Configuring VBR Streams
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You can use variable bit rate (VBR) encoding to produce high quality streams for local files or for downloading and playing. There are three options for VBR: quality-based (one-pass), unconstrained (two-pass), and constrained (two-pass). For more information about the types of VBR encoding, see Variable Bit Rate (VBR) Encoding.
You can configure VBR encoding in a profile by setting properties with the IWMPropertyVault interface. The following table describes the properties used to configure VBR encoding.
| Property | Description |
|---|---|
| g_wszVBREnabled | Boolean value. Set to True to use VBR encoding. |
| g_wszVBRQuality | DWORD value. Set to the desired quality level (1 to 100) for quality-based VBR encoding. |
| g_wszVBRBitrateMax | DWORD value. Set to the maximum bit rate, in bits per second, for constrained VBR encoding. |
| g_wszVBRBufferWindowMax | DWORD value. Set to the maximum buffer window, in milliseconds, for constrained VBR encoding. |
The following sections describe how to use the different types of variable bit rate encoding.
| Section | Description |
|---|---|
| To Configure Quality-Based VBR | Describes how to use variable bit rate encoding based on a static quality level. |
| To Configure Unconstrained VBR | Describes how to use variable bit rate encoding based on a target average bit rate without an explicit peak value. |
| To Configure Constrained VBR | Describes how to use variable bit rate encoding based on a target average bit rate and an explicit peak value. |
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