-copyts is unnecessary for -c:s copy to SRT and slows extraction ~5x. Without -flush_packets 1, ffmpeg buffers all output until exit, leaving .srt files at 0 bytes for minutes while the player shows no subtitles. Fixes #16438
-copyts is unnecessary for -c:s copy to SRT and slows extraction ~5x. Without -flush_packets 1, ffmpeg buffers all output until exit, leaving .srt files at 0 bytes for minutes while the player shows no subtitles. Fixes #16438