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resampling mpeg-2, keeping (stripping+returning?) cc with mpegrepairhd

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Jeff McDonaldresampling mpeg-2, keeping (stripping+returning?) cc with mpegrepairhd
by on Apr 27, 2012 at 1:10:50 am

In a broadcast environment, trying to get some more of our syndicated stuff in HD.

Still in "proof of concept" stage.

Got a cheezy satellite receiver, an "Openbox S10" that records 720p (as provided by the feed) MPEG-2 transport/ program streams to a USB hard drive.

These look fantastic. I feed them through tsmuxer to dump the spanish audio and sew the 1GB .ts files all into a .mpg (mpeg2) that our automation software could theoretically handle. VLC media player shows captions fine on these initial files.

The problem is too much bandwidth: 34Mbits/sec. Our Vela card (unknown to me model) chokes at over ~25 Mbits. Came to my attention that ffmpeg etc dump 708 captions when resampling. Also, standard definition satellite captures work fine with CC as they're small enough to not need resampling.

Our automation program suite included Pixeltools MpegrepairHD and its 130 page manual offers no clue about retaining CC. It can ADD it from a file. Great, so I have to strip it first. (Right?) There is a checkbox for nuking old cc, and a checkbox for adding from a file. One would assume if neither check box were checked, CC would pass through, but the manual authors did not clarify this.

Discovered CCExtractor does a great (and fast) job extracting captions to a .srt file. Changing the .srt file to one that mpegrepairhd is my current stumbling block. Found a bunch of command line utils "SCC tools" but they choke on the .srt file, freezing or making null outputs. I did successfully do a 40 second clip, but the captions only displayed very briefly, and I haven't repeated it. Captions are our only block to airing this program/ syndicator in 720p; FCC won't let us "block" them. (Incidentally, CCExtractor needs a video source with captions in the first minute or so of video. Untrimmed video with lots of bars/tone/slate confuse it and it gives up.)

MPEGRepairHD is no help at all; their "left side" analyzer will make me a caption text file, but one not readable (or at least the file moniker) by the "right side" encoder. Unbelievable!


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