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QUESTION: I used handbrake to convert dvd to mp4 using the placebo lossless option and I want to edit down clips from it using Corel Videostudio 8. My concern is saving new files from the original video. Are video files at all like jpgs? Do they recompress and lose data and quality everytime they are saved? How can I prevent any loss?

My ultimate goal is to use Windows DVD Maker to put the videos on a new DVD and I want to retain the same quality. I understand the DVD Maker may compress if the video exceeds a certain length, but is it safe to assume it will be uneffected if I keep it short enough?

ANSWER: Hi James

Sorry for the late reply - for some reason I didn't see the request in my mailbox.

This is quite a complex issue, and there is a good site to read up on all the ins and outs: https://ericolon.wordpress.com/2013/01/06/the-secrets-of-yify-and-high-quality-and-small-file-sizes-are-not-so-secret-after-all-encoding-high-quality-low-bitrate-videos-in-handbrake-for-any-device/

Something to consider: the VOB file on a DVD is actually an Mpeg-2 file - you can open it in VLC and look at the info (>Tools>Codec Information) to see what the file is (or change the .VOB to .MPG and play it on anything). On a DVD, due to file system issues any movie is split up into file sizes no larger than 1.1 GB. The standard was set back in the day to accommodate the limits of a DVD's capacity and also the decoding capabilities of what could be handled by a DVD player.

The problem is that it is already a compressed format, being Mpeg (Motion-jpeg). Every time it is decompressed and recompressed in software it is going to lose some clarity. So your thinking is correct -- ideally you should 'up-res' it to a lossless format and codec, like uncompressed AVI. I'm not all that familiar with Corel Videostudio, but you should use the highest resolution that the software (and your hardware) can handle.

Then, unfortunately, when you convert it to DVD it is going to lose some quality. I'm not sure how DVD Maker works, but I know of some people working in Mac equivalents who will compress the finished product to mpeg-2 in software like Compressor (Mac) and then the DVD authoring software would not need to recompress it, as it's already in a format it can handle. Even DVD Studio Pro would not compress as well as Compressor could, plus Compressor and Handbrake should give you a lot more control over how exactly you recompress the finished movie for best results. The above link should give you some pointers on which way to go.

A standard DVD is 4.7 GB in size, while commercial DVDs use double-sided DVDs, which have 9GB of space. But you should be able to get an hour or so onto a standard DVD at a compression rate that's equivalent to your original footage.

Compression is a bit of an arcane subject, so you're going to have to do some trial and error on your own before you hit the 'sweet spot'.

Sorry I couldn't be of more assistance, as this isn't really my area of expertise.


---------- FOLLOW-UP ----------

QUESTION: Well assuming I can't combine all VOBs and edit the large file as needed I would need to convert to a common Windows file? MP4 and a similar format are all handbrake makes I believe. As far as editing and saving in video studio someone else told me that if I try to save it at the same frame rate, compression type, and everything else that it will not touch the compression. Does that seem accurate? Also I would prefer to avoid AVI format. I read it can produce a weird banding effect. Do they make uncompressed MP4 or something like it?

ANSWER: Hi

MPEG-4 is not exclusive to Handbrake. It's just a very common and popular container for web video (streaming and youtube). For a bit more on containers and codecs please look at the link I posted above -- there is a lot of good information there.

One of the problems of MPEG(1/2/4) is they are good for playback but not so great for editing, due to the way they compress. Read up on GOP structure if you want to understand the exact mechanism, but the problem is that no matter how good the compression, there will always be some information lost, and this will get worse the more times the footage is decompressed and recompressed.

What some people recommend is what is called 'demuxing' - i.e. extracting the video from the VOB container as an mpg or mkv, which is fast because there is no recompression taking place. This link has info about a free Windows app to do this: http://www.videohelp.com/software/VOB2MPG.  You can hopefully pull this directly into Corel Video Studio and edit it there, exporting the final with the same frame-rate and frame size as the original.

Re: AVI; I'm not sure what you mean by banding... have you tried a test on a short clip? And bear in mind that AVI is a container, but the codec used could also be causing issues. Most people recommend H-264 these days.

Moving on, there is another conversion utility I always recommend: MPEG Streamclip. I used this for years on the Mac and it would seldom balk at any format you threw at it. It's free and you can download it from http://www.squared5.com/

It allows you to select sections of a clip (including a VOB file) and export it in many formats, including uncompressed AVI.

Again, it's going to be trial and error, but I suggest pulling a few clips through MPEG Streamclip into uncompressed AVI, edit them in Corel, export the final clip as an Mpeg-2 with a high bitrate: audio and video combined should be a bitrate of no more than 10.8 Mbps, or aim for a video bitrate of 8-9.8 Mbps (8000 to 9800 bps). (Suggest use 'difficult' clips with lots of detail and movement, which is where any bad artefacts are going to show up).

If things go as planned, Windows DVD Maker will not need to re-encode the video, just MUX and author the disk - so it should go a lot quicker than if you use an MPEG-4, which would need to be converted by DVD Maker, adding another compression/decompression step.

If the AVI is not working for you (or simply for comparison), try using MPEG Streamclip (or VOB2MPEG) to demux the video to MPEG-2, edit that in Corel (assuming Corel can) and then export it at the same settings. That should allow for the least amount of conversion artefacts to start showing.

Hope this helps

---------- FOLLOW-UP ----------

QUESTION: I assume windows dvd maker compresses after a certain length of time? Should it be 80 minutes for a 4.7GB disc or only an hour?

Answer
Hi

I am shooting in the dark here, as my experience is in the Mac equivalent (i-DVD/DVD Studio Pro). All DVDs need to be in MPEG-2 format -- that's hardcoded into the hardware of a standard DVD player. So it goes back to my previous point that a .VOB file is just an MPEG-2 file, but put in a format that a DVD player will be able to read and convert to a picture on a TV screen.

If you create a file that is too big, then DVD Maker *may* have to compress it further to make it fit. But you should be able to get about 90 minutes of standard NTSC with stereo onto a DVD. The only variable would be additional menus, subtitles and soundtracks (which might bring it up to the 4.7GB size limit).

If your editing software exports an MPEG-2 file that is around 4GB-4.5GB then I would imagine DVD Maker would be able to handle it quite easily, and split it into the VOB files and make the DVD structure, along with menus etc. that you create when authoring.

If Corel doesn't allow you to export MPEG-2 at the right specs (see my previous reply) then export an uncompressed AVI from Corel and convert it to MPEG-2 in MPEG Streamclip. Then as long as it's not more than say 4.5GB in size, allowing for menus and other small files that DVD MAker will create, you should be able to have a 90 minute DVD at the best possible quality for DVD.

If your movie is longer, say 120 min, then you might have to bring the quality down to about 5000bps-6000bps to make it fit, sacrificing a bit of quality.

If you're not getting the results you want, maybe look at investing in a more pro solution,like Corel's DVD MovieFactory Pro (http://www.videostudiopro.com/en/products/) -- should be compatible with your existing Corel products. (Again, I don't know this software, so maybe look around at alternatives from Sony (Vegas) and Adobe.

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Jonathan H Pienaar

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Professional Final Cut Pro HD editor, with some experience in DVD Studio Pro, Motion and Shake. Currently working mainly for South Africa's version of "60 Minutes" - "Carte Blanche". I have not yet made the transition to FCP X -- I'm waiting for the dust to settle on that, so in the meantime a good resource is Larry Jordan (www.larryjordan.biz). Please don't post questions about hooking up PVRs, DVDs and hi-fis - there must be an Expert in the Home Entertainment section who can help you better than I can.

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20 years as a professional editor: worked in feature films, commercials, music videos and actuality.

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High school, 2 years of university degree.

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