Default Peak Video Bitrate Encodes As CBR 2 Pass Instead of VBR 2 Pass in WMCmd.vbs Script (813398)

SYMPTOMS

When you use the default settings for Windows Media Encoding Script to compress files into the Windows Media Format, the setting for the peak video bitrate (-v_peakbitrate) will be set at 1.5 times the average video bitrate (-v_bitrate). This setting switches the encoding mode to a constant bitrate (CBR) 2 Pass instead of the variable bitrate (VBR) 2 pass mode.

CAUSE

When the peak video bitrate default setting of 1.5 in the Wmcmd.vbs script is detected, Windows Media Encoder multiplies it by the average video bitrate and switches the encoding mode from peak bitrate VBR Mode to the CBR 2 pass mode.

Note By default, Windows Media Encoder sets the peak video bit rate at 1.5 times the average video bit rate. The file will still appear to be a VBR even though the codec processes the actual file as a CBR 2 pass.

RESOLUTION

To change the default video peak bitrate, see the quick reference Help for the command-line options appropriate to your project. For example, the following command line sets the video mode, bitrate, peak bitrate, and buffer size:

cscript.exe wmcmd.vbs -input C:\My-Clips\Myfile.avi -output C:\My-Clips-Coded\Myfile.wmv -v_mode 4 -v_bitrate 100000 -v_peakbitrate 300000 -v_peakbuffer 8000

To access quick reference Help from the command line, follow these steps:

Click Start, click Programs, and then click Accessories.
Click Command Prompt.
Type: cd c:\program files\windows media components\encoder, and then press ENTER.
Type cscript.exe wmcmd.vbs, and then press ENTER.

MORE INFORMATION

Windows Media Encoding Script (Wmcmd.vbs) is installed in the same folder as Windows Media Encoder. By default, the folder is in the following location:

c:\Program files\Windows Media Components\Encoder