Stream Whisper segments so the UI can show live transcript text.

Consume faster-whisper SSE instead of blocking on one JSON response, persist growing text and progress over Reverb, and drop the fake percent heartbeat.
2026-08-13 12:34:47 +02:00
parent 5cea5192c2
commit 4c73620458
9 changed files with 574 additions and 138 deletions
@@ -0,0 +1,161 @@
+<?php
+
+namespace App\Services;
+
+class WhisperTranscriptionStream
+{
+    /**
+     * Pull complete SSE `data:` payloads out of a rolling buffer.
+     *
+     * @return list<string>
+     */
+    public function extractPayloads(string &$buffer): array
+    {
+        $frames = explode("\n\n", str_replace("\r\n", "\n", $buffer));
+        $buffer = array_pop($frames) ?? '';
+        $payloads = [];
+
+        foreach ($frames as $frame) {
+            foreach ($this->dataLines($frame) as $payload) {
+                if ($payload === '[DONE]' || $payload === '') {
+                    continue;
+                }
+
+                $payloads[] = $payload;
+            }
+        }
+
+        return $payloads;
+    }
+
+    /**
+     * Flush a trailing incomplete frame at end-of-stream.
+     *
+     * @return list<string>
+     */
+    public function flushBuffer(string &$buffer): array
+    {
+        $trimmed = trim($buffer);
+
+        if ($trimmed === '') {
+            $buffer = '';
+
+            return [];
+        }
+
+        $buffer .= "\n\n";
+
+        return $this->extractPayloads($buffer);
+    }
+
+    /**
+     * Parse one SSE JSON payload into append/replace/end/done fields.
+     *
+     * @return array{append: ?string, replace: ?string, end: ?float, done: bool, legacy: bool}|null
+     */
+    public function parseEvent(string $json): ?array
+    {
+        $data = json_decode($json, true);
+
+        if (! is_array($data)) {
+            return null;
+        }
+
+        $type = $data['type'] ?? null;
+
+        if ($type === 'transcript.text.delta') {
+            $delta = $data['delta'] ?? '';
+
+            if (! is_string($delta) || $delta === '') {
+                return null;
+            }
+
+            return [
+                'append' => $delta,
+                'replace' => null,
+                'end' => $this->nullableFloat($data['end'] ?? null),
+                'done' => false,
+                'legacy' => false,
+            ];
+        }
+
+        if ($type === 'transcript.text.done') {
+            $text = $data['text'] ?? '';
+
+            return [
+                'append' => null,
+                'replace' => is_string($text) ? $text : '',
+                'end' => $this->nullableFloat($data['end'] ?? null),
+                'done' => true,
+                'legacy' => false,
+            ];
+        }
+
+        if ($type === null && isset($data['text']) && is_string($data['text']) && $data['text'] !== '') {
+            return [
+                'append' => $data['text'],
+                'replace' => null,
+                'end' => $this->nullableFloat($data['end'] ?? null),
+                'done' => false,
+                'legacy' => true,
+            ];
+        }
+
+        return null;
+    }
+
+    /**
+     * Apply a parsed event to the accumulated transcript.
+     *
+     * @param  array{append: ?string, replace: ?string, end: ?float, done: bool, legacy: bool}  $event
+     */
+    public function applyEvent(string $accumulated, array $event): string
+    {
+        if (is_string($event['replace'])) {
+            return $event['replace'];
+        }
+
+        $chunk = $event['append'] ?? '';
+
+        if ($chunk === '') {
+            return $accumulated;
+        }
+
+        if ($event['legacy']) {
+            $chunk = trim($chunk);
+
+            if ($accumulated === '') {
+                return $chunk;
+            }
+
+            return rtrim($accumulated).' '.$chunk;
+        }
+
+        return $accumulated.$chunk;
+    }
+
+    /**
+     * @return list<string>
+     */
+    private function dataLines(string $frame): array
+    {
+        $payloads = [];
+
+        foreach (explode("\n", $frame) as $line) {
+            if (str_starts_with($line, 'data:')) {
+                $payloads[] = ltrim(substr($line, 5));
+            }
+        }
+
+        return $payloads;
+    }
+
+    private function nullableFloat(mixed $value): ?float
+    {
+        if (! is_numeric($value)) {
+            return null;
+        }
+
+        return (float) $value;
+    }
+}