Why does fansubbed anime sizes fluctuate so much?

[IronicRhetoric]

After reading a couple of threads, (namely the oldest active fansub groups) this question came to mind. When I first started watching fansubbed anime from groups like ANBU, Live Evil, Anime Kraze, etc., all fansubbed anime were the same size (around 175MB). I don't know anything about encoding, and obviously encoding in 8bit, 10bit, .mp4 or .mkv will all affect the size of the file, but for now I'm referring to anime subbed by the same group using the same container and or HD standard. e.g. The fansub group GG subs Tokyo Ravens and the file sizes range from 250-440MB. Commie Log Horizon and Yibis One Piece are the same. Not to make Horriblesubs sound great as I know you all dislike the group, but they're one of the few that manages to put out encodes that are pretty much the same sizes. What exactly are they doing different?

[Quarkboy]

Originally Posted by IronicRhetoric

After reading a couple of threads, (namely the oldest active fansub groups) this question came to mind. When I first started watching fansubbed anime from groups like ANBU, Live Evil, Anime Kraze, etc., all fansubbed anime were the same size (around 175MB). I don't know anything about encoding, and obviously encoding in 8bit, 10bit, .mp4 or .mkv will all affect the size of the file, but for now I'm referring to anime subbed by the same group using the same container and or HD standard. e.g. The fansub group GG subs Tokyo Ravens and the file sizes range from 250-440MB. Commie Log Horizon and Yibis One Piece are the same. Not to make Horriblesubs sound great as I know you all dislike the group, but they're one of the few that manages to put out encodes that are pretty much the same sizes. What exactly are they doing different?

Short answers:

1. In the old days people would often backup episodes to CD-R or later DVD-R. Filesizes were usually chosen to optimize the space that episodes would take up.
2. Lately people tend to store their episodes on hard discs of arbitrary size, so exact filesizes are less important, most use constant quality encoding instead so the size will depend on the content.
3. Horriblesubs rips Crunchyroll's streaming videos, which by the nature of streaming must be somewhat consistent bitrate, leading to approximately the same size each ep.

[IronicRhetoric]

Accepting your first answer as I too have anime on DVD-R (Last Exile anyone), in essence are you saying Horriblesubs use Constant Bitrate encoding while most fansubbers use Variable Bitrate encoding?

[Quarkboy]

Originally Posted by IronicRhetoric

Accepting your first answer as I too have anime on DVD-R (Last Exile anyone), in essence are you saying Horriblesubs use Constant Bitrate encoding while most fansubbers use Variable Bitrate encoding?

Horrible-subs doesn't do their own encoding at all, they just rip legal streaming encodes.

Encodes for streaming are usually encoded so the average overall bitrate is approximately the same. They aren't "constant bitrate", however, but the average bitrate is the same for each episode.