Why SampleLab™?

A master chef always tastes a variety of samples before finalizing a recipe. A master video compressionist does the same thing.

Many years ago, I was teaching a DV Revolution workshop at Apple headquarters in Cupertino and became friends with Doug Werner, the person who compresses movie trailers for the Apple website (including the famous Star Wars trailer in 2000 that got 35 million downloads.)

I invited him to teach an encoding segment at our workshop, and afterward, we sat in his office and compared notes on our methods. I consider Doug, along with myself , to be one of the world’s leading video encoding experts, and not coincidentally, Doug had independently developed the identical process I had used for years to determine the best encoding settings for movies. This process consists essentially of encoding a series of short experiments to determine optimum bitrate and other settings.

The problem is, there’s never been an software environment designed to make this process easy (until now!). I’ve used products ranging from $400 to over $1000, and they all make this process so excruciatingly cumbersome and inefficient, that for 90% of people who publish video on the internet, it’s just not worth the trouble.

SampleLab™ is the world’s only software environment designed to efficiently determine the best settings for your movie, which is one big reason why DV Kitchen is (among many other things) the world’s highest quality encoding software.

What determines the visual quality of movies delivered over the internet?

Once you have a finished movie exported from your editing software, quality to your viewers is determined by three factors:

1. codec (the encoding algorithm used)
2. bitrate
3. frame size

Which codec is the best?

In the beginning years of web video, you might encode Real, Windows Media, and Quicktime versions of your movie, in several sizes, so anyone visiting your site could watch, figuring everybody was bound to have at least one of those plugins.

Then a lot of people got cable modems and DSL so you don’t have to provide the tiny movies for dialup customers any more.

Flash then updated their nearly universal browser plugin to show FLV video content. Many developers migrated to Flash video, because posting one movie is easier than posting three. Flash seemed to have won, for the time being.

But then, the H.264 codec, also known as AVC, burst upon the scene, popularized by its support in Quicktime 7 starting in April 2005. It immediately blew everyone away with its amazing quality and low bitrate requirements, being able to present stunning quality HD video that started playing almost immediately (when encoded by an expert compressionist).

H.264 became the standard codec adopted by manufacturers for all kinds of devices - from camcorders from Canon and Panasonic to Apple iPods, iPhones, and Apple TVs, Sony PlayStations & PSPs, Archos TV, Microsoft Xbox 360s and Zune players, cell phones and many other devices.

Meanwhile, hundreds of millions of Windows computer owners were buying the Apple iPods, which neccesitated downloading iTunes & Quicktime, so the Quicktime browser plugin was gaining ground very quickly on Windows computers (as well as being installed on 100% of Macs).

So then, there was once again a dilemma for internet video producers; stick with Flash with wider browser support; or go with Quicktime H.264 for better quality and device compatibility? Or both?

Finally, the momentous announcement came from Adobe in August of 2007- that the ubiquitous Flash plugin would support H.264-encoded video, and even provide special hardware acceleration to make fullscreen H.264 video play more smoothly. The confusion was over. H.264 had won the codec wars, perhaps forever.

The incorporation of the H.264 standard into so many hardware devices, in addition to being adopted as a standard for encoding Blu-Ray DVDs, means this codec will be around, if not forever, for a very, very long time. Future computers will come with special hardware chips optimized for the H.264 codec that will present stunning quality fullscreen H.264 HD movies without taxing the CPU.

So with any given codec, quality is determined by frame size and bitrate.

SampleLab allows bitrate data size/quality trade-offs to be gauged quickly and accurately. It’s simple to use but incredibly useful, and therein lies its genius.

- MacUser UK review

How does frame size affect visual quality?

The larger the frame size, the more bitrate you need for the same quality. Think of bitrate like paint - you need enough bitrate to paint the whole picture accurately. Remember doubling the size of the video frame actually quadruples the number of bits that make up the picture.

What bitrate is best?

With any given codec and frame size, bitrate is the most important factor in video quality. More bitrate will give you better quality (up to a point of diminishing returns). But that definitely doesn’t mean you should go crazy and use a ridiculously high encoding bitrate.

If you simply observe two rules, your video will be perfectly optimized.

The rules are:

Rule #1: Don’t encode with too high a bitrate.

Rule #2: Don’t encode with too low a bitrate.

Follow these two simple rules and you’ll be fine.

Hehe, seriously, folks, here’s why:

• You don’t want to encode movies with bitrate too high, for many reasons:
  • you will make your viewers wait unnecessarily long before they can start viewing your movie
  • higher bitrate movies put an extra strain on your server and will cost you more money in extra bandwidth
  • older computers will have a hard time decoding very high bitrate H.264 in real time, leading to dropped frames and jerky appearing motion
  • uploading will be slower
  • you’ll use up unnecessary room on your server and local drives
• You don’t want to encode movies with bitrate too low, for only one reason - the visual quality will suffer - there will be pixelization and blockiness, especially in any areas with motion.

Shopping for bitrate

The mindset I’d like you to use when choosing the bitrate for your encoded movies is “shopping for the best deal”.

This means, you want quality - but you’re not willing to pay any more (in kbps) than you need to. If 3000 kbps gets you quality that’s only barely better than 1200 kbps, then 3000 is a bad deal, save the kb and go for 1200 kbps. But if dropping to 800 kbps destroys quality, then definitely pony up the extra 400.

There are too many variables on the internet not to play it safe and keep your bitrate as low as possible while still preserving excellent quality.

That’s why the Bitrate Budget Calculator is so valuable.

If you’re a bandwidth big spender and encode your movies at too high a bandwidth, you will probably regret it at some point.

Having said all that, you also don’t want to encode your video at such a low setting it looks pixelated and blocky, or even worse, as bad as YouTube or other popular video sharing sites! You want high quality.

So determining the ideal bandwidth is an exercise in tradeoffs. There is always a point of diminishing returns, where increasing bandwidth doesn’t really get you that much better quality, and so it’s not worth it. With a talking head video at a small frame size, it’s likely you could just barely tell any difference between 300 kbps and 1000 kbps. But, dropping the bandwidth to 200 kbps makes the picture start to look pixelated. So why not be smart, go with 300 kbps, make your video look good, but don’t spend any more bandwidth than you need to.

What is the “threshold of quality? (TOQ)?”

“TOQ” is a term I made up to describe the diminishing returns of increasing bitrate over a certain amount for a particular movie.

The TOQ of a clip is the “sweet spot” - just enough bitrate so the movie looks fabulous, but no more.

SampleLab is by far the best way to find the TOQ for each clip you encode.

For any given frame size, the only factor affecting how much bitrate is needed for great quality is content.

How does content affect the bitrate I need to make a movie look great?

When encoding video to an interframe codec like H.264, only the pixels that have changed from the previous frame are stored. So, movies where few pixels change from frame to frame require much less bitrate for high quality, compared to movies where most or all the pixels change from frame to frame.

TIP: For video that looks excellent at a very low bitrate, shoot mostly “locked-down” shots (with a tripod where the camera doesn’t move), and a background that is simple, either large areas of solid color or use shallow depth-of-field to blur out the background.

Footage needing the highest bitrate to look great would be a handheld shot with a busy, distracting, in-focus, moving background.