Drain desktop tracks independently and cancel obsolete media on reset

src/stream/stream_viewer.c

@@ -343,7 +343,7 @@ int stream_viewer_request(struct stream_viewers *v, uint64_t id, int64_t positio
         int changed = s->position != position || s->video != video || s->audio_ahead != audio_ahead || s->records != records;
         if (!s->requested && !s->record) s->demand_us = get_time_us();
         s->position = position; s->video = video; s->audio_ahead = audio_ahead; s->records = records;
-        s->requested = video || audio_ahead >= 0;
+        s->requested = 1; /* Нулевой media-бюджет всё равно разрешает управляющие события. */
         result = 0;
         if (s->requested && !s->record && (!s->waiting || changed)) { s->waiting = 0; result = schedule(v); }
     }