extend hack to safari

Author: Wumpf

crates/utils/re_video/src/decode/ffmpeg_h264/ffmpeg.rs

@@ -884,7 +884,10 @@ impl AsyncDecoder for FFmpegCliH264Decoder {
     }
 
     fn min_num_samples_to_enqueue_ahead(&self) -> usize {
-        // TODO: describe this and add ticket.
+        // TODO(#8848): On some videos (which??) we need to enqueue more samples, otherwise ffmpeg will not provide us with any frames.
+        // The observed behavior is that we continously get frames that are 16 frames older than what we enqueued,
+        // never reaching the frames of all currently enqueued GOPs prior.
+        // (The same happens with webcodec decoder on Safari for affected videos)
         16
     }
 }

crates/utils/re_video/src/decode/webcodecs.rs

@@ -190,8 +190,28 @@ impl AsyncDecoder for WebVideoDecoder {
 
         Ok(())
     }
+
+    fn min_num_samples_to_enqueue_ahead(&self) -> usize {
+        // TODO(#8848): For some h264 videos (which??) we need to enqueue more samples, otherwise Safari will not provide us with any frames.
+        // (The same happens with FFmpeg-cli decoder for the affected videos)
+        if self.video_config.is_h264() && IS_SAFARI.get() {
+        {
+            16 // Safari needs more samples queued for h264
+        } else {
+            // No such workaround are needed anywhere else,
+            // GOP boundaries as handled by the video player are enough.
+            0
+        }
+    }
 }
 
+const IS_SAFARI: Lazy<bool> = Lazy::new(|| {
+    web_sys::window()
+        .and_then(|w| w.navigator().user_agent().ok())
+        .map(|ua| ua.contains("Safari"))
+        .unwrap_or(false)
+});
+
 fn init_video_decoder(
     on_output_callback: Arc<OutputCallback>,
     timescale: Timescale,