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 - [Resampling](encoding/resampling.md)
 - [Codecs](encoding/video-encoding.md)
   - [x264](encoding/codecs/x264.md)
-
+- [Mastroka Container Tricks](encoding/mkv.md)
 
 ## Typesetting
 
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+# Mastroka Container Tricks
+
+*Disclaimer: this page assumes some basic knowledge of the mastroka container,
+python,
+and VapourSynth.*
+
+
+## Background and Preparation
+
+The Mastroka Media Container is an open source,
+open standard multimedia container
+that is heavily used in the fansubbing scene.
+Mastroka video, or `.mkv` files
+are the standard for soft-subbed releases
+as they allow for multiple subtitles tracks and chapters
+which are a somewhat unique feature to the container.
+The MPEG-4 Part 14 or MP4 is another container format
+but it is limited in its usefulness for fansubbing.
+
+The following steps will require
+VapourSynth,
+[MKVToolNix GUI + CLI][toolnix],
+a tool to demux transport stream files (i.e. [tsMuxeR][]),
+and [FFmpeg][] to be installed
+(or readily available as binaries).
+A [mastroka-friendly player][mk-playback], preferably [MPC-HC][] or [mpv][],
+will also be required for testing the files.
+
+The examples will be using pre-made subtitle tracks,
+a BDMV source,
+[VSEdit](preparation.md#the-editor),
+an [audio-cutting python script][acsuite.py],
+and a [script to change frame numbers into timestamps][f2ts.py].
+
+What we will be doing:
+1. Trimming audio to match our VapourSynth video trims
+1. Creating mkv files from individual tracks
+1. Creating chapters for said files
+1. Creating virtual timelines with ordered chapters
+1. Using multiple audio codecs in the same 'apparent file'
+1. Using editions to change between NCOP and OP
+1. Creating a playall file with ordered chapters
+
+*Most of the example files can be found in [this repository][mkvtricks]
+if you'd like to follow along.*
+
+[toolnix]: https://mkvtoolnix.download/downloads.html
+[tsMuxeR]: https://www.videohelp.com/software/tsMuxeR
+[FFmpeg]: https://ffmpeg.zeranoe.com/builds/
+[mk-playback]: https://github.com/hubblec4/Matroska-Playback/blob/e48149b500ce80c38ebc07ccf8f74f8af45e89b2/src/PlayerOverview.md
+[MPC-HC]: https://github.com/clsid2/mpc-hc/releases
+[mpv]: https://mpv.io/installation/
+[acsuite.py]: https://github.com/OrangeChannel/acsuite/blob/04194ad6d4e65e491b5c09219d3f9e832651f2c0/acsuite.py
+[f2ts.py]: https://gist.githubusercontent.com/OrangeChannel/330a032e4d6cf9265b8b007c41112937/raw/frame-to-timestamp.py
+[mkvtricks]: https://github.com/OrangeChannel/mastroka-tricks-files
+
+
+## Starting with trimming the video
+
+Obviously, the goal here is not to teach how to encode,
+but provided are examples of trims that may need to be made
+to cut the OP/ED out of an episode,
+and possibly any other unwanted frame-ranges
+(some blu-ray streams have a silent black screen at the end,
+which should be cut out).
+
+Starting with four files,
+our first step is to trim the main episodes out.
+This requires knowing the frame ranges, shown below.
+Second, we will crop out the NCOP/NCED files
+as they also have unwanted frames at the end.
+
+```py
+import vapoursynth as vs
+core = vs.core
+
+bdmv =  core.lsmas.LWLibavSource(r'/BDMV/STREAM/00003.m2ts')
+bdmv2 = core.lsmas.LWLibavSource(r'/BDMV/STREAM/00004.m2ts')
+bdmv3 = core.lsmas.LWLibavSource(r'/BDMV/STREAM/00005.m2ts')
+bdmv_NCOP = core.lsmas.LWLibavSource(r'/BDMV/STREAM/00007.m2ts')
+bdmv_NCED = core.lsmas.LWLibavSource(r'/BDMV/STREAM/00008.m2ts')
+
+ep1 = bdmv[:30042]+bdmv[32201:34046]
+# 0-30041, 32201-34045 is main episode 1
+ep2 = bdmv2[:1678]+bdmv2[3837:30978]+bdmv2[33111:34023]
+# 0-1677, 3837-30977, 33111-34022 is main episode 2
+ep3 = bdmv3[:1942]+bdmv3[4104:30474]+bdmv3[32609:34023]
+# 0-1941, 4104-30473, 32609-24022 is main episode 3
+
+op = bdmv[30042:32201] # the first time the OP plays is during episode 1
+                       # 30042-32200 is the OP
+ed = bdmv2[30978:33111] # the first time the ED plays is during episode 2
+                        # 30978-33110 is the ED
+ncop = bdmv_NCOP[:2158] # 0-2157 is the NCOP
+nced = bdmv_NCED[:2133] # 0-2132 is the NCED
+```
+
+Assuming the codec used is h.264/AVC,
+this will result in the following files:
+
+- `vid_ep1.264`
+- `vid_ep2.264`
+- `vid_ep3.264`
+- `vid_OP.264`
+- `vid_ED.264`
+- `vid_NCOP.264`
+- `vid_NCED.264`
+
+
+## Trimming the audio + generating chapters
+
+In order to start the audio processing,
+we first need to extract the audio track from the transport stream files.
+Using the tsMuxeR GUI set to *demux* mode,
+grab the likely pcm or dts audio streams,
+only changing the extension.
+
+- `00003.m2ts` > `00003.wav`
+- `00004.m2ts` > `00004.wav`
+- `00005.m2ts` > `00005.wav`
+- `00007.m2ts` > `00007.wav`
+- `00008.m2ts` > `00008.wav`
+
+Now, either in a new python instance
+or from within our VapourSynth script above,
+we will use `acsuite.py` to trim our audio,
+and generate chapter timings.
+(The lines should be commented out when not in use.
+If running from within VSEdit,
+you must name and save the script first if you do not specify full paths
+for the `outfile` and/or `chapter_file`.)
+
+**Note:** the frame numbers used in `ac.octrim(...)` and `ac.eztrim(...)`
+are from the untrimmed source clips.
+The exact syntax is explained in the docstrings for `acsuite.py`.
+
+```py
+...
+import acsuite
+ac = acsuite.AC()
+
+afile =  r'/BDMV/STREAM/00003.wav' # 260.2 MiB
+afile2 = r'/BDMV/STREAM/00004.wav' # 260.0 MiB
+afile3 = r'/BDMV/STREAM/00005.wav' # 260.0 MiB
+afile4 = r'/BDMV/STREAM/00007.wav' # 16.7 MiB
+afile5 = r'/BDMV/STREAM/00008.wav' # 16.5 MiB
+
+chap = [(0, 'Part A'), (3771, 'Title Card'),(3861, 'Part B'), (20884, 'Middle Card'), (21004, 30041, 'Part C'), (32201, 'Part D'), (33686, 34045, 'Preview')]
+chap2 = [(0,1677,'Part A'),(3837,'Part B'),(17239,'Middle Card'),(17359,30977,'Part C'),(33111,'Part D'),(33663,34022,'Preview')]
+chap3 = [(0,1941,'Part A'),(4104,'Part B'),(13668,'Middle Card'),(13788,30473,'Part C'),(32609,'Part D'),(33663,34022,'Preview')]
+
+ac.octrim(bdmv, chap, afile, 'ep1_cut.wav', 'ep1_chapters.txt')
+ac.octrim(bdmv2, chap2, afile2, 'ep2_cut.wav', 'ep2_chapters.txt')
+ac.octrim(bdmv3, chap3, afile3, 'ep3_cut.wav', 'ep3_chapters.txt')
+
+ac.eztrim(bdmv, (30042,32201), afile, 'op_cut.wav')
+ac.eztrim(bdmv2, (30978,33111), afile2, 'ed_cut.wav')
+ac.eztrim(bdmv_NCOP, (0,2158), afile4, 'ncop_cut.wav')
+ac.eztrim(bdmv_NCED, (0,2133), afile5, 'nced_cut.wav')
+```
+
+This will result in the following files:
+
+- `ep1_cut.wav`  (243.6 MiB)
+- `ep2_cut.wav`  (227.1 MiB)
+- `ep3_cut.wav`  (227.1 MiB)
+- `op_cut.wav`   (16.5 MiB)
+- `ed_cut.wav`   (16.3 MiB)
+- `ncop_cut.wav` (16.5 MiB)
+- `nced_cut.wav` (16.3 MiB)
+
+and MKVToolNix GUI will open the following OGM chapter files:
+
+- [ep1_chapters.txt][ep1txt]
+- [ep2_chapters.txt][ep2txt]
+- [ep3_chapters.txt][ep3txt]
+
+[ep1txt]: https://github.com/OrangeChannel/mastroka-tricks-files/blob/b9a079b04efd7e3891c05251a1dc6ccf3a1671ba/ep1_chapters.txt
+[ep2txt]: https://github.com/OrangeChannel/mastroka-tricks-files/blob/b9a079b04efd7e3891c05251a1dc6ccf3a1671ba/ep2_chapters.txt
+[ep3txt]: https://github.com/OrangeChannel/mastroka-tricks-files/blob/b9a079b04efd7e3891c05251a1dc6ccf3a1671ba/ep3_chapters.txt
+
+
+### Encoding the audio
+
+We will be using FFmpeg's *libopus* and *flac* encoders.
+The following examples simply loop[^1] the command for every `ep*.wav` file,
+and all four op/ed files.
+
+For the main episode, we will be using opus:
+
+```sh
+$ fd -e wav -E 'op*' -E 'ed*' -E 'nc*' -x ffmpeg -i {} -c:a libopus -b:a 128k -cutoff 20000 {.}.opus
+```
+
+And for the op/ed's, we will use FLAC:
+
+```sh
+$ fd -e wav -E 'ep*' -x ffmpeg -i {} -c:a flac -compression_level 12 {.}.flac
+```
+
+This results in the following files:
+
+- `ep1_cut.opus`  (21.2 MiB) (91% reduction)
+- `ep2_cut.opus`  (19.3 MiB) (91% reduction)
+- `ep3_cut.opus`  (19.5 MiB) (91% reduction)
+- `op_cut.flac`   (10.0 MiB) (39% reduction)
+- `ed_cut.flac`   (9.9 MiB) (39% reduction)
+- `ncop_cut.flac` (10.1 MiB) (39% reduction)
+- `nced_cut.flac` (9.9 MiB) (39% reduction)
+
+Normally, using two different audio codecs within the same file
+would not be possible.
+However, ordered chapters make it possible for each file to use its own codec
+(as long as the track order is the same).
+
+*For the audiophiles who like to keep their anime music lossless,
+we've encoded only the OP/EDs with FLAC.
+This leaves the episode to be compressed more efficiently with a lossy codec
+such as opus, for those who don't like 'wasting' space with lossless audio.
+Since we are encoding around 90%[^2] of the show with opus,
+and only have the OP/ED + NCOP/NCED files occurring once,
+the filesize difference and lossless music should satisfy both groups.
+Normal dialogue should be nearly transparent at 128 kbps with opus,
+but this comes with some caveats.
+If there are 'insert' songs within an episode that you'd like to keep lossless,
+you will need to encode the entire episode with a lossless codec.*
+
+
+## Working with ordered chapters
+
+### Muxing
+
+Before we can start using ordered chapters,
+we will have to mux the current files into mkv's.
+This is because ordered chapters reference other mkv's by their UID
+to generate the virtual timeline for the player.
+MKVToolNix can save chapters *into* existing mkv files,
+so this step will be the only time we mux.
+
+This can be done with the MKVToolNix GUI,
+in which case the order the tracks appear in the bottom list is important.
+Although mpv will only warn that tracks are mismatched,
+it is a good idea to keep the same track order in all of the mkv's.
+In our example, we will use
+*Video*, *Audio*, then *Subtitles*
+as the order for every file.
+
+The order can be changed with the arrows or by dragging the tracks
+in the bottom box of the *Mulitplexer* window in the GUI:
+
+![Track order matters!](images/mkv/gui_order.png)
+
+This can also be done automatically using the command line.
+An example python script:
+
+```py
+import shlex, subprocess
+
+names = ['ep1', 'ep2', 'ep3', 'op', 'ed', 'ncop', 'nced']
+audios = ['ep1_cut.opus', 'ep2_cut.opus', 'ep3_cut.opus', 'op_cut.flac', 'ed_cut.flac', 'ncop_cut.flac', 'nced_cut.flac']
+
+for n, a in zip(names, audios):
+    cmd = 'mkvmerge -o {0}.mkv {0}.264 {1} {0}.ass'.format(n, a)
+    args = shlex.split(cmd)
+    subprocess.Popen(args)
+```
+
+Since this is the only time we will actually be muxing,
+all attachments should be added here as needed with their subtitle tracks
+(if a font is used in `op.ass`, only add it to the `op.mkv` file).
+Adding a title and setting track languages
+should also be done at this point.
+
+
+### Main episode
+
+In the example above,
+the *Chapter editor* GUI should at first look like this:
+
+![Chapter editor](images/mkv/chapter_editor_01.png)
+
+Ordered chapters require a start *and* an end timestamp,
+so we will need to generate the *End* column here.
+This can be accomplished by right-clicking the *Edition entry*,
+and selecting *Additional modifications*.
+
+![Derive end timestamps](images/mkv/chapter_editor_derive.png)
+
+After deriving the end timestamps,
+delete the last chapter,
+as it was a placeholder generated by `octrim()`
+to determine the end timestamp of the last chapter.
+
+On the *Edition entry*, we can now tick *Ordered*:
+
+![Ticking ordered](images/mkv/chapter_editor_ordered_tick.png)
+
+At this point, if we were to mux these chapters into our episode 1 file,
+they will act like normal chapters,
+and the episode will play without the OP towards the end.
+
+
+### Adding in our OP
+
+Before we add in the OP,
+we need to determine the timestamps needed for the timeline
+to reference our `op.mkv`.
+
+If we had chapters generated for the OP,
+we could simply copy over those timestamps
+(we will do this with our *playall* file later).
+Instead, we will simply use the number of frames in the entire op
+to determine the end timestamp.
+
+From our trim, `op = bdmv[30042:32201]`,
+we find that the clip is $$32201-30042=2159$$ frames long.
+This can also be found from `op.num_frames` in VapourSynth.
+
+Using a small [script to change frame numbers into timestamps][f2ts.py],
+we find that `2159 > 00:01:30.048291667`.
+
+We will add a chapter titled *OP* between *Part C* and *Part D*,
+where it was originally in the uncut video.
+
+![Right-click menu to add a chapter](images/mkv/add_chapter_after.png)
+
+The timestamp above becomes this chapter's end timestamp.
+
+Now, in order for the mkv to know what chapter this file comes from,
+click the folder icon next to *Segment UID:* and open the `op.mkv` file.
+This will automatically find the UID of the mkv
+and input it for this chapter's SUID:
+
+![Adding our OP chapter](images/mkv/op_chapter.png)
+
+Players will only search within the current directory for referenced files,
+so `op.mkv` must be kept in the same folder as our episode 1
+if we want it appearing in the timeline.
+
+```
+File uses ordered chapters, will build edit timeline.
+This file references data from other sources.
+Will scan other files in the same directory to find referenced sources.
+Match for source 1: ./op.mkv
+Timeline segments have mismatching codec.
+```
+
+*Although mpv shows this mismatching codec warning,
+playback is not affected.*
+
+By adding this chapter,
+any compatible player will add frames 0-2158 from the `op.mkv`
+into the timeline of `ep1.mkv` when episode 1 is played.
+The `op.mkv` file will remain unaffected,
+meaning it can be played separately on its own.
+
+
+[f2ts.py]: https://gist.githubusercontent.com/OrangeChannel/330a032e4d6cf9265b8b007c41112937/raw/frame-to-timestamp.py
+
+
+#### Episode 2 and 3 Example
+
+*If you are comfortable with how to create ordered chapters now,
+you can skip this section.
+This is just going to continue the same process above for
+episodes 2 and 3.*
+
+Example files can be found in the [repo][] mentioned above.
+
+<!TODO - add some screenshots here of the other episodes' chapters>
+
+[repo]: https://github.com/OrangeChannel/mastroka-tricks-files
+
+
+### Using editions to add in an NCOP
+
+Similar to adding in the OP,
+we will find the timestamp for the NCOP clip.
+`ncop = bdmv_NCOP[:2158]` > $$2158-0=2158$$ therefore,
+`2158 > 00:01:30.006583333`.
+
+Using the same *Chapter editor* GUI,
+duplicate our first *Edition entry*.
+Rename the *OP* chapter to *NCOP*,
+modify the end timestamp,
+and change the SUID by opening `ncop.mkv` with the folder button:
+
+![Adding an NCOP edition](images/mkv/ncop_edition.png)
+
+Note: *Although it doesn't affect playback,
+duplicating the chapters' UIDs is not ideal.
+The only way around this is to delete the string in the *UID* field for
+any chapter that is duplicating another.
+Upon saving the file,
+new UIDs will be generated.*
+
+At this point,
+we are done with this episode's timelines,
+so we will *Chapter editor > Save to Mastroka or WebM file*
+and select our already muxed `01.mkv`.
+On playback, you should now see the OP chapter
+inserted towards the end of the episode seamlessly.
+
+To create a playall file later,
+it is best to also save these chapters to external xml files.
+
+- `ep1.xml`
+- `ep2.xml`
+- `ep3.xml`
+
+---
+
+
+#### Advanced edition tagging
+
+*You can skip this section if you're not using editions,
+or if you don't want to bother with re-muxing.*
+
+By default, the two editions we've created above will not have names.
+Players will likely show either their number or a blank title.
+However, there is a way to name editions with a *tags* file.
+If we erase what's currently in the *UID* field for both of our editions
+(as the duplication we did above may have copied the UID),
+and then save this to a normal xml chapters file,
+we can find our *EditionUID* that we need to proceed.
+
+*At this point, the chapters should be finalized.*
+
+Using yet another [tiny script][e-namer] to automate this,
+we will generate a tags xml file with our wanted names.
+
+```sh
+$ python edition-namer.py
+input the edition uids (2906622092 4906785091): 4972756538813441817 3956363165969893955
+input the edition names ('normal' 'no credits'): 'Normal' 'No-Credits'
+desired file name (example.xml): ep1_editions.xml
+```
+
+[ep1_editions.xml][]
+
+In order to get these tags to work,
+you need to mux this tags file under *Global tags*.
+On the Multiplexer GUI, *Output > General > Global tags*.
+This file must be muxed with the original tracks,
+and probably should be muxed along with the chapters
+(*Output > Chapters > Chapter file*)
+as they are now both final.
+
+[e-namer]: https://gist.githubusercontent.com/OrangeChannel/b14f7142c5814d86454da8cde7ec5a94/raw/edition-namer.py
+[ep1_editions.xml]: https://github.com/OrangeChannel/mastroka-tricks-files/blob/20429481f7479de9500124673d10917b0642e4fe/ep1_editions.xml
+
+
+### Creating a playall file
+
+At this point, you should be comfortable with how ordered-chapters work.
+Using the ideas above,
+we are going to create a small `playall.mkv` file that will generate
+a virtual timeline of our 3 episodes, and the OP/ED once.
+Originally, the order was:
+
+```
+Ep1:
+ep1_A + OP + ep1_B + preview1
+
+Ep2:
+ep2_A + OP + ep2_B + ED + ep2_C + preview2
+
+Ep3:
+ep3_A + OP + ep3_B + ED + ep3_C + preview3
+```
+
+Our goal is to create a small file that when played,
+creates the following timeline...
+
+```
+ep1_A + OP + ep1_B + ep2_A + ep2_B + ep2_C + ep3_A + ep3_B + ED + ep3_C
+```
+
+...with the OP occurring at the same point it first happened in the source,
+and the ED occurring at the same point it last happened in the source.
+In reality, if we had all 12 episodes to work with,
+we could put the ED at the *real* last time it plays
+(likely towards the end of episode 12).
+
+In order to create our playable file,
+we need a small mkv in the same format as our other files,
+with the tracks in the same order.
+A quick way to do this is cropping the entire file with FFmpeg.
+
+```sh
+ffmpeg -i ep1.mkv -c copy -fs 5M playall.mkv
+```
+
+`-fs 5M` will 'limit' the output file to around 5 MiB,
+while `-c copy` ensures all tracks and relevant headers are copied.
+
+If we were to play this file now,
+it would likely be the first 1 or 2 seconds of our episode 1.
+In order for this file to become entirely a virtual timeline,
+*all* of the chapters must be ordered
+and point to other files in the folder.
+
+Using the GUI, we can speed up this process somewhat.
+In the chapter editor,
+open our three chapter files,
+`ep1.xml`, `ep2.xml`, `ep3.xml`,
+and open a new blank chapter file.
+
+On this new file,
+delete the top edition entry.
+
+On our episode 1 tab,
+right-click our top *Edition entry*,
+and *Copy to other tab* into our blank file.
+On our blank file,
+we will now need to add segment UIDs to every episode 1 chapter.
+We can do this by opening the folder icon to our ep1.mkv file
+for every chapter that will be referencing our episode 1 file.
+
+The OP chapter should already have the SUID to the op.mkv file,
+so it does not need to be changed.
+
+Sadly, there is no further shortcuts for copying our other two episodes'
+chapters into this new blank file,
+so they will need to be copied over by hand.
+The name, start timestamp, end timestamp, and segment UID
+are the only fields we need. (For chapters coming from episode 2,
+the segment UID must be from our `ep2.mkv` file, etc.)
+
+![playall chapters without cutting](images/mkv/play_chapters.png)
+
+Once we have all of these chapters ordered and using the correct SUIDs,
+we can save this to our `playall.mkv` file.
+
+It is also possible to create a better timeline as stated above,
+that skips previews, and only plays the OP/ED once over the entire series.
+We will create a copy of our `playall.mkv` file
+and rename it `playall-skip.mkv`.
+Since we already have a timeline of all (3 currently) of our episodes' chapters,
+we only need to cut out the chapters titled *Preview*
+and any extra times the OP/ED play.
+Since we only have 3 example files,
+we'll be playing the OP on its first occurrence,
+and the ED on its last occurrence.
+
+![playall chapters skipping the previews and OP/ED](images/mkv/play_chapters_skip.png)
+
+Saving this to our playall-skip file results in the following...
+
+- `playall.mkv      - 01:10:57.880` virtual timeline in player
+- `playall-skip.mkv - 01:05:43.774` virtual timeline in player
+
+...despite each file only being ~5 MiB.
+
+
+#### Note about playall files
+
+Although in our example,
+we are referencing files that they themselves reference other files,
+this doesn't have to be the case.
+If you prefer not to use ordered-chapters in your release
+for splicing in the OP/ED,
+**you can still create a playall file simply referencing your normal files**.
+In the same way as the example above,
+you can simply remove the OP/ED and previews from your playall timeline
+by simply not including those chapter timings from each episode.
+
+
+### Final notes
+
+Editions mixed with ordered chapters can be used for a myriad of purposes
+besides those shown here.
+Although these are likely the most common uses in the fansubbing scene,
+editions can also be used for shows with multiple 'play orders'.
+Ordered chapters can link together multiple seasons of the same show,
+or can be used to hide certain sections of a file
+(maybe for creating an easter egg in your release).
+Similar to how our playall file only plays content from *other* files,
+parts of a file can be skipped over
+(or in the case of playall, entire files become completely removed).
+Obviously, simply removing the chapters will reveal the real tracks
+of the source file,
+in our case just a couple of frames from our first episode.
+
+Notes about playback issues and possible artifacts:
+
+- Because some subtitle information within Sub Station Alpha files
+is [privately stored in the mkv's header][mastroka-ass],
+**all styles** and information under `[Script Info]`
+that are present in **all** referenced files
+(i.e. styles only used in the OP not main episode)
+must also be present in the single file containing the chapters
+that references the other files.
+(i.e. ep#.mkv in our case).
+  - This means that all relevant styles **must** be included in the playall file for proper playback.
+  - Fonts however only need to be included
+    in the file that uses them ** [citation needed]
+- Subtitles stretching over ordered chapters boundaries may cause some issues,
+including in our playall file.
+In our playall file,
+a way to circumvent some of this problem
+would be to combine all consecutive chapters
+from the same file into one large chapter simply named "Episode 1" or similar.
+- Audio *should* be (close to) silent at the exact moment
+the timeline changes between different files it's referencing.
+Although this shouldn't cause sync issues,
+an abrupt cut in audio may not be something you'd want in your release.
+
+[mastroka-ass]: https://www.matroska.org/technical/specs/subtitles/ssa.html
+
+---
+
+
+#### Some boring math
+
+We are going to use some basic assumptions here[^3].
+- The series we are encoding is 13 episodes long
+- 24 minutes per episode
+  - with a 90 sec OP + ED that plays each episode
+- FLAC audio will be around 950 kbps, opus will be 128 kbps.
+
+**Our first goal will be to keep the release under 12 GB total:**
+
+The FLAC audio track for each episode will be 171 MB,
+leaving 752 MB (**4,178 kbps**) for the video.
+If we were to encode the audio entirely in opus,
+the audio track for each episode will be 23 MB,
+leaving 900 MB (**5,000 kbps**) for the video.
+
+Changing from FLAC to opus gives us an *extra 19.7% bitrate for our video*,
+at the cost of audio quality.
+
+Instead, if we used ordered chapters:
+
+The total amount of video time decreases from 312 min
+to 273 min for main episodes and 3 min for the OP/ED.
+(If you are applying heavy filtering to this series,
+and encoding time is a important factor,
+this would result in a *11.5% reduction in encoding time*).
+FLAC for the OP + ED results in 21.4 MB total for our lossless audio tracks.
+opus for the main episodes (273 min)
+results in 262 MB total for our lossy audio tracks.
+Assuming the OP/ED are kept at the same bitrate as the rest of our video,
+we are left with 11.7 GB for our 276 minutes of video (**5,660 kbps**).
+
+Using ordered chapters in this case,
+gives us an *extra 35.5% bitrate for our video*,
+with the benefit of still having lossless audio for the OP/ED music.
+
+**If instead we are aiming to save on space:**
+
+Without using ordered chapters,
+and keeping the video bitrate at **4,178 kbps**,
+encoding all audio as lossy gives us a *16% filesize reduction*
+(12 GB to 10.1 GB).
+
+With ordered chapters,
+at the same video bitrate of **4,178 kbps** from before,
+we reduce our video tracks to 8.65 GB from 9.78 GB (*11.5% reduction*).
+We reduce our audio tracks to 283.4 MB from 2.22 GB (*87.2% reduction*).
+Total filesize gets reduced from 12 GB to 8.93 GB, a *25.6% reduction*.
+
+---
+
+[^1]: the `fd` utility can be installed from its [GitHub repo][fd].
+
+[^2]: This number is actually much higher as we only encode the music once. For a 12 episode show, with 24 minutes per episode and 3 minutes of OP/ED music in each episode, we would be encoding 255 minutes total, with only 3 minutes (1.2%) being the lossless music.
+
+[^3]: These calculations can be checked with this [bitrate and filesize calculator script][brate-fsize].
+
+[fd]: https://github.com/sharkdp/fd/releases
+[brate-fsize]: https://gist.githubusercontent.com/OrangeChannel/816a87cf760d9be19bde18db8818d4bc/raw/bitrate_filesize.py