docs: Stubbing out some of the audio / video technical pages. Based initially off the wiki but edits. Will need further edits and improvements.

source/en/latest/table-of-contents.markdown

@@ -142,21 +142,21 @@ May affect compatiblity! Use a preset!
 - Containers
   - Known issue: MP4 edit lists
 - Video
-  - Codecs
-  - x264 presets, tunes, and custom settings
-  - x264 profile and level
-  - Constant quality versus average bit rate
+  - [Codecs](technical/video-codecs.html) 
+  - [x264 presets, tunes, and custom settings](technical/video-x264-presets-tunes.html) 
+  - [x264 profile and level](technical/video-x264-profiles-levels.html) 
+  - [Constant quality versus average bit rate](technical/video-cq-vs-abr.html) 
   - VFR/PFR, CFR, custom frame rates
 - Advanced picture and filters
   - Anamorphic modes
   - Modulus
   - Custom filter settings
 - Audio
-  - Codecs: autodetection, read/passthru
+  - [Codecs](technical/audio-codecs.html)
     - Known issue: Dolby Atmos
-  - Gain
-  - DRC
-  - Mixdown
+  - [Gain](technical/audio-gain.html)
+  - [DRC](technical/audio-drc.html)
+  - [Mixdown](technical/audio-mixdowns.html)
 - Subtitles
   - Formats
 - Advanced preferences

source/en/latest/technical/audio-codecs.markdown

@@ -0,0 +1,101 @@
+---
+License_Abbr: CC BY-SA 4.0
+License_URL: "https://handbrake.fr/docs/license.html"
+Language: English
+Project_Version: Latest
+Language_Code: en
+Title: Audio Codecs
+License: Creative Commons Attribution-ShareAlike 4.0 International
+Text_Encoding: utf-8
+Copyright: 2016 HandBrake Team
+Project: HandBrake
+Authors: Scott (s55)
+Project_URL: "https://handbrake.fr/"
+---
+
+Audio Codecs
+============
+
+ 
+
+Encoding vs Passthrough
+-----------------------
+
+HandBrake supports two modes of operation for handling audio tracks from the
+source.
+
+It can either:
+
+-   Re-Encode the track into a new format. For example, AC3 or DTS audio from a
+    DVD or BluRay into AAC for playback on mobile devices.
+
+-   Passthru copies the audio track from the source to the newly encoded file.
+
+ 
+
+Audio Encoders
+--------------
+
+-   AAC:
+
+    -   Advanced Audio Coding (AAC) is one of the most popular formats available
+        in HandBrake and is widly supported by media players and mobile devices.
+
+    -   On Linux and Windows, HandBrake uses the LibAV AAC encoder.
+
+    -   On Mac, HandBrake uses Apple's CoreAudio AAC encoder. It's known to be
+        much better quality and is the default option for Mac users.
+
+-   HE-AAC ( Mac Only)
+
+    -   High Efficiency AAC encoder. This encoder is optimized for low-bitrate
+        applications which may be useful for streaming.
+
+    -   Available on OS X only.
+
+-   MP3:
+
+    -   HandBrake also offers the MP3 audio codec, for which it uses the very
+        well-regarded lame encoder.
+
+-   Vorbis:
+
+    -   HandBrake offers Vorbis audio encoding as well, for which it uses the
+        aoTuV branch that offers quality tweaks.
+
+-   AC3:
+
+    -   HandBrake can encode to AC3 using LibAV.
+
+    -   This is not the same as Passthru. You can encode any audio track to AC3.
+
+-   Flac 16 and 24bit (Libav)
+
+    -   Loss-less audio compression.
+
+    -   Available in MKV files.
+
+    -   It is not currently possible to passthru the compression level to the
+        ffmpeg encoder which is currently defaulted to "5"
+
+ 
+
+Passthru options.
+-----------------
+
+HandBrake supports passthru for a limited number of popular source formats.
+These are: AC3, DTS, DTS-HD, TrueHD, MP3 or AAC (Passthru)
+
+This copies the audio bit-for-bit from the source so offers no loss in audio
+quality. These audio tracks can be quite large so can impact the final size of
+the output file quite substantially.
+
+ 
+
+Auto Passthru
+-------------
+
+In the audio encoders list, there is an option called "Auto Passthru". When
+encoding, this will automatically passthru any supported format to the source
+file. If the source format is not supported, or not supported in the output
+container, the fallback encoder will be used. The default is AAC.

source/en/latest/technical/audio-drc.markdown

@@ -0,0 +1,51 @@
+---
+License_Abbr: CC BY-SA 4.0
+License_URL: "https://handbrake.fr/docs/license.html"
+Language: English
+Project_Version: Latest
+Language_Code: en
+Title: DRC - Dynamic Range Compression
+License: Creative Commons Attribution-ShareAlike 4.0 International
+Text_Encoding: utf-8
+Copyright: 2016 HandBrake Team
+Project: HandBrake
+Authors: Scott (s55)
+Project_URL: "https://handbrake.fr/"
+---
+
+DRC - Dynamic Range Compression
+===============================
+
+ 
+
+Dynamic Range Compression
+-------------------------
+
+The dynamic range of an audio track is the difference between the softest and
+loudest sounds.
+
+Dynamic range compression reduces the gap between those extremes.
+
+On the Audio tab, each track provides an option to set the level of compression
+you wish.
+
+-   1.0-2.5 are good values to use.
+
+-   0, the default, turns it off completely.
+
+-   1.0 uses the compression hints embedded in the AC3 track.
+
+Values greater than 1.0 compress the range further by boosting the volume of
+soft sound samples while leaving loud samples as they are. This squeezes down
+the range between the softest and loudest parts, but should make the softer ones
+easier to hear in noisy listening environments. Note, this is not the same as a
+gain or volume boost control.
+
+ 
+
+Compatibility
+-------------
+
+Dynamic range compression only works when the source audio is AC3 and you are
+encoding to another format, like AAC. It has no affect on AC3 pass-through or on
+DTS or MPEG-2 audio.

source/en/latest/technical/audio-gain.markdown

@@ -0,0 +1,19 @@
+---
+License_Abbr: CC BY-SA 4.0
+License_URL: "https://handbrake.fr/docs/license.html"
+Language: English
+Project_Version: Latest
+Language_Code: en
+Title: Audio Gain
+License: Creative Commons Attribution-ShareAlike 4.0 International
+Text_Encoding: utf-8
+Copyright: 2016 HandBrake Team
+Project: HandBrake
+Authors: Scott (s55)
+Project_URL: "https://handbrake.fr/"
+---
+
+Audio Gain
+==========
+
+[TODO]

source/en/latest/technical/audio-mixdowns.markdown

@@ -0,0 +1,58 @@
+---
+License_Abbr: CC BY-SA 4.0
+License_URL: "https://handbrake.fr/docs/license.html"
+Language: English
+Project_Version: Latest
+Language_Code: en
+Title: Audio Mixdowns
+License: Creative Commons Attribution-ShareAlike 4.0 International
+Text_Encoding: utf-8
+Copyright: 2016 HandBrake Team
+Project: HandBrake
+Authors: Scott (s55)
+Project_URL: "https://handbrake.fr/"
+---
+
+Downloading and installing HandBrake
+====================================
+
+ 
+
+Available Down Mixes
+--------------------
+
+HandBrake supports the following downmixes:
+
+-   Mono
+
+-   Mono (Left Only)
+
+-   Mono (Right Only)
+
+-   Stereo
+
+-   Dolby Surround
+
+-   Dobly Pro Logic II
+
+-   5.1 Channels
+
+-   6.1 Channels
+
+-   7.1 Channels
+
+-   7.1 Channels (5F/2R/LFE)
+
+ 
+
+Automatic
+---------
+
+"Automatic" will default to DPL2
+
+ 
+
+Upmixing
+--------
+
+HandBrake does not currently support upmixing audio.

source/en/latest/technical/video-codecs.markdown

@@ -0,0 +1,77 @@
+---
+License_Abbr: CC BY-SA 4.0
+License_URL: "https://handbrake.fr/docs/license.html"
+Language: English
+Project_Version: Latest
+Language_Code: en
+Title: Video Codecs
+License: Creative Commons Attribution-ShareAlike 4.0 International
+Text_Encoding: utf-8
+Copyright: 2016 HandBrake Team
+Project: HandBrake
+Authors: Scott (s55)
+Project_URL: "https://handbrake.fr/"
+---
+
+Video Codecs
+============
+
+ 
+
+-   H.264 (x264): For MPEG-4 part 10, also known as H.264/AVC.
+
+    -   This is HandBrakes default encoder. It provides excellent performance,
+        filesizes and quality.
+
+    -   It is widely supported by players and mobile devices.
+
+-   H.264 (Intel QuickSync): For MPEG-4 part 10, also known as H.264/AVC.
+
+    -   Available on Intel processors with Intel HD Graphics.
+
+    -   QuickSync is a hardware based H.264 encoder so is very fast, with
+        significantly lower CPU usage than x264.
+
+    -   Intel Haswell or newer CPU's are recommended as these offer the best
+        results in terms of Quality and Filesize.
+
+    -   You can typically expect larger (but usually not significantly larger)
+        file sizes and slightly lower quality to an equivilent x264 encode. This
+        is a trade off that is fine for most.
+
+-   H.265 (x265): Also known as HEVC
+
+    -   This is the next generation of encoder that offers even higher quality
+        encodes and better filesizes over H.264
+
+    -   Note, encoding to H.265 is a significantly more complicated process, so
+        it is expected to be slower than !HandBrake's H.264 encoders.
+
+    -   Playback support is rather limited at the moment, particularly with
+        mobile devices but this should improve drastically throughout 2015/16
+
+-   MPEG-4 (ffmpeg): !HandBrake offers FFmpeg's MPEG-4 part 2 encoder for fast,
+    low quality encoding.
+
+    -   Better support from older devices such as DVD players and cheap "MP4
+        Players"
+
+    -   Lower quality than the H.264 encode option but typically faster encodes.
+
+-   MPEG-2 (ffmpeg): !HandBrake offers FFmpeg's MPEG-2 part 2 encoder for fast,
+    low quality encoding.
+
+    -   Fast Encoding, but requires larger files than MPEG-4 for the same
+        quality level. Useful for testing but not much else.
+
+-   VP8 (Libvpx):
+
+    -   A free and open video codec which offers significant improvements over
+        Theora.
+
+-   VP3 (Theora): !HandBrake can also encode Theora video. Theora video with
+    Vorbis audio in the Matroska container represents a truly free option for
+    multimedia encoding.
+
+    -   However, Theora has yet to reach maturity when measured by quality at a
+        given bitrate.

source/en/latest/technical/video-cq-vs-abr.markdown

@@ -0,0 +1,133 @@
+---
+License_Abbr: CC BY-SA 4.0
+License_URL: "https://handbrake.fr/docs/license.html"
+Language: English
+Project_Version: Latest
+Language_Code: en
+Title: Constant Quality vs Average Bit Rate
+License: Creative Commons Attribution-ShareAlike 4.0 International
+Text_Encoding: utf-8
+Copyright: 2016 HandBrake Team
+Project: HandBrake
+Authors: Bradley Sepos
+Project_URL: "https://handbrake.fr/"
+---
+
+Constant Quality vs Average Bit Rate
+====================================
+
+HandBrake supports two modes of encoding video.
+
+-   With the average bitrate, you control the size of the output file but give
+    up control over the video's quality.
+
+-   Constant quality mode does the opposite; you specify a quality level and
+    HandBrake adjusts the bitrate (that is, the size) to meet it.
+
+ 
+
+Constant Quality
+----------------
+
+### Benefits over Average Bitrate
+
+-   Faster Encoding - No need to do 2-Pass encoding (thus almost halving the
+    encode time.) Constant Quality can produce the same quality as a 2 pass
+    encode.
+
+-   Reduced file sizes Videos usually have a mix of complex and less complex
+    frames. (The latter requiring less bitrate to achieve a set quality level)
+    If less complex frames do not have bits wasted on them, your overall output
+    filesize is reduced without any loss of quality.
+
+### Output File Sizes
+
+Because it takes a different bitrate to reach a given quality level for any
+given part of any movie, the output size is unpredictable and varies from source
+to source.
+
+Example: Given 2 sources of the same length, one could turn out to be 1.2GB, the
+other 1.9GB. The difference can be more or less depending on the source. If your
+source material is consistent, you will get roughly the same file sizes out for
+each.
+
+In particular, grainy sources tend to come out larger as they require a higher
+bit-rate to maintain all that extra detail in the video. In this case, you may
+try turning on the "Denoise" filter or reduce the RF value a few points.
+
+You should also note that even if a file size is significantly smaller than a
+counterpart encoded with target filesize, it does not mean it is any lower
+quality. It's simply encoded more efficiently.
+
+### x264 Recommended Quality RF Values
+
+The Quality slider ranges from (Low Quality) 51 to 0 (High Quality) For good
+quality output at reasonable file sizes, the following values are recommended:
+
+-   Standard Definition (e.g DVD's) Use an RF value of around 20 +/- 1 As an
+    example using the AppleTV2 preset at RF20, with 20 different sources, the
+    average size was 925MB per hour of video. (Min: 625MB/h Max:1,503MB/hr)
+
+-   High Definition (e.g Blurays 720/1080) Use an RF value of 22 +/- 1 Since HD
+    sources are typically quality, you can get away with a slightly higher RF
+    value than SD content without any perceived difference in quality.
+
+You should note that the quality slider is not linear for x264. It is
+logarithmic (like the Richter or pH scales.) This means small movements in the
+numbers can have large results. You can control the granularity of the slider in
+the preferences / options.
+
+You can encode a few chapters of a source to experiment with different quality
+values if the above recommendations are not suitable. Encoding a 10minute sample
+in the middle of your source should give you a good idea of what to expect.
+
+### x264 and RF 0
+
+RF 0 applies no compression. It is lossless: it compresses the source without
+throwing away practically any detail.
+
+So should you use RF 0 to perfectly preserve the source? Nope. Not at all. In
+fact, you'll end up with video that's way larger than the DVD, but doesn't look
+any better.
+
+See, DVDs use lossy compression to squeeze down the raw video the studios use to
+make them -- sort of like a quality level of RF 20. It throws away detail. When
+!HandBrake uncompresses the video prior to conversion, the quality lost when the
+DVD was made is still gone. When you use RF 0 quality with x264, you're telling
+it to losslessly preserve the decoded, uncompressed video feed, not to
+losslessly preserve the DVD. Both have the same picture quality, but the
+uncompressed feed takes up a lot more space.
+
+To sum up: when converting from a DVD source, there is no reason to go above an
+RF of \~19, which is roughly equivalent to how heavily the DVD is compressed. If
+you do go higher, your output will be larger than your input!
+
+### Recommended values for other encoders
+
+[TODO]
+
+ 
+
+Average Bitrate
+---------------
+
+Unless you really need to aim for a target filesize (which we recommend
+against), it is highly recommended that you use Constant Quality.
+
+Bitrate is the number of bits dedicated to the video in a second. And remember,
+that gets split between \~24-30 frames. When you set an average bitrate, the
+encoder will vary the number of bits given to any one portion of the video, but
+try to keep everything at the average you set.
+
+-   The video bitrate can be set on the "Video Tab"
+
+-   It is recommended that you use 2-Pass encoding.
+
+-   This will provide better quality and better bit-rate distribution. A single
+    pass will lead to sub-optimal results.
+
+    -   The "Turbo" checkbox will make the first pass quicker at the expense of
+        quality. Most of the time this loss is minimal and not appreciable by
+        the viewer.
+
+-   The downside is it can take up to twice as long to encode a file.

source/en/latest/technical/video-x264-presets-tunes.markdown

@@ -0,0 +1,77 @@
+---
+License_Abbr: CC BY-SA 4.0
+License_URL: "https://handbrake.fr/docs/license.html"
+Language: English
+Project_Version: Latest
+Language_Code: en
+Title: x264 Presets and Tunes
+License: Creative Commons Attribution-ShareAlike 4.0 International
+Text_Encoding: utf-8
+Copyright: 2016 HandBrake Team
+Project: HandBrake
+Authors: Scott (s55)
+Project_URL: "https://handbrake.fr/"
+---
+
+x264 Presets and Tunes
+======================
+
+ 
+
+x264 Presets
+------------
+
+x264 exposes a preset and tune system. Presets range from:
+
+-   UltraFast - Very high speed encoding, but requires much higher bit-rates to
+    maintain quality. This means you can expect much larger file sizes.
+
+-   Placebo - Extremely slow encoding but provides the best Quality and/or
+    filesize for a given source. - This option is often considered a placebo
+    because it offers diminishing returns in terms of quality and filesize.
+
+Typically, it's recommended to use the Very Fast to Slow settings range for best
+results, or one of the slower options if you don't mind the speed loss. Medium
+is a good balance and most of !HandBrakes presets use this option.
+
+ 
+
+x264 Tunes
+----------
+
+The x264 tune options assign some additional options which will optimize the
+encoder for certain types of content.
+
+If you are unsure or your content doesn't really fit into one of the following
+tunes, you can simply leave this option at "None".
+
+-   Film
+
+    -   Real life footage, films etc may benifit. (Not Cartoons or Anime).
+        Typically won't do any harm to if left on for most content.
+
+-   Animation
+
+    -   Used for hand-drawn animated content.
+
+-   Grain
+
+    -   Typically used for very grainy or old content.
+
+-   Still Image
+
+    -   Can be used for Slideshows, Presentations etc where there is very little
+        moving content.
+
+-   PSNR
+
+    -   Used for benchmarking quality. Should not be used for normal use.
+
+-   SSIM
+
+    -   Used for benchmarking quality. Should not be used for normal use.
+
+-   Fast Decode
+
+    -   Optimise for faster decoding. Useful for low power devices that struggle
+        to decode the video.

source/en/latest/technical/video-x264-profiles-levels.markdown

@@ -0,0 +1,86 @@
+---
+License_Abbr: CC BY-SA 4.0
+License_URL: "https://handbrake.fr/docs/license.html"
+Language: English
+Project_Version: Latest
+Language_Code: en
+Title: x264 - Profiles and Levels
+License: Creative Commons Attribution-ShareAlike 4.0 International
+Text_Encoding: utf-8
+Copyright: 2016 HandBrake Team
+Project: HandBrake
+Authors: Bradley Sepos
+Project_URL: "https://handbrake.fr/"
+---
+
+x264 - Profiles and Levels
+==========================
+
+ 
+
+H.264 profiles
+--------------
+
+Define the features / capabilities that the encoder can use.
+
+HandBrake exposes 3 profiles for H.264 Encodes. You can think of the profile as
+the level of complexity required in encode / decode. The higher the complexity,
+the more CPU power is needed to encode/decode. Setting a profile, constrains the
+encode to using settings that are allowed for that profile level.
+
+Typically, devices will advertise that they are compatible for a particular
+profile and level, so you can simply set the option that matches your device for
+the best chance of compatibility.
+
+-   Auto (Recommended)
+
+    -   This will automatically set the profile based on all the options that
+        have been selected.
+
+    -   It is recommended that you use this option unless you need to set a
+        profile to ensure compatibility for a particular device.
+
+-   Baseline
+
+    -   Baseline encodes are the most basic form of encoding. While decoding is
+        much easier, it may also require much higher bit-rates to maintain the
+        same level of quality.
+
+-   Main
+
+    -   The middle ground. Most modern / current devices will support this
+        profile.
+
+-   High Profile
+
+    -   For best quality and filesize at the expense of CPU time in both decode
+        and encode.
+
+Note that setting a profile does not mean your encoded file will end up being
+that profile. It simply prevents options being used that would breach that
+profile constraint.
+
+ 
+
+H.264 Levels
+------------
+
+The levels are another form of constraints that define things like maximum
+bitrates, framerates and resolution etc. The wikipedia article lists the
+relevant information for each level.
+http://en.wikipedia.org/wiki/H.264/MPEG-4\_AVC\#Levels
+
+Most devices (and sometimes, software decoders) support a "maximum" level. When
+the video's specifications exceed that level's constraints, the decoder won't be
+able to decode the video properly (it may simply refuse to play the file).
+
+!HandBrake's H.264 encoder, x264, sets the appropriate level automatically based
+on all the other settings. To make sure your video doesn't exceed a specific
+level, you simply have to make sure the other parameters fit within the
+constraints imposed by the level.
+
+It is recommended that you leave this setting on "Auto" unless you require to
+set it for device compatibility.
+
+For a more detailed guide, see
+https://forum.handbrake.fr/viewtopic.php?f=6&t=19368