From 25f399f9322198ce22c7a991e679f8346d2625c4 Mon Sep 17 00:00:00 2001
From: CDrummond <craig.p.drummond@gmail.com>
Date: Mon, 3 Mar 2025 17:26:38 +0000
Subject: [PATCH] Document libav feature

---
 README.md | 38 ++++++++++++++++++++++++++++++++++++--
 1 file changed, 36 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index 29690c9..75b3e5f 100644
--- a/README.md
+++ b/README.md
@@ -7,7 +7,39 @@ bliss analysis. This is then intended to be used by [Bliss Mixer](https://github
 
 # Building
 
-clang, pkg-config, and ffmpeg are required to build, as well as
+This application can be built in 2 variants:
+
+1. Using command-line `ffmpeg` to decode files
+2. Using `libavcodec`, etc, to decode files
+
+Using `libavcodec` is about 70% faster, but might have issues with library, versioning, etc.
+Using `ffmpeg` whilst slower produces a more portable application.
+
+## Build for 'ffmpeg' command-line usage
+
+`clang` and `pkg-config` are required to build, as well as
+[Rust](https://www.rust-lang.org/tools/install)
+
+To install dependencies on a Debian system:
+
+```
+apt install -y clang pkg-config
+```
+
+To install dependencies on a Fedora system:
+```
+dnf install clang pkg-config
+```
+
+Build with `cargo build --release`
+
+`ffmpeg` is then a run-time dependency, and should be installed on any system where this application
+is to be run - it should also be in the users `$PATH`
+
+
+## Build for 'libavcodec' library usage
+
+`clang`, `pkg-config`, and `ffmpeg` are required to build, as well as
 [Rust](https://www.rust-lang.org/tools/install)
 
 To install dependencies on a Debian system:
@@ -21,8 +53,10 @@ To install dependencies on a Fedora system:
 dnf install ffmpeg-devel clang pkg-config
 ```
 
-Build with `cargo build --release`
+Build with `cargo build --release --features=libav`
 
+The resultant application will be less portable, due to dependencies on `libavcodec` libraries (and
+their dependencies).
 
 # Usage