Why convert m2ts to mkv ?

[dude905]

Hi ... I notice if i rip my blu ray movie unto my hard drive and change only one option from the software ripper I am using ? The English language selection option, the movie is still large in gb size . But if I convert m2ts to mkv its roughly a quarter of the size ... Is it not the case as to why most people convert m2ts to mkv because they don't want all the extra languages ? I mean the video output is the same , no ? 1080 to 720 ... Or is their more loss beside the audio ? Thanks

[fritzi93]

Just to be clear on the terminology, "ripping" is generally understood here to mean decrypting/copying to hard drive. If you're "converting", you're putting the video into a different container, and perhaps re-encoding as well.

MKV is just a container. If the file size is widely different after putting the video into an MKV, you've either de-selected some streams and/or re-encoded to reduce file size.

You don't say what "software ripper" you used, but I suggest you look more carefully at the settings you used. Anyway, yes, if you didn't re-encode, you've merely put the video in a different container, with no quality loss.

The advantage of a container like MKV is that a wider range of (free) software players can play it with selectable audio, subs and chapters, as opposed to Blu-Ray with menus. You can still play BD files (no menus) with most players by selecting the playlist file (mpls) or the m2ts, but it's convenient to play an MKV without having to drill down into the directory. Note that you can extract movie-only from a BD and/or re-encode to reduce the file size as well, while outputting BD files.

[dude905]

Thanks for responding ... I'm using dvdfab hd ripper and yes i am just ripping to hard drive and just selecting the English language only option . If it's in m2ts it's huge and if it's in MKV style it's way much less . So what happen while it's being rip to mkv as towards size , I mean is any of the video part being loss ? Thanks

[redwudz]

You will always loose some quality on a re-encode, but H.264 used in a MKV container is a very efficient codec and you can minimize quality loss while still getting a much smaller file. I use RipBot for BD>MKV backups. I size the resulting file to about 8GB and the quality looks quite good. I also convert the audio to 5.1 AC3 to save space. I also toss out extras, alternate languages and subtitles since I have the original disc and I don't need those taking up hard drive space.

The downside of conversion to MKV is that it takes a lot of computing prower to encode quickly and a fair amount for playback. I use two pass, but a single encoder pass with a constant quality setting of about 20 should retain quite a bit of quality and still reduce the file size, and is much quicker than two pass encoding. Most times you can reduce the size to about 1/4 of the original size and still retain quite a bit of the original quality.

[fritzi93]

If it's in m2ts it's huge and if it's in MKV style it's way much less . So what happen while it's being rip to mkv as towards size , I mean is any of the video part being loss ?

MKV requires less overhead but not a big difference. So Fab must be re-encoding, and yeah, that means quality loss, no way around it. There has to be a target size setting you're missing. I've only used Fab to encode a few times, enough to satisfy myself that other options are better.

Fab's encoding isn't all that good. You'd be better off just ripping with DVDFab, then converting/re-encoding with something else. Like RipBot per redwudz' suggestion, or BDRB.

[EDIT] Can you put a specific number on "huge" or "way much less"? That would be helpful.

[dude905]

I only convert to m2ts files not mkv but I notice when ever my friend would give me his hd movies they were in mkv and they were much smaller in size ... So if I understand you correctly he must of re-encoded with a software which does just that and this so call software made it smaller in size once it got converted ? Thanks