HackTVLive

HackTVLive is a Go application that captures live video from your webcam and transmits it as an NTSC analog television signal using a HackRF SDR device. It leverages FFmpeg for video capture and processing, and the go-hackrf library for interfacing with HackRF hardware.

Features

• Live Webcam Capture: Uses FFmpeg to grab video from your webcam and scale it to NTSC resolution.
• NTSC Signal Generation: Converts RGB video frames into NTSC color video with proper sync, blanking, and color burst.
• SDR Transmission: Transmits the NTSC signal over the air using a HackRF device at your specified frequency.
• Cross-Platform: Works on Linux, macOS, and Windows (with platform-specific FFmpeg input options).
• Callsign Overlay: Optionally overlays your callsign on the video for identification.
• Experimental Parameters: Easily adjust transmission parameters for experimentation.

Command-Line Flags

You can experiment with the following flags to customize your transmission:

• -freq: Transmit frequency in MHz
  Type: float
  Default: 427.25
  Example: -freq 439.25
  Description: The center frequency for HackRF transmission. Common amateur TV frequencies include 427.25, 439.25, etc.

• -bw: Channel bandwidth in MHz
  Type: float
  Default: 8.0
  Example: -bw 6
  Description: Sets both the sample rate and the channel width for NTSC. Standard NTSC channels are 6 MHz wide (use -bw 6). You may experiment with other values for signal shape and robustness.

• -gain: TX VGA gain (0-47)
  Type: int
  Default: 40
  Example: -gain 47
  Description: Controls the HackRF transmit amplifier gain. Higher numbers mean more output power, but can cause distortion if set too high.

• -device: Video device name or index
  Type: string
  Default: "" (auto-detects platform default)
  Example (Linux): -device /dev/video0
  Example (macOS): -device 0
  Example (Windows): -device "Integrated Webcam"
  Description: Selects the webcam to use. See below for how to list available devices.

• -callsign: Callsign to overlay on the video
  Type: string
  Default: "NOCALL"
  Example: -callsign N7XYZ
  Description: Overlays your callsign at the bottom left of the transmitted video for identification.

Example Usage

Linux:

./HackTVLive -freq 427.25 -bw 6 -gain 40 -device /dev/video0 -callsign N0CALL

Experimentation

HackTVLive is designed for experimentation:

• Try different -freq and -bw values to match local channel plans or test signal robustness.
• Adjust -gain for best power and minimum distortion.
• Change -callsign for identification or fun overlays.
• Use different video devices by specifying the -device flag.

If you omit -device, the application will try to use a reasonable default for your platform.

How It Works

1. Video Capture: FFmpeg grabs raw RGB video frames from your webcam and optionally overlays your callsign.
2. NTSC Generation: The Go code converts the video frames into NTSC signal format, including all sync pulses and color encoding.
3. RF Transmission: The NTSC signal is sent to the HackRF, which transmits it at the specified frequency and bandwidth.

Finding Your Video Device

To list available webcams:

• Linux: v4l2-ctl --list-devices or look in /dev/video*
• macOS: Devices are usually indexed (0, 1, etc.)
• Windows: Use the full device name as shown in device manager or FFmpeg logs.

Safety & Legal Notice

Transmitting on TV frequencies may be illegal in your country without a license. HackTVLive is intended for educational and experimental use only. Always operate within your local laws and regulations.

Troubleshooting

• If the HackRF TX LED does not light up or the program exits immediately, check your device permissions and wiring.
• Stopping the application or transmission (Ctrl+C or "Stop Transmission" in GUI) will also turn off the HackRF TX LED.
• For best results, use a direct USB connection and avoid running other heavy processes while transmitting.

Contributions

Pull requests and issues are welcome! See go-hackrf for hardware support.