test-content.md

Creating Test Content

Table of Contents

• CEA-608 Content

Creating CEA-608 Content

• Use ffmpeg to create an MP4 file to start with:

  ffmpeg -f lavfi -i testsrc=duration=300:size=1280x720:rate=30 -profile:v baseline -pix_fmt yuv420p output.mp4 (no audio)

  ffmpeg -f lavfi -i testsrc=duration=300:size=1280x720:rate=30 -profile:v baseline -pix_fmt yuv420p -filter_complex "anoisesrc=d=300" output.mp4 (audio + video)

  This uses ffmpeg's built-in testsrc source which generates a test video pattern with a color and timestamp. For this example, we are using a duration of 300 seconds, a size of 1280x720 and a framerate of 30fps. We also specify extra settings profile and pix_fmt to force the output to be encoded using avc1.42C01F.

• Create an srt file with the captions you would like to see with their timestamps.

• Use ffmpeg to convert ouput.mp4 to a flv file:

  ffmpeg -i output.mp4 -acodec copy -vcodec copy output.flv

• Use libcaption to embed the captions into the flv:

  flv+srt output.flv captions.srt with-captions.flv

• Use ffmpeg to convert with-captions.flv to mp4

  ffmpeg -i with-captions.flv -acodec copy -vcodec copy with-captions.mp4

• Use Bento4 to convert the file into a FMP4 file:

  bento4 mp4fragment with-captions.mp4 \ --verbosity 3 \ --fragment-duration 4000 \ --timescale 90000 \ with-captions-fragment.mf4

Then do either of the following:

• Use Bento4 to split the file into an init segment and a fmp4 media segments:

  bento4 mp4split --verbose \ --init-segment with-captions-init.mp4 \ --media-segment segs/with-captions-segment-%llu.m4s \ with-captions-fragment.mf4

• Use Bento4 to create a DASH manifest:

  bento4 mp4dash -v \ --mpd-name=with-captions.mpd \ --init-segment=with-captions-init.mp4 \ --subtitles with-captions-fragment.mf4

  This will create a DASH MPD and media segments in a new directory called output.