owncast/build/javascript/node_modules/@videojs/http-streaming/docs/creating-content.md

Creating Content

Commands for creating tests streams

Streams with EXT-X-PROGRAM-DATE-TIME for testing seekToProgramTime and convertToProgramTime

lavfi and testsrc are provided for creating a test stream in ffmpeg -g 300 sets the GOP size to 300 (keyframe interval, at 30fps, one keyframe every 10 seconds) -f hls sets the format to HLS (creates an m3u8 and TS segments) -hls_time 10 sets the goal segment size to 10 seconds -hls_list_size 20 sets the number of segments in the m3u8 file to 20 -program_date_time an hls flag for setting #EXT-X-PROGRAM-DATE-TIME on each segment

ffmpeg \
  -f lavfi \
  -i testsrc=duration=200:size=1280x720:rate=30 \
  -g 300 \
  -f hls \
  -hls_time 10 \
  -hls_list_size 20 \
  -hls_flags program_date_time \
  stream.m3u8

Commands used for segments in test/segments dir

video.ts

Copy only the first two video frames, leave out audio.

$ ffmpeg -i index0.ts -vframes 2 -an -vcodec copy video.ts

audio.ts

Copy only the first two audio frames, leave out video.

$ ffmpeg -i index0.ts -aframes 2 -vn -acodec copy audio.ts

caption.ts

Copy the first two frames of video out of a ts segment that already includes CEA-608 captions.

ffmpeg -i index0.ts -vframes 2 -an -vcodec copy caption.ts

id3.ts

Copy only the first five frames of video, leave out audio.

ffmpeg -i index0.ts -vframes 5 -an -vcodec copy smaller.ts

Create an ID3 tag using id3taggenerator:

id3taggenerator -text "{\"id\":1, \"data\": \"id3\"}" -o tag.id3

Create a file macro.txt with the following:

0 id3 tag.id3

Run mediafilesegmenter with the small video segment and macro file, to produce a new segment with ID3 tags inserted at the specified times.

mediafilesegmenter -start-segments-with-iframe --target-duration=1 --meta-macro-file=macro.txt -s -A smaller.ts

mp4Video.mp4

Copy only the first two video frames, leave out audio. movflags:

• frag_keyframe: "Start a new fragment at each video keyframe."
• empty_moov: "Write an initial moov atom directly at the start of the file, without describing any samples in it."
• omit_tfhd_offset: "Do not write any absolute base_data_offset in tfhd atoms. This avoids tying fragments to absolute byte positions in the file/streams." (see also: https://www.w3.org/TR/mse-byte-stream-format-isobmff/#movie-fragment-relative-addressing)

$ ffmpeg -i file.mp4 -movflags frag_keyframe+empty_moov+omit_tfhd_offset -vframes 2 -an -vcodec copy mp4Video.mp4

mp4Audio.mp4

Copy only the first two audio frames, leave out video. movflags:

• frag_keyframe: "Start a new fragment at each video keyframe."
• empty_moov: "Write an initial moov atom directly at the start of the file, without describing any samples in it."
• omit_tfhd_offset: "Do not write any absolute base_data_offset in tfhd atoms. This avoids tying fragments to absolute byte positions in the file/streams." (see also: https://www.w3.org/TR/mse-byte-stream-format-isobmff/#movie-fragment-relative-addressing)

$ ffmpeg -i file.mp4 -movflags frag_keyframe+empty_moov+omit_tfhd_offset -aframes 2 -vn -acodec copy mp4Audio.mp4

mp4VideoInit.mp4 and mp4AudioInit.mp4

Using DASH as the format type (-f) will lead to two init segments, one for video and one for audio. Using HLS will lead to one joined. Renamed from .m4s to .mp4

$ ffmpeg -i input.mp4 -f dash out.mpd

webmVideoInit.webm and webmVideo.webm

$ cat mp4VideoInit.mp4 mp4Video.mp4 > video.mp4
$ ffmpeg -i video.mp4 -dash_segment_type webm -c:v libvpx-vp9 -f dash output.mpd
$ mv init-stream0.webm webmVideoInit.webm
$ mv chunk-stream0-00001.webm webmVideo.webm

Other useful commands

Joined (audio and video) initialization segment (for HLS)

Using DASH as the format type (-f) will lead to two init segments, one for video and one for audio. Using HLS will lead to one joined. Note that -hls_fmp4_init_filename defaults to init.mp4, but is here for readability. Without specifying fmp4 for hls_segment_type, ffmpeg defaults to ts.

$ ffmpeg -i input.mp4 -f hls -hls_fmp4_init_filename init.mp4 -hls_segment_type fmp4 out.m3u8