Analog video modulation

GNU Radio
1

After finishing my AM Stereo transmitter, I have decided to build an
NTSC
modulator. I think I have the actually modulation and filter blocks
down, I
just need to firgure out how to get the right signals from a digital
video
file. The file source wouldn’t work; I would probably have to use
gstreamer. Anyone know exactly what I’m looking for and how to get it? I
need brightness, hue, saturation, and I believe that is it.

Thanks.

  • Jordan
2

On 7/16/14 9:50 PM, Jordan J. wrote:

After finishing my AM Stereo transmitter, I have decided to build an
NTSC modulator. I think I have the actually modulation and filter blocks
down, I just need to firgure out how to get the right signals from a
digital video file. The file source wouldn’t work; I would probably have
to use gstreamer. Anyone know exactly what I’m looking for and how to
get it? I need brightness, hue, saturation, and I believe that is it.

Thanks.

  • Jordan

Try ffmpeg:

https://www.ffmpeg.org/

It’s sort of the swiss army knife of video file processing.

@(^.^)@ Ed

3

All video decoders use the YCbCr colorspace. You’ll need
to convert that to YIQ for NTSC.

You can create a YCbCr file with vlc.

vlc -I rc -V yuv --yuv-file=
–yuv=chroma=UYVY

This will create a YCbCr file with 4:2:2 chroma in the format
Cb Y Cr Y Cb Y Cr Y …

vlc does put a header and frame markers in the file. I don’t know
if that can be disabled.

YCbCr files only contain the active video (720x480 for NTSC). You’ll
have to create and insert the vertical and horizontal blanking.

Ron

4

Made a typo. --yuv=chroma=UYVY should be --yuv-chroma=UYVY

Ron