ffmpeg -i /tmp/c0d8f94a322b5e750248f2c9b0875c047f6824.mkv -map 0:2 -c:a aac -map 0:4 -hls_time 10 -hls_playlist_type vod -hls_segment_filename /tmp/audio_high_2_test_%04d.m4a /tmp/audio_high_2_test.m3u8

cat /tmp/audio_high_2_test.m3u8
#EXTM3U
#EXT-X-VERSION:3
#EXT-X-TARGETDURATION:22
#EXT-X-MEDIA-SEQUENCE:0
#EXT-X-PLAYLIST-TYPE:VOD
#EXTINF:10.005333,
audio_high_2_test_0000.m4a
#EXTINF:10.005333,
audio_high_2_test_0001.m4a
#EXTINF:10.005333,
audio_high_2_test_0002.m4a
#EXTINF:9.984000,
audio_high_2_test_0003.m4a
#EXTINF:18.469333,
audio_high_2_test_0004.m4a
#EXTINF:16.831333,
audio_high_2_test_0005.m4a

mediainfo /tmp/audio_high_2_test_0004.m4a | grep Duration
Duration                                 : 9 s 963 ms
Duration                                 : 9 s 963 ms