Blu Ray to MKV (.x264) - What is the compression?

[james_stewart]

I have a 4.3 gb mkv file of the movie Casino Royale (it's a movie I own on blu ray). The file is supposed to be 720p with AC3.

Is there compression and loss of quality that goes into converting this Blu Ray movie into a 4.3 Mkv file? If so, what is the loss of quality? Back in the day when I was trying to squeeze a entire DVD movie onto a 4.7 DVD I saw significant loss in quality. I'm just wondering if this is the same thing. The reason I'm testing this movie is because I want to eventually convert my Blu Ray library into some form of movie file.

thanks in advance.

[poisondeathray]

"Visual quality" is a subjective measure, so you can't put a number on it very effectively

You need a proper setup (in terms of hardware and viewing distance) to get the most out of blu-ray and see the differences clearly. eg. If you are viewing both on a 720p you might not see the differences as clearly as if you were watching on a 1080p

If you look at the video bitrate, the blu-ray might be ~25mbps and the .mkv might be ~5mbps, so in this example it would be 5x the bitrate. Does that mean 5x the quality? of course not - because quality is very subjective

If you look at the pixel count, 1920x1080 has 2.25 more than 1280x720.

The encoding settings used can make a difference on quality as well

[Dschultz]

While I am absolutely NO expert in this matter, I can speak a bit about this.

My initial plan was to have a means by which I can watch any and all of my movies using my Media Center and 42inch 1080P LCD Television. Things just all came together at the right time. The 42inch TV's came down in price below the $1,000 mark for a 1080p, the BluRay drive that I could slip into my media center came down below the $150 mark. Not to mention that Bluray has become the standard now in the standard war. Add the fact that the selection of BluRay movies has skyrocketed... I was now ready to make the move from DVD to BluRay.

Biggest question. How much am I going to loose when I turn a 1080p 2 hour long BluRay movie into a 12-15gig MKV file?

I don't know all the technical terms... I don't know a whole lot about what the geniuses and serious hobbyists do on this website but I do know one thing... my 20/20 vision works and I can use my eyes to see if the loss is too much to go forward with my project.

I loaded a Bluray movie (The Dark Knight) into my BluRay player and filled 1/2 of my screen with the movie straight off of the BluRay using PowerDVD. I then filled the other 1/2 of my screen with the MKG file I ripped and converted from the BluRay movie.

The verdict?

Slight, very very slight difference. The very new movies that were recorded in high definition look great in both formats but the old movies that were upconverted to BluRay do not look quite as good. Is it a HUGE difference? Absolutely not but in old movies.. and especially when there is a lot of black in the screen, you can see some pixels. Some tiny dots where the black is NOT pure black. But when you watch the BluRay, you don't see those tiny dots in the pure black.

If you want more details on what I use to watch my movies, let me know. I'm happy with the way the newer movies look (10 years ago and newer) but the old movies... don't look so good after the converstion.. but then again... they don't look great on BluRay because... let's face it... they were never meant to be seen in such high detail. 1999's The Matrix looked fantastic. Blade from 1998 looked awesome! So even 10 year old movies look good after conversion.

[jman98]

Biggest question. How much am I going to loose when I turn a 1080p 2 hour long BluRay movie into a 12-15gig MKV file?

Not much in my opinion. If anything, I'd say that at 12-15 GB your final MKV file might be almost indistinguishable from the original source.

[poisondeathray]

Honestly I don't bother anymore, hard drives are much more affordable now.

A big HD can store many blu rays in the fraction of the space and quality is 100%. The time you save from re-encoding everything is priceless IMO

[redwudz]

The OP seems to be asking if a ~25GB Blu-ray converted to a 4.3GB MKV will have a quality loss. Yes, a lot, IMO. However, as mentioned, converting to a ~12 - 15GB MKV should have minimal quality loss, especially if you only convert the main movie and 'lose' the extras.

[RabidDog]

Why bother buying the old movies on Blu-ray? surely they will lose nothing simply by being upconverted from DVD. Its possible Blu-ray exceeds the quality of the original film. Gspot will tell you details of any avi file.

[redwudz]

Gspot will tell you details of any avi file.

It has a problem with MKV format, but MediaIfo seems to mostly work.

As a test, I recently converted a Blu-ray I own to a 4.3GB MKV. It looks better than any of my commercial DVDs when projected on my video screen. (It also took about 5 hours to encode. ) Does it look as good as the original Blu-ray? No, but still very good. The compression was from 23GB to 4.3GB, main movie only.

[dimtim]

How do you have the dark knight already? I thought it didn't come out until December?

[jagabo]

As a test, I recently converted a Blu-ray I own to a 4.3GB MKV. It looks better than any of my commercial DVDs when projected on my video screen.

1920x1080 h.264 BD to 1280x720 h.264 MKV?