    }


    if ( $options[ 'no-audio' ] || count( $audioTracks ) == 0 ) {
        $audio = [ '-an' ];
    } else {
        $audioBitrate = $options[ 'audio-bitrate' ];
        $audio = [
            '-b:a', $audioBitrate,
        ];
        if ( $options['audio-channels'] ) {
            $audio[] = '-ac';
            $audio[] = $options[ 'audio-channels' ];
        }
        if ( $options[ 'audio-rate' ] ) {
            $audio[] = '-ar';
            $audio[] = $options[ 'audio-rate' ];
        }
        $bitrate -= $audioBitrate;
    }

    if ( $options[ 'width' ] && $options[ 'height' ] ) {
        // Use exact given dimensions.
        $frameWidth = intval( $options[ 'width' ] );
        $frameHeight = intval( $options[ 'height' ] );
    } else {
        // Select target resolution from the target bitrate...
        if ( !$bitrate ) {
            // If we didn't get given one, default to 5Mbits 1080HD
            $bitrate = 5000000;
        }
        $mbits = 1000 * 1000;
        $base = intval( $mbits * floatval( $options['quality'] ) );
        if ( $bitrate < 0.125 * $base || $height < 144 ) {
            $frameWidth = 256;
            $frameHeight = 144;
        } elseif ( $bitrate < 0.25 * $base || $height < 180 ) {
            $frameWidth = 320;
            $frameHeight = 180;
        } elseif ( $bitrate < 0.5 * $base || $height < 288 ) {
            $frameWidth = 512;
            $frameHeight = 288;
        } elseif ( $bitrate < 1 * $base || $height < 480 ) {
            $frameWidth = 640;
            $frameHeight = 360;
        } elseif ( $bitrate < 2 * $base || $height < 540) {
            $frameWidth = 854;
            $frameHeight = 480;
        } elseif ( $bitrate < 2.5 * $base || $height < 720) {
            $frameWidth = 960;
            $frameHeight = 540;
        } elseif ( $bitrate < 4 * $base || $height < 1080) {
            $frameWidth = 1280;
            $frameHeight = 720;
        } elseif ( $bitrate < 8 * $base || $height < 1440) {
            $frameWidth = 1920;
            $frameHeight = 1080;
        } elseif ( $bitrate < 16 * $base || $height < 2160) {
            $frameWidth = 2560;
            $frameHeight = 1440;
        } else {
            $frameWidth = 3840;
            $frameHeight = 2160;
        }
    }

    $aspect = $width / $height;
    $pixels = $width * $height;

    if ( $options[ 'stretch' ] ) {
        // Use this option when making non-square output
        $scaleWidth = $frameWidth;
        $scaleHeight = $frameHeight;
    } else {
        // Assumes square pixels
        $wide = $aspect > ( $frameWidth / $frameHeight );
        $crop = boolval( $options['crop'] );
        $letterbox = boolval( $options['letterbox'] );
        if ( $crop ) {
            if ( $wide ) {
                $scaleHeight = $frameHeight;
                $scaleWidth = evenize( $frameHeight * $aspect );
            } else {
                $scaleWidth = $frameWidth;
                $scaleHeight = evenize( $frameWidth / $aspect );
            }
        } else {
            if ( $wide ) {
                $scaleWidth = $frameWidth;
                $scaleHeight = evenize( $frameWidth / $aspect );
            } else {
                $scaleHeight = $frameHeight;
                $scaleWidth = evenize( $frameHeight * $aspect );
            }
        }
    }

    $exposure = floatval( $options['exposure'] );
    $peakNits = floatval( $options['peak'] );
    $sdrNits = 80;
    $peak = $peakNits / $sdrNits;
    $vibrance = floatval( $options['vibrance'] );
    $tonemap = $options['tonemap'];

    $filters = [];
    if ( $options['crop-width'] || $options['crop-height'] ) {
        $filters[] = "crop=w=$width:x=$cropLeft:h=$height:y=$cropTop";
    }
    $filters[] = "scale=w=$scaleWidth:h=$scaleHeight";
    if ( $hdr ) {
        $filters[] = "zscale=t=linear:p=709:m=709";
        if ( $exposure ) {
            $filters[] = "exposure=$exposure";
        }
        $colortemperature = $options['color-temperature'];
        if ( $colortemperature ) {
            $filters[] = "colortemperature=$colortemperature";
        }
        $filters[] = "tonemap=$tonemap:peak=$peak:desat=0.0";
        if ( $options['dither'] ) {
            $dither = ":dither=ordered";
        } else {
            $dither = "";
        }
        $filters[] = "zscale=tin=linear:t=709:p=709:m=709:r=full$dither";
        if ( $vibrance ) {
            $filters[] = "vibrance=$vibrance";
        }
    }
    $filters[] = "format=yuv420p";
    if ( $crop ) {
        $filters[] = "crop=w=$frameWidth:h=$frameHeight";
    } elseif ( $letterbox ) {
        $offsetX = round( ( $frameWidth - $scaleWidth) / 2 );
        $offsetY = round( ( $frameHeight - $scaleHeight) / 2 );
        $filters[] = "pad=w=$frameWidth:h=$frameHeight:x=$offsetX:y=$offsetY";
    }
    $vf = implode( ',', $filters );

    $fps = $options['fps'];

    if ( $options['preset'] ) {
        $preset = [ '-preset', $options[ 'preset' ] ];
    } else {
        $preset = [];
    }

    $extension = pathinfo( $dest )[ 'extension' ];
    if ( $extension === 'mp4' || $extension === 'mov' ) {
        $format = [ '-movflags', '+faststart' ];
    } else if ( $extension === 'webm' || $extension === 'mkv' ) {
        $format = [ '-cues_to_front', 1 ];
    } else {
        $format = [];
    }

    $vcodec = $options['vcodec'];

    $tempPrefix = 'pack-vid-passlog' . rand(0,1 << 31);
    $passlog = tempnam( '.', $tempPrefix );
    run( 'ffmpeg',
        array_merge( [
            '-i', $src,
            '-f', 'mp4',
            '-fpsmax', $fps,
            '-vf', $vf,
            '-c:v', $vcodec,
            '-b:v', $bitrate,
        ], $preset, [
            '-pass', '1',
            '-passlogfile', $passlog,
            '-g', $keyframeInt,
            '-an',
            '-y', '/dev/null'
        ] )
    );
    run( 'ffmpeg',
        array_merge( [
            '-i', $src,
            '-vf', $vf,
            '-fpsmax', $fps,
            '-c:v', $vcodec,
            '-b:v', $bitrate,
        ], $preset, [
            '-pass', '2',
            '-passlogfile', $passlog,
            '-g', $keyframeInt,
        ], $audio, $format, [
            '-y', $dest
        ] )
    );
    
    $len = strlen( $tempPrefix );
    if ( $len > 0 ) {
        $dir = dir( './' );
        for ( $entry = $dir->read(); $entry !== false; $entry = $dir->read() ) {
            if ( substr( $entry, 0, $len ) === $tempPrefix ) {
                print "...deleting temp file: $entry\n";
                unlink( $entry );
            }
        }
        $dir->close();
    }
}