About: Compression, Codecs, and the Windows Media Encoder

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.

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.

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. 

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.

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.

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.

I look forward to any comments or discussion about this newsletter on the forums at www.windowsmoviemakers.net/forums/

PapaJohn

Movie Maker 2 - http://www.papajohn.org/
Photo Story 2 - http://www.photostory.papajohn.org/

Products and Services

I'm involved in many things that support the users of Movie Maker and PhotoStory, and adding more daily. Here's a list of those that are available to the public. Some are free and others are reasonably priced.

Books:

Movie Maker 2 - Do Amazing Things (with its online companion on http://www.papajohn.org/)

Movie Maker 2 - Zero to Hero (with support on the Friends of Ed forum)

Wrote 14 hacks that will be included in a new O'Reilly book about Windows Media Hacks

When ordering these books, I'd appreciate you using the links to Amazon on the main page of http://www.papajohn.org/

Websites:

Movie Maker 2 - www.papajohn.org - with two goals: to help you solve problems, and to be the online companion to the Do Amazing Things book

PhotoStory 2 - www.photostory.papajohn.org

Online Support - Forums and Newsgroups:
I'm a regular at many online forums and newsgroups, the main ones being:

Movie Maker 2 and PhotoStory 2 forums at www.windowsmoviemakers.net/forums/

Movie Maker 2 forum at SimplyDV.com -  www.simplydv.co.uk/simplyBB/viewforum.php?f=21

Movie Maker 2 newsgroup at microsoft.public.windowsxp.moviemaker

PhotoStory 2 newsgroup at microsoft.public.plus

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Newsletter:

 

Weekly Movie Maker 2/PhotoStory 2 newsletter. Subscribing is free via the link on the main page of  www.papajohn.org

 

Tentative topics for upcoming newsletters (subject to change):

#11 - (open to your suggestions)

#12 - (open to your suggestions)

Previous newsletters are archived at: www.windowsmoviemakers.net/PapaJohn/Index.aspx

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Software:
Transition Maker 2 - a utility that you can use to make the ultimate in personal and custom transitions for Movie Maker 2 - www.PapaJohn.org/PapaJohn/MM2/TM2

I routinely do beta testing for Pixelan and think very highly of their people and products: Their SpiceFX packages of additional transitions and effects for Movie Maker 2 are available at: www.pixelan.com/mmp/intro.htm

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Fee-based services:

If you can't save a movie from your project, I'll divide an overly complex one into manageable sub-projects and provide detailed instructions to render the parts and assemble them into your final movie. $49.95 - for details, see the sidebar on the Problem Solving > Can't Save Movie page of www.papajohn.org

Movie Maker 2/Photo Story 2 training and support services start at $50 per hour - email PapaJohn@CharterMi.net with an outline of your needs. I'll work with you to define and implement the project.

 

About John 'PapaJohn' Buechler from Microsoft.com John "PapaJohn" Buechler, of Kalamazoo, Mich., goes by PapaJohn online. An avid user of Movie Maker since its first release, and a regular supporter of the community of Movie Maker users, John received a 2003 MVP award from Microsoft for that support. In March 2003, he started a comprehensive website about Movie Maker 2 at www.PapaJohn.org. He maintains the website, writes books and articles, teaches, and provides support services - all for the community of Movie Maker 2 users. An engineer by formal education, John is a computer database and multimedia expert by business and personal experience. He co-authored the first book about Movie Maker 2 and is actively working on a second one. You can find his advice in the Windows XP Movie Maker newsgroup and in the Windows Movie Makers Forums. This newsletter is republished with permission of John "PapaJohn" Buechler. Please note that this is an archive of newsletters and some information may become outdated. PapaJohn, and the webmaster of this site, provides this information "AS IS" with no warranties.