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## playback_subtitle_stream_index

# Function playback_subtitle_stream_index

Source

    pub fn playback_subtitle_stream_index() -> i32

Expand description

The `SubtitleStreamIndex` to negotiate with: always “none”.

The reported bug: a source with an E-AC-3 track and a PGSSUB default subtitle track. Sending no index let the server honour that default, and since PGS cannot go out as a sidecar it chose `SubtitleMethod=Encode` — burn-in. That turned an audio-only transcode (the HEVC video was directly supported) into a full HEVC→h264 re-encode, which the server could not sustain in real time: the buffer never grew beyond one segment and playback stalled every few seconds, taking seeking down with it.

Asking for no subtitle stream costs nothing, because the app never wanted the server’s composited version — it fetches the text tracks separately and renders them itself (UR-020).

TRACES: UR-020, UR-004 | DR-176 | UT-168