newbie file size questions

[btk55343]

I have a lot of ripped dvd files using dvdshrink. I'm starting to run out of storage space.

Recently, I have gotten some .mp4 video which I then convert to .mkv so my player will play them.

It appears that the .mkv files are about a tenth the size of the video_ts files. If I converted my dvd files to .mkv I would no longer have storage space issues.

Can anyone speak to what I will lose if I do convert everything to .mkv?

[Chetwood]

Nothing, cause MakeMKV does not compress the video. You would need Handbrake to compress.

[ndjamena]

This is what a Vob File is:

http://en.wikipedia.org/wiki/MPEG_program_stream
http://en.wikipedia.org/wiki/Packetized ... ary_stream

This is what a Matroska file is:

http://www.matroska.org/technical/specs/index.html

Basically, the amount of bytes Matroska uses to organise the information it contains is less (vob files repeat themselves a lot, which ultimately is unnecessary for playback).

Among other things MP4s contain rather detailed descriptions of each and every frame within the file in its index. Matroska doesn't bother, it has a relatively simple index that just points out where the important frames are located in the file.

It's called "container overhead" and Matroska has a lot less of it, that's all you're losing.

(If you remux the mkv back to an MP4 or vob, you'll get all that overhead back, just as if it had never gone.)

[btk55343]

Thanks for all the quick replies.

Sounds to me like there is little downside to converting my vid files to .mkv. It sounds like there will be no loss of video quality.

It will just take a long time as converting the files is a slow process...

[ndjamena]

The only thing I'm aware of you might be losing if converting DVDs to MKV is 608 closed captions, but that's only an issue with NTSC discs. If you really want to preserve 608 in an mkv, you'd need to run ccextractor on the vobs and convert them to srt (which loses all the formatting). MP4 takes captions, but it's fiddly and unless you plan on playing the thing in iTunes there's not much point in trying.

[ndjamena]

FFMPEG MKV 889,613,257 bytes
FFMPEG MP4 889,789,933 bytes

MP4Box 889,539,635 bytes
MKVMerge 889,292,478 bytes

All muxed from identical streams.

Less than 1% difference but the MKV wins.