Add notes about ffmpeg version required for complexfilter to function properly

README.md

@@ -38,7 +38,7 @@ Demo/test site: [clearnet](https://fatchan.org) [tor hidden service](http://cimi
 - Nginx - webserver/proxy, serve static files, handle https, GeoIP lookup
 - Certbot/letsencrypt - to get a free https certificate
 - Graphicsmagick+Imagemagick - identify and thumbnail images, generate captchas
-- Ffmpeg - identify and thumbnail audio and video
+- Ffmpeg - identify and thumbnail audio, video and gifs
 
 -----
 
@@ -49,7 +49,7 @@ Demo/test site: [clearnet](https://fatchan.org) [tor hidden service](http://cimi
 
 **2. Install dependencies.**
 
-NOTE: You may need to add sources depending on your distro.
+NOTE: You may need to add sources depending on your distro. If you intent to have animated gif thumbnails, ffmpeg 4.3.x is recommended. For debian, it can be found in the testing repos or compiled from source.
 ```bash
 $ sudo apt-get update
 $ sudo apt-get install nginx ffmpeg imagemagick graphicsmagick

configs/main.js.example

@@ -1,3 +1,4 @@
+ffmpeg
 module.exports = {
 
 	//mongodb connection string
@@ -132,7 +133,8 @@ module.exports = {
 	thumbExtension: '.jpg',
 	//.gif images > thumbnail size will have animated .gif thumbnails, overriding thumbExtension
 	animatedGifThumbnails: false,
-	//if animatedGifThumbnails is true, use ffmpeg for better animated gif thumbnailing. RECOMMENDED
+	/* Recommended if animatedGifThumbnails is true. Uses ffmpeg for faster animated gif thumbnailing. Requires ffmpeg
+		>=4.3.x	to handle transparent gifs properly. You can install from debian testing repo, or compile from source. */
 	ffmpegGifThumbnails: true,
 
 	//generate waveform thumbnails for audio