How To Preserve Detail in Mini-Media Movies
COW Library : Compression Techniques Tutorials : Aharon Rabinowitz : How To Preserve Detail in Mini-Media Movies
After scores of podcasts and tutorial videos for Creative COW, the single question I get asked most often is: how can I make my own web and iPod video look as good? I don't claim to have all the answers and what follows is far from comprehensive. But it's a good look at what I've learned from a lot of trial and error - and from talking with others who have faced similar challenges.
What are the best settings to use for your videos? Ah, if it were only that easy. Since every situation is different, you first need to determine your target audience or end product, and based on that, the format and settings to use.
I use QuickTime for all of my inhouse production needs, but as a shareable format for the web, it's just not as strong as Flash.
For starters, not everyone has the version of QuickTime they'll need to play your video, and it can be a pain to download. That's a pain for you if the download stands between your audience and your video.
Windows Media, while better in quality than QuickTime Sorenson 3, and with a bigger footprint - 84% of the web for WMV, compared to 74% for QuickTime - still doesn't reach the majority of Mac users. Like QuickTime, it's also a nuisance when an updated player stands between your viewer and your video. Also, scrubbing in time does not give you instant feedback with Windows Media. The images don't update until you let go of the slider, whereas in QuickTime, you can "see as you scrub."
NEARLY A BILLION FLASHES
Flash gets around all of this. The Flash player is already installed on 98% of the world's computers. Once you add mobile phones, PSP, etc., you're looking at nearly a billion Flash-enabled devices. So if you really want to reach the world, Flash is the format.
It's also the easiest player to update on the fly. It's virtually instant. No barriers of format or updated players remain between your movies and your audience. The bonus is that the latest Flash codec (On2 VP6) offers unsurpassed video quality for the web.
FLASHING RED LIGHTS
However, one of the biggest turnoffs of the Flash format is the lack of native player controls that make other formats more user-friendly. I hate it when I can't stop or rewind a video, and I'll bet your web audience does too.
The good news is that if you create your Flash video as a FLV file, instead of a SWF, you have the ability to easily add player controls to the video.
Create a blank document (SWF) in Adobe Flash, and then add a FLV Player to load and play your movie. You can find this "FLVPlayback" component in Flash's "Components" window. You can then use the Component Inspector to link the payer to your external FLV video file, as well as choose what (if any) player controls are shown.
If you prefer a player that's both simple and sleek, you can buy Flash player components such as the FLV player I got from www.afcomponents. com for $10.
THE YouTube™ CONUNDRUM
What about uploading files to You- Tube? The answer once again is Flash.
YouTube states that you can upload QuickTime, MP4, DivX, Windows Media, or Mpeg-1 - as long as they're under 100 MB. To make a video of decent length under 100 MB, you need to compress it at your end.
Unfortunately, YouTube compresses it again. YouTube converts what you upload into Flash video, compressing it to a level that allows immediate playback from their server. It usually looks terrible - and it should! But don't blame it on Flash. Remember, you're watching a highly compressed video of a highly compressed video.
THE SECRET TO GREAT YouTube VIDEO - OR NOT
What YouTube doesn't tell you is that if upload FLV files under 100 MB as well, they don't recompress them when uploaded to their server!
I should mention that this only works with Flash 7's Sorenson Spark Codec, not the newer Flash 8 VP6 codec. Regardless, it means that you can upload a FLV whose quality you control, and YouTube won't touch it.
There's a delicate balance between video quality and download size but, if you can find that balance, your videos will look better on You- Tube using Flash than any other format.
WHEN TO "JUST SAY NO" TO FLASH
Of course, Flash isn't appropriate for every situation. While it's an ideal format for the Internet and tutorial DVDs played back on computers, you can't use it for home theaterstyle DVDs, or for video podcasts.
Since we're talking about quality, how many times have you asked yourself why some web videos look so much cleaner than yours while being smaller in file size? The answer is actually quite simple. While most people export video from their native applications - such as using After Effects to make a Quick- Time for the web - the experts render uncompressed, then use 3rd party applications like Apple Compressor and Sorenson Squeeze for much more control.
PUTTING THE SQUEEZE ON
For example, Squeeze can output video in a ton of formats for the web, podcast, MP3 Player, or DVD. Once you have a target medium, Squeeze has a huge number of presets for almost any situation: dial-up or broadband connections, video streaming, SD and HD video, or Blu-ray DVD. If for some reason you need to tweak the settings, you can do that too. Squeeze even has player controls that it can add to your Flash video.
The presets include settings for larger videos. So much of what's shown on the web sits in a tiny 320x240 window, but Squeeze has allowed me to show training videos as large as 800x600 while keeping the file size quite small and without sacrificing quality.
Speaking of keeping file size down, if you have a limit on webspace, want to keep your bandwidth down, or want to let your clients download your video faster, you can tell Squeeze to constrain the file size to a specific number of kilobytes.
Another issue to consider is keyframes. These are not the same keyframes we refer to when setting up animation in a program like After Effects or a 3D program.
In compression, keyframes are complete frames of video. Other frames are just an updating of any pixels that have changed since the keyframe. So the more your video changes - such as scene cuts - the more keyframes you will need to keep the quality up. Of course , with more keyframes, the larger your file will be.
If you are doing a video of just a person sitting in front of the camera with very little motion, then you don't need many keyframes. Many compression programs give you the option of adding keyframes every X amount of frames, and detecting a scene change to add one in there as well - this can be very helpful in managing file size vs. quality.
VARIABLE BIT RATES
Whether you use Squeeze, Compressor or something else, you can limit the impact of compression on your video through 2-Pass or Multi-Pass VBR (Variable Bit Rate) encoding.
The first pass analyzes the video, and based on the analysis, figures out where it can cut corners on bit rate while keeping image quality up.
ON2'S FLIX STUDIO
There are other compression programs out there, such as On2's Flix Studio, which is specifically designed for creating high-quality Flash video files. If your only target is Flash, then this is a package worth looking at.
So remember: when it comes to preparing your mini-media, do what video experts do - use specialty software. It will make your life a lot easier and your video quality significantly better.
Aharon Rabinowitz hosts the world's most popular After Effects podcast, as well as the Multimedia 101 podcast. He's one of the leaders of the Adobe After Effects community at Creative COW, and is working on a full-length DVD that will cover many more aspects of preparing video for the web, iPods and other mobile devices.
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