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The CTR Muxing Standards Guide

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Standards For Muxed Releases: What and Why

preface: these are the standards used by all CTR releases as of 2017-06-19. Older releases were not up to standard on all sections (mostly the Forced flag).

this standard is not required and is merely a recommendation for future release groups to follow, because archiving is important, consistency is wonderful, and having information stored in the filenames and container tags is very useful.

some content has been adapted from the BTN uploading guide.


I. The Filename

II. The Container

III. The Torrent

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I. The Filename

This might seem like a very simple thing at first, but honestly, there's a lot of confusion here in the anime crowd. 

Gunslinger Girl Ep 01v2 'Fratello (Siblings)' [Blu-Ray 1080p].mkv
[Kametsu] ERASED - 01v2 (BD 1080p Hi10 FLAC) [EC9FFC4B].mkv
[LostYears] Citrus - 01 (Web 720p Hi10 AAC) [FB0A14A2].mkv

Only two of these actually follow the same standard. It's a mess.


Why have standards at all? Why not just let people name things what they like so long as it's clear?


Standardizing filenames does a lot for us. It means tools like Sonarr (an automatic download application), Kodi (a full-featured media center) and Plex (a media server and transcoder) can function properly because they don't have to try and figure out what on earth each file is supposed to be.


Scene Standard vs Anime Standard (or lack thereof)

The "scene" is a loosely affiliated web of release groups spread across various "topsites". Scene releases have been around since long before bittorrent was even a thing, and are generally the fastest to release any given media. The scene is largely responsible for establishing most of the rules followed by every other media type besides anime. This guide is advocating to follow scene standard so that compatibility is maintained with other media types. This ensures that applications like Kodi and Plex, as well as other future media centers can be relied upon to work properly without having to write strange exceptional rules simply to accommodate anime. They're not going to do it, most users aren't going to have a clue how to do it. Anime groups are punishing themselves by not adapting to a scene or scene-like naming scheme.


But having periods and no spaces in your filenames looks dumb and outdated!


Actually, the periods are not required. They do make a lot of command line systems easier by not having to deal with quote marks and the like, but it's not a strict requirement outside the scene.

IF YOU WANT TO USE PERIODS: Their placement is very important in the name structure. A period should only be used to separate one of three things:

  • A new piece of information in the filename. These pieces are detailed below.
  • The channel count on the audio format. For example, stereo sound would be "FLAC2.0". Six-channel surround sound is usually "DD5.1". So on. More specific examples found in the Audio Format section below.
  • Words in the episode title, found after the version number. Episode titles are optional and generally not included.


The Two Acceptable Filenaming Schemes:

ERASED S01E01 v2 (1080p Hi10 BD FLAC) [Kametsu] [EC9FFC4B].mkv

These two schemes contain the same information, in largely the same order and can both be relied upon for proper parsing. I'll break them down in order.



ERASED S01E01 v2 (1080p Hi10 BluRay FLAC2.0) [Kametsu] [EC9FFC4B].mkv


Title of the Show: This one should be obvious, and is placed at the beginning because that's the most important part of the media, and also serves to properly alphabetize media folders by show name.

The name, including capitalization, should be taken from TheTVDB. Please note this does not mean all shows must be in English titles (although that would be preferable since this is a guide for English-oriented releases). TVDB does supposed aliases, as shown here:



The reason we match to TVDB is because it is the primary media scraping database for virtually all media center software. Plex even maintains an official mirror of it for their users. Some media centers will support other scrapers like AniDB or even MAL, but these are inconsistent, not enabled by default and will not properly integrate with the rest of a given media library. 


Episode Number: Episode numbers should always follow the S##E## format, even for a single-season show. This is where the anime community will have to adjust most significantly. The anime industry and the anime community have a terrible habit of ignoring or misusing the season format. Despite shows clearly airing in a seasonal structure like the rest of the world, new seasons will be declared at seemingly random points for no particular reason, or won't be when they absolutely should. 


Without season numbering, any season past the first of an anime will simply not function in most media centers. Plex has started to adjust for this, but recognition is patchy at best and will miss any special episodes, OVAs, etc. without a lot of manual adjustment. We can do better than that. We can match to TVDB ahead of time and avoid headaches as well as preserve content identification by matching to an existing, ID-number focused database like TVDB.


Episode numbering and season numbering should always follow whatever matches up to TVDB. Even if it ends up looking strange, this should still be followed. At the end of the day, filenames are only important to help identify what a show is. The database can give us all the important information after the fact, and the season numbering still shows the correct order to view episodes (with some exceptions, see Specials below). This does not account for shows with strange chronologies (Monogatari, Haruhi Suzumiya), but we can't accommodate someone wanting to watch a show in a different order than originally intended. Unless the ordering was actually incorrect and was fixed by a DVD release - in which case Plex and Kodi already have options built in to handle different orders for DVD vs Airing order, so the problem is already handled by simply following the numbering scheme to match the database.


Specials, OVAs and Movies

This is where naming gets weird. Unfortunately, there's no good way to handle filenaming for specials and movies. The best we can do is mark them to match up with TVDB so the correct information still scrapes, using the season 0 mark to identify it as a special episode. 




Why not name the episodes things like S01E16.5 to show where it's meant to be aired?


This would be a decent solution, but unfortunately many scrapers will read this as another copy of "season 1 episode 16" (actually they'll read it as part 5 of episode 16, to account for multi-part single episodes, but I digress). Instead, we use S00E## format, matching the "Specials" season 0 according to TVDB. This will match the episodes to their proper entries, as usual, and it will also allow media centers and Plex to do some neat tricks. In Cowboy Bebop, by naming the episode S00E01, we now get the following episode listing: 



Notice that the movie has neatly inserted itself in between episodes 22 and 23, right where it's supposed to be. 


Now, you may have noticed I added a few extras to the special episode. On Specials, we include the title of the episode to help users identify what it is at a glance, since the numbering might be otherwise strange. I also included a rough episode number after the title, to help anyone who doesn't want to go look up episode chronology themselves and risk spoilers. However, these two pieces are optional and if you want, you can adjust these parts as needed. Specials are where standards are slightly more lax, so long as the basics are still accounted for. A few additional examples:






You'll notice I did include an episode number on S00E34, as this episode is intended to be watched during season 1, after episode 7 (thus 7.5). However, since the movie (and the 3 minute mini-special) are both to be watched after the main series, I did not include an episode number. The standards are a bit looser, but at the end of the day, with or without standardized naming, all users would end up needing to look up chronology to know when to watch these. Given that, I think it's still worth using S00E## in order to support media centers, since it comes as no cost to non-media center users.



Version Numbering: Ideally, you'll never need to use this, but we all know better by now. A version number should go immediately after the episode number. This is already standard amongst both scene and anime (though scene uses keywords like PROPER, REPACK and DIRFIX instead of numbering. I think anime is a bit clearer here, so I'm happy to switch to their standard here). A v2 should be issued in the event of any fixes that either

  • Are created after a torrent was released. Torrents are considered publication, in a sense, and any revisions made after a torrent has been published should be labeled accordingly. Once a torrent has been released, it has already been mirrored a dozen times over by various scrapers, so there's no going back.
  • Are created after a day or so of a DDL upload that's only on Nandato. This one is a little more iffy, but I personally don't think it's necessary to v2 things when you're still actively working on a project just on the board. Up to you though, just remember to keep your downloaders informed. If you want to be strictly following standard, then¬†any change that results in a new CRC should be a new version. We'll discuss CRCs toward the end.


OPTIONAL: You can include an episode title after the version number (or lack of a version number). However, I personally don't like including episode titles. They're usually unnecessary fluff to the filename. On special episodes, they are included because identification can be otherwise difficult, but for normal season episodes I would leave them off.



Video Composition: This is where you detail out what your media is made of. Specifically, the resolution and video profile. In the case of all my examples above, this is 1080p with the High 10 profile (10-bit video). This info can be found in any MediaInfo dump of your files, or usually from whatever your sources are if you're doing a remux. If you're the one encoding, you should know what this is already (and if you don't, you need to go learn more about encoding before you release anything). 

Other examples: 720p-Hi444pp (increasingly common, especially in airing releases), 480p (no profile needed on non-10bit), 2160p-Main10 (this is the Main 10 profile of HEVC x265). This section is pretty easy to understand and hard to get wrong.



Source Media: Where your media comes from! Source tags have changed over time, and some abbreviations are okay if desired. Source Media tag only applies to video.  Possible sources include:

ENCODED FORMATS: The video was encoded from this source media. It has been compressed and possibly filtered by the encoder (tagged at the end of the file). 

  • BluRay/BD: feel free to abbreviate if you wish.¬†
  • DVDRip/DVD
  • WEBRip: This is taken from a WEB source (Netflix, Amazon, Funimation, Crunchyroll, etc), either by a capture card or by direct download and then re-encoding the video.
  • HDTV


REMUXED FORMATS: These formats are the video taken from the source untouched, using software like eac3to, MakeMKV, etc. They can still be remuxed with subtitles, other audio tracks, etc, but the video track has not been altered in any form from its original source.

  • BluRay.Remux
  • DVD.Remux
  • WEB-DL


Audio Format: Audio formatting should be included as a notation of lossless availability or otherwise. This will also stave off questions of why your releases are so bloated if you include the audio and channelcount, as FLAC 5.1 is massive.

Note that the channel count should be included. Most, if not all Western media (including virtually all Funimation dubs) is released in 5.1 surround, if not higher, but Sentai/Aniplex dubs are in 2.0, Hulu streams are in 2.0, etc. Channel counts can vary quite a bit these days, so it is a very useful piece of information to include.

Audio formats and their respective tags:

  • Free Lossless Audio Codec: FLAC
  • Dolby Digital (also known as AC-3): DD
  • Dolby Digital Plus (also known as Enhanced AC-3 or E-AC-3): DDP
  • Advanced Audio Codec: AAC
  • DTS
  • Atmos
  • TrueHD


Channel counts are marked with a notation of Primary Channels.Low Frequency Channels. Stereo sound (e.g. Front Left, Front Right) is just 2.0.

Standard surround sound (Channel positions : Front: L C R, Side: L R, LFE) is 5.1, as  there is one LFE track. If multiple LFE tracks are listed, you might have 7.2 audio or so on.

Some unusual cases occur, like Girls und Panzer, which has 2.1 audio (Channel Positions: Front: L R, LFE). 


Encoder: This one's really simple. Include whatever encoder was used to make the video. Possible options are H264 (usually only BluRay.Remuxes), x264, H265 (some WEB-DLs, UHD.Remux, etc), x265, so on. 


Group Tag: Your group tag goes here. A few important notes.

  • DO NOT EVER USE THE ORIGINAL GROUP TAG. If you are remuxing an existing group, do¬†not¬†use something like "FFF-Remux" or any derivative¬†of the original. You should only use a tag containing another group's name if you are directly working with that group to produce the release. If they don't give permission to use their tag in the filename, do not include it.
  • Even if you only plan to do the one release and be done, still include a group tag of some kind. Even if it's just your username. Don't use a generic tag like [BBT-RMX]. By using a generic tag you've lost the entire purpose of having group tags, as a generic tag does not give any real information about what sort of release it is.
  • Group tags should not have spaces or punctuation.
  • Consider using a shortened version of your full group name if it's particularly long. For example, GoodJob!Media tags their files as [GJM]. I tag my files as CTR instead of "Catar".


[CRC32]: A CRC32 is included at the end of every file. These are used to verify files did not get corrupted when moving between devices, as well as to verify one has the right version of a file. CRCs can be added to files easily using RapidCRC. 

CRCs will change if any part of the file changes, even if you only change one letter in one tag in the file. If your CRC changes, you should label it as a new version (see version numbering above). 


If you are just renaming the file, the CRC does¬†not¬†change. You can rename files as much as you like without affecting the CRC ‚ÄĒ even if it's already been uploaded to Drive or MEGA! yay.

Edited by Catar
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II. The Container

We use the Matroska video container for releases (.mkv). This container has a lot of features that can be used to store information.


This section will be very image heavy.




You can edit all of these fields in the MKVToolNix Header Editor without having to remux the file. This will save you a lot of time as you won't be sitting around waiting for disk I/O.

It will take a bit to get fast at editing the fields, but you can work through a full series very quickly with proper hotkey usage. Here's me working through a small set of Arslan episodes for a future release, as an example.


Ctrl-Tab, Shift-Tab and Ctrl-Shift-Tab will move you between files, and excessive use of Tab/Ctrl-Tab and copy paste will let you work through stuff very fast. I trust this more than batching, as I can visually see every episode being set properly as I go instead of relying on batches that have failed me in the past for inexplicable reasons.


HEADS UP: Changing any values in the header editor will cause the CRC to change for the file. Remember to re-run RapidCRC when you're done!



Container Overview




Dual Audio releases are typically aimed at English dub viewers, hence the track order listed above. To move tracks up and down, use Ctrl + Arrow keys when selecting a track.


Tracks should be ordered as follows:

  1. Video Track(s)
  2. English Feature Audio Track (the primary dialogue, sound effects, etc.)
  3. Japanese Feature Audio Track
  4. Extra English Feature Audio Tracks (Descriptive audio, alternate dubs, etc.)
  5. Extra Japanese Feature Audio Tracks
  6. Bonus English/Japanese Audio Tracks (Commentaries, etc.)
  7. English Sign/Foreign Dialogue Subtitles (aka Signs track).
  8. English Full Subtitles (aka Subs track)
  9. English Commentary subtitles (and any other subtitles)
  10. Chapters (note that this will automatically always move to the bottom, and can't actually be re-arranged. If you have any tracks below it, they will be moved when you re-open the file).



Video Tracks

Video tracks should be labeled with the encoder's tag. The Language tag should be set to the origin country of the source media. If this is unknown, mark the language as unknown. Many encoders include the full file information in this tag already; if it's already included, no need to change it.



Multiple video tracks can be used, as in the case with [philosophy-raws] release of Ouran High School Host Club. Because the US BD is less cropped and contains more details, but the JP BD had less banding, philosophy-raws elected to encode both. In that case, you would label both video tracks with their respective language tags, so the viewer could see which to choose from.




Audio Tracks

The audio track that you intend the viewer to watch in should be set as default and listed first. If this is an English-dub dual audio release, put English audio first and set as default.

Audio tracks naming isn't technically required, but I include it as a convenience to Kodi users as well as a way to credit my audio sources (generally @Etzimal). 

I will be using the media center Kodi as an example, but the following applies to most media centers or servers in general (half of which are based on XBMC/Kodi anyway). This gives us a useful baseline to make assumptions from.


In Kodi, audio will appear in the menu as such:



The Language tag is already rendered, so there's no need to include it in the title over again, but the format is not, so I include it in the title tag. There is a slight redundancy in that 2.0 and Stereo are both listed, but Kodi does not handle formats like 2.1 very well, as seen in Girls und Panzer here:



Given this, having the channel count always included is better in the long run.




Subtitle Tracks

Traditionally, subtitle tracks should be marked according to the language track they should be played with. For example, English audio and English signs would get the ENG language tag, and Japanese audio and English Subtitles would get the JPN track.

This is a standard established by dual audio groups like Exiled-Destiny way back in the DVD era, but is not necessarily required anymore thanks to the Forced flag.


This is where we can do some cool things. There is a flag on all tracks called "Forced". This flag is a little unintuitive, so bear with me:


  1. A player loads the video and audio tracks, then decides if it needs to have subtitles or not. Most players assume by default that a viewer does not want subtitles.
  2. If a player encounters a Forced track, however, it will then enable subtitles regardless of the user's preference. 
  3. The player will enable the Forced subtitle track that matches the user's language preference for subtitles. 
  4. However, if the player does not find a Forced track that matches the user's subtitle preference, it will fall back to the default subtitle selection.
  5. If the user then enables subtitles after starting the video, the player will swap to the next subtitle track, which is your full subtitles.


The Forced flag is intended to be used on the default audio track for all subtitles and signs not in the default language. This is a standard flag used by all media, and is even included in Netflix WEB-DLs, BluRay video files, etc. 


If a user has set their player to ask for Japanese, the Signs track will not be enabled, even if it has the Forced flag.


If the user has set their player to ask for English, the Signs track will be enabled.


If the user has not set any preference (THIS IS THE MAJORITY OF USERS, ESPECIALLY NEWCOMERS), the Signs track will be enabled alongside the English track. This is ideal, as Signs tracks should always be enabled for English audio viewers, and this also means that users don't have to have special subtitle rules just for anime.



The Forced flag also is the only way to differentiate subtitle tracks in Plex currently. 



Unfortunately, Plex (and some other players) do not support the Title tag for subtitle tracks. Because of this, the Forced flag can be utilized to show which track is the Signs track.

(This also means that remuxers who prefer all subtitle tracks to be in English can use it to differentiate their Signs and not use Japanese as the flag).



The Forced flag has no disadvantages for Subtitled viewers of dual audio releases, and significant advantages for English/Signs viewers. It should always be applied.





Chapters have never been standardized, even among scene. The general consensus amongst anime is that at minimum, there should be a chapter mark at the OP, beginning of the episode proper, the ED, and any post-ED content, as applicable. Extra chapter marks can be included at the muxer's discretion (post-episode preview, mid-episode break, etc.) An easy rule of thumb is that if it's on the original BD, it should be on the release. For example, Madoka Magica has a full set of named chapters throughout each episode. This is rare, though.



A typical chapter set will look like this: 





The MKV format includes a field in the main container for "Movie Name". This is still used by some players to identify the video title. For maximum compatibility with your users, you can fill that field in here:


however, in all honesty I've never filled that one out myself (and received some complaints for leaving it out on occasion). Fill in as you wish.

Edited by Catar
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III. The Torrent

Making the torrent according to proper standard is also important, as this will help with cross-seeding and making sure your releases don't die out. There are two parts to creating the torrent. For this guide, I will be using uTorrent 2.2.1, which you can obtain from OldApps here. Other torrent  creators are perfectly acceptable (rutorrent, qbittorrent, deluge, or mktorrent if you want to get really fancy and automated), but I like utorrent for its ease of use, preserving all my entered properties correctly and that it still retains the "Preserve File Order" flag which some torrent creators have dropped in recent times.




  • Index: A website that lists torrents. An index is¬†not¬†a tracker. Not all indices have trackers, and not all trackers have indices. An example of an index is¬†https://nyaa.si/,¬†https://anidex.info/, or¬†https://thepiratebay.org/
  • Public Tracker:¬†A tracker that does not require any registration to use.¬†
  • Private Tracker:¬†A tracker that cannot be used without registration. Note that this does not necessarily mean it must be invite-only (though most are).


Public Torrents

You only need to make one public torrent. A public torrent can be uploaded to any public trackers you like, so long as their tracker is in the list. You should select whatever tracker you want to have the most accurate stats as the first tracker in the list, but beyond that it doesn't matter.


However, I do strongly recommend you include at least 3-4 indexless trackers in your list. These trackers stick around for forever and are unlikely to ever go down, and they can help keep your torrent alive through the turbulent world of trackers living and dying. Indexless trackers can be found at places like http://coppersurfer.tk/


The CTR Standard Trackerlist









I upload my torrents to three public indexes currently, Anidex, Nyaasi and Anirena. You can upload the same .torrent file to all three without any issue. Feel free to add or subtract from this list as you wish, but make sure there is always a blank line between each tracker or it will not work.


Remember, torrents on an index-based tracker (Anidex/Nyaasi/Anirena) will not function on those trackers until they have been uploaded to the index.



Private Trackers

Private trackers require you to make a new torrent for each one. Private trackers include BakaBT, Animebytes, AnimeTorrents, U2, etc. Your tracker will have instructions on how to properly create a torrent for them, so I won't include that here, but I will include a few important notes.


First, never upload the torrent you created at a private tracker anywhere. Users must download the torrent themselves from the tracker. Do not give a direct download link, as this contains your own personal tracker key. If you do, you'll have to reset it (and you really don't want to do that, trust me).


Second, private trackers can be cross-seeded, but only if the torrents are not identical. To account for this, you can change one of two fields in the torrent creator.




If you change the piece size, clients will recognize it as a new torrent and be able to seed to that tracker as well. This is not an ideal solution, of course. Some private trackers have started to account for this by modifying the "Source" field in torrents instead. This field is not yet editable by qbittorrent, deluge, rutorrent or utorrent, so I have not included it here. Hopefully, qbittorrent supports it soon (it's already been listed as a commit but has not been merged into 4.0.x yet).




Make sure your folder name is appropriate for your release. If you are following naming standards, it should be virtually identical to the filename of any given episode, with just the episode number and CRC dropped. For example:





It is very important you name your folders appropriately and keep them consistent between trackers, or you end up with messes like this: 


what happens when other people who don't know what they're doing upload my releases to AnimeTorrents ._.



The easier you make it to cross-seed, the more likely it is your torrents will survive and thrive.

Edited by Catar
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Again, this guide is just an optional standard to follow. I'd love to see these implemented across all releases, but I'm not that optimistic.

Since you made it to the end of the guide, be aware that I'm happy to mirror and provide basic hosting for any projects that follow this standard. If you use it, feel free to @tag me in your release thread and I'll pop by to provide XDCC mirroring on command. Please don't tag me unless you actually have files up and ready though, or I might miss your later edits in my flood of notifications.

any thoughts or hatemail can be left below. I'm also open to suggestions or improvements, as always. thanks for reading.



Edited by Catar
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yay I can edit my bookmark now, thanks

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Note for consideration: BTN releases most typically have Hi10P after codec (x264/etc) in the naming order, rather than resolution (1080p/etc).





I don't really care for how the dash-dash syntax looks at the end, but it makes sense to include it with the codec in the naming order.

Edited by shamil11

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10 minutes ago, shamil11 said:

Note for consideration: BTN releases most typically have Hi10P after codec (x264/etc) in the naming order, rather than resolution (1080p/etc).





I don't really care for how the dash-dash syntax looks at the end, but it makes sense to include it with the codec in the naming order.

true. However, you don't actually have to use this in your filenames, only in the "release name" (i.e. the name of the torrent). So you can still follow the above naming instead and upload it to BTN unchanged (since we're "P2P" groups here), which I prefer. I like keeping video profile information all in one place, so you see it's 1080-progressive-High 10 profile.

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My setup's such that I have to use mktorrent. How should I choose piece size?

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11 minutes ago, The0x539 said:

My setup's such that I have to use mktorrent. How should I choose piece size?

mktorrent supports setting the piece size with the -l flag. The argument is a power of two in bytes. For example, -l 19 == 524288b, or 512KB.


Stolen from bytesized-hosting:

219 = 524 288 = 512 KiB for filesizes between 512 MiB - 1024 MiB

220 = 1 048 576 = 1024 KiB for filesizes between 1 GiB - 2 GiB

221 = 2 097 152 = 2048 KiB for filesizes between 2 GiB - 4 GiB

222 = 4 194 304 = 4096 KiB for filesizes between 4 GiB - 8 GiB

223 = 8 388 608 = 8192 KiB for filesizes between 8 GiB - 16 GiB

224 = 16 777 216 = 16384 KiB for filesizes between 16 GiB - 512 GiB This is the max you should ever have to use.

225 = 33 554 432 = 32768 KiB (note that utorrent versions before 3.x CANNOT load torrents with this or higher piece-size)

This is a pretty solid breakdown of advised piece sizes. I'd also say 16MB pieces aren't usually necessary either, but if you're making a really large torrent (BDMVs, Scyrous, etc.) then go for it.

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