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Exporting / Encoding
File-Based Delivery for Broadcast TV
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CaptionMaker 6.3 User’s Guide
Overview of TV Formats
Here is an overview of the types of captions that can be used for broadcast TV files:
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Captions embedded into the video file:
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Closed Captioning track. An extra track of closed captions is added to the file.
This is most often used with QuickTime files (QuickTime CC track) and MXF files
(SMPTE 436m VANC track). However, not every server that can play QuickTime or
MXF files is able to read this closed captioning track.
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User data captions. Captions are added as metadata into the contents of the
file. This is often used with MPEG-2 (ATSC DTV 608/708 captions), and
occasionally with H.264 video (NAL SEI 608/708 captions), or DV video for
standard definition (DV VAUX captions).
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Line 21 VBI. This is used for standard definition video only. The VBI line 21
"Morse Code" dots-and-dashes are embedded into the top line of the video. The
video resolution must be 720x486 for most QuickTime and AVI formats (rather
than 720x480, which excludes the extra 6 lines of VBI where the captions go), or
sometimes 720x512 for certain MPEG-2 formats.
•
Sidecar caption file - a standalone file containing just the captions:
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SCC files are commonly used, but they contain 608 (analog) captions only. Make
sure the station has a system that can upconvert this data into CEA-708 digital
captions, such as using Telestream Vantage.
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MCC files are a next-generation improvement on SCC files, and contain native
CEA-708 digital captions. They are supported by Adobe Premiere Pro CS5.5 and
later, Blackmagic Hyperdeck, Manzanita muxers, Harris Nexio, and some other
systems.
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If the station uses Avid systems, they may want an Avid AAF caption track file.
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Rarely, a station might ask you for a different type of caption interchange file,
such as Cheetah .CAP, TDS, and so on.
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If the video will be shown on the internet, you may be asked to provide a web
format caption file, such as SMPTE Timed Text (TTML), DFXP, WebVTT, and so on.
Next Steps for Delivery to the TV Station
Once you have confirmed with a TV station what kinds of video files they can accept
with captions, you need to export that type. Keep in mind that CaptionMaker is not
transcoding software - that is, it does not convert one type of video file into another.
If you're editing your video in NLE software, you may be able to export directly to the
format you need (without captions), but not every NLE can export to every format. If
you're starting with a QuickTime file and need to deliver a MPEG-2 file, you need to do
some steps outside of the captioning software to create the MPEG-2 file first. Only then
can CaptionMaker insert the captions into the MPEG-2 file.
For transcoding, we recommend Telestream Episode or Vantage software. Make sure
you select the right bit rate and other specifications as required by the TV station.