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Fix 40ms gap in rolling teletext subtitles #2292

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Fix 40ms gap in rolling teletext subtitles #2292

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7 changes: 5 additions & 2 deletions src/lib_ccx/telxcc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1054,8 +1054,11 @@ void process_telx_packet(struct TeletextCtx *ctx, data_unit_t data_unit_id, tele
ctx->page_buffer.text[yt][it] = telx_to_ucs2(ctx->page_buffer.text[yt][it]);
}
}
// it would be nice, if subtitle hides on previous video frame, so we contract 40 ms (1 frame @25 fps)
ctx->page_buffer.hide_timestamp = timestamp - 40;
// Previously subtracted 40ms (1 frame @ 25fps) to hide subtitle "early".
// This is wrong for non-25fps content and causes a visible ~41ms blink gap
// in rolling teletext subs, because the WebVTT exporter already subtracts
// 1ms to prevent timestamp boundary collisions. That 1ms is sufficient.
ctx->page_buffer.hide_timestamp = timestamp;
if (ctx->page_buffer.hide_timestamp > timestamp)
{
ctx->page_buffer.hide_timestamp = 0;
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