APALink — dynamic bitrate switching for APFPV

APALink is a C program for the APFPV firmware, created to keep the video link stable.
It uses fallback logic, automatically lowering the bitrate (for example, to 2 Mbps) when the signal is weak.

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Installation

1. Go to GitHub
2. Follow the instructions in the README.md file
3. Copy the executable to /usr/bin:

chmod 777 +x /usr/bin/ap_alink

4. Copy the configuration file ap_alink.conf to the /etc/ directory
5. (Optional) Copy vtxmenu.ini to /etc/ to enable the APFPV menu
6. Go fly! 🚀

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Configuring ap_alink.conf

The configuration file lets you change the bitrate and threshold parameters:

bitrate_max=22     ## Maximum bitrate with a good signal
bitrate_min=2      ## Minimum bitrate in fallback mode
dbm_threshold=-47  ## Threshold for activating fallback (dBm)

Tip

• Lower threshold → better image quality for longer, but possible lag with a weak signal
• Higher threshold → fallback activates sooner, reducing lag, but quality is lower

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Recommended settings

• BL-M8812EU2

bitrate_max=12
bitrate_min=2
dbm_threshold=-52

• BL-R8812AF1

bitrate_max=10
bitrate_min=2
dbm_threshold=-48

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The VTXMENU menu

Through the MSP menu (as in HDZero or WFB-NG) you can configure:

• Tx Power: 1500 or 2000 (25mW / 100mW)
• Channel: all available 5GHz channels
• AutoPower: 0 or 1 — automatic power adjustment via iw

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