PapaJohn's Newsletter #10 - Movie Maker 2 and Photo Story 2 - July 17, 2004
 

 
About: Compression, Codecs, and the Windows Media Encoder
 
This week's topic was requested by a newsletter reader. It's always a good one to discuss, and I appreciate getting requests to cover specific topics.
 
All video files are compressed. They need to be in order to be more easily stored and transmitted. The codecs are the underlying hardware or software devices that do the compression or decompression. And software such as Movie Maker, PhotoStory and the Encoder help you pick appropriate compression settings and produce your movies.
 
Codecs achieve compression by removing redundant info in the file.... and even more compression by eliminating some of the video/audio info that it thinks you won't miss, or will miss the least...
 
And of course, everyone feels their codec is better than the others. There are thousands of codecs. You might be familiar with Divx AVI files, Apple's MOV files, MPEG1 and 2, and Windows Media Video and Audio (WMV and WMA files). You might not be familiar with Panasonic's Digital Video, Cinepak, Huffy or even Microsoft Video 1.
 
Windows Media version 9 codecs are newer and better than the others!!!! That's one of the reasons we use Movie Maker and PhotoStory.
 
In this newsletter, I'll explore video file compression, the topic of compression versus quality, spend some time on bit rate (a measure of compression and quality), the Windows Media 9 codecs, and a mini-tutorial on using the Windows Media Encoder to convert a file. 
 

 
Notices
 
How about a poll this week? I'm curious about your knowledge and skill levels. I don't want to overwhelm newbies, nor do I want to hold back info for advanced users. So I'll warn you up front that I might not change my subject matter or style, but I'll share the statistics with you in the next newsletter.... and use the results as guidance.
 
Pick from the following the one that most closely aligns with you. Just send an email to papajohn@chartermi.net and tell me what letter you pick:
 
A - I'm a newbie to video editing and computers, learning about digital movie editing but not yet into doing it. For now, I'd just like to read and think.
 
B - I'm a newbie to video editing and computers, and dabbling in the early phases of doing digital movie editing. Any topic is great, but most of what I read goes over my head.
 
C - I'm skilled in digital video editing but not with computers.
 
D - I have high computer skills but digital video editing is new to me.
 
E - I have moderate skills with both computers and video editing. I'd like to read more about advanced topics.
 
F - I am very skilled with computers, and would like to bring my video editing knowledge up to that level.
 
G - I know more about computers and digital video editing than you do. I just read your newsletters for fun.
 
If it's hard to choose between a couple, give me both.
 

 
Some Basics About Video File Compression
 
99.99% of the video files that we use on our computers are compressed. The rare person who is working with uncompressed video files probably isn't using Movie Maker or reading these newsletters, so I'll make the statement a bit stronger and say that all video files we use are compressed. Some are more compressed than others.
 
Compression is a process for removing redundant data from a digital media file or stream to reduce its size or the bandwidth used.
 
The closest we get to uncompressed is the Digital Video file that is recorded on the tape of our mini-digital or digital8 camcorder. There's about a 5:1 compression ratio from the info captured by the camcorder versus what it can lay down on the tape as the tape moves through the camcorder in standard play mode. In a recent post, I called DV-AVI uncompressed and was promptly corrected.... it's compressed.... but it's still pretty big.
 
It's actually easier to start with the basis that all video files we work with are compressed because that leads directly into the next part of the topic.... the compression format and the amount.
 

 
Digital video files are compressed to make them more easily stored or transmitted. They need compression when heading for storage, and decompression when being viewed.
 
Some compression can be done by hardware... a camcorder or some sort of hardware capture device are a couple examples. Other compression is done by software using codecs.
 
We've all heard of codecs by now. Many of us got part of our orientation with Movie Maker by learning that some codecs clashed with Movie Maker, and Movie Maker lost and crashed.
 

 
There are thousands of audio and video codecs, and many of the codecs have adjustable settings.... so the possibilities are almost endless. Look at the GSpot utility (see the Setup > Software page of the website for a link to GSpot) and the info it has about video compression codecs. Here's the list of known video compression formats sorted alphabetically by codec. I'm just showing you the 28 in the list that start with the letter 'A'... I'm not even wanting to count how many there are in the full GSpot list.
 
Video Codecs
 
The full GSpot list of audio codecs isn't near as long. Here's the GSpot listing of the audio codecs currently installed on my laptop.
 
Audio Codecs
 
It would be complex enough if there was only one video or audio codec associated with a video file, but there are usually two, one used for the video and the other for audio. And they might be mixed or matched.
 
'Flash forward' - you preview a clip in your collection and it plays great.... Movie Maker only needs to deal only with a couple codecs for the single source file..... then you have 50 video and music/audio clips on the timeline and preview your movie. With the many codecs involved, previewing the timeline is that much more complex, so Movie Maker has to shift gears to preview things differently. Sometimes a clip plays fine in the collection but not on the timeline.... that's how things work or don't with codecs.
 
An interesting thing about codecs is that a number of them on your computer might be used to play a particular file. Movie Maker will start at the top of the list to pick one that will probably work. If the first one doesn't, it'll go to the second, and then the next, etc.
 

 
File Compression Versus Video Quality
 
I'll generalize again. The bigger the file size, the less it is compressed. The smaller the file size, the more it is compressed.
 
Bigger, less compressed files, have higher quality. Smaller, more compressed files have lower quality.
 
I have a whole website page devoted to showing dozens of different versions of the same file... it's the Saving Movies > Sample Video Clips page. The original DV-AVI file runs 21 seconds and is 70 MB in size. Scroll the page and see that the compressed files made from it run from 84K to 57 MB.
 
You want both smaller files and higher quality. That's the quest for compression processes. What's a good tradeoff of file size versus quality? From the perspective of a Movie Maker 2 user, you get two file format choices - DV-AVI and WMV.
 
If you are heading toward showing your movie on a TV, then DV-AVI is your preferred path.... it might look or play poorer on your computer, but a little faith says it's the best choice when it gets to a TV. Your choice of compression is taken care of... whatever the Digital Video codec gives you. Of course the next step to convert the DV-AVI file to an MPEG2 one will be a significant compression process that will determine the viewing quality, more so than the starting DV-AVI file.... but that's beyond Movie Maker.
 
If you'll be viewing your movie on your computer, or via discs or the internet on other computers, then WMV is the preferred format. But it won't be as easy as picking DV-AVI; you'll have lots of options for settings to deal with.
 
If some of your audience will watch it on a TV, others on a disc on their computers, and still others via downloads or streaming video from an internet server, you might want to render the movie a few times and give each the best choice for their viewing.
 

 
About Bit Rates
 
A good practical indicator of quality is bit rate. Consider two aspects of your viewers' assessment of quality.... (1) the visual/audio quality, and (2) the smoothness of playback.
 
When discussing bit rate, we're usually talking about the total bit rate... that's the bits for the video and the audio, and a few more bits for 'overhead'. The figure we'll see in MM2 is the total.
 
Playing a High Definition movie on a low end computer isn't a good experience, as the bits of data overwhelm the system and the movie pauses, hesitates, misses frames, etc. The computer tries its best, but there is too much data flowing into it to give a good quality presentation. You might think the file is bad, but it's the ability of the computer to play it smoothly.
 
And using a high end computer to view a highly pixilated video made from poor quality video and audio inputs isn't pleasant either, no matter how smoothly it plays.
 
Movie Maker 2 provides an easy way to gauge how many bits of data the saved movie will need to flow each second to be able to see the rendered movie play smoothly... regardless of visual/audio quality.
 
This screen of the Save Movie Wizard shows the highest bit rate I've dealt for WMV files so far in MM2, the 8.4 Mbps rate for my emulated 1080p high definition movies. It's easy to see what the bit rate will be, even before committing to rendering the movie. Movie Maker tells you (unless you picked a Variable Bit Rate option). Change the option in the pick list and see the change in the bit rate figure.
 
High Bitrate
                                            
A computer with a 3.0 GHz CPU is needed to play a 1080p file smoothly. Most people don't have one.
 
And, with the same project on the timeline as for the above figure, here's the situation if I select a good setting for those viewing on a dial up modem. See the 38 Kbps figure, which is over 2000 times less bits per second than the high quality choice above. Two extreme choices for saving the same movie.
 
 
For the same playing time, the measure of file size versus quality between these two choices is: 274+ MB for 1080p and 1.3 MB for a dial up modem.
 
Custom profiles for use with MM2 must have video target bit rates between 4 Kbps and 20 Mbps.... note that Digital Video (DV-AVI) is 25 Mbps for both NTSC and PAL.
 
What's a Good Bit Rate? 
 
Look for your personal sweet spot in bit rate for each movie you render... a rate that depends on your usual methods of distribution and your viewers ability to play your movies smoothly.
 
For my web-based movies, I use a bit rate of about 350 Mbps as a rule of thumb. I'll usually pick my option by using the choice 'Best fit to file size ___', toggling the file size figure and watching the bit rate at the lower left of the wizard. When the display size is right for web-based movies (320x240 is good for my standard aspect ratio ones), and the bit rate is about 350 Mbps, that's what I'll go with.
 
The standard profiles in MM2 go as high as 2.1 Mbps.... you can drive the rate up higher with custom profiles, as I've done in my simulated High Resolution ones.
 

 
Windows Media 9 Codecs
 
There are seven Windows Media Audio and Video 9 Series codecs.
 
Codec Description
Windows Media Audio 9 Audio codec for general use in encoding complex audio, such as music. (the normal one used by Movie Maker 2)
Windows Media Audio 9 Professional Audio codec for encoding complex audio, such as music. Supports multichannel and 24-bit encoding. (used by the Encoder)
Windows Media Audio 9 Lossless Audio codec for lossless encoding.
Windows Media Audio 9 Voice Audio codec optimized for encoding the human voice at high compression ratios. This is the preferred codec for streams consisting mostly of spoken words. For content that is mixed music and speech, this codec can dynamically change the encoding algorithm used to get optimal quality.
Windows Media Video 9 Video codec for general use in encoding complex video, such as movies. (used by Movie Maker 2 - with a few exceptions for the Pocket PC choices)
Windows Media Video 9 Screen Video codec optimized for encoding sequential screenshots. This codec is often used for software training or support by recording monitor images as computer applications are used. (used by Encoder when doing screen capture)
Windows Media Video 9 Image
Video codec for converting bitmap images (still photographs) with deformation information into compressed video. (used by PhotoStory)
 
 
 
 
Seven Media Series 9 codecs. But we know from MM2 experience that there are lots of choices when using these seven.... the choices are in the settings.
 
The profiles we select from in MM2, or the custom ones we create by tweaking the settings in the Profile Editor, are all dealing with the settings within these codecs.
 
Think of the hundreds or thousands of codecs that we saw in GSpot.... many of those have as many possible settings as those presented by the Windows Media series codecs.
 

 
Some Windows Media Products
 
Movie Maker is good for capturing video from camcorders or recorded analog tapes, making a movie with a single bit rate, and mono or stereo audio. It was intended for home or casual users.
 
For businesses, Microsoft Producer enters the scene, allowing you to render a movie to a number of different bit rates at the same time, and to integrate info from Power Point presentations with other material such as a video of the person doing the presentation.
 
For professionals (and anyone else who wants to use it), the Windows Media Encoder also supports features such as screen capture, live video capture, multiple-data streams in one file, and surround sound audio.
 

 
Windows Media Encoder - Mini-Tutorial
 
Let's quickly step through the Encoder, using it to convert a file. I'll take a high definition trailer file of the Magic of Flight and convert it to a DVD quality file.
 
Here's the opening window of the Encoder.
 
 
Once you pick Convert File, you get this screen to specify the source file and the output. I'm picking the Magic of Flight trailer and making a copy of it in the same folder.
 
File Conversion
 
Next is your choice of distribution method. Let's pick the one that includes a DVD.
 
 
Then use the Video and Audio pick lists to select something appropriate for a DVD.
 
 
See the Tip at the bottom of the window about being able to adjust the settings after completing the wizard. The wizard sets you up with a good balance of settings, but the Encoder lets you tweak them further.
 
I'm not going into tweaking the settings.... let's just render the new file from the source file. See that the Encoder shows both the source file being used and the new file being rendered (for the second pass of a two pass VBR process).
 
 
After the rendering is done, the Encoder shows you the tally of the results. I aborted this rendering before it was finished, as I was doing it just to get some screen shots for this newsletter, so don't look too closely at the figures.
 
 
Note that the above info includes such things as dropped video frames and audio samples.
 
There are different approaches that users of Movie Maker can use. The person who requested this topic saves his movies as DV-AVI and then uses the Encoder to tweak the settings of his WMV files. My approach is to learn about profile settings, make custom profiles and use them with Movie Maker 2... skipping the step of saving the movie to a DV-AVI file. Both approaches work.
 
My personal interest is in the 82 profiles in the c:\Program Files\Windows Media Components\encoder\Settings subfolder. They have been setup by Microsoft to achieve a good balance in the various profile settings, a great starting point to make custom profiles for MM2. Use any of them with the Profile Editor to make additional choices for Movie Maker 2.
 

 
That's more than enough for this newsletter. See you on the newsgroup and forums. Don't forget to respond to the poll.
 

 
 
PapaJohn