Configuring the ASF Writer
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4/8/2010
The following table shows the properties that you can set or read for the Windows Media encoder DMO.
| Property | Description |
|---|---|
L"_KEYDIST" |
This value is read / write. The maximum time, in milliseconds, between key frames in the codec output. The internal logic of the codec determines the actual location of each key frame. The distance between any two key frames may be less than the value of this property, however, it will never be greater. The default value is 8000. |
L"_CRISP" |
A numeric representation of the tradeoff between motion smoothness and image quality of codec output. This value can range from 0 to 100. The higher the value, the more the codec will optimize encoding for the image quality of individual frames, to the detriment of motion smoothness. The default value is 75 This property should only be set for constant-bit-rate (CBR) encoding. The optimizations for variable-bit-rate (VBR) work differently. |
L"_COMPLEXITYEX" |
This value is read / write. This property is a measure of the encoder algorithm complexity. This value ranges from 0 to a maximum value defined by codec. Lower values cause the codec to use less-complicated encoding algorithms. Although the simpler algorithms produce lower-quality output, the encoding process is faster and requires less processing power. This can be important when encoding content from a live source. In such a case, the encoder must process inputs fast enough to keep up with the source. When encoding from an offline source, you should usually use the highest complexity. |
L"_VBRQUALITY" |
This value is read / write. This property indicates the quality level for quality based (1-pass) VBR encoding. This value can range from 0 to 100. Higher values indicate a higher quality. If the value is 0, the codec will not perform quality based VBR encoding. Not all of the values in the range have a unique meaning. The values that represent a step up in quality from the previous level are: 1, 4, 8, 11, 15, 18, 22, 25, 29, 33, 36, 40, 43, 47, 50, 54, 58, 61, 65, 68, 72, 75, 79, 83, 86, 90, 93, 97, and 100. For audio encoder DMOs, the quality modes are provided in the WAVEFORMATEX (Waveform Audio) structure of the output types that you retrieve using the IMediaObject::GetOutputType method |
L"_AVGFRAMERATE" |
This value is read only. The average frame rate, in frames per second, of video content. You can get this value after you are finished passing samples. |