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aminnausinaminnausin
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feat: subtitle extraction logic
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6 files changed

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‎app/Http/Controllers/Api/V1/Metadata/SubtitleController.php‎

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<?php
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namespace App\Http\Controllers\Api\V1\Metadata;
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use App\Http\Controllers\Controller;
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use App\Models\Metadata;
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use App\Services\Subtitles\SubtitleResolver;
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use Illuminate\Http\Request;
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class SubtitleController extends Controller {
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public function __construct(protected SubtitleResolver $subtitleResolver) {}
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/**
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* Look for a specified subtitle resource.
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*
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* Subtitle Extraction Process ->
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* Initially scan file, set subtitles_scanned_at time and make partially identifying subtitle rows in the subtitle table
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* then when requested by stream or file type, if the exact requested file matches an existing one, return that but if not probe again,
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* and for each found stream, extract it, write to a file and update the row in the subtitle file, and then convert it to the requested format and return that file
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* on subsequent requests, a matching file (usually vtt) will already exist and get returned directly
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*/
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public function show(
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Request $request,
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Metadata $metadata,
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int $track = 2, // track number to specify file like 2.vtt or 3.vtt
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string $format = 'vtt'
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) {
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// TODO: Log activity from request (requires future activity feature)
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return $this->subtitleResolver->resolveSubtitles($metadata, $track, $format);
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}
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// TODO: Add an API route that gets subtitles for a specific metadata or video row and cache the results. These are only used to determine the filepath used in the <track/>
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}

‎app/Services/Subtitles/Formats/SubtitleFormatStrategy.php‎

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<?php
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namespace App\Services\Subtitles\Formats;
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interface SubtitleFormatStrategy {
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public function convert(string $inputPath, string $outputPath): void;
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}

‎app/Services/Subtitles/Formats/VttStrategy.php‎

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<?php
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namespace App\Services\Subtitles\Formats;
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use Illuminate\Support\Facades\Storage;
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use Symfony\Component\Process\Process;
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class VttStrategy implements SubtitleFormatStrategy {
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public function convert(string $inputPath, string $outputPath): void {
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$process = new Process([
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'ffmpeg',
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'-y',
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'-i',
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Storage::disk('local')->path($inputPath),
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'-c:s',
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'webvtt',
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Storage::disk('local')->path($outputPath),
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]);
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$process->mustRun();
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}
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}

‎app/Services/Subtitles/SubtitleExtractor.php‎

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<?php
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namespace App\Services\Subtitles;
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use App\Models\Metadata;
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use App\Models\Subtitle;
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use Illuminate\Support\Facades\Log;
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use Illuminate\Support\Facades\Storage;
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use Symfony\Component\Process\Process;
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class SubtitleExtractor {
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public function extractStream(Metadata $metadata, Subtitle $subtitle) {
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try {
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$mediaPath = $metadata->video->path;
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$ext = $this->getExtentionFromCodec($subtitle['codec']);
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$outputPath = $this->getOutputDir($subtitle, $ext);
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$command = [
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'ffmpeg',
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'-y',
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'-i',
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Storage::disk('public')->path($mediaPath), // Media is on public disk for now
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'-map',
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"0:$subtitle->track_id",
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Storage::disk('local')->path($outputPath),
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];
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$process = new Process($command);
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$process->run();
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if (! $process->isSuccessful()) {
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throw new \Exception('Subtitles Failed: "' . implode(' ', $command) . '"');
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}
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$subtitle->update([
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'path' => $outputPath,
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'format' => $ext,
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]);
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return $outputPath;
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} catch (\Throwable $th) {
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Log::error('Unable to get file subtitles', ['error' => $th->getMessage()]);
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throw $th;
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}
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}
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/**
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* Get the relative output path given the subtitle and file extention
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*/
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private function getOutputDir(Subtitle $subtitle, string $ext) {
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$outDir = "data/media/{$subtitle->metadata_uuid}/subtitles"; // Relative output directory
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Storage::disk('local')->makeDirectory($outDir); // Ensure directory exists
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return "{$outDir}/{$subtitle->track_id}.{$ext}"; // Add track.ext to get final output address
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}
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private function getExtentionFromCodec(string $codec): string {
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return match ($codec) {
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'subrip' => 'srt',
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'ass' => 'ass',
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'ssa' => 'ssa',
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'webvtt' => 'vtt',
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'hdmv_pgs_subtitle' => 'sup',
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'dvd_subtitle' => 'sub',
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default => 'bin',
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};
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}
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}

‎app/Services/Subtitles/SubtitleFormatter.php‎

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<?php
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namespace App\Services\Subtitles;
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use App\Services\Subtitles\Formats\VttStrategy;
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use Illuminate\Support\Facades\Storage;
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class SubtitleFormatter {
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public function convert(string $input, string $output, string $format): string {
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if (! Storage::disk('local')->exists($input)) {
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throw new \RuntimeException("Input file not found: {$input}");
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}
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$strategy = match ($format) {
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'vtt' => new VttStrategy,
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default => throw new \InvalidArgumentException('Unsupported format'),
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};
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$strategy->convert($input, $output);
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if (! Storage::disk('local')->exists($output)) {
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throw new \RuntimeException("Conversion failed: {$output} not created");
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}
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return $output;
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}
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}

‎app/Services/Subtitles/SubtitleResolver.php‎

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<?php
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namespace App\Services\Subtitles;
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use App\Models\Metadata;
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use Illuminate\Support\Facades\Response;
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use Illuminate\Support\Facades\Storage;
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use Symfony\Component\HttpFoundation\BinaryFileResponse;
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class SubtitleResolver {
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public function __construct(protected SubtitleExtractor $extractor, protected SubtitleFormatter $formatter) {}
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public function resolveSubtitles(Metadata $metadata, int $track, string $format): BinaryFileResponse {
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$subtitle = $metadata->subtitles()->where('track_id', $track)->firstOrFail(); // 404 on no result
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$format = ltrim(strtolower($format), '.');
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$requestedPath = "data/media/{$subtitle->metadata_uuid}/subtitles/{$track}.{$format}";
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if ($this->fileExists($requestedPath)) {
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return Response::file(
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Storage::disk('local')->path($requestedPath)
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);
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}
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if (! $subtitle->path || ! $this->fileExists($subtitle->path)) {
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$this->extractor->extractStream($metadata, $subtitle); // Native format subtitle file (usually srt)
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$subtitle->refresh();
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}
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$nativePath = $subtitle->path;
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$convertedPath = $this->formatter->convert(
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$nativePath,
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$requestedPath,
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$format
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);
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if (! $this->fileExists($convertedPath)) {
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abort(500);
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}
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return Response::file(
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Storage::disk('local')->path($convertedPath)
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);
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}
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private function fileExists(string $path): bool {
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return Storage::disk('local')->exists($path);
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}
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}

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