How to Segment Video for HLS Streaming

FFmpeg is the most versatile tool for creating HLS segments. Here's the basic command:

ffmpeg -i input.mp4 -c:v libx264 -crf 23 -c:a aac -b:a 128k -f hls -hls_time 6 -hls_playlist_type vod playlist.m3u8

This creates a VOD HLS stream with 6-second segments, H.264 video, and AAC audio.

For adaptive streaming, create multiple variants:

ffmpeg -i input.mp4 -filter_complex "
  [0:v]split=3[v1][v2][v3];
  [v1]scale=-2:360[v1out];
  [v2]scale=-2:720[v2out];
  [v3]scale=-2:1080[v3out]
" 
  -map [v1out] -map [v2out] -map [v3out] -map 0:a 
  -c:v libx264 -crf 23 -c:a aac 
  -f hls -var_stream_map "v:0,a:0 v:1,a:1 v:2,a:2" 
  -master_pl_name master.m3u8 
  -hls_time 6 -hls_playlist_type vod 
  "variant_%v.m3u8"

Choosing the right segment duration:

• 2-4 seconds: Lower latency, more files, higher server load. Good for live streams.
• 6 seconds: Industry standard. Good balance for most use cases.
• 10 seconds: Better compression, fewer files, higher latency. Best for VOD.

For smooth quality switching, all variants must have aligned keyframes (GOP size equals segment duration):

ffmpeg -i input.mp4 -c:v libx264 -g 60 -keyint_min 60 -sc_threshold 0 ...

With -g 60 and a 30fps source, keyframes occur every 2 seconds. Adjust based on your segment duration.