How low can you go?

[jntaylor63]

When it comes to the timeless question "What's the lowest bitrate I can use for DVD and still look good", no one can answer.

The only thing I have been able to help me guess is a minute to file size example.

Take Backdraft for example. This moive has a great soundtrack and picture quality. If you rip it as main movie only, you get a 135 min movie, 5.1 soundtrack, one subtitle and it all comes out to 4200 mb in size. If you run it with a bitrate calc the ave bitrate is about 4.0 mbps.

Is that the magic lowest number? I guess its a good start, but Hollywood has much better encoders than we have. (Would bet that CCE and some others would give them a run for the money)

So when backing up my DVDs, I use DVD-Rebulider with the HQ encoder (Highest Quality) and only as a main movie option. My floor is 125 mins with 5.1 AC3. After that, I'm looking at doing Dual Layer Disks.

Hope this helps some people here, I'm sure many will have a different say on this subject.

[whitejremiah]

this has been discussed time and time again....there is no "magical" number....what it amounts to...well, there's a few things...the reason hollywood can get away with it, is first off they use professional encoding programs, and secondly they are generally sourcing from an even HIGHER quality input than what us "amatures" use.........secondly, what looks "good" to one person, looks like garbage to another person........another thing to consider is the compressability of the video....videos with more action require higher bitrates to look decent compared to differant videos with little action...there's not really a set number, it's all kinda in the eyes of the viewer...and by the way, there's some people with monstorous tv's that will argue that even retail dvd's such as the one you mentioned has visual flaws when viewed on that type of tv.....heck, you can even see it to some extent on a pc monitor, most likely.....hollywood may use higher quality programs than what we use, however they arent miricle programs....

[yoda313]

Hollywood has much better encoders than we have.

It's not that it's that they have the original masters to work with. And also they press their discs professionally so it meets the dvd specs. And they can do pro-level dual layer discs that work right so as to get a good quality picture.

Personally I don't really care about percantages in shrinking too much. I dump the extra audio except for commentary on some movies. Sometimes I keep extras a lot of times I do just the movie only. Depends on the particular disc.

Since I only have a standard def tv right now anything looks just fine. Though I have noticed some blocking if I push it to the 50% range so I try to not go belwo 60 ish. Generally though I never notice the compression.

[lumis]

It's not that it's that they have the original masters to work with. And also they press their discs professionally so it meets the dvd specs. And they can do pro-level dual layer discs that work right so as to get a good quality picture.

having the original master would matter.. but having your discs pressed professionally so they meet dvd spec really doesnt matter much in terms of quality.. it wouldnt matter if you burned it to a dvd-r, dvd+rw or watched it from your hdd. the quality would still be the same.. it's not the medium it's on that makes the difference, it's the source, as you mentioned, and the encoding method.

i'm sure they've got hundred thousand dollar machines that transfer the original film to a super high quality digital format, which they then encode to dvd.. and any other format they want.

[ROF]

When it comes to the timeless question "What's the lowest bitrate I can use for DVD and still look good", no one can answer.

There is no single answer to this question. It's subjective to the viewer. Some people claim to use DVD shrink at 75% and can't tell the difference between the original and horribly compressed version. To them the magic number for shrink may be 55%. To me the magic number is 92%. Anything less than that and I find it unacceptable to my viewing standards.

[mikiem]

My own 2 cents...

As ROF, start to worry when shrink gets into the lower 90's -- figure time for re-encode. For vbr re-encode *usually* an average of ~5 is as low as I'll go, & then I'll look at other options.

[SCDVD]

Hollywood has much better encoders than we have.

I dump the extra audio except for commentary on some movies.

That's a good way to save some space. It's a good idea to check which audio tracks you take out though. a couple of times in the past I have inadvertently deleted the main sound track and was only left with the director's commentary sound track.

[edDV]

Easy answer and should be obvious to the clueless

Lowest possible realtime bitrate is 23.976 or 24 BITS per second.

That would be one colorless pixel. If you want 255 levels to your pixel then you are up to 24x8=192 bits/s. If you want more pixels, add more.

352x240 flickering monochrome pixels would be ~2Mb/s but you can apply MPeg1 or Mpeg2 compression under the DVD spec. as you see fit. Don't forget to add audio. If you want color in 4:2:0 add 50% more bitrate.