Write basics of x264 guide

encoding/codecs/x264.md

@@ -25,7 +25,12 @@ Here's how we get a copy of the x264 encoder:
 
 ### Windows
 
-TODO
+Official Windows builds are available
+[here](https://download.videolan.org/pub/x264/binaries/win64/).
+For these examples,
+you'll want the latest version
+of the standard 8-bit build,
+which is the version without "10b" (for 10-bit) in the name.
 
 ### Linux/macOS
 
@@ -35,7 +40,7 @@ Here are a few examples:
 
 - **Ubuntu/Debian**: `sudo apt install x264`
 - **Arch Linux**: `sudo pacman -S x264`
-- **macOS**: `brew install x264`
+- **macOS**: `brew install x264`https://download.videolan.org/pub/x264/binaries/win64/
 
 ## Getting Started
 
@@ -47,14 +52,16 @@ and understanding a few basic concepts.
 We'll walk through those concepts
 with the following examples.
 
-## Example 1
+## Example 1: General-Purpose Encoding
 
 Open up a terminal window,
 and navigate to the folder
 where your VapourSynth script lives.
 Let's run the following command:
 
-`vspipe --y4m myvideo.vpy - | x264 --demuxer y4m --preset veryfast --tune animation --crf 24 -o x264output.mkv -`
+```
+vspipe --y4m myvideo.vpy - | x264 --demuxer y4m --preset veryfast --tune animation --crf 24 -o x264output.mkv -
+```
 
 Let's run through what each of these options means:
 
@@ -69,7 +76,7 @@ If you're not,
 it's basically a way of chaining two commands together.
 In this case, we want to chain `vspipe`,
 the program that reads VapourSynth scripts,
-with x264, our encoder.
+with `x264`, our encoder.
 
 #### `--demuxer y4m`
 
@@ -83,18 +90,18 @@ x264 has a set of presets
 to switch between faster encoding, or higher quality.
 The full list of presets, from fastest to slowest, is:
 
-- ultrafast
-- superfast
-- veryfast
-- faster
-- fast
-- medium
-- slow
-- slower
-- veryslow
-- placebo
-
-You will almost never want to use the very extreme settings,
+1. ultrafast
+1. superfast
+1. veryfast
+1. faster
+1. fast
+1. medium
+1. slow
+1. slower
+1. veryslow
+1. placebo
+
+You will almost never want to use the extreme settings,
 but generally, if you want good quality
 and don't care about how long the encode takes,
 `slower` or `veryslow` are recommended.
@@ -104,7 +111,8 @@ we want a fast encode and have chosen `veryfast`.
 
 For the curious,
 you can see a full list of the settings enabled by each preset
-by running `x264 --fullhelp | less`.
+by running `x264 --fullhelp | less` (Linux/Mac)
+or `x264 --fullhelp | more` (Windows).
 However, this probably won't mean much at the moment.
 Don't worry,
 this guide will explain later
@@ -133,7 +141,7 @@ CRF is a constant-quality, 1-pass encoding mode.
 In layman's terms,
 this means that we don't need the output to meet a specific filesize,
 we just want the output to meet a certain quality level.
-CRF ranges from 0 to 51,
+CRF ranges from 0 to 51 (for 8-bit encoding),
 with 0 being the best quality
 and 51 being the smallest filesize,
 but there is a certain range of CRF settings
@@ -166,11 +174,15 @@ We use `-o` to tell which filename to write the encoded file to.
 In this case, x264 will write a file at `x264output.mkv`
 in the current directory.
 
-The last argument to x264 is always the input file.
+The last argument we are passing to x264 is the input file.
 In this case, we pass `-` for the input file,
 which tells x264 to use the piped output from vspipe.
+The input argument is the only positional argument,
+so it does not need to be last;
+x264 will recognize it
+as the only argument without a `--` flag before it.
 
-## Example 2
+## Example 2: Targeted File Size
 
 For the next example,
 let's say we want to make sure our encode
@@ -186,23 +198,30 @@ This means we'll need to know a couple of things:
   For this example,
   let's say our movie is 2 hours (120 minutes) long.
   We'll convert that to seconds:
-  120 \* 60 = **7200 seconds**.
+  120 minutes \* 60 minutes/second = **7200 seconds**.
 - Our target filesize.
   We know that this is 4.7GB,
   but we need to convert it to kilobits.
   We can do this with the following steps:
-  - 4.7GB \* 1024 = 4812.8MB
-  - 4812.8MB \* 1024 = 4928307.2KB (uppercase B = bytes)
-  - 4928307.2KB \* 8 = **39426457.6Kb** (lowercase b = bits)
+
+```
+4.7GiB * 1024MiB/GiB = 4812.8MiB
+4812.8MiB * 1024KiB/MiB = 4928307.2KiB
+4928307.2KiB * 8Kbits/KiB = 39426457.6Kbits
+```
 
 Now we divide the kilobit size we calculated by our video length,
 to find our kilobit per second target bitrate:
 
-39426457.6Kb / 7200 seconds = **5475 Kbps**
+```
+39426457.6Kbits / 7200 seconds = 5475 Kbps
+```
 
 And here's how we could add that to our x264 command:
 
-`vspipe --y4m myvideo.vpy - | x264 --demuxer y4m --preset veryfast --bitrate 5475 -o x264output.mkv -`
+```
+vspipe --y4m myvideo.vpy - | x264 --demuxer y4m --preset veryfast --bitrate 5475 -o x264output.mkv -
+```
 
 The `--bitrate` option, by itself,
 says that we want to do a 1-pass, average-bitrate encode.
@@ -211,7 +230,7 @@ to sections of the video that have more detail or motion,
 but the average bitrate of the video
 will be close to what we requested.
 
-## Example 3
+## Example 3: 2-Pass Encoding
 
 So far, we've only done 1-pass encodes.
 While using CRF 1-pass is great
@@ -235,12 +254,16 @@ if you need to target a certain bitrate.
 
 Here's how we would run our first pass:
 
-`vspipe --y4m myvideo.vpy - | x264 --demuxer y4m --preset veryfast --pass 1 --bitrate 5475 -o x264output.mkv -`
+```
+vspipe --y4m myvideo.vpy - | x264 --demuxer y4m --preset veryfast --pass 1 --bitrate 5475 -o x264output.mkv -
+```
 
 This creates a stats file in our current directory,
 which x264 will use in the second pass:
 
-`vspipe --y4m myvideo.vpy - | x264 --demuxer y4m --preset veryfast --pass 2 --bitrate 5475 -o x264output.mkv -`
+```
+vspipe --y4m myvideo.vpy - | x264 --demuxer y4m --preset veryfast --pass 2 --bitrate 5475 -o x264output.mkv -
+```
 
 You'll notice all we had to change was `--pass 1` to `--pass 2`. Simple!