Set top-level encode options
You can use the top-level video options in Microsoft Expression Encoder to define the format and codec of your encoded media. These are the first options available in the Encode panel.
Click the Encode tab. If you can't see the Encode tab, on the Window menu, click Encode.
Set your top-level options in the Encode panel according to the following guidelines:
The option of choosing MP4 as an output format is available only in Expression Encoder with IIS Smooth Streaming.
Output Format This setting specifies the type of file that you will create. When you choose a format, all the other pertinent fields in the panel automatically populate with the optimal settings for that format.
Container This setting specifies the container type that you will use to wrap your data. (A container is a file format that identifies the type of data that is wrapped within it.) This data could be as simple as a single stream of encoded video, or it could consist of several audio and video streams, metadata, subtitles, and so on. For Windows Media output formats, choose WMV to create a WMV or WMA file. Choose Smooth Streaming to create a file that can be played back using Smooth Streaming technology. For H.264 output formats, choose MP4 to create an MPEG 4-compressed file.
For more information about Smooth Streaming, see About IIS Smooth Streaming.
Video This setting specifies the codec to be used for encoding. Click the adjacent box to include video in your encoded file. Depending on your format choice, you will have a choice of either VC1 or H.264 codecs.
For the Windows Media output format, you have three choices of VC1 codec types. VC1-Advanced is optimized for high-bit-rate encoding (20 Mb per second and up), though it is also effective with lower bit rates down to 2 Mb per second. VC1-Main is optimized for bit rates below 20 Mb per second. VC1-Simple is optimized for bit rates below 400 kb per second. All VC1 codecs provide high-quality encoding for both downloading and streaming content.
For the MP4 output format, you have two choices of H.264 codec types. H.264-Main is optimized for most streaming scenarios. H.264-Baseline is optimized for mobile devices and scenarios with very low bandwidths.
Audio This setting specifies the type of codec to be used for encoding your audio. Select this setting to include audio in your encoded file. For H.264, you can choose AAC-LC (Low Complexity). For WMV, you have four choices. Choose WMA for most situations. Choose WMA Professional to compress high-resolution, multiple channel audio. Choose WMA Lossless to employ lossless compression to your audio, retaining the exact characteristics of the original file when decompressed. Choose WMA Voice to compress audio that primarily contains human speech.