Two pass encoding allow user to have more control on the output filesize.
Use case
Let's say you want to upload a video of 10min, that is 400MiB for some reasons. That'd mean 1 min of video is 40MiB. We want each video to not be upon 20MiB per minute.
We need to use two-pass encoding to achieve this :
- 10 minutes = 600 seconds
- 20 MiB = 20 000 KiB
(20k / 600) * 60 = 2000 MiB
2M - 192k = 1 808 000 kBit/s is our target video bitrate.
That'd produce the following settings :
encoding:
strategy: crf
minute_filesize: 40000
renditions:
- name: <defined by user>
width: <defined by user>
height: <defined by user>
video_bitrate: ( (minute_filesize [kB] / duration [sec]) * 60 )
audio_bitrate: 192000
framerate: <from original or defined by user>
audio_rate: 48000
video_codec: libx265
audio_codec: aac
target_bandwidth: (video_bitrate + audio_bitrate)
preset: mediumWhich would produce the following ffmpge options :
$ ffmpeg -i original -y -vf scale=w=1280:h=720:force_original_aspect_ratio=decrease -c:v libx265 -b:v 778k -c:a aac -b:a 192k -sc_threshold 0 -g 48 -keyint_min 48 -hls_time 4 -hls_playlist_type vod -hls_segment_filename output/360p_%03d.ts output/360p.m3u8
References
Two pass encoding allow user to have more control on the output filesize.
Use case
Let's say you want to upload a video of 10min, that is 400MiB for some reasons. That'd mean 1 min of video is 40MiB. We want each video to not be upon 20MiB per minute.
We need to use two-pass encoding to achieve this :
(20k / 600) * 60 = 2000 MiB2M - 192k = 1 808 000 kBit/s is our target video bitrate.
That'd produce the following settings :
Which would produce the following ffmpge options :
References