size avi, mp4, mkv

[hotsprout]

I have converted a vob file to avi, mp4, and then to mkv, with format factory, I know that avi, mp4 and mkv, are like bottles and contain the audio and video magic stuff that creates your finished film clip, but am still confused. I was under the impression that mkv is a more modern bottle which results in a smaller film, so why is my and avi and mp4 much smaller than my mkv film.

[yoda313]

The file extension has little to nothing to do with the file size itself. That is dertermined by bitrate (and of course the "codec" used to encode it - be it divx, xvid or h264 etc). That is how much "quality" is put into the encoded video. The higher the bitrate the better the quality and the larger the file size all things being equal.

Of course you won't get better quality then the original source and you will lose some quality in just about any encoding job (albeit it should be minimal and generally only video snobs would generally be able to tell - unless you really screw around with things like resolution and tamper with a lot of settings that normally wouldn't need to be changed).

You can do filters and stuff to do some improvements to the video but there is no magical "fix it" button to press to make a video look 10 times better.

You can browse around and search the term "bitrate" for more background.

The glossary (found on the left of the screen on this website) will give you a good starting point:

https://www.videohelp.com/glossary

edit - and as I mentioned the "codec" used makes a difference in file size too. You can use just about any codec in the file extensions you mentioned. The type of video you put in it makes a difference. Newer codecs like h264 can be more compressed at the same quality level than divx/xvid - though its a little more confusing these days since the newest divx does employ its own form of h264 if I'm not mistaken).

[hotsprout]

Thanks for your swift reply:

Think I understand were I might have gone wrong, by default the mkv bottle had the avc h264 codec in and my avi and mp4 bottles had xvid codecs in. So are you saying that if the xvid video codec plus the mp3 audio codec of 128 bitrate goes in the mkv, avi and mp4 bottles I will end up with a the same size film clip from all those bottles, in a nutshell the same stuff in the same stuff out size wise.

If thats case whats the point of having 3 different bottles,other than being able to cram more magic stuff in the mkv bottle. So this gets me thinking is h264 bigger than a xivid codec, if so why is h264 considered the new king of video codecs if it makes bigger files.

[edDV]

Other things being equal, h.264 can compress more than xvid for similar quality. This would be encoding from the same higher quality source, not re-encoding. Unlike avi and mp4 bottles, mkv incorporates extra stream tech like menus and subtitles. See
http://en.wikipedia.org/wiki/Matroska

[Cornucopia]

Think of those bottles as having a certain "thickness". This is the overhead of a certain container type. There is a little difference between the various containers, but they are miniscule compared to the size of the actual media streams.

If you had V+A streams of the same kind & bitrate in each of the avi, mp4, mkv and even mov, the sizes will all be NEARLY identical. The choice of which to use should have more to do with compatibility/support...

Scott

[Sphinx121]

I am looking to store a large amount of dvds on my computer to eliminate the physical copies. I am concerned with the amount of storage it takes to save one movie (about 6gb in MKV format). Can anybody help me figure out a better solution, to save more movies in less space.

Thanks!

[manono]

I am concerned with the amount of storage it takes to save one movie (about 6gb in MKV format).

Meaning what? That when using MakeMKV on the VOBs the average resulting size is about 6 GB? And you know it's not being reencoded, don't you, if using MakeMKV? If you want a smaller size reencode using a different program and a lower bitrate.

[Krispy Kritter]

It would help if you posted the specs of each of your output files so that everyone can see what your doing. Use an app like Mediainfo and post a screenshot. I suspect the quality of each of those files is not equal.