[FFmpeg-user] extract a segment from a live HLS encoding

Louis Letourneau lletourn49 at gmail.com
Thu Oct 27 21:06:13 EEST 2016

I'm capturing a video using:

ffmpeg -y -f decklink -i "DeckLink Mini Recorder (2)@14" -pix_fmt yuv420p
-vf "fps=29.97" -force_key_frames "expr:gte(t,n_forced*5)" -codec:a
libfdk_aac -b:a 128k -codec:v libx264 -crf 24 -preset fast -bf 0 -hls_time
5 -hls_list_size 0 -hls_wrap 0 -hls_allow_cache 1 -hls_allow_cache 0
-hls_segment_filename segment_%07d.ts segment.m3u8

Say an hour passes, should it be possible, while this command continues
capturing, to extract a segment, say 10 minutes after the start:

ffmpeg -y -ss 00:10:00 -i segment.m3u8 -codec copy -bsf:a aac_adtstoasc -t
60 my_segment.mp4

At the moment it seems that ffmpeg keeps reloading the HLS manifest, m3u8,
until the #EXT-X-ENDLIST appears and never starts the encoding process,
even if the segments to copy are complete.

I do realise that a wraping HLS stream could be problematic, but still I
was wondering if a parameter existed to force it to try anyways.


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