docs: en: update codec lists, clarify the m4v and mp4 extension issue…

… on modern devices.

source/docs/en/latest/introduction/about.markdown

@@ -27,7 +27,7 @@ HandBrake is a post-production tool. Its primary purpose is to convert videos fr
 
 HandBrake takes videos you already have and makes new ones that work on your mobile phone, tablet, TV media player, game console, computer, or web browser—nearly anything that supports modern video formats.
 
-HandBrake works with most common video files and formats, including ones created by consumer and professional video cameras, mobile devices such as phones and tablets, game and computer screen recordings, and DVD and Blu-ray discs. HandBrake leverages tools such as FFmpeg, x264, and x265 to create new MP4, MKV, or WebM video files from these `Sources`.
+HandBrake works with most common video files and formats, including ones created by consumer and professional video cameras, mobile devices such as phones and tablets, game and computer screen recordings, and DVD and Blu-ray discs. HandBrake leverages tools such as FFmpeg libavcodec and libavformat libraries, x264, x265, and svt-av1 to create new MP4, MKV, or WebM video files from these `Sources`.
 
 HandBrake **does**:
 

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

@@ -61,10 +61,9 @@ Audio Encoders
 
 -   Vorbis:
 
-    -   HandBrake offers Vorbis audio encoding as well, for which it uses the
-        aoTuV branch that offers quality tweaks.
+    -   HandBrake offers Vorbis audio encoding as well.
 
--   Opus (FFmpeg)
+-   Opus
 
     -   Available in MKV files, Opus is the successor to Vorbis. HandBrake uses libopus for encoding.
 

source/docs/en/latest/technical/containers.markdown

@@ -25,23 +25,23 @@ HandBrake creates the widely supported container formats MKV and MP4 (sometimes
 
 Features and playback compatiblity varies between MKV, WebM, and MP4. The following is a summary of some of these differences:
 
-- In an MP4 container, you can store MPEG-4 video created by ffmpeg or x264.
-  - Supports H.264, H.265, MPEG-4, MPEG-2 video. 
-  - It stores audio in the AAC format. It is also possible to pass through Dolby Digital 5.1 Surround Sound (AC3) audio from a DVD in an MP4 file, although it is a new standard and not widely supported. VLC can decode it, and the AppleTV can pass it through to a surround sound receiver. 
+- MP4 container.
+  - Supports H.264, H.265, MPEG-4, MPEG-2, AV1 video.
+  - It stores audio in the AAC, MP3, AC3, E-AC3, and Opus format. AAC is recommended for better compatibility on most players. It is also possible to pass through Dolby Digital 5.1 Surround Sound (AC3) audio from a DVD or Blu-ray, and E-AC3 and TrueHD.
   - MP4 also supports chapters, for which HandBrake uses Apple's chapter format. 
   - MP4 also is capable of storing [VariableFrameRate Variable Frame Rate] video. 
-  - Be aware that chapters and AC3 audio can only be seen by QuickTime if you change the file extension from .mp4 to .m4v. HandBrake will do this for you automatically when you enable those features, although this can be disabled in the preferences if you really want .mp4 at the end of the name. 
-  - The MP4 format can also be optimized for "fast start" progressive downloads over the Web. 
+  - Be aware that chapters and AC3 audio can only be seen by QuickTime 7 and earlier if you change the file extension from .mp4 to .m4v. HandBrake will do this for you automatically when you enable those features, although this can be disabled in the preferences if you really want .mp4 at the end of the name. QuickTime X and later don't require the extension change.
+  - The MP4 format can also be optimized for "fast start" progressive downloads over the Web.
   - It can also include "soft" text subtitles that can be turned on or off, instead of always being hard burned into the video frames.
 
-- In an MKV container, you can store MPEG-4 video created by ffmpeg or x264, or Theora video. 
-  - Supports H.264, H.265, MPEG-4, MPEG-2 video and VP3 (Vorbis) 
-  - It stores audio in the AAC, MP3, Vorbis or FLAC formats. It can also pass through the Dolby Digital 5.1 (AC3) and Digital Theater Systems (DTS) surround sound formats used by DVDs. 
+- MKV container.
+  - Supports H.264, H.265, MPEG-4, MPEG-2, VP8, VP9, AV1, Theora video.
+  - It stores audio in the AAC, MP3, AC3, E-AC3, Vorbis, Opus, or FLAC formats. It can also pass through the Dolby Digital 5.1 (AC3), Digital Theater Systems (DTS), and TrueHD surround sound formats used by DVDs and Blu-rays.
   - It supports chapters, as well as [VariableFrameRate Variable Frame Rate] video. 
   - It can include "soft" subtitles that can be turned on or off, instead of always being hard burned into the video frame. These can either be bitmap images of the subtitles included on a DVD (known as vobsub) or text.
 
-- In a WebM container, you can store VP8 or VP9 video.
-  - Supports VP8 and VP9 video codecs.
+- WebM container.
+  - Supports VP8, VP9, and AV1 video codecs.
   - It stores audio in either Vorbis or Opus formats.
   - It can include "hard" burned in subtitles. "Soft" subtitles are currently unsupported.
 
@@ -55,4 +55,4 @@ You can simply change the file extension between .mp4 and .m4v as the file is ex
 
 You can disable the option to automatically set this in !HandBrakes preferences.
 
-Note: QuickTime or any QT based application will not be able to play a MP4 file with these features enabled, unless it has the extension ".m4v"
+Note: QuickTime 7 or any QT 7 based application will not be able to play a MP4 file with these features enabled, unless it has the extension ".m4v". This limitation does not apply to QuickTime X or iOS.

source/docs/en/latest/technical/source-formats.markdown

@@ -16,7 +16,7 @@ License_URL:     https://handbrake.fr/docs/license.html
 Supported source formats
 ========================
 
-One of HandBrake's strengths is its ability to open a wide variety of video formats. HandBrake uses [FFmpeg](https://ffmpeg.org/) under the hood and generally can open whatever FFmpeg will, in addition to disc-based formats like DVD and Blu-ray.
+One of HandBrake's strengths is its ability to open a wide variety of video formats. HandBrake uses [FFmpeg](https://ffmpeg.org/) libavformat and libavcodec libraries under the hood and generally can open whatever FFmpeg will, in addition to disc-based formats like DVD and Blu-ray.
 
 **Note:** HandBrake does not defeat or circumvent [copy protection](https://en.wikipedia.org/wiki/Copy_protection) of any kind. It does not work with video files employing [Digital Rights Management](https://en.wikipedia.org/wiki/Digital_rights_management) (DRM). See [About HandBrake](../about.html) for more information about what HandBrake *does* and *does not*.
 

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

@@ -38,13 +38,13 @@ The following video codecs are available for encoding in HandBrake.
       - In software: x265  
       - In hardware: Intel QuickSync, AMD VCE, Nvidia NVENC and ARM devices though MediaFoundation.
 
-- MPEG-4 (ffmpeg):
+- MPEG-4:
 
     - MPEG-4 Part 2, also known as MPEG-4 Visual
     - Predecessor to H.264/AVC offering fast encoding with lower overall quality than H.264/AVC
     - Compatible with older devices, inexpensive DVD/flash/network players
 
-- MPEG-2 (ffmpeg):
+- MPEG-2:
 
     - MPEG-2 Part 2, also known as MPEG-2 Visual and H.262
     - Predecessor to MPEG-4 Visual offering very fast encoding with lower quality than modern codecs