Segmented format

To support Dynamic Ad Insertion (and Replacement) with broadpeak.io, you will need to ensure that your subtitles are packaged into a segmented format, ideally with segments of the same size as the video segments.

It is frequent, especially for VOD, to have all the subtitling data to be contained into a single file. This type of file cannot be used with DAI, and will cause issues of alignment between subtitles and the video and audio media.

Subtitles in HLS

In the vast majority of cases, ad creatives returned by ad servers do not contain subtitle tracks.

In HLS, segmented subtitles are contained in their own playlist. To ensure continuity within the playlist, when ads are inserted, broadpeak.iowill insert references to dummy subtitle segments. This ensures that the players always have segments to download, even if empty. Not doing so would cause most players to get into unrecoverable errors.

Example of Live Ad replacement:

#EXTM3U 
#EXT-X-VERSION:5 
#EXT-X-INDEPENDENT-SEGMENTS 
#EXT-X-MEDIA-SEQUENCE:0 
#EXT-X-TARGETDURATION:6 
#EXT-X-PROGRAM-DATE-TIME:2011-01-01T00:00:03.000000+00:00 
#EXTINF:4.0001, no desc 
originalstream_12451841_deu=8000-391772911.webvtt 
#EXTINF:4.0001, no desc 
originalstream_12451841_deu=8000-391772912.webvtt 
#EXTINF:4.0001, no desc
originalstream_12451841_deu=8000-391772913.webvtt 
#EXTINF:4.0001, no desc
originalstream_12451841_deu=8000-391772914.webvtt 
#EXT-X-DISCONTINUITY
#EXT-X-PROGRAM-DATE-TIME:2011-01-01T00:00:19.016000+00:00  
#EXTINF:4.0001, no desc
/empty.webvtt
#EXTINF:4.0001, no desc 
/empty.webvtt
#EXTINF:4.0001, no desc 
/empty.webvtt
#EXT-X-DISCONTINUITY 
#EXT-X-PROGRAM-DATE-TIME:2011-01-01T00:00:31.016300+00:00  
#EXTINF:4.0001, no desc 
originalstream_12451841_deu=8000-391772920.webvtt 
#EXTINF:4.0001, no desc 
originalstream_12451841_deu=8000-391772921.webvtt 
#EXTINF:4.0001, no desc 
originalstream_12451841_deu=8000-391772922.webvtt 
#EXTINF:4.0001, no desc 
originalstream_12451841_deu=8000-391772923.webvtt 

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Limitations

• This only applies to WebVTT subtitling format. Other subtitling formats are not supported.
• To ensure that the subtitle segments inserted are in the right place, make sure that the conditioning of the source content also applies to subtitle tracks.