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Set Video options

The Video settings in the Encode panel of Microsoft Expression Encoder specify overall video quality and playback parameters. The choices that you make here determine the complexity of the encoding process, and also how smooth the playback will be.

  1. Click the Encode tab. If you can't see the Encode tab, on the Window menu, click Profile.

  2. Set the Video options in the Profile panel according to the following guidelines:

    • Set Mode to specify whether Expression Encoder uses Constant Bit Rate (CBR) or Variable Bit Rate (VBR) encoding. For CBR encoding, you can choose CBR 1-pass or CBR 2-pass encoding. This specifies that the codec will make either one or two passes through the data when encoding it. In one-pass encoding, Expression Encoder uses only one pass through the content to analyze and compress it. In two-pass encoding, the codec first analyzes the content, and then, in the second pass, encodes it. This creates a higher-quality file.

      For VBR encoding, choose VBR peak constrained to limit the variation in the average bit rate. Large variations in the bit rate could disrupt playback. Choose VBR peak unconstrained to specify that there be no limit on bit rate variance. Choose VBR Quality to achieve the highest bandwidth based on the Quality value that you choose. Note that the VBR Quality setting may cause spikes in the encoding if the scene being encoded is a complex one.

      For more information, see Understanding different types of bit rate encoding.

    • Set Buffer Window to specify, in seconds, the amount of content that you want to preload before playing back.

    • Set Frame Rate to specify the number of frames per second (fps) in the encoded file.

    • Set Key Frame Interval to specify the number of seconds, or frames, between key frames.

    • Use the Stream tabs to add multiple streams to your content. Multiple streams allow you to present content of varying bandwidths to compensate for the different playback scenarios of your audience. You can control both the number of streams and the bit rate and size of each stream. Select Create separate file per stream to save an individual file for each bit rate you specify. If you do not select this option, Expression Encoder combines all the streams into the final encoded file. To display the settings for a particular stream, click a tab. To add a new stream, click New.

      Drag the Bitrate, Peak Bitrate, Width and Height values to change them. The bit rate values are expressed in kilobits per second. Higher Bitrate values create larger files and higher quality, but also require more bandwidth for streaming. Set the Peak Bitrate value to the maximum bit rate that you want for your file. For the width and height values, note that increasing these dimensions may cause distortion. To avoid distortion, either decrease the image size or keep the image at its source size.

      On the Size Mode menu, choose the size you would like your encoded video to be. Quarter Source reduces the size of the width and height to be a percentage of the original source. The source retains its original dimensions. Choose Custom to specify your own dimensions. This mode appears automatically if you manually adjust the Width and Height parameters.

    • Select a Video Aspect Ratio from the menu either to match your source or to match one of the listed aspect ratios. If you want to create a custom aspect ratio, click the lock icon and drag either of the Display values.

    • Select Allow automatic resizing (this option is active only if you have selected IIS Smooth Streaming as the output format and VBR as the video mode) to instruct the encoder to resize an encoded frame if doing so results in a better quality image.

    • Select Force Square Pixels to make sure that your output contains square pixels.

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