My initial task was to find a segmenter for Windows that will split a h264\aac video file without changing its codecs and make it playable through HLS.
The best way that worked for me is to use ffmpeg like this:
ffmpeg -i encoded.mp4 -c copy -map 0 -vbsf h264_mp4toannexb -flags -global_header -f segment -segment_time 10 -segment_format mpegts stream%d.ts
Now, this splits the file more or less correctly, although mediastreamvalidator threw a couple of warnings, still I was able to play the video.
But, here's the tricky part: ffmpeg cannot create .m3u8 files for you. Which is not a problem, unless you need to create a variant playlist file what I do need.
So now I need to either find or write an app for Windows that imitates varianplaylistcreator
So let's say you have the same video encoded for each different bandwidth: 64, 150, 300, 500, 800, 1200 and 2400. Now after you segment each video, you'd probably like to put those segments into separate folders including playlist files for each rendition.
Now we can create a variant playlist file where we list all the rendtions with instructions on what bandwidth server automatically should switch serving different rendition.
Typically variant playlist look like this:
#EXTM3U
#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=512376
500/500k_512x384_x264_372_quicktime_128.m3u8
#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=68795
64/64k_256x192_x264_32_quicktime_32.m3u8
#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=155580
150/150k_256x192_x264_118_quicktime_32.m3u8
#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=308895
300/300k_512x384_x264_172_quicktime_128.m3u8
#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=811310
800/800k_512x384_x264_672_quicktime_128.m3u8
#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=1210182
1200/1200k_1024x768_x264_1072_quicktime_128.m3u8
#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=2408106
2400/2400k_1024x768_x264_2272_quicktime_128.m3u8
Notice the BANDWITH attribute values. These I suspect are values calculated by varinatplaylistcreator.
And I don't know how it does that. I guess somehow it takes average bitrate of videos(segments) for each rendtion and based on that does that.
So my question is: how those get calculated. Or maybe someone already created a tool that can run on Windows and create varinant playlists.
FFmpeg can report the bitrate of the ts stream. Use the ffprobe tool and you'll get output like this:
Input #0, mpegts, from 'foo.ts':
Duration: 00:04:50.87, start: 2.000011, bitrate: 10381 kb/s
Program 1
Stream #0.0[0x810]: Video: h264 (High), yuv420p, 1280x720 [PAR 1:1 DAR 16:9], 25 fps, 25 tbr, 90k tbn, 50 tbc
The bitrate is being given in kilobits per second, so multiply it by 1024 and you'll have the value you need for the BANDWIDTH tag.