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CD, DVD, Blu-ray Burning Software, Video Converter, AVI to DVD, Photo Slideshow, DVD Copy
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greylander
Joined: 12 Jan 2009
Posts: 2
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 Posted: Mon Jan 12, 2009 1:32 am Post subject: 3] Size, Quality, "what fits on a DVD"... |
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Hello,
I'm looking for some clarification on the issues surrounding target size, bitrate, qualtiy, and "how much you squeeze onto a DVD". I hope this is not a total newb question well answered elsewhere -- I have looked.
In brief, my question is this: If I am starting with compressed sources of modest quality (let's say a 700MB avi file for a 116 minute movie -- roughly an average 800kbps source), how much can I fit on the DVD (say the standard 4.3MB) using convertXtoDVD before the quality of the result is noticeably worse than the source?
A more technical version of my question is: What is the minimum ratio of converted bit rate to source bit rate that will mostly preserve the quality of source?
I would tend to think that as long as the bit rate of the result is at least a little higher than the source, then the result should be about as good as the source. In other words, I would expect to have only slight degradation from the source if data size of the result is a bit larger than the source. There will always be some (likely imperceptible) loss of quality in any conversion, even if the target bit rate is much higher than the source.
Of course there could be quirks of the encoding scheme used by DVD's such that a much larger file is required after conversion, just to preserve the same quality of a more compressed avi file. Is that the case?
Maybe the simplest way to ask my question -- when converting typical avi files, what ratio of target size to source size will result in no noticeabel loss of quality? |
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souper
Joined: 17 Feb 2008
Posts: 85
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| Posted: Mon Jan 12, 2009 2:01 am Post subject: |
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Well with most modern mpeg2 encoders, Usually a bitrate of 3000-4000 will almost always result in a output that looks like the original input.
| Quote: | What is the minimum ratio of converted bit rate to source bit rate that will mostly preserve the quality of source?
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This is one of those questions that relies on a few factors. The big one being what was used to encode the source xvid, mpeg2, x264 etc etc. So its not a easy question to answer. This would go back to a bitrate of 3000-4000kb depending on the source.
Xvid and mpeg2 are 2 different encoding methods, so mpeg2 requiring more of a bitrate to perserve quality is true. Xvid is more efficient so thus will require less of a bitrate. From my observation from encoding to maintain a transparent encode from dvd to xvid the bitrate would be half. So if a dvd was 4gigs, a xvid at 2gig would be transparent quality IMO.
And your last question, just don't go under 3000kb and you'll be fine. You can get away with using 2500kb but I would say thats for sources with not much motion. It's really upto whats best, do some testing decide what looks good for yourself, All I can do is provide a opinion (a good one  ) |
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JoeB
Joined: 02 Jul 2007
Posts: 2858
Location: Canada
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| Posted: Mon Jan 12, 2009 3:37 am Post subject: Re: Size, Quality, "what fits on a DVD"... |
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| greylander wrote: | Hello,
I'm looking for some clarification on the issues surrounding target size, bitrate, qualtiy, and "how much you squeeze onto a DVD". I hope this is not a total newb question well answered elsewhere -- I have looked.
In brief, my question is this: If I am starting with compressed sources of modest quality (let's say a 700MB avi file for a 116 minute movie -- roughly an average 800kbps source), how much can I fit on the DVD (say the standard 4.3MB) using convertXtoDVD before the quality of the result is noticeably worse than the source?
A more technical version of my question is: What is the minimum ratio of converted bit rate to source bit rate that will mostly preserve the quality of source?
I would tend to think that as long as the bit rate of the result is at least a little higher than the source, then the result should be about as good as the source. In other words, I would expect to have only slight degradation from the source if data size of the result is a bit larger than the source. There will always be some (likely imperceptible) loss of quality in any conversion, even if the target bit rate is much higher than the source.
Of course there could be quirks of the encoding scheme used by DVD's such that a much larger file is required after conversion, just to preserve the same quality of a more compressed avi file. Is that the case?
Maybe the simplest way to ask my question -- when converting typical avi files, what ratio of target size to source size will result in no noticeabel loss of quality? |
If you search for posts by ckhouston you'll find tons of stuff that not only explains the basics, but that provides graphs and sample images to illustrate them. I don't have the links at hand so I'll just post the text of one of his nice summaries below (between the asterisk lines):
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1. For productions short enough that High does not fill the target disc, it will produce the best quality for all scenes.
2. For productions long enough where High fills the disc but Medium does not, the High conversion has to be compressed to fit the target, it lowers bitrates for most scenes to do so. Medium will typically use a lower bitrate than High to describe simple scenes thereby allowing higher bitrate in more complex ones. So there is a slight loss of detail only in simple scenes but detail in complex ones is improved compared to High.
Based on analysis of many tests, I think it is fair to say that High overemphasizes most simple scenes. There can be very little loss of detail in simple scenes even when Medium uses only a fraction of the bitrate used by High for them.
So the tradeoff of less detail in simple scenes for better detail in complex ones can be more attractive than one might think, if the natural bias toward High, because of its name, can be overcome when viewing the converted result.
3. For longer productions where even Medium fills the target, Low will produce even less detail for simple scenes but more for complex ones.
*******************************
I'll add a couple of comments to ckhouston's stuff. My comments try to quantify the runtime that might correspond to his categories (above). Ckhouston has posted his own corresponding times but again I don't have the links to the posts, so I may be using slightly higher numbers than he would have in terms of runtime (i.e., you likely lose nothing noticeable by changing the "quality" setting for movies that run slightly shorter than the times I have used below):
The main factors about quality are the runtime of the video, the amount of detail in the video, and of course the input quality. The file size of the input video is basically irrelevant.
Assuming a decent input, when using DVD5 then any movie longer than about 90 minutes should be converted using the Medium setting, and any movie longer than about 3 hour - 4 hours (particularly around the 4 hour or longer mark) should be done on low. I don't use DVD9 discs but would assume you could double those numbers for a DVD9, but stand to be corrected.
Anytime that a conversion will occupy more than 95% of the disc at a High setting then you should be using Medium insteat. The runtimes above are a reasonable guide to this situation in most cases of theater releases, but again it depends on the content of the video.
Just to let you know, when using Medium you will often find that you do not use all of the disc, but that is irrelevant to the output quality. Most commercial DVDs wouldn't fill a disc either if they didn't add warnings, trailers, extras, very fancy menus with music, etc.
The advisor lights in the ConvertX program are a very rough guide and shouldn't be used to determine settings. Use total video runtime instead. ckhouston has done extensive testing of these settings and posted many graphs and screenshots with the results. Basically, for most feature length movies on DVD5 just keep your setting on Medium and you'll get best overall results.
Regards,
JoeB |
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greylander
Joined: 12 Jan 2009
Posts: 2
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| Posted: Mon Jan 12, 2009 6:25 am Post subject: |
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Wow! Two thoughtful replies in a very short time. Thank you, JoeB and souper. I'll see if I can find the posts by ckhouston.
I think I should rephrase my question, though. I'm mainly concerned with not wasting DVD's doing only one or two movies per DVD, when the sources I'm using are AVI's that are only around 700MB or 800MB. Assuming the compression algorithms for DVD are comparable to those in the avi files, I should be able to cram about six movies per DVD without losing much. Or not. Hence, my question. From what souper says, it sounds like about 3 movies per DVD would be a safer bet.
About the quality settings, my impression from what I've found in these forums and elsewhere is that "high" doesn't do much unless you have a high quality source and you are not overloading the DVD. So I could just leave it at "high", overload, and let convertXtoDVD compress it down to squeeze it all in. From what JoeB says, it sounds like the quality settings can still change the emphasis on where it compresses most, and so if I'm wanting to overload the DVD with six or ten hours of video, it will be better to use the medium or low settings (plus the conversion will go faster?).
I just had one experiment finish cramming 6.5 hours of movies onto one 4.3GB disk... The convert actually went over the target by 24MB for 4324MB total -- but I think the 4.3's are really about 4.35...so I figured it is OK. The burn was "successful"... but interestingly enough the drive that did the burn can not read the disk, so in this case the question of video quality is moot.
I'm wondering if the "high" setting is likely the reason the conversion cut it so close and went slightly over target? Going to burn the same project with "low" setting and see what happens differently, if anything. |
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ckhouston
Joined: 08 Aug 2007
Posts: 2022
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| Posted: Mon Jan 12, 2009 8:38 am Post subject: |
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The High setting is not the likely reason you had a small overflow on your conversion, that can happen regardless of the setting. CX2D continually makes estimates during conversion of what bitrate to apply considering the amount of space used and time remaining. But it has no way of knowing if the remaining video will compress to the same extent as what it has already converted because it uses a single pass conversion. So it may underflow or overflow the target size if video scenery changes much in the final moments of the conversion. It attempts to be conservative in this respect though, so it usually underflows the target. That is why the 95% occupation sited by JoeB usually means that additional compression was used to fit the video on the DVD and it is time to switch settings.
And the overflow is also not likely the reason your drive could not read the disc it burned - read the sticky topic about burning problems.
JoeB gave some very good advice, but I differ with him in one respect that I think is important, the most appropriate times to change settings.
The optimum switch time depends very much on the type of scenery in the video and those switch times can vary considerably with different videos. You can convert at one setting and check if the target occupation is greater than 95% and then switch to a lower setting if you want to get the ultimate output quality.
Or, and this is an important point, you can follow my general advice and use Medium for projects longer than 80 minutes and Low for those longer than 160 minutes regardless of the video being converted. That recommendation is based on the fact that you will usually lose very little output quality, if any at all, if you switch too early for a given video but you can lose a lot if you wait even slightly too long.
If you want to read about the "quality" settings, you can start with http://forums.vso-software.fr/how-to-convert-mkv-properly-my-primer-t6734.html . There are some links there to other topics with more detail.
You will have to experiment to see how much you can put on a DVD. No one can help you with that because everyone has different ideas of what is acceptable. I have seen users happy with 8 and even 11 hours on a DVD5. Many people are also adamant that anything over 3 hours is unacceptable.
However, average bitrates for anything over 6 hours must be very low in order to fit the output on a DVD5. You should see some noticeable macroblock (fairly large) pixelation with typical videos at that point. You can use an output resolution lower than the standard Full D1 to circumvent that problem. Half D1 has about half as many pixels so about twice as much bitrate per pixel can be applied, SIF will allow about 4 times as much bitrate per pixel. The tradeoff is jaggies on near vertical edges with Half D1 and on both near vertical and near horizontal with SIF. Those can be annoying when they trickle along the edge as the edge moves around the screen, a shimmering effect. The problem happens with all TVs but is more noticeable on HD, |
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souper
Joined: 17 Feb 2008
Posts: 85
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| Posted: Mon Jan 12, 2009 2:58 pm Post subject: |
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The high, medium, low settings are meant for quality at a different bitrate. henche high, medium,low. So you should set these according to what the bitrate is going to be. I would say 2-3 movies depending on the bitrate. When I say 4gig dvd > 2gig Xvid (The 4gigs is usually a movie of 2hrs). A 700meg movie you download off the internet considering thats what you do. Already has lost alot of detail, the resolution has been shrunk. This also makes it easier to encode. If you don't wanna waste space on DVD while retaining the same or similar quality stay below 4hrs or around. But this goes back to the bitrate thing, time = bitrate they go hand in hand.
low = 2000 or less
medium = 2000-3000
high = 3000 and up
These are just my estimates, from my experience, Remember when you are you trying gain a certain level of quality, use the bitrate as guide not the time. |
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ckhouston
Joined: 08 Aug 2007
Posts: 2022
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jolo
Joined: 03 May 2009
Posts: 7
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| Posted: Sun May 03, 2009 6:28 am Post subject: Can ConvertXtoDVD use DVD DL, blank DVDs |
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On the topic fo quality of output, can I tell ConvertXtoDVD, to use a DVD +DL (double sided) blank DVD ?
In this way, it can make use of the double size DVD capacity and therefore encode to the best quality that it can because it is has double the capacity to output to ??
In general, I think when creating output for any DVD video that will be 2 to 3 hours in length, that it is better to use a DVD + DL double-sided DVD, as is down with DVD movies.
Normally, a conventional, single sided DVD gives top quality on 90 minutes or less of video and AC3 dolby stereo.
Thanks,
Jon |
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Claire
VSO Team Member
Joined: 02 Apr 2007
Posts: 1686
Location: France
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| Posted: Mon May 04, 2009 9:21 am Post subject: |
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| yes, select DVD - 9 in the one of the encoding tab in the settings. |
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ckhouston
Joined: 08 Aug 2007
Posts: 2022
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| Posted: Mon May 04, 2009 12:49 pm Post subject: |
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| jolo wrote: | | In general, I think when creating output for any DVD video that will be 2 to 3 hours in length, that it is better to use a DVD + DL double-sided DVD, as is down with DVD movies. |
Commercial DVDs usually have extras that take a lot of space on those DL discs.
Without going into detail already discussed elsewhere, for videos 2 to 3 hours long, a conversion to a DVD9 DL disc at High will give you the best quality if it does not fill the disc. The quality will usually be only slightly less for one done to a DVD5 SL disc at Medium quality, again if it does not fill the disc. Most cannot tell the difference and can save a lot of DL discs using the latter setup. |
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jolo
Joined: 03 May 2009
Posts: 7
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| Posted: Tue May 05, 2009 1:51 am Post subject: |
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| ckhouston wrote: | In general, I think when creating output for any DVD video that will be 2 to 3 hours in length, that it is better to use a DVD + DL double-sided DVD, as is down with DVD movies.
Commercial DVDs usually have extras that take a lot of space on those DL discs.
Without going into detail already discussed elsewhere, for videos 2 to 3 hours long, a conversion to a DVD9 DL disc at High will give you the best quality if it does not fill the disc. The quality will usually be only slightly less for one done to a DVD5 SL disc at Medium quality, again if it does not fill the disc. Most cannot tell the difference and can save a lot of DL discs using the latter setup.
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Don't you think that "quality" is "in the eyes of the beholder?" What I mean is that so much depends on what the needs of the individual are. If someone wants to see something on a Cowon D2, portable multi-media player (like I have), I want 320 x 240 as the top level for my video. It depends. For audio on my Cowon D2, I use losless FLAC or Lossy Ogg (but I can't hear the loss), because the little Cowon sends out 76 watts of audio power and has some powerful ways of customizing the audio to taste, as well as takes advantage of the superior, license free audio codecs that are available.
I cringe, really cringe when I see someone say, "It Sucks". Throwing out everything if one small feature they would like isn't there, etc. When I see, a product or an approach is labeled "It Sucks", I just ignore it.
Although, the truth be told, Windows Vista really sucks.  
Some people seem to be extremely sensitive to the slightest pimple in a video. For me, I feel that clarity of the audio was more important.
I understand that most/many commercial DVDs would have extras and sometimes the extras make them very special. For example with Music concerts, etc.
But, sometimes movies are also just long movies and can have various audio tracks for different languages, audio quality, and have better video quality etc.
But I also have the videos that I make myself which might be longer than 1.5 hours.
When I encode in the latest Divx, I do select a one pass quality pass that will have a very low quantizer gives me a very high level of quality and puts quality ahead of output size.
My cheapo, Philips 5990 Ultra Divx certified DVD player does upshifting also and if my source is of high quality, then my Divx output will be of high quality.
If someone was backing up a commercial film, there is always the option to strip out the "extras" as well as the additional languages and some an audio track (like DTS for me), that I am not able to use.
It is rare, but sometimes if something is long and important for me, I will use DL DVD media. I only use Verbatim for DL (I believe they invented it), but NOT the ones made in mainland China. For my other DVDs and CDs, I use Taiyo Tuden.
_________________
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Blu-Ray is for suckers !!
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ckhouston
Joined: 08 Aug 2007
Posts: 2022
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| Posted: Tue May 05, 2009 12:02 pm Post subject: |
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Your quote is wrong, it attributes some of what you wrote to me, so I refer readers to my post above for clarification.
You might want to start a separate topic if you want to discuss preferences, various approaches, etc. |
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