Re: Lossy & Compression (sort of on topic)
From: Digger (nospam_at_junkmail.com)
Date: 03/29/04
- Next message: timwerx: "No Audio; VCR connection to MM2"
- Previous message: Julie: "Media audio won't go away"
- In reply to: Bob [MVP]: "Re: Lossy & Compression (sort of on topic)"
- Next in thread: noone: "Re: Lossy & Compression (sort of on topic)"
- Reply: noone: "Re: Lossy & Compression (sort of on topic)"
- Reply: Bob [MVP]: "Re: Lossy & Compression (sort of on topic)"
- Messages sorted by: [ date ] [ thread ]
Date: Mon, 29 Mar 2004 02:31:01 -0600
Bob, someone asked for an opinion and I gave one. I was speaking in broadly
defined terms and used "virtually lossless" only in a reference to the
difference between I-Frame and let's say GOP = 18. Reading carefully, you
will no doubt note the semicolon immediately preceding the phrase, and yes,
it was indeed a reflection back to the original subject..."I-Frame only."
If that was misleading, my apologies to you and all others mislead. I never
intended for anyone to think that the process of mpeg encoding is lossless.
As for losses incurred during transcode to lower bitrates, yes, losses are
inevitable and I would think most good folks understand the concept.
Perhaps I am wrong, but I do not think it is always necessary to state the
obvious. Considering the DVD standard is currently about as good as it
gets, motion compensation is literally a fact of life at burn-time anyway
and thus, for purposes of archival, it is simply an either - or - situation.
I choose to save the space up front. I do not however, encourage anyone
else to use my system to the exclusion of all other alternatives, but yes,
it works for me.
As I understand newsgroups, you are certainly free to offer your own
thoughts regarding a less compromising system for permanent archival. Your
reply seems to suggest a fairly good understanding of means and methods and,
as such, I would highly encourage you to contribute something more
beneficial to everyone here, including myself. I look forward to seeing
your own suggested solution with great interest.
-- Digger "Bob [MVP]" <bob@nospam.org> wrote in message news:uDlr4UJFEHA.2768@tk2msftngp13.phx.gbl... > Digger, it's nice that you found an archive format that works for you, > but to claim to get "virtually lossless" MPEG-2 compression???? C'mon > now... > > With I-frame-only encoding, you won't be performing any temporal > compression. But since your total bit rate is fixed at 8Mbps, you will > get more spatial compression. > > If your video has lots of motion, but not very complex images, the > I-frame-only encoding can produce good results. But if you have video > with complex images, and not a lot of motion, the I-frame-only encoding > will produce worse results. > > You can't have your cake and eat it too, and you can't get the same > quality with 8Mbps MPEG-2 as you can get with 25Mbps DV. > > -Bob > ____________________________ > Microsoft MVP > Windows XP Media Center Edition > www.microsoft.com/ehome > > > "Digger" <nospam@junkmail.com> wrote in message > news:ONxJtvIFEHA.2052@TK2MSFTNGP10.phx.gbl... >> My own opinion is that any archive format should, even though > compressed, be >> at least as good as DVD in terms of quality. I have personally > settled upon >> MPEG-2 (Constant bitrate, 8000 kbps, 720x480, 29.970, I-Frame only) > and LPCM >> Audio (lowest common denominator). The DVD standard is maxed out at > 9000 >> kbps and so, in terms of bitrate, I really haven't lost much. >> >> Irregardless, at 8000 kbps one can easily fit 60 minutes of high > quality >> video data per/ DVD+R and, using MPEG-2, the files are already in a > format >> suitable for subsequent editing, additional compression to other > formats, >> and/ or burning directly to DVD. The idea here is to archive the > source >> files as I-Frame only; effectively assigns a GOP = 1; DV format is >> essentially an I-Frame only format; virtually lossless mpg > compression. >> >> -- >> Digger >> >> "QuietDavid" <davidxxx@REMOVE-ME-TO-REPLYtpg.com.au> wrote in message >> news:4065702D.1B39BA33@REMOVE-ME-TO-REPLYtpg.com.au... >> >I am wondering how othr people store their movies - I found that 60 > minutes >> >of shooting results in a 13 gig file when I save it to my HD. > Although I >> >have >> > just fitted a 120 gig HD for my movie work, it will not take long to > fill >> > that up. >> > >> > Leaving the shots on miniDV tape is too expensive for me, and to > save them >> > on DVD means using 3 to 4 DVDs for each hour of shooting. That too > is >> > will get >> > pretty expensive after a while. >> > >> > Naturally it is no good storing them in one of the compression > formats >> > that result in losses, so what do others do? >> > >> > When I make them into a movie they go on DVD OK, but that is no good > for >> > the clips that I might want to use for another movie later on. >> > >> > Ideas much appreciated >> > >> > David >> > >> > noone wrote: >> > >> >> hello bob I am not the person who wrote about massive amount of > storage >> >> space. 30% is at least a significant saving I think anyway lets > leave it >> >> at that >> >> >> >> ----- Bob [MVP] wrote: ----- >> >> >> >> > So zipping DV-AVI files for archiving clips after finished >> >> > with a project should save massive amount of storage >> >> > space, correct, or not? >> >> >> >> This is the message I had originally replied to. So I guess > you and >> >> I >> >> just have a difference of opinion as to the definition of > MASSIVE. >> >> Anyway, glad to hear you're satisfied with the results you're >> >> getting >> >> with WinZip. Zip away!.... >> >> >> >> -Bob >> >> ____________________________ >> >> Microsoft MVP >> >> Windows XP Media Center Edition >> >> www.microsoft.com/ehome >> >> >> >> >> >> "noone" <anonymous@discussions.microsoft.com> wrote in message >> >> news:2133D7DA-757E-436E-8419-27712178CA38@microsoft.com... >> >> > I seem to have missed several messages on this topic. I had > not >> >> realised that a comparison between what you can get with a bmp >> >> against a >> >> jpeg still image was in question or that putting the resultant >> >> compressed file onto a cd. I just wanted to say that here I > can >> >> compress >> >> a DV-AVI file so that it ends up being 2/3 its original size, > I have >> >> now >> >> tried it with the three files I have the results were 30% for > a >> >> 114mb >> >> file, 34% for a 1.8gb file and 28% for a 1.5gb file. I would > say >> >> that >> >> that result is a long haul from what bob said. maybe i am > wrong but >> >> lets >> >> not labour it any more >> >> >> ----- PapaJohn (MVP) wrote: ----- >> >> >> When I think about compression, like taking a BMP > image and >> >> making a zipped >> >> > file from it, I expect about 85% compression.... and I > don't >> >> expect much >> >> > gain when compressing a JPG.... >> >> >> I think Bob's point is valid in that the gain by a > zipping >> >> isn't >> >> substantial >> >> > because of the already compressed nature of the > format... but >> >> sometimes a >> >> > 30% gain is all you need to make a short DV-AVI clip > fit on a >> >> CD >> >> without >> >> > having to get into multiple discs. >> >> > -- >> >> > PapaJohn >> >> >> Movie Maker 2 - www.papajohn.org >> >> > Photo Story 2 - www.photostory.papajohn.org >> >> >> .. >> >> > "noone" <anonymous@discussions.microsoft.com> wrote in >> >> message >> >> > > news:4D2B7A3C-82FB-41DB-9259-F95106AE691F@microsoft.com... >> >> >> Hi Bob, yes thats right, you did not say you could not > compress >> >> it....you >> >> > said You will not be able to compress it much (if any) > more >> >> by >> >> zipping it >> >> > and all I was trying to show was that even with a > fairly >> >> small >> >> DV-AVI you >> >> > can get up to 30% compression. as the size of the file > to be >> >> compressed >> >> > increases then usually so does the chance of even > higher >> >> compression. >> >> >>> you should try compressing a small file you can sometimes > end >> >> up with a >> >> > file that is bigger than the original and thats because > of >> >> the >> >> gain >> >> > compressing the small file is less than the overhead in >> >> tagging >> >> all the >> >> > code. >> >> >>> I did not realise that DV-AVI was compressed I always > thought >> >> it was a >> >> > differential stream of data and sometimes called RAW. I >> >> suppose >> >> you could >> >> > call that a compression of a kind. >> >> >>> you might also be interested to know that the new version > of >> >> winzip has an >> >> > even higher compression capability. I did not use that > higher >> >> ability in my >> >> > examples because it is only available to users of > version 9. >> >> >>> ----- Bob [MVP] wrote: ----- >> >> >>> I didn't say you could not do it. I just said you >> >> wouldn't be able >> >> > to >> >> >> compress it much more. And the reason I suggested > that >> >> you not waste >> >> >> your time, is that I assumed you were going to try to >> >> compress much >> >> >> larger files, like several GB. >> >> >>> But the main point I was trying to make was that > DV-AVI >> >> video _IS_ a >> >> >> compressed format. Many people incorrectly believe it > is >> >> > uncompressed. >> >> >>> -Bob >> >> >> ____________________________ >> >> >> Microsoft MVP >> >> >> Windows XP Media Center Edition >> >> >> www.microsoft.com/ehome >> >> >>>> "noone" <anonymous@discussions.microsoft.com> wrote > in >> >> message >> >> >> > news:96F02072-2120-4101-9915-CF8814FCC70A@microsoft.com... >> >> >>> My message was to Bob, who said that you cannot zip a > DV-AVI >> >> file. >> >> > I >> >> >> was telling him that you can by up to 30% and still > have >> >> access to >> >> > the >> >> >> uncompressed format of DV-AVI. It was not meant in any > way >> >> to be a >> >> >> comparison over what the uncompressed video quality of > a >> >> DV-AVI would >> >> > be >> >> >> like when compared to the highly compressed and lossy >> >> format of WMV >> >> >>> >> > >> >
- Next message: timwerx: "No Audio; VCR connection to MM2"
- Previous message: Julie: "Media audio won't go away"
- In reply to: Bob [MVP]: "Re: Lossy & Compression (sort of on topic)"
- Next in thread: noone: "Re: Lossy & Compression (sort of on topic)"
- Reply: noone: "Re: Lossy & Compression (sort of on topic)"
- Reply: Bob [MVP]: "Re: Lossy & Compression (sort of on topic)"
- Messages sorted by: [ date ] [ thread ]
Relevant Pages
|
|
