General MKV question re. file size and compression

MKV playback, recompression, remuxing, codec packs, players, howtos, etc.
Post Reply
OliverTwist
Posts: 35
Joined: Wed Oct 09, 2013 2:04 am

General MKV question re. file size and compression

Post by OliverTwist » Tue Dec 20, 2016 5:42 am

I'm in the midst of re-organizing my collection of animated short films and I've come upon a strange circumstance that I'm hoping someone might be able to lend some insight into...

I've got several duplicate film shorts of roughly 7 min. lengths from different sources. I'm currently sorting through these to replace certain films that are incomplete or less than ideal (i.e. lacking original title and end cards, etc). While doing so, I've been able to "upgrade" certain standard definition films with new BD-Rips.

In analyzing and comparing the films, I've noticed that a 7 min. animated short in SD has a file size of 1.89 GB while the same 7 min. animated short in 1080P has a file size of 291 MB. Is this entirely the result of advances in encoding technology?

I'm trying to understand how an MKV file which is of considerably higher resolution can be so much smaller in size than one of much lesser quality?

This might sound dumb, but I'm almost hesitant to delete and replace the SD files out of paranoia that there must be some flaw that I'm overlooking.

I also don't completely understand how or why an MKV rip of a 7 min. theatrical cartoon can exceed 1 GB in file size; roughly the equivalent of a feature length SD-Rip, depending on encoding methods?

Can anyone please shed some light on this.

Woodstock
Posts: 6916
Joined: Sun Jul 24, 2011 11:21 pm

Re: General MKV question re. file size and compression

Post by Woodstock » Tue Dec 20, 2016 3:04 pm

Yes, modern compression can do wondrous things on file sizes, especially for animated stuff.

Anohana the Movie, raw BD rip size, 31.5GB. Compressed by handbrake using h.264 compression, just under 2GB. Compressed using h.265 compression, 1.1GB.... Although a lot fewer players can handle h.265 files.

Visit handbrake.fr if you want to start playing with compression. The combination of MakeMKV to rip and handbrake to re-encode more efficiently can give you much more space on your media server. Other content doesn't compress as well as anime (usually) does, but it is rare to not save at least 30% on space by using a better encoding.
How to aid in finding the answer to your problem: https://www.makemkv.com/faq/item/8

ndjamena
Posts: 830
Joined: Mon Jan 07, 2013 12:23 am

Re: General MKV question re. file size and compression

Post by ndjamena » Wed Dec 21, 2016 3:03 am

A 1.89gb 7 minute SD clip would actually use a bitrate three times that allowed by the DVD standard. Since DVD is the best available consumer source of SD content and everything else would use a lower bitrate your file was either re-encoded by an idiot or you've misinterpreted something.

Either that or you have a master or an intermediate.

OliverTwist
Posts: 35
Joined: Wed Oct 09, 2013 2:04 am

Re: General MKV question re. file size and compression

Post by OliverTwist » Wed Dec 21, 2016 7:06 am

Well if it was re-encoded, I must be that idiot. :)

It's possible (though unlikely) that I trimmed the file using MKVToolnix and possibly re-encoded it somehow without knowing it. The files all came off my own DVDs so there are no other idiots to blame this on.

As for the BDR, I also ripped straight from disc, which is why I find the file size so surprising. As far as I'm aware, I didn't play around with compression so it must've been the way the file was originally encoded...

ndjamena
Posts: 830
Joined: Mon Jan 07, 2013 12:23 am

Re: General MKV question re. file size and compression

Post by ndjamena » Wed Dec 21, 2016 10:37 am

https://en.wikipedia.org/wiki/DVD-Video
DVD-Video discs have a raw bitrate of 11.08 Mbit/s, with a 1.0 Mbit/s overhead, leaving a payload bitrate of 10.08 Mbit/s.
1.89GB for 7 minutes = 1,890,000,000 / (7x60) = 4,500,000 BYTES per second which is 36000000 bits per second or 36 Mbits/s.



Season 3 episode 17 of Teen Wolf has a file size of almost 1.9GB, lasts for about 45 minutes and has a bitrate of 6,206 kb/s, which is more than half of the maximum DVD bandwidth.

There's something off with what you're saying, and unless you can figure out what exactly your question is kind of redundant. Are these supposed to be commercial disks?

Post Reply