There are many high-end hardware and software solutions for encoding closed captions for broadcast purposes, but if you are using a file-based workflow Apple Compressor is an easy and cost-effective option. This tutorial describes how to add CEA-608/708 closed captions to video using Compressor and an SCC output file from CaptionSync.
Attached MOV sample file, and SCC caption file, at the bottom of this tutorial. You can download the encoded MPEG from our website (119.1 MB) (MPEG-2 Program Stream file encoded with captions using the process described in this article).
Many television and cable networks are phasing out tape submission in favor of file-based content delivery. CaptionSync can provide captions in several output formats commonly used by broadcast producers, such as the Sonic Scenarist (SCC) format, which can then be used to encode closed captions into the final video files delivered to your station or distribution network. The question then becomes how best to encode the closed captions into your video file. Many high-end hardware and software solutions exist for this, but if you don’t have a large volume of files to process, Apple Compressor is a simple, fast, and inexpensive solution. This tutorial walks you through the steps required to insert broadcast captions into a video using Apple Compressor and an SCC file from CaptionSync.
Required Input Files:
To use this method you will need two input files: a high-quality, final version of your video to use as the source file, and a time-coded caption file in SCC format. You can get the SCC file using our CaptionSync service, by selecting the Sonic Scenarist DVD Captions (.scc, .ndf.scc) as an output format. When you select this option you will receive two versions of the SCC file: one with drop frame time codes and one with non-dropframe (NDF) time codes. Select the version of the file that matches the time coding of your video source file.
Setup in Apple Compressor:
1. The first step is to add the source file to your batch. Typically this will be an exported version of your final video in a ProRes or DNx codec. Click Add File, select the source file, and it will appear as the starting point for a new batch.
2. Next select the settings for your output files. You'll need to confirm with the stations or distribution networks that you are using the exact file format requirements, but you will find several common presets for broadcast under the MPEG Files section on the Settings pane. Drag the setting you want to use onto the batch on the project pane.
3. If you need other target formats you can add them to the batch in the same way. If you do not have a broadcast monitor for previewing the captioned output, you many want to create a proxy video using the same caption file and a more compressed Quicktime file. For broadcast output formats like the MPEG-2 Program or Transport streams, Compressor will encode the captions into the video using the EIA-708 protocol. For Quicktime outputs, Compressor adds the closed captions as a track in the Quicktime file, and you can use most versions of Quicktime, version 7.2 or later, to view both the video and the captions.
4. Next, check and set your destination on the Destinations tab of the Settings pane.
5. Now you can select the SCC file. Select the batch first so it is highlighted, then go to the Inspector pane. Under Additional Information, there is an option to choose a closed caption file. Select the SCC file. This will add the closed captions in the SCC file to all of the target files in the batch.
6. Click Submit in the project pane.
Please note that this program requires the media file and the captions to have the same start time. If the media and the caption file have a different start time (eg: the media starts at timecode 01:00:00, but the captions start at time 00:00:00), then you could have a problem when adding the closed captions to your media file. So, make sure that the media start time offset is the same as the caption file offset timecode.
When the job is complete, the transcoded files with closed captions will be found in the output folder that you selected under Destinations. You can use Quicktime to preview the video and captions if you created a Quicktime proxy, or use a broadcast monitor to view the MPEG video with captions.
- If you are experiencing problems making the results work on this program, check out these troubleshooting tips.