Quality loss when rendering mini-DVD
by Johan Lundqvist
on
Sep 26, 2008 at 6:04:11 pm
I´m using a Sony camera with mini-DVD´s. I record the movies in 16:9 PAL format. I am using Vegas pro 8 to edit my movies and DVD architect 4.5 to make the DVD:s. The movies looks ok, BUT there is some quality loss in the picture on the edited DVD´s. The quality loss in not very big - most people would not think about it - but I think about it.
My question is - is there anyway to render the movies in Vegas without ANY quality loss in the picture? I mean - it´s already in DVD-format from the beginning, why would there be any quality loss...
In the project properties area I use PAL standard/IMX Widescreen (720x576...), upper field first, Pixel aspect ratio 1,4568 (PAL DV Widescreen).
When I render the movies I use MainConcept MPEG-2 with customized template. I use:
Video rendering quality: Best
Output type: DVD
Frame rate: 25.000
Aspect ratio 16:9
Variable bitrate (max 9 500 000, average 6 000 000, minimum 192 000)
Is there anyway that I could change my settings for the better? And is there anyway I can edit the movies and burn them onto DVD´s without any quality loss whatsoever?
Re: Quality loss when rendering mini-DVD by John Rofrano on Sep 26, 2008 at 6:18:39 pm
If you do nothing but straight cuts and never add any color correction or other FX, then Vegas will simply copy the input MPEG to the output MPEG assuming your output has the exact same attributes. The problem comes when you start to add FX and transitions. Vegas has to render those and unfortunately, your camera is already recording in a highly compressed format that starts to degrade when re-rendered.
My advice: if you are serious about editing videos... buy a new camera that doesn't shoot DVD quality MPEG-2. Those miniDVD cameras are meant for people who just want to "shoot and watch". The sad thing is that camera manufacturers all claim you can edit the videos. Just because you physically CAN edit them, doesn't mean that you SHOULD! (as you have seen) Unfortunately, they forget to tell you that part.
You are getting about the best quality you can given what you are starting with. Like I said, if you just do cuts, you should see the video preview display a message like "no recompression needed" while rendering which is telling you that it's just copying from the source to target media with no loss.
Re: Quality loss when rendering mini-DVD by Johan Lundqvist on Sep 26, 2008 at 8:47:28 pm
Thank you for your answer!
Well, I don�t think that I use any color correction or other FX that could cause the problem.
The only thing I�ve added is music and time marks (in Vegas) and subtitles (in DVD architect) and I don�t think that could cause the problem. I use the option "save project markers in media file" when rendering.
When rendering the movies, it says "no recompression needed" in the preview window from time to time (the text is shown very fast many times) - so I guess I�m ok on that area.
I have not made separate streams for video and sound, but is that really necessary to solve this problem? I have found this text in Vegas help menu though:
"If you're using the MainConcept MPEG-2 encoder, use the DVD Architect PAL video stream template to render your video stream (you'll need to render your audio stream separately according to the parameters listed in the AC-3 audio or PCM audio headings)."
As I said, I have added music in Vegas. I have added mp3-streams and DVD architect tells me - before burning the DVD - that the audio tracks will be compressed. DVD architect does not however tell me that any video files will be compressed.
To sum it up - why is the picture quality not exactly the same on the edited DVD I have made? Should I use separate streams for video and audio? The audio is fine now - I only want to improve the picture.
Re: Quality loss when rendering mini-DVD by John Rofrano on Sep 26, 2008 at 9:31:16 pm
If you are seeing the "no recompress..." message than the quality should be the same because Vegas is telling you that it's just making a copy of the file. Rendering separate streams will not affect this. The reason it is suggested to render to separate streams is to keep your audio from being recompressed twice. Once to MPEG2 and then again to AC3. You'll get higher quality audio if you only render once to AC3.
Re: Quality loss when rendering mini-DVD by Johan Lundqvist on Sep 26, 2008 at 10:02:50 pm
Thanks again!
About the picture: As far as I can tell, the picture should be exactly the same on the Mini-DVD and on the edited DVD (although it´s not)... So the question is - where does the quality loss come from? I mean - if it was a question of me having the wrong settings in Vegas, i guess the preview window would not say "no recompress...". And DVD Architect does not tell me that it does anything with the movie. Before I burn the DVD, I check "Optimize DVD" in DVD Architect and there is no warning sign of recompression of the movie at all.
About the audio: In my case - is render to .wav pointless? Should I use Dolby Digital AC3 Pro or Studio?
Re: Quality loss when rendering mini-DVD by John Rofrano on Sep 26, 2008 at 10:15:58 pm
I can't say why the video looks different. It should not. Have you viewed this miniDVD on your TV? Is that what you are comparing it to? You might want to try taking a file right from the camera a burning it to DVD just to bypass Vegas and see if it's DVD Architect? It really is strange.
As for the audio, render to Dolby Digital AC3 Pro using the Stereo DVD template and it should be fine.
Re: Quality loss when rendering mini-DVD by Johan Lundqvist on Sep 26, 2008 at 10:41:38 pm
I do like this - I put the Mini-DVD in my DVD-player connected to a Sony LCD-TV (40"). Then I found a typical "weak" spot in the movie where the compression has made its mark. I try to remember the look of the weak spot and afterwards, I directly put in my edited DVD. The weak spot now looks somewhat different and even worse. I will try to see if I can solve this problem, perhaps I´ll get back to you if I have any more questions.
My last question for now is this: When the "No recompression.."-sign shows in the preview window during rendering, it is not constant. The movie keeps running and the "no recompression"-sign just blinks very often for like 10/100 of a second (sometimes you can´t really see the text, it goes so fast). Is that what it should be like? Or does the "no recompression"-sign show only a few frames that are actually not recompressed?
Re: Quality loss when rendering mini-DVD by Johan Lundqvist on Sep 26, 2008 at 11:55:39 pm
Oh, this is a strange thing that perhaps tells us that Vegas is the "problem" here and not DVD Architect. In Vegas, I imported a DVD Camcorder disc. The content was 1,26 GB. Then I took all the content to the timeline in Vegas and rendered the content. The "No compression"-sign showed during the process. I used MainConcept and did'nt do separate audio and video tracks. The rendered file is 896 MB. Could this difference (1,26 GB - 896 MB) be all related to the audio compression - doesn't the video have to be rendered (and shrunk) for the difference to be this big?
Re: Quality loss when rendering mini-DVD by John Rofrano on Sep 27, 2008 at 12:37:54 am
"No Recompression Required" should be on solid and not blinking. There must be something different about the MPEG-2 on your miniDVD and the MPEG-2 template you are using to render which is causing some rendering to take place. Maybe it's the bitrate? or the GOP? but something is different. A video without audio is going to be smaller in size than a video with audio so the difference in size isn't a bad thing.
Re: Quality loss when rendering mini-DVD by Johan Lundqvist on Sep 27, 2008 at 1:48:50 pm
So the "no recompression required" should't blink on the preview screen during rendering. So I guess, during rendering - the preview screen should not show any movie at all, just the "no recompression..."-sign.
I have now been sitting for hours trying different settings on a small test-movie (26 secs completely uncut), but the best I can get is the blinking of the "no recompression...". The sign is never steady for more than like 1/100 sek. If I try settings that I know are wrong, the "no reco..." never shows at all and the rendering goes much slower.
If I right-click my 26 sec movie in the project media window and choose "properties", I get this:
Accessed: den 18 september 2008, 22:34:22
Attributes: Archive
ACID information
ACID chunk: no
Stretch chunk: no
Stretch list: no
Stretch info2: no
Beat markers: no
Detected beats: no
Other metadata
Regions/markers: no
Command markers: no
Media manager
Media tags: no
Plug-In
Name: mcplug.dll
Folder: C:Program FilesSonyVegas Pro 8.0FileIO Plug-Insmcplug
Format: MainConcept MPEG-2
Version: Version 2.0 (Build 4349)
Company: Sony Creative Software Inc.
I'm trying different settings in project properties and custom settings in templates before rendering, and I have no imagination left. You were talking about changing the bitrate or the GOP. What is GOP (and how do I change it) and how do I know what bitrate my original file has? During rendering, I usually use the default options on varable bitrate. The only setting I have found where it says GOP is in the custom template where it says "insert sequence header before every GOP", "use closed GOPs" and "length of GOPs".
From what I understand, the PAL Standard/IMX Widescreen option should be used in project properties, but I have to have the "upper field first" (because the original file comes from the mini-DVD). I have tried lower field first (which is usually default) but then the rendered file looks truly awful.
Re: Quality loss when rendering mini-DVD by John Rofrano on Sep 27, 2008 at 3:32:06 pm
Is the original footage widescreen? What miniDVD camera are you using? Would it be possible to post a few seconds of a file from the camera? Maybe someone here can detect what the correct settings to use are. You might also want to contact the camera manufacturer and ask them for the specs on the MPEG-2 stream that they use.
Re: Quality loss when rendering mini-DVD by Johan Lundqvist on Sep 27, 2008 at 3:58:02 pm
I use a Sony DCR-DVD205. It's bought in Sweden (Europe) where i live. Iv'e formatted the disc to shoot in 16:9 so the original footage is in widescreen. I'd love to post a few seconds from a file - any good suggestion where I can put it?
Re: Quality loss when rendering mini-DVD by Johan Lundqvist on Sep 27, 2008 at 8:48:56 pm
I have a friend who can help me to put up the 4 sec file on the internet tomorrow.
I have found this information in Vegas help menu:
"When you render video to any of the following formats, unedited video frames are passed through without recompression:
DV AVI
DV MXF
IMX MXF (IMX 24p MXF is not supported for no-recompress rendering)
HD MXF
HDV
In order to perform rendering without recompression, the width, height, frame rate, field order, and bit rate of the source media, project settings, and rendering template must match. Frames that have effects, compositing, or transitions applied will be rendered."
I actually don't understand what the above means. When you select "Render As", there is no option that says "IMX MXF" for example. I use MainConcept MPEG-2 and as template I first select DVD Architect PAL Widescreen video stream. I then have to make a custom setting in the template - "Upper field first". Is this the same as "IMX MXF"?
Re: Quality loss when rendering mini-DVD by John Rofrano on Sep 27, 2008 at 9:03:26 pm
What that says is if the streams match in resolution and bitrate, the source will not be re-compressed. The trick is knowing the attributes of your source MPEG-2 file. I did some searching on the web and one review site said that in SP mode your camera tops out at 8.5Mbps. You might want to try setting the MPEG-2 bitrate to 8,500,000 and see if that helps.
Re: Quality loss when rendering mini-DVD by Johan Lundqvist on Sep 28, 2008 at 12:42:15 am
I have now tried - in "Render As...", custom template - to change the bitrate. I´ve tried constant bit rate: 8 500 000 as well as variable bit rate with 8 500 000 as maximum. None of this changes anything (the "No Recompression..."-sign is not constant during rendering). The "No Recompression..."-sign shows for like 1-4 times when I render my 26 sec movie-clip.
This is really starting to feel hopeless. I just want the "No compression..."-sign to be constant during rendering so I know that there is no quality loss in the picture from the original file. Perhaps I'm trying to do something impossible. Or perhaps there is a bug in Vegas. I mean - why would the "No Recompression..." just blink a few times during rendering? If the sign bothers to appear at all - why is it not constant? It's the same clip and it's pure an not changed in any way! I can't find information anywhere about "No Rec.."-sign just showing up very fast like on my screen.
Perhaps people with Mini-DVD:s dont care about editing, but I do. And when the picture quality is not very good from the start, I surely do not want the quality to be worse just because I edit my movies without effects and add some music.
I'll try to link to a 4 sec clip tomorrow. The clip I will link to was created on my harddrive when importing a DVD Camcorder disc in Vegas. It's not been processed by Vegas other than that and it has not been edited in any way.
Re: Quality loss when rendering mini-DVD by John Rofrano on Sep 28, 2008 at 1:55:32 pm
> Perhaps people with Mini-DVD:s dont care about editing, but I do. And when the picture quality is not very good from the start, I surely do not want the quality to be worse just because I edit my movies without effects and add some music.
That's why people who want to edit should not buy a miniDVD camera. I realize it's hard for you to admit this to yourself, but you purchased the wrong camera for your needs. I've been doing more reading on it and apparently, Sony didn't even try and trick you and ship editing software with this model. They have basically said it's a "soccer mom" camera. You have to realize that and move on.
I would highly recommend that you buy a cameras that shoots in a format that is meant to be edited. MiniDV uses a 25Mbps data rate and your camera uses 8Mbps. That's a big difference (3x) and while bitrate isn't the only thing that determines quality, it is a big contributor.
You could try convert all of your footage to DV Widescreen and edit with that. This might preserve the footage better. You will loose some color information because of the difference in the way MPEG and DV store color but it's worth a try.
Here is one final thing to try:
Start a new project.
Set your project properties to match one of the MPEG files by going into the Project Properties using the Match Media Settings button. (it's the yellow folder to the right of the project dropdown)
Drop the same MPEG file on the timeline.
Then Render to MainConcept MPEG-2 using the Default Template!
The Default Template gets it's properties from the project. Since you matched the project to the media, this just might use the proper format and not recompress.
Re: Quality loss when rendering mini-DVD by Johan Lundqvist on Sep 28, 2008 at 6:30:02 pm
I like the Match Media Settings function, and it works perfectly! The project settings turn out to be the same that I set manually before, but that was to be expected after my 15 hours of work on this problem. Like I thought, Match Media Settings sets the template of the project to PAL Standard/IMX Widescreen, and the field order to upper field first. Rendering to MainConcept MPEG-2 using the Default Template is not, however, working fine at all. It looks horrible after rendering with that template. The Default Template does not seem to comply with the project settings at all. It uses Aspect ratio 4:3 (!), and LOWER field first (!). Because the field order differs from the project settings, the picture looks very strange. And the 4:3 aspect ratio is obviously totally wrong. Needless to say - the "No compression..."-sign is not shown at all during rendering with the default temple.
So - my last hope is that someone (perhaps you John?) can have a look at this 4 sec clip and try to find the right rendering-settings for MainConcept MPEG-2 in Vegas (so that rendering is done without any recompression). The Match Media Settings function does the job in Project Settings - it�s all about finding the rendering-settings i guess.
(I´ve tried to put a few copies of the 4 sec clip after each other on the timeline and then render them to one file. If I use the best rendering settings that I can come up with, the "No recompression..."-sign blinks a couple of times in the preview window during rendering.)
Re: Quality loss when rendering mini-DVD by John Rofrano on Sep 29, 2008 at 12:55:30 am
> my last hope is that someone (perhaps you John?) can have a look at this 4 sec clip and try to find the right rendering-settings for MainConcept MPEG-2 in Vegas
Well... it really helps having the file because I figured it out. I looked at the file in GSpot and it said it was in DVD VOB format with AC3 audio. (which actually makes perfect sense since this camera shoots video that can be directly played in a DVD player) Since Vegas can't output AC3 audio in an MPEG file I knew that we needed to start with a template that didn't include audio. Then I opened the file in Womble and that confirmed that the audio was AC3 but also told me that the bit-rate was 9.1Mbps Variable. We already knew from using the Match Media button that the MPEG was Upper Field First. With those three pieces of information I was able to create a render template that did not require recompression.
Here's how:
Start with the DVD Architect PAL Widescreen video stream template
Press the Custom... button
Select the Video tab
Change the Field Order to Upper Field First
Change the Maximum (bps) to 9,100,000
Select the System tab
Check Save as separate elementary streams (very important)
Change the Template name to PAL Widescreen (No Recompress)
Press the Save icon
Press OK
You should now have a new template called PAL Widescreen (No Recompress) that will render without recompression to a .m2v file. The secret was rendering to m2v as an elemental stream that can be used to build the VOB again for DVD. If you go back and render the audio as AC3 and drop the M2V file into DVD Architect it will act just like an MPG file and create a button with video and audio.
Re: Quality loss when rendering mini-DVD by Johan Lundqvist on Sep 29, 2008 at 1:59:00 pm
Wow, you made it! You are a genious, thanks!
I thought all my problems were solved, but unfortunately I have discovered a new problem when I use the new settings...
I have made a few projects in Vegas and I tried to render one of them with the new settings. It worked out fine during the rendering process and the "No Recompression"-sign was constant in the preview-window for most of the time. Sometimes the sign disappeared for a very short time on places where I had made cuts in Vegas, but I didn't expect this to be a problem. However, this really turned out to be a problem.
When I rendered with my previous settings, there was some loss in quality during rendering. The quality loss was however stable throughout the rendered file and there were no special "quality-dips" on places where I had made cuts.
Now, there are on many occasions severe "quality-dips" on places where I have made cuts. This means that the picture quality now is excactly the same throughout most of the movie - but on places where I have made cuts in Vegas, it's much worse than it was before. You look at the movie and its like "oh, yes, the picture quality is not altered at all" and then there is a cut made in Vegas and its like "what just happended there, it looked horrible".
This can be seen if you use the 4 sec clip I put on the internet.
For example: Take the 4 sec clip and put it 10 times after each other in Vegas. Then render with the new settings. At first the "No recompression..."-sign blinks one time (this does not seem to affect the quality though) and then its constant during the whole rendering process. BUT - if you then try to do a few cuts in the project, you'll notice that the "No recompression"-sign starts blinking when you render. It blinks every time you've mad a cut. If you look at the movie after rendering, you'll notice that the quality-loss is severe around some of the cuts (not all perhaps, but some). Unfortunately this 4 sec clip hasn't got much motion in it - but I can assure that it looks much worse when you've make cuts during motion.
Do I make straight cuts? Well, I don't know how to make them more straight. I highlight the part I want to get rid of by pressing the left mouse-button and draw the mouse over the unwanted area. Then I push the delete button.
And if there is nothing wrong with my cutting technique, is there anything left to be done when it comes to settings?
Is it possible to make cuts in a project and still have the "No recompression"-sign constant during rendering? If not - is there any way to make the quality loss smoother around the clips?
Re: Quality loss when rendering mini-DVD by Johan Lundqvist on Sep 29, 2008 at 2:37:07 pm
By the way, I just noticed that the only thing I really had to change in my previous settingss to get the "No Rec..."-sign constant (on parts with no cuts) during rendering was to change the maximum bps to 9 100 000.
Re: Quality loss when rendering mini-DVD by Johan Lundqvist on Sep 29, 2008 at 3:36:55 pm
I have found one way to improve the picture at the cuts - setting the bitrate to constant 9 100 000. When you do this, the picture in itself looks ok (and the "No Rec..."-sign i shown during rendering. But one problem remains - and this problem was there with the variable bitrate as well: There are som "time-shifts" at the cuts. The picture is not "flowing" and it looks like there are several cuts sometimes. This sensation is best seen when the cut is made at a place where there is motion in the picture (so it could be hard to detect it in the 4 sec clip).
Re: Quality loss when rendering mini-DVD by John Rofrano on Sep 29, 2008 at 4:42:45 pm
What you are seeing is caused by the way MPEG-2 is encoded. Remember the GOP I talked about? That stands for Group Of Pictures. In your case, a group of 12 pictures where only 1 contains all of the information to build a complete frame. This is called an I-Frame. Then there are 2 B-Frames which are deltas from the I-Frame and one P-Frame which is a predictive frame following the format IBBPBBPBBPBB then it repeats with another I-Frame and so on. When you cut at any location except an I-Frame, the data change is so dramatic that the delta and predictive frames fall apart until the next I-Frame is encountered. Unfortunately, there is no way in Vegas to know where the I-Frames are.
There is a tool called Womble (I used it before to determine the data-rate of your video) that does a great job and cuts-only MPEG editing. You might want to try the trial and see if it gives you better results.
Of course... buying a camera that shoots in a format made for editing is the ultimate solution. I know I keep repeating that but you are doing a lot of workarounds and limiting your potential because of the format you are using.
Re: Quality loss when rendering mini-DVD by Johan Lundqvist on Sep 29, 2008 at 5:22:45 pm
Before I start with Womble - don't you think that there's any setting(s) in Vegas that would make the cuts look ok? The picture looks so fine now in between the cuts, and it feels like I´m very close to what I want to achieve.
I mean - the cuts were never a problem before when the overall quality was weakened. Now the quality is great, but the cuts are horrible. Right now, I would have to go with my previos settings if I wanted to make a DVD. The bad cuts are much worse than the quality issue I had before.
Well, I might start looking for a new camera. But the thing is I have 2,5 years of footage stored on mini-DVD:s that I've edited. Even if I buy a new camera, I still want to make the best of the content on my mini-DVD:s.
Re: Quality loss when rendering mini-DVD by Johan Lundqvist on Sep 30, 2008 at 12:13:31 am
I´ve been looking at the Womble-program. Perhaps it´s ok, but it doesn´t seem very user-friendly.
I still want to solve this thing in Vegas. It seems absurd that now - when I finally know the right bitrate - that same bitrate should totally mess up parts that were ok when the bitrate-setting was wrong! Any suggestions?
Re: Quality loss when rendering mini-DVD by John Rofrano on Sep 30, 2008 at 4:19:08 am
> It seems absurd that now - when I finally know the right bitrate - that same bitrate should totally mess up parts that were ok when the bitrate-setting was wrong! Any suggestions?
Perhaps you didn't understand my explanation. When the bitrate was wrong, the file was being re-encoded so that the delta and predictive frames were similar to the I-frames (because they ALL got rebuilt). When you splice a long GOP format together, and you don't cut at an I-frame, you throw too much data at the encoder than it can represent as just a delta from the previous frame so it breaks apart for a second. I don't know how else to explain it.
Re: Quality loss when rendering mini-DVD by Johan Lundqvist on Sep 30, 2008 at 8:26:51 am
Ok, I understand. But I still find it strange that Vegas can't compensate this in any way - or that Vegas can't find I-frames automatically if I'd like the program to. The way I understand it, it's all about luck if I cut the movie in Vegas and render it in the right bitrate. On every cut I have less than 10 % chance of cutting at a right spot. If I don't cut at a right spot, there's a big chance that the cut will look very strange if rendered in the right bitrate. This means that Vegas forces me to use a bitrate I know is wrong, in order to recompress the movie from the beginning.
The "No recompression"-thing seems totally pointless - even for people with other cameras. If the cutting is made in Vegas that is. Would you agree?
Re: Quality loss when rendering mini-DVD by John Rofrano on Sep 30, 2008 at 10:36:52 am
> The "No recompression"-thing seems totally pointless - even for people with other cameras. If the cutting is made in Vegas that is. Would you agree?
"No Recompression" isn't only a feature of MPEG-2. It also works for DV AVI's. Since DV AVI has a full frame every frame it is not affected by this and works extremely well. So it's not totally pointless, it's just that editing DVD MPEG-2 doesn't lend itself as well to this concept.
You might try changing your cuts to crossfades. This will allow the encoder to gradually change from one scene to the next and it should look similar to what you had before.
Re: Quality loss when rendering mini-DVD by Johan Lundqvist on Sep 30, 2008 at 11:25:24 am
I've tried some crossfading but I'm not too happy about it. Well, I think I give up now on the "No-Compression..."-thing. Instead, I'll try to look for the optimal "wrong" bitrate when rendering in Vegas.
I´m thinking about setting the bitrate to constant on 9 200 000. Or perhaps variable with a maximum of 9 200 000, average of 6 000 000, and a minimum of 4 000 000. The default minimum, 192 000, sounds very low. Do you have any ballpark suggestion?
One last question: Right now, I'm downloading 26 GB of film, split onto two files .mov-files, filmed with a normal DV-camera (a friend of mine filmed my wedding with his camera and I'll edit myself in Vegas). Is it possible to cut .mov-files in Vegas and use the right bitrate during rendering without getting the problem I just had?
Well I guess these were my last questions to you for now. You've been extremely helpful and I have learned a lot! Two weeks ago, I had never edited movies at all, so forgive me for my noobie questions... Thank you very much, John!
Re: Quality loss when rendering mini-DVD by Douglas Spotted Eagle on Sep 30, 2008 at 1:59:57 pm
Bit rate is determined by resolution x length. You get to choose quality based on length, because resolution is essentially determined for you. There is no "right" bitrate. Ultimate S gives you a bitrate calculator to help figure out the "opimized" bitrate for the length of your project. Anything lower than about 4.5 is challenged, anything higher than 8.5 runs a risk of not being playable on some systems.
What codec is contained in your .mov file? DV? MJPEG? MPEG? something else?
Douglas Spotted Eagle
VASST
Certified Sony Vegas Trainer
Aerial Camera/Instructor
Re: Quality loss when rendering mini-DVD by Johan Lundqvist on Sep 30, 2008 at 2:36:01 pm
Hi!
Every clip that I've edited had a variable bitrate of 9 100 000 before I started working with it. I don't know if you've read the whole thread, but if I set the bitate to vbr 9 100 000 (as max) the "no recompression"-sign show during most of the rendering. The problems is that my cuts look horrible if i render with that bitrate. This is because the cuts are not at the I-frames as far as I can understand. If all my cuts were at I-frames, then the "no recompression"-sign would show during the whole rendering process and I would not loose anything at all during rendering. Since Vegas has no way of showing where the I-frames are, most of my cuts are not at I-frames.
Because of this, I've decided to render my movie with another bitrate than vbr 9 100 000 (max).
If I choose for example: Variable bitrate (max 9 500 000, average 6 000 000, minimum 192 000); then there is some quality loss across the whole movie (and the "no recompression"-sign is not constant during rendering), but the cuts look good.
My .mov-files are not fully downloaded yet. I'll get back to you when they are.
Re: Quality loss when rendering mini-DVD by Bill Goyette on Oct 2, 2008 at 4:05:20 pm
I want to thank John for explaining this in great detail. I have a Panasonic SDR-H60 HDD camcorder that records directly to hard disk in MPEG-2 format (704x480). I have been recording at the HQ setting and editing in Vegas Pro 8c. Even rendering at the highest quality settings, the results were clearly degraded from the original. However, I have figured out the settings to force no compression loss, except for cuts / fades and FX:
Project properties need to match aspect ratio, but the other settings here do not seem to matter.
The important thing is the output render template match...I am also streaming out the audio in one shot, no separate stream:
Source video at 4:3, HQ to 4:3 NTSC DVD:
Rendering settings (start with DVD NTSC)edit to these settings:
Project Tab: Best
Video Tab: 704 x 480 (panasonic format), Max: 9,510,00 bps, Ave: 6,000,000 bps, Min: 4,200,000 bps
Advanced Video: no change
Audio: up rate to 384 kbps (little higher quality, original is Dolby AC3)
System: no change.
Source video at 16:9, HQ to 16:9 NTSC DVD:
Same as above except:
Project properties to widescreen DVD (1.2121) aspect ratio.
Either set media switch for all source media on timeline to turn off "Maintain Aspect Ratio". This will force the media to fill the widescreen template. (16:9 or 4:3 footage from Panasonic camcorder looks the same to vegas, and the media defaults to 4:3 unless the properties for each clip are set individually, I found it much faster to group select and turn off the "Maintain Aspect Ratio" switch).
Or set make sure the properties for each clip are set to widescreen.
Rendering settings: same as above except select 16:9 on the video tab.
Results are very good, but raising the minimum compression rate, the transitions and cuts are pretty good, and overall, the results are much better than a re-render, even at highest quality rates.
Thanks again for the discussion and I hope this helps someone else using a mini-DVD or HDD camcorder.
