Distribution - Presents various options for playing back HD content.
Conclusion - Describes what you can expect from the next articles in the series.
Welcome to the first in a series of articles that I'll be writing for Microsoft® about HD encoding with Microsoft® Windows Media® 9 Series. This article series will provide practical
solutions and techniques to create and deliver Windows Media-based content in the real world.
This first article is about how to quickly repurpose existing HD content by encoding with the Windows Media Video 9 Series codec for HD delivery. Future articles in this series
Ben Waggoner offers industry-leading digital video consulting, training, and encoding services. Ben was formerly Director of Consulting Services
for Media 100 and Terran Interactive, and before that Chief Technologist and founder of Journeyman Digital. He is a contributing editor for DV Magazine, and frequently writes about video
compression for it. Visit Ben's Web site
to learn more.
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will cover the nuances of HD capture, editing, and compression. This article is about how to get that first HD piece built during lunch, to prove to yourself and your bosses that Windows Media
provides the highest quality encoding available.
The Explosion of HD
After years of hype, HD has finally gone mainstream. While over-the-air HD and DVD HD haven't really caught on yet, HD is being used by production and post production in a wide variety of ways.
For example, the pioneering DVD company Criterion uses D5 HD for digital intermediates from their telecine captures. Suddenly, companies are finding that they have HD content to distribute,
and are looking for ways to distribute it.
Windows Media to the Rescue
The great news is that today Windows Media provides everything you need to author and deliver HD content for playback on computers running Microsoft Windows®, and to distribute that content
on DVD-R, transfer it over the Internet, or even play it back in digital cinemas or next-generation consumer electronics players.
So, let's spend 60 seconds getting your first encoding started. No, really.
You'll want to have an AVI file (more on how to get one in the next section if
you don't already have it). You'll also want to have Microsoft® Windows
Media® Encoder 9 Series installed. Windows Media Encoder is a free
download to licensed users of Microsoft Windows® operating systems. You can download it from the Windows Media 9 Series Download Center.
To set up your encoding
Launch the encoder, which will open the New Session dialog box.
Click the Convert a file wizard.
Select a source file.
Create a name for your output file.
In Content Distribution, click Hardware devices (CD, DVD, portable).
By default, you'll be assigned some encoding settings for video, audio, and bit rate. For this first encoding, accept the defaults, and click Next.
In Display information, you can enter a title or other metadata.
The next screen is a review of your settings. Make sure Begin converting when I click Finish is selected, and click Finish!
And that's it. A 1280 x 720-pixel file with stereo audio and 5 Mbps video will be created. Go get a cup of coffee while the file is encoded. Depending on the speed of the encoding
computer (and the length of the content), the encoding process might take a while, but the actual human labor is minimal.
Some of you didn't have a ready-made AVI file to use as source for the first encoding, so this section is about how to get your content from an HD nonlinear editing (NLE) timeline to a file
that you can use to encode. If you don't have an NLE tool, don't be concerned. I'll be covering HD capture solutions in a future article.
Export Format and Codec
The first step is to get your HD source out of the application you're using and
into a high-quality format that your encoding tool can use as a source for
converting by using Microsoft® Windows Media® 9 Series. If you use
an NLE like Adobe Premiere Pro that can export directly to Windows Media
9 Series, you can skip this section.
If you're using Windows Media Encoder, you'll need to make an AVI file. For users of QuickTime-based workflows, you can use an encoding tool like Canopus ProCoder or Discreet cleaner XL that
read QuickTime files.
It's simplest to export your content by using the same settings that you used
during the capture and editing processes. These settings include codec, frame
size, frame rate, encoding mode (progressive or interlaced), and so on. When
you use the same settings, it avoids the need to recompress the content, which
makes for higher quality and faster export.
It is also possible to preprocess the content while exporting. Preprocessing
means exporting to the same frame size, frame rate, field mode, and so on, that
will be used in the final encoding operation. Doing preprocessing during export
can give you better control over how the image looks, and can make the
intermediate file smaller (a 2-hour film encoded at 1920 x 1080
pixels, 60 interlaced frames per second (60i), at 10 bits per channel is
just over 1 terabyte, or 1,000 gigabytes).
Note to Macintosh users You can copy
from an Apple Final Cut Pro workstation to a Windows-based computer easily with
Mac OS X by using the Server Message Block (SMB) protocol. From the Go
menu on your Macintosh computer, select Connect To Server, and type
"smb://" followed by the IP address of the Windows-based computer.
Now let's look at the parameters we can adjust for a better experience.
This tutorial uses Microsoft® Windows Media® Encoder 9 Series for
the examples. The advice given here will largely apply to other applications
that can encode to Windows Media format. Three of particular note are Canopus
ProCoder, Discreet Cleaner XL, and Adobe Premiere Pro.
My favorite professional encoding tool for Windows Media 9 Series is Canopus ProCoder. It can read native QuickTime files, it supports batching, and it allows for much deeper preprocessing.
Figure 3. Canopus ProCorder enables you to fine-tune your encoding settings
Discreet cleaner XL
Discreet cleaner XL also supports QuickTime source files and all the features of Windows Media 9 Series that are needed to create great Windows Media 9 Series HD files. Cleaner XL is the only
encoding application that supports Microsoft .NET technology. By default, the project window in cleaner XL uses Windows Media 9 Series, making it easy to create outputs just by starting the
application. Watch folders and preview capabilities make it easy to integrate Windows Media 9 Series HD workflows.
Figure 4. Discreet cleaner XL has preprocessing filters for Windows Media 9 Series HD output
Adobe Premiere Pro
Adobe Premiere Pro can natively encode straight to Windows Media 9 Series from the timeline. It's also easy to export to an AVI file from Adobe Premiere Pro, and to then use a different
computer for the final encoding operation.
Figure 5. You can easily export to an AVI file from Adobe Premiere Probr>
Properties and Sessions
A great way to learn encoding is to modify existing settings. There are many features available in Windows Media Encoder 9 Series, but we're only going to talk about those features that
are relevant to this project.
We'll be doing most of our work with Windows Media Encoder 9 Series in the Compression tab. To locate the Compression tab, launch Windows Media Encoder, click Cancel
in the New Session dialog box, click Properties on the encoder toolbar, and then click the Compression tab.
You can pick new presets, but we want finer control. Click the Edit button to open the Custom Encoding Settings dialog box. From here, you can adjust your current settings, and
even export them for later use. For HD file-based content, you'll leave most of the settings alone.
Bit rate VBR (peak limited) is the optimum encoding mode, and Windows Media Video 9 Professional and Windows Media Audio 9 Professional are the optimum codecs.
Video format should be set to whatever format you're working with. Note that 24p isn't an option hereyou'll set that later. You should select Allow interlaced processing
if you intend to deliver your content to an interlaced display (to a video monitor rather than a computer monitor). While Windows Media 9 Series can certainly deliver interlaced content,
interlaced video requires more bits and CPU power to deliver equivalent quality and should only be used if interlacing is truly required.
Using the Allow nonsquare pixel output feature enables anamorphic encoding. This normally is not used for 1280-pixel wide projects, but is used for 1920-pixel wide projects (details below).
In the Custom Encoding Settings dialog box, click the tab showing the current data rate to see the additional controls that are explained below.
Audio Parameters Audio format depends on your source. You'll use the sample rate, bit depth, and channels of your source. Windows Media Player can fold 5.1 audio back to stereo on computers running
earlier versions of Windows, while providing a stellar audio experience for those computers with multichannel speakers running Windows XP.
For any given combination, there will be several data rate options. With the Windows Media Audio 9 Professional codec, even the lowest data rate will sound very good. Note that these are
average data rates, and do affect the total file size.
What affects playback performance are the Audio peak bit rate and Peak buffer size options. Two seconds is good for the peak buffer size. For stereo content, the default audio
peak bit rate is fine. For 5.1 audio, raise it to 1,500 Kbps.
Be sure to match the bit depth (16 or 24 bits) and sampling rate
(44.1 kilohertz (kHz), 48 kHz, 96 kHz) to the properties of your
source content to avoid resampling. For most content and most playback systems,
sample rates above 48 kHz don't provide an audible improvement.
For Video size, type the size of the frame you want. If this source is already the correct size, just select Same as video input. Video size is critical because it strongly affects
playback performance. A frame size of 1280 x 720 pixels plays back nicely on almost any Intel Pentium 4 or AMD Athlon XP processor. A frame size of 1920 x 1080 pixels
requires the latest performance-tuned systems (and is almost never used as is). It's important that the output aspect ratio matches the aspect ratio of the source. For example, a 1.85:1 movie
from a 1280 x 720-pixel source would be resized to 1280 x 688 pixels by cropping 16 pixels off the top and bottom. For optimum compression, it's best to have height
and width measurements that are divisible by 16.
Frame rate actually specifies the maximum frame rate, but if the source has a lower rate, then that rate will be used instead.
Key frame interval controls how often a key frame is inserted. Key frames are the only frames that can be jumped to using random access. The default of 4 seconds is appropriate for
most HD content.
Video bit rate is the average bit rate, and hence determines average quality and final file size.
Video peak bit rate controls the maximum bit rate of the parts of the video that are most complex to encode. The peak bit rate has a big impact on playback requirements. Even if you are
raising the average data rate to improve quality, raise the video peak bit rate only if you can test playback on your target computers.
Five seconds for Peak buffer size is a fine default setting.
Decoder complexity will affect playback on future hardware. We don't have the details yet on this, so leave it on Auto.
The Video Size tab controls cropping and pixel aspect ratio.
Figure 6. The Video Size tab in Windows Media Encoder
Because computer displays don't have a "safe area," any blanking or letterboxing should be removed. Watch out for even a few pixels of black, which can cause distortion when compressed. Because
Windows Media Encoder lacks cropping preview, nontrivial cropping is easier with Canopus ProCoder or Adobe Premiere Pro.
Pixel Aspect Ratio
For lower resolution HD, like 1280 x 720 pixels or less, use square pixels to achieve the best compression. However, because 1920 x 1080-pixel content is too difficult to
play back, using a different pixel aspect ratio to compress the video horizontally can help playback. For example, take a 1920 x 1080-pixel source of a 2.35:1 movie, where (after letterboxing
is removed) the resolution is really 1920 x 816 pixels. This can be encoded with a 4:3 pixel aspect ratio, producing 1440 x 816 pixels. If played on a 1920 x 1080-pixel
projector, Windows Media Player will stretch the video to 1920 x 816 pixels. Make sure the Output aspect ratio (in the gray box on the right side of the screen) matches your
The Processing tab is mainly used to select the deinterlacing mode. You do not need to select this mode unless your content comes from an interlaced source and is going to a progressive
display. For progressive sources, this setting should be left at None. For 60i sources, pick Deinterlace, or Maintain interlacing to deliver your content in interlaced mode.
For 60i source content that was converted from film in a telecine process, use Inverse telecine. For either, the Auto mode should work fine. The Detect button can be used
to guess the proper mode, but it often gives an erroneous result.
So, you've made an HD video file. How to do you share it?
The biggest challenge with HD in general is making sure that users can play back the files. The higher the frame size, frame rate, and peak data rate, the faster the computer that is required
for playback. A Pentium 4 or Athlon XP running Windows 2000 or (ideally) Windows XP and Windows Media Player 9 Series is a minimum requirement. However, rating performance
in simple clock speed doesn't present the full story, because memory, bandwidth, motherboard, video card, video card memory, video card driver version, and other components play a dramatic role
in performance. Clearly communicating this to your audience can help avoid some user anguish.
Burning the Windows Media Video (WMV) file to a DVD-R is a simple way to move the file around. A DVD-R stores 4.7 GB, which gives a little less than two hours at the default bit rate of
5,000 Kbps for video and 192 Kbps for audio. Putting less content on the disc means that a higher average data rate can be used.
When FedEx isn't fast enough, the Internet comes to the rescue. HD files are too large for real-time streaming or even progressive downloadit's better to just put the content on a server,
and download it like a normal file. Download time is proportional to both data rate and connection speed. That two-hour film at the default data rate would take nearly 24 hours to download
over a 512 Kbps DSL connection. Adjust accordingly.
So that's it for now. Over the next few months we'll be delving deeper into many of the topics introduced here. By the end of this series you will have the information you need to become an
expert in capturing, encoding, and delivering Windows Media-based HD content.
And what if you don't want prying eyes to be able to view your files without permission? We'll also be covering digital rights management (DRM) later in this series.
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