PapaJohn Productions

Movie Maker 2 and Photo Story
Newsletter #95 - March 18, 2006
 

 

Quality Settings in Custom Profiles
 
This is another of those deeper newsletters, in which I muck around trying to learn something, and say too much in hopes that some of it is of current interest to you, and another part will be helpful someday... when you're ready for it.
 
Not having access to the program code, nor to a pool of Microsoft confidential info, I have to do much of my learning experientially. However I get it, I try to sort things out a bit and pass it along to you.
 
Next week I'll do a much lighter topic, looking at some strange and some wonderful things you can do by applying different special video effects to your clips... but that's next week. Today is about the quality setting number in a custom profile, somewhat an extension of last week's issue. 
 
The Profile Editor is a wizard for making or editing a custom profile... for Photo Story 3 and Movie Maker 2, the custom profile working window has two tabs... on the General tab you get to pick one of 4 modes, and a codec... and on the second tab you can select various settings, one of which can be the quality setting.
 
The first mode is CBR (constant bit rate), and the other three are VBR (variable bit rate). We'll be studying one of the VBR modes.
 
Wizards are great... pick a mode and the choices of codecs are limited to those appropriate for the mode, and the second tab of the window gives you only the appropriate choices for the other settings. With the dynamic nature of how the options change, I put together this flow chart to help you see all the choices at one time.
 
The wizard also knows what codecs are on your computer. For example, if your system doesn't have the MPEG-4 Video V1 codec, you won't see that choice. The flow chart is made of screen shots from the choices on my HP laptop.
 
For now, the path of interest starts with the Quality VBR mode, then the Windows Media Video 9 Advanced Profile, and finally the Video quality setting. Other settings we'll enter are the video size, frame rate, Key frame interval, and decoder complexity.
 
As a sequel to last week's newsletter in which we used a Vista HD 1080 VC-1 movie to determine appropriate settings for Photo Story 3 and Movie Maker 2 custom profiles... I conveniently side-stepped the video quality setting for Movie Maker 2 by using a CBR codec with a defined bit rate.
Flow Chart
The video quality setting can be anything from zero to 100. I guess it takes a programmer's mind to tell users that a quality setting of zero isn't the same as 'no quality'... or that given a choice of quality from 1 to 100, maybe 100 isn't the best choice. I'm not a programmer, so my initial instinct is to opt for 100 and avoid the zero... I'll try to be open-minded. 
 
The flow chart shows that I ended up with a video quality of 90, and most of this issue is about how I got to that number.
 
When I rolled out my website page about custom profiles, I skipped the subject of Quality VBR and the quality setting. Photo Story 3 wasn't part of the website at that time, and as Quality VBR is the only profile option for a story, it's time to do the homework and decide on a number.
 
 
... before getting into it, here are a few notes...
 

 
Notes...
 
the Vista Corner...
 
As usual, right after distributing last week's newsletter I thought of other things to check. Some more reading about the VC-1 codec showed it's meant for use when heading toward TV viewing with HD DVDs.... the blue-ray discs coming along soon.
 
When making the custom profiles for PS3 and MM2 last week, I took a guess at the key frame intervals, setting Photo Story's at 15 seconds and MM2's at 6 seconds. Using WMSnoop to check a couple VC-1 files saved by Vista, I can see that key frames (bigger than the other frames around them as they contain the full info rather than partial) are spaced at 4 second intervals... I changed the two profiles to align with Vista.
Key Frames
 

 
8 people attended my monthly MM2/PS3 class at my local library on Monday. A quick opening poll showed that all 8 were using XP, all were there to learn about Movie Maker, 2 had already tried it a bit at home, and none of them had seen or heard of Photo Story.
 
The library classroom is equipped with a dozen laptops so each student starts off in the driver's seat, doing hands-on learning with me there to overview and guide. In almost a year of sessions, I haven't seen one system hang or crash, such a common subject of newsgroups and forums.
 
 
.... on to the main topic...
 

 
the Quality Setting
 
Let's go back to the story of Big Ben used last week to check the VC-1 option in Vista, and take the first cut at making comparable custom profiles for Photo Story 3 and Movie Maker 2. With the 4 second key frame interval established, it's time to go into the video quality setting.
 
Here's some guidance from the help file of the Profile Editor:
Video quality
 
Specify the image quality that you want to maintain by typing a value from 0 through 100. While encoding, the bit rate is adjusted as necessary to achieve the quality level that you specify without dropping any frames.
 
Currently, there are 30 discrete quality settings, so several quality levels refer to each quality setting. The following quality levels equate to discrete quality settings: 1, 4, 8, 11, 15, 18, 22, 25, 29, 33, 36, 40, 43, 47, 50, 54, 58, 61, 65, 68, 72, 75, 79, 83, 86, 90, 93, 97, and 100. The numbers between two values equate to the same quality setting as the lower number. For example, 2 and 3 both equate to the same quality setting as 1. 
And I found that a setting of 0 is the same as using number 1. Let's use the listed discrete settings and check the video quality... first with Photo Story 3, and then with Movie Maker 2.
 

 
Photo Story 3 Profile   
 
I rendered the same story over and over, changing only the quality setting. The composite image shows the change in visual quality as the setting goes from 100 to 0.
 
Quality Setting
The steps taken to make the composite:
You can see from the composite how the URL dissolves into highly jagged pixilated images as the quality setting goes from 100 to 0.
 
Obviously the quality setting drives the visual quality, the bit rate, and the file size....
 
Here's a list of the video bit rate and file size for each of the discrete quality points. The quality setting of 72 was curious, as it's the only one to break the pattern of increasing bit rate and file size as the setting moves up from 0 to 100. I don't know why... if you use 72, then your file will be a higher bit rate and bigger than if you use 75 or 79. Curious, but enough so to warrant digging into it.
 
Quality Video Bit Rate File Size
  kbps MB
1 25 1.7
4 26 1.8
8 27 1.8
11 28 1.8
15 29 1.9
18 30 1.9
22 31 1.9
25 32 2
29 33 2
33 35 2
36 36 2.1
40 38 2.1
43 40 2.2
47 43 2.3
50 46 2.4
54 49 2.5
58 53 2.6
61 58 2.7
65 63 2.9
68 71 3.1
72 79 3.4
75 71 3.1
79 78 3.3
83 86 3.6
86 98 3.9
90 114 4.4
93 138 5.1
97 183 6.5
100 284 9.6
 
The help file says you can also use zero (0) as the setting... I tried it and got the same result as using a quality of 1... the story viewing quality didn't fall through the floor, so a setting of zero doesn't mean 'no quality'. If you need the smallest file size, then a setting of zero might be best.
 
All of the stories played smoothly on my laptop, and with file sizes so small compared to movie files, there wasn't any need or desire to go with something less than 100.
 
There's a shimmering of horizontal lines during the zooming that's been the subject of some recent newsgroup and forum posts... why is it there and what can be done about it? I didn't see enough changing of the condition as the quality was lowered to conclude that it's something that drives the selection of the quality setting. One person testing it feels that applying a dose or two of Gaussian blur to the still picture before bringing it into Photo Story is the solution. He may be right, but the checking is on-going and not yet conclusive.
 
After going through all these renderings and viewing the stories, I left the custom story profile from last week at a quality setting of 100. I saw no reason to lower it.
 
If you get into custom story profiles, consider the settings used in the profiles that came from Microsoft in the PhotoStory 3 software installation package:
Discs and computer playback are the types of files I most often use, so the higher quality settings are appropriate.
 

 
Movie Maker 2 Quality Based VBR Profile
 
We know from the file properties that the Vista VC-1 files are VBR... we know the file size, bit rate, and key frame interval, but we don't know the quality setting for a comparable Quality VBR profile for MM2. Of course we could just use a constant bit rate profile and go to it directly like we did last week, but that wouldn't fit into this week's topic. So we'll need figure it out.
 
Let's check the properties of files rendered by MM2 when using different quality based VBR settings, and compare the files to Vista's... using the same input Big-Ben story file that we've been using. If things work out OK, we should be able to home in on the right quality setting.
 
Our benchmark is the Vista VC-1 file with a video bit rate of 15,816 kbps and a file size of 62.1 MB.
Starting with a quality setting of 100, the MM2 file has a video bit rate of 58,529 kbps and a file size of 226.3 MB.... that's way too high. With that high a bit rate, I can't play it smoothly on my laptop.
The next break point, a quality setting of 97, results in an MM2 file with a video bit rate of 31,782 kbps and a file size of 123.9 MB.... about half of the quality 100 file, but still too high. I can almost play it smoothly, but not quite.
Quality 90 snapshotWith a quality setting of 93, the MM2 file has a video bit rate of 21,227 kbps and a file size of 83.9 MB... and plays smoothly on my laptop. If I didn't know the Vista file info, and only wanted files to play well on my laptop, I'd probably stop here.
With a quality setting of 90, the MM2 file has a video bit rate of 15,787 kbps and a file size of 61.9 MB... it plays smoothly and aligns almost exactly with the properties of the VC-1 file from Vista... looks like 90 is the setting.
How is the visual quality of the movie when using 90 as the quality setting compared to the story itself made from a profile set at 100? The image at the right is a full size segment of the last frame... and the image below is the same segment from the last frame of source file, the story with a setting of 100. It's interesting that the story set to a quality of 90 is of less visual quality than the movie set to that number.
 
I see them as being comparable and used 90 in my revised custom MM2 profile...
PS3-Quality100
 
Our exercise leaves us with a story, an MM2 movie, and a Vista movie of comparable quality... each aligned with the properties of the HD 1080 VC-1 file, and each starting with a Photo Story.
 

 
Conclusions and Closing
 
For the most part, this week is just an exercise to learn more about the quality setting in quality-based VBR profiles.
 
I changed last week's PS3 and MM2 custom profiles, and rolled copies out to the regular download folder of the site. They'll be permanent downloads and I'll be adding these links soon:
 
Photo Story 3 - 1440x1080
 
Movie Maker 2 - 1440x1080
 
The subject isn't finished... not when it comes to the aspect ratio of the viewed movies rendered with the Vista profile. Mine all play at standard 4:3 mode when I give it widescreen 16:9 files and use a Movie Maker setting of 16:9.... Microsoft told me today there's a bug in my version of Vista which is resolved in the next one.
 
If you're read this all the way through, I hope you got at least a little out of it.... see you next week with some fun special video effects.
 

Have a great week...
 
PapaJohn