Streaming Video for the Masses
by Reno Marioni 19 Jan 2001
Just a couple of years ago, producing your own short movie meant going to film school, raising a lot of money, buying expensive equipment and looking for distribution via film festivals.
Basically, it was out of reach for most people. Today, with the right talent and desire, we all have a shot at being filmmakers for 1/10th or 1/20th of the cost. A whole new creative world has opened up, thanks to the advent of several new consumer technologies: high-quality and low-priced digital video, powerful desktop PCs, inexpensive and easy-to-use video editing software and a new distribution channel on the Web.
And as broadband DSL and cable modem access increase, so will the audience for digital video on the Web. In addition to the Internet, numerous new devices and appliances will be available to distribute your work. We are already beginning to see short videos on airplanes, in hotel lobbies, on handhelds and through interactive TV.
To produce and showcase your own digital video involves several key steps:
a. Shoot your video footage (use an analog or digital video camera)
b. Capture (input video onto your Mac or PC hard drive using a Firewire connection or video capture card)
c. Edit (use consumer-level software video editing tool)
d. Compress/Encode (use bundled video editing tool or dedicated video compression tool)
e. Distribute (to Web, CD, DVD, etc.)
In this article, we're going to focus primarily on the encoding and compression process with special emphasis on encoding for the Web, which as you'll find out is a fine art.
Video Encoding
What is video encoding and why is it important?
First of all, digital video files are HUGE. Roughly five minutes of uncompressed video will consume nearly one gigabyte of space on your hard drive, and no one - not even your adoring mother -- is going to download or stream a video that large. So compression helps you optimize the video while retaining the highest quality possible for distribution on the Web.
Before compressing/encoding video for the Web, you need to consider the following settings and criteria:
1. What Video Format/Architecture (QuickTime, Real, Windows Media)?
2. What Data Rate?
3. What Frame Rate?
4. What Window Size?
5. Streaming Method: Progressive or Real-time?
The file compression process begins when you take your edited video clip and encode to a particular video format -- e.g., QuickTime, Windows Media, or Real Media -- and compress the file size to output to either CD, DVD, or the Web. Encoding for the Web is the trickiest part as there are far more variables to deal with, such as constrained bandwidth, which results in jerky, annoying videos on the Web.
In order to encode a steady sample, it's important to have a well-shot video source. This is why you don't see many MTV-style videos on the web -- the transitions are too fast, rapid camera movement doesn't compress well, and you're likely to have jerky, delayed images, even when compressed at a low frame rate.
Before encoding your edited video files you have to ask yourself the following questions:
a. Which streaming method is best for my setup, progressive (HTTP) or Real-time (RTSP) streaming?
b. What format do I want to use (Real, QuickTime, Windows Media, or other)?
c. What is my delivery mechanism (Web, CD, DVD, etc.)?
d. If output is for the Web, what Web connections am I targeting (56k modem, ISDN, DSL/Cable, T1)?
Pick a Stream, Any Stream
There are two main types of streaming: progressive streaming (on demand) and real-time streaming (live or in real-time). Progressive streaming takes a compressed video file and downloads it to your hard drive via HTTP over the Internet. Real-time streaming is usually broadcast to your browser directly from a server. Real-time streaming uses RTSP (real time streaming protocol) so you'll need access to a special video streaming server.
Progressive Streaming
Progressive streaming is the easiest route for beginners as it requires no special server, such as a streaming server. You can use a standard Web server to upload your compressed video file. Quality is generally better using progressive streaming than with real-time. And once you decide to play the video online, the whole file begins to download to your hard drive. Progressive users also can't jump ahead to other sections of the video.
Depending on the format of the video (such as Real), some progressive files may require you to download the entire video before playing it. This creates one of those annoying "hurry up and wait" scenarios. Thankfully, QuickTime supports a 'fast start' feature which automatically kick-starts your video player as it downloads. In an age of instant gratification, this is a great feature and QuickTime is the only major video architecture that supports it for now. For that feature alone, QuickTime is much better suited for progressive streaming than RealVideo 8 or Windows Media 7.
In general, progressive streaming works best for videos under three minutes, such as movie trailers, and the shorts you see on sites such as Apple Quicktime TV , iFilm, Atom Films , and on home video sites such as Share Your World.
Real-time Streaming
Unlike progressive streaming, real-time streaming requires a special streaming server. This can be a QuickTime Streaming Server (RTSP), a Real Networks Server or a Windows Media Server.
Video streamed for real-time plays automatically. You don't need to download the entire video before playing. You can jump to any location in the video clip. And the clip always resides on the server. Video encoded for real-time streaming generally tries to keep pace with the user's connection speed in order to minimize interruptions and stalling. There's nothing you can do about general Net congestion, but the streaming server at least tries to compensate by maintaining a constant connection.
You'll find real-time streaming is best suited for longer videos -- such as live event broadcasts, presentations, training videos and lectures -- where users can skip ahead to other parts of the clip and don't have to download a huge video file. It also offers good protection for your content as users can't download it to their hard drives and redistribute your work. Unfortunately, the video quality isn't as good with real-time as with progressive. But getting quality video on the Web is all about trade-offs.
If you're just starting out, you might want to create a simple Web page, encode your video using a progressive streaming method, and embed the clip into your site. Or, if you're determined to stream the video, you might consider using a third party and their servers. Companies such as Media 100 and Sorenson Broadcast Services offer a range of encoding, hosting and streaming services.
Video Architectures and Codecs
The three main video formats on the Web are RealVideo, Quicktime and Windows Media. When choosing a video architecture and format, you need to evaluate current market trends and also decide which is the best fit for you and your audience.
Currently, RealVideo is the most popular and widespread video format used on the Web. Real recently released version 8, but you must buy the server software to use it; the cost after software purchase is based on connection usage. Windows Media from Microsoft is also widespread and is currently in version 7. Although Windows runs its own proprietary server protocol (not the standard RTSP), it's free and it runs on the widely available Windows Server Platforms.
QuickTime Streaming Server from Apple, the third major format, is based on RTSP. It's an open standard and available on multi-platform servers from UNIX to NT. As Apache is to Web servers, QuickTime Streaming is to video servers. And the best part is it's free. Many professionals believe QuickTime offers the best quality, as well as the elegant interface that Apple products are famous for.
Video Codecs
In order to understand video compression, you first need to become familiar with "codecs" and how they work. Codec stands for compression/decompression, and it's the piece of software you use to compress very large files, such as video or audio, into much smaller files that can be sent out to multiple media. Normally, you will choose a codec according to the video format you are using.
For example, Sorenson Video 3 codec from Sorenson Media is compatible with the QuickTime format and is the de facto codec for QuickTime Video compression. Real Video 8 codec runs in conjunction with Real Server. The same compatibility issues apply to audio codecs such as Qdesign Music Pro for QuickTime. Codecs generally come bundled with your video editing software or with compression suites such as Media Cleaner. Every year, new and improved codecs are released to make files even smaller, while encoding faster and producing better quality video.
You'll probably use one of the following codecs for video compression:
a. Sorenson Video
b. RealVideo
c. Windows Media Video
d. MPEG-1, MPEG-2, MPEG-4
e. H261/H263
f. On2
MPEG-4
Although Windows Media, Quicktime and Real Media are the major players, an open format called MPEG-4 holds great promise and could become the de facto video codec standard in the same way that MP3 has become the dominant format for music on the Web. MPEG-4 has momentum behind for several reasons:
1. Ubiquity: Streaming video today is mostly viewed on the Web, but the future in streaming video will be far more prolific across multiple devices, appliances, platforms and computers. Streaming Video will be seen in hotel lobbies, supermarkets, airplanes, videophones, TVs and more. MPEG-4 appears to be the codec and standard for future devices to come.
2. Unified Standard: Today, there are many codecs. The problems that people face is sorting out which codecs to use with which video architectures in the encoding process. The job would be far easier for digital media professionals if people could encode just once for all platforms and devices.
3. Quality: MPEG-4 appears to be the most efficient encoding standard and will encode at incredibly high-quality over the most constrained bandwidth requirements. From what we have seen, people will be able to have full screen VHS quality video. Sorenson media is developing an ISO-compliant MPEG-4 codec, as is Microsoft for use in Windows Media.
The bottom line is that MPEG-4 will be awesome in quality and will be embedded into many new and exciting devices.
Video Encoding
The vast majority of video content creators use Media Cleaner Pro from Terran Interactive as their full-service compression/encoding suite. It's an essential software package and is widely used in the digital entertainment industry. The Media Cleaner Pro EZ version is priced around $250 per copy, and more often than not it comes bundled with popular video editing tools.
Here's how a sample encoding process might go:
Once you've finished editing your video using software such as Apple's iMovie or Final Cut Pro, Adobe's Premier, Media100 CineStream and Cleaner EditDV or Microsoft's Moviemaker, you save and export the edited clip to a folder on your desktop.
In some editing suites such as EditDV or Premiere, you can export directly from the editing tool into Media Cleaner Pro, removing an extra step in the encoding process. Once your clips are in a compression suite such as Media Cleaner Pro, you're ready to prepare the clip for a particular distribution medium. You then go through a series of check box options, which determine the size of the clip, the data rate, the frame rate, etc. Media Cleaner, for example, allows you to select your video format (e.g. QuickTime), your delivery method (e.g. Web), your data rate (e.g. for 56k-modem), your frame rate (e.g. 10 frames per second), and the size of your video viewing area (e.g. 240 x 180 pixels).
Real World
At Adventure Zone Network, we use Final Cut Pro as our editing tool, Adobe After Effects for composing and effects, and Media Cleaner Pro v5 for compressing and preparing each video file for output. We also use Real Video 8, Sorenson Developer 2.1, and Windows Media 7 as our primary video codecs and Qdesign Music Design for preparing audio files for QuickTime. We also use Real Audio.
We use Apple G4s for editing and encoding our videos. There's not an Avid system in the house. Everything is done digitally, on the desktop, and all the software is available at consumer level prices. To see some streaming video samples that use these codecs and tools, go to the Channel Zero section and see videos from around the globe.
We shoot video using mini DV tapes (NTSC) as our source and capture digital video using a Firewire (IEEE1394) connected to the Firewire port of our Apple Macs. We don't generally use an analog source, as it creates an extra step to convert to digital using a Sony DMA-200 digital converter. As well as the standard Firewire connection, you can use a video capture card such as those produced by Osprey to capture video at the source into your computer for editing. Without a doubt, you get the best results using a digital video camera hooked up to your computer via Firewire. All the latest Mac systems include a Firewire port.
The Trade-offs
The optimal goal is to produce the highest quality video that streams with minimal or no interruptions and a quick download. For Web delivery, this means trade-offs.
On one hand, if you produce a high quality video with a high frame rate (regular movies play at 24 frames per second), a large viewing window, and a high data rate, you will get a video that looks great but will only be viewable for people with fast connections. If you encode with speed and delivery in mind, the quality suffers. In an era of instant gratification, there is no quick fix for making quality video accessible to a wide audience. Finding a balance between video quality and connection speed that best serves your target audience is the key.
Sample Settings
A sample encoding settings for 56kbit modem delivery using NTSC DV source might look like this:
Streaming Method: Real-time Streaming
Data Rate: 40 Kb
Although we may have a 56 Kb modem, our true connection speed is nearly always lower than 56 Kb. Therefore, setting to 40 Kb or around that rate minimizes the interruptions that occur due to general Net congestion.
Window Size: 160 x 120 pixels
For 56 Kb, if you increase the display size of your video, quality will immediately suffer due to the larger file size. You need to keep the display size to 160 x 120 pixels or only slightly larger. This is what many people disparagingly call a "postage stamp" display.
Frame Rate: Use 5 for 6 frames per second (fps).
Uncompressed video typically plays at around 30 fps (NTSC) or 25 fps (PAL). Choose a frame rate that evenly divides into the above figures. Since many of us use NTSC in the US, you'll need to select a frame rate such as 5, 6, 7.5, 10, or 15 fps depending on connection speed. As modem delivery is very slow, we suggest 5 or 6 fps, then scaling up based on data rate and Web connection.
Encoding Methods and DVD
If you're encoding for progressive streaming delivery, use the 2-pass Variable Bit Rate (VBR) setting, which is supported both in Real Video 8 and QuickTime 4 & 5 versions. You won't find this feature in Windows Media 7. VBR encoding is a great feature to enhance the overall quality of your video. It works like a 2-pass encoding approach, analyzing your video first for choke points, then compressing it. It's a longer process but the results are better.
Some techniques used in video streaming actually mix encoding techniques. It's more common now to see companies encode for modem (e.g. 56kb) delivery using progressive download and for higher data rates (e.g. ISDN and DSL) using real-time streaming methods. The mix and match approach works well because it's hard to do real-time streaming for 56Kb delivery unless you're streaming a talking head video, which compresses better due to minimal camera movement.
When you start the encoding process, use a very short clip because it will take a long time (even with a fast computer). You can enter different settings into Media Cleaner Pro 5 until you get the best results for the type of video you are compressing. Then be sure to save these settings for future use.
Media Cleaner Pro offers new users a wizard interface, which takes you through the encoding process to create your own settings. However, the results are often poor and you have to go through a lot of trial and error before you really start to see optimized results. Start with the wizard interface then try the advanced settings until you find the results you like best. There is no magic bullet here. The experimental phase can be very frustrating and time consuming to say the least, but once you have the settings you like, you can reuse them for future encoding jobs.
DVD Distribution
If you go to a Blockbuster store today, you might notice that DVD is well on its way to replacing analog VHS tapes. Up until this point, the main focus in digital video has been on Web distribution, but producing your own videos and 'burning' them on DVD is also possible for 'pro-sumers'.
Until recently, encoding and 'burning' DVDs required very expensive equipment. Apple Computer has introduced new but powerful consumer level DVD software called iDVD and iDVD Studio that can deliver professional results.
Media100's Terran Division also has a product called Cleaner MPEG Charger that helps you create and encode for DVD. Generally, DVDs use MPEG-2 codecs and you can encode at far greater data rates than you might for the Web, with a full screen window size to boot.
Community Sites
There are several useful video community sites that can help you find further information about video encoding.
See 2-pop, which supports a vast bulletin board for everything from video encoding, editing and capture to special effects.
Another Site called Streaming Media is a great portal which offers media talk radio shows, highlights everything from content and technology to industry trends and news, discussed by the latest luminaries.
Digital video creation, distribution and communication represents the next killer app. And it's a very exciting and fun process once you get the hang of it. Like everything, it requires learning a few key tools, some perseverance to get them working in tandem, and some trial and error until you're happy with the results. And beware -- once you get into it, you might get hooked.
