Unai.VITC is a simple VITC (vertical interval timecode) signal generator, written in C# for .NET 6.0.

Unai.VITC is a console application: you must use it through a terminal and control how it works by passing arguments to it (like changing the framerate; see below).

If no arguments are specified, the program's default behaviour will write the result on the console's standard output as a raw bitmap stream, resolution 90x2 and 8-bit grayscale pixel format. It will default to a 25 FPS progresive video and will render indefinitely. Also, you will get a bunch of gibberish getting printed on your console, which represent the generated VITC code. Press Ctrl+C on the terminal to stop it.

To save the output to a file, you can redirect it:

Unai.VITC.exe > my-vitc.raw

Or you can also do the same thing using the -o parameter:

Unai.VITC.exe -o my-vitc.raw

Unai.VITC only generates the raw VITC signal. If you want to take the output and turn it into a video file, you can use FFmpeg. In this case, we can use a simple pipeline to communicate both processes. The command should start like this:

Unai.VITC.exe | ffmpeg.exe -f rawvideo -video_size 90x2 -pixel_format gray -framerate 25 -i - […]

This will make FFmpeg take the VITC raw signal and interpret it like a raw video stream. Now we can finally generate a VITC signal and save it as a video file:

Unai.VITC.exe | ffmpeg.exe -f rawvideo -video_size 90x2 -pixel_format gray -framerate 25 -i - -f mp4 -c:v h264 -pix_fmt yuv420p -vf scale=360:4:flags=neighbor my-vitc.mp4

NOTE: since there are some video codecs that cannot process video streams below n pixels of resolution, you must upscale it. And to avoid a blurry output, make sure it's using nearest neighbor mode when upscaling. Also, make sure you are converting the 8-bit grayscale pixel format to another pixel format if the former is not supported by the output codec (in this case, H.264 uses YUV 4:2:0).

FFmpeg has a video filter called readvitc which allows us to decode VITC lines from a video. All the possible framerates have been tested with this filter, giving the following results:

24 FPS

25 FPS

29.97 FPS

30 FPS

It determines the video file/stream that the VITC lines will be stamped on. This does not overwrite the original file. Use -o to specify the output file. If this option is not specified, no base video is used and instead, only the VITC line is rendered on the output file.

It determines the output file where the result will be saved at. Use - (dash) to indicate the standard output of the console. Default: -.

It indicates the pixel format of both input and output video streams. Default: Grayscale8.

Common values are Grayscale8 and R8G8B8 (24-bit RGB).

Sets the input and/or output frame size in pixels. Default: 90x2.

-s WxH where:

• W is width.
• H is height.

It allows you to set the frames per second, but the only accepted values are 24, 25, and 30 (29.97). Default: 25.

-fps [24/25/30]

-fps 30

-fps 30 -d (see also the -d modifier)

It changes the initial timecode. Default: 00:00:00:00.

-tc HH:MM:SS:FF

-tc 14:59:00:06

It determines how long will be the output. Default: indefinitely.

-t HH:MM:SS:FF

-t 00:00:15:00

You can set an event at a specified time in order to change parameters or variables. EventType must be UserBits, UserBitsClear, and Timecode (case insensitive). Some events may require an additional parameter that must be joined with the EventType field with a = character.

-ev HH:MM:SS:FF EventType=input

In the VITC signal, there are some reserved bits that can be used to transmit a maximum of 4 custom bytes per frame. Those custom bits are called user bits and can be set at any time with the -ev modifier. To clean the user bits, use UserBitsClear.

Clears all the user bits. That is, the user bits are filled with zeros.

It allows you to change the timecode at any time.

-ev 00:00:00:00 UserBits=Test

-ev 00:01:00:00 TimeCode=23:00:00:00

Specifies whether the video is interlaced or not. In the case of being interlaced, the program will generate two VITC lines per frame: one for each field.

Specifies whether use drop-frame time code or not. If 30 FPS video is indicated with this option enabled, then the program will generate a 29.97 FPS VITC instead.

Create a VITC signal of 10 seconds long. At second 2, set the user bits to "Test" and at second 4, clear them.

Unai.VITC.exe -t 00:00:10:00 -ev 00:00:02:00 UserBits=Test -ev 00:00:04:00 UserBitsClear