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Captioning 720x512 MPEG-2 Videos

This proprietary format is often used for digital delivery of TV commercial spots, such as for DG Fast Channel.  The format is similar to a typical 720x486 standard definition video (Picture A), except that there are an extra 26 rows for VBI data encoded at the top of the frame.  The line 21 for closed captions is positioned below the extra 26 rows of VBI data and just above the active video area (Picture B).

 

A: 720x486 w/ Line 21 CC	B: 720x512 w/ Line 21 and VBI

If you need to caption these kinds of files regularly, our software will allow you to do all of the captioning in-house.  Or, CPC's service department can caption your 720x512 MPEG-2 file for a one time fee.

Note that CPC software does not convert other kinds of video files into 720x512 MPEG-2 files.  You need other compression software or hardware to do this.  However, CaptionMaker/MacCaption can add captions to the video before the conversion to 720x512 MPEG-2 step (Method 1), or MacCaption can add captions after the conversion to 720x512 MPEG-2 (Method 2).

Method 1:

1. Start with a QuickTime 720x486 file. 

2. Prepare your captions and add line 21 captions to it using our NLE workflow (CaptionMaker-NLE or MacCaption-NLE or higher) using a setting of Row 1, Column 24.

3. The result will be a QuickTime 720x486 file with your video & audio and also the line 21 captions at the top of the frame. (It will look like Picture A above.)

4. Bring this video file into your compression program (e.g. Episode, Rhozet, Digital Rapids, Sorenson, etc.) and compress it to 720x512 MPEG-2.  As long as your encoder settings are correct, the line 21 captions will be preserved in correct place in the output file, and the extra 26 lines of black space for VBI data will be added to the top as well.  The result will look like Picture B above.

Method 2 (requires MacCaption NLE+ or HD+ version):

1. Start with a 720x512 MPEG-2 file which is otherwise already compliant for delivery, but does not contain captions (such a file can be created by software compressors such as Episode, Rhozet, Digital Rapids, Sorenson, etc. or certain hardware boards).

2. Make a proxy version of this movie using VLC or similar free tools to convert it to QuickTime.  This step is necessary if you want to time stamp/auto sync your captions in MacCaption, because MacCaption cannot play native 720x512 MPEG-2 files in the movie window.

3. Prepare captions in MacCaption-NLE+ or HD+ based on the proxy movie.

4. In MacCaption, go to Export > NLE > CCIR 601 4:2:2P@ML.

5. Choose the new file to save as.  In the next dialog, choose your source file (the original 720x512 MPEG-2 file without captions).

6. Select the bitrate that the original file was encoded at (for metadata purposes).

7. MacCaption will copy the original MPEG-2 data while inserting the line 21 captions into the new MPEG-2 file, without re-compressing the rest of the frame.  The result will look like Picture B above.

    

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