Andrea Pruneda
Microsoft New Media Platforms Division
November 2002
Introduction
Microsoft Windows Media 9 Series includes Windows Media Encoder, a powerful production tool for converting audio and video into files and streams in Windows Media Format. End users can use the Windows Media Encoder user interface to configure an encoding session, which at a minimum includes specifying the audio and video input sources, the output, and the encoding profile to use. Additionally, end users can crop and resize video, add metadata attributes, and specify preprocessing settings.
Windows Media Encoder is based on the Windows Media Encoder SDK, which is available to developers who want to create custom encoding applications. This SDK supports C++, Microsoft Visual Basic®, Microsoft Visual Basic Scripting Edition (VBScript), Microsoft JScript®, and any of the programming languages supported by the Microsoft .NET Framework. In addition, developers can automate the encoding process in different ways, which is the focus of this article.
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Abstract
Using Microsoft® Windows Media® Encoder 9 Series and the Microsoft Windows Media Encoder 9 Series SDK, you can convert audio and video into Windows Media-based content. This article describes different ways that you can automate this process by using the Windows Media Encoder SDK and its sample applications.
This article describes how to automate the encoding process in the following topics:
The Windows Media Batch Encoder is a sample application written in Microsoft Visual Basic .NET. It is intended to be a starting point for automating your process. You can modify the source code to suit your needs.
The sample shows how to encode a list of files without having to configure the encoding session for each file. Each file you add to the list can have different settings as needed; for example, you can use a different profile for each file. This sample includes other important features, allowing you to enable two-pass encoding, specify video preprocessing, and add digital rights management (DRM) protection using an existing DRM profile.
When you start encoding, the sample application displays status information, such as the percentage completed and the encoding status. You can also preview the video output while encoding. After you set up a batch encoding list, you can save your encoding session and use it again; this feature is useful when you encode the same files on a regular basis.
Figure 1. The Windows Media Batch Encoder sample
This sample can be found in the \WMSDK\WMEncSDK9\Samples\vb\batcher folder where you installed the Windows Media Encoder SDK. For more information, see the Batch Encoding topic in the Windows Media Encoder SDK Help.
The Command Line Encoder sample is written in VBScript, and allows you to run an encoding session from the command line. Many command-line parameters are available, allowing you to take advantage of most encoding features. You can specify CBR or VBR encoding and create custom profiles. To automate the encoding process, you can also write as many commands as needed to a batch (.bat) file. For example, you could save the following text to a batch file:
Using this utility, you can also enumerate the available source devices on your computer, as well as the available audio and video codecs.
This sample (wmcmd.vbs) can be found in the \WMSDK\WMEncSDK9\Samples\vb\wmcmd folder where you installed the Windows Media Encoder SDK, and you can modify it as needed. Run the sample with CScript.exe from a command window. To get a complete list of all the command line parameters and what they do, execute the script with this command line:
The Remote Administration sample is written in C#, and shows how you can monitor encoding applications running on remote computers, over a local area network (LAN), or over the Internet.
For example, if you have multiple instances of an encoding application running, the sample application enumerates the encoding applications, and then allows you to monitor their status on one page. You can monitor the samples dropped, the current bit rate, the CPU usage, and so forth.
This sample uses a Web service that allows clients to monitor the status of a remote encoding application. Typically, you would use three computers to set up remote administration, including a computer to:
Run the encoding applications with the Web service installed.
Act as a Web server that contains an ASPX page to call the encoder Web service.
Serve as a client computer to connect to the Web server to monitor the encoding applications, for example, using Microsoft Internet Explorer.
Using such a Web service, you have greater flexibility since you can write code to run on the client computer in any of the programming languages supported by the .NET Framework to communicate with the Web service. Web services also work well on a LAN and across the Internet. Using the sample as a starting point, you could write code in order to automatically update the monitoring page, rather than refreshing it manually. Or, you could use the DHTML WebService behavior to call the encoder Web service directly. You could also add methods to configure and control the remote encoding application, and expose this functionality as part of your Web service.
The following illustration shows the sample ASPX page that is used to monitor encoding applications.
Figure 2. The Remote Client page for monitoring encoding applications
This sample can be found in the \WMSDK\WMEncSDK9\Samples\c#\remadmin folder where you installed the Windows Media Encoder SDK. For more information about remote administration, see the Windows Media Encoder SDK Help. For more information about the DHTML WebService behavior, see the WebService Behavior page on MSDN® Online.
In addition to using the SDK sample applications, you can incorporate the following features to help automate your encoding process:
Statistics. Helps you monitor the status of the encoding process, which is useful when your encoding applications are running on remote computers.
Stream editing. Allows you to split and recombine streams. For example, you can produce one encoded file containing multiple bit rates, and then use stream editing afterwards to create a separate file for each bit rate.
Basic editing. Allows you to work with encoded files by trimming the beginning and end times, and by adding metadata, markers, and scripts. For example, you could add basic editing at the end of your encoding process to add additional metadata attributes.
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