You can use x264vfw codec or VFW codec such as xVid in Ocam.

Click on CODEC menu of OCAM and pop up menu as below.
(External codec only supports AVI container.)

A window will appear as shown below, and check the Use external codec checkbox.

After checking, click the combo box item below to display the installed external codec of your computer.
Select the desired external codec and press the OK button.  

Now, when you start recording, the recording will proceed with the selected external codec.

If you do not want to use an external codec, click the External Codec menu as before, and uncheck the Use External Codec checkbox, the system will automatically select the last internal codec you used.

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