问题
I'm using DirectShow with a simple approach (IGraphBuilder RenderFile) and try to control everything else with querying supplemental interfaces.
The option in question is aspect ratio. I thought that it is maintained by default, but actually the same program behaves differently on different machines (maybe versions of DirectX). This is not a huge problem for a video in a window, because I can maintain the aspect ratio of my window by myself (based on the video size), but for full-screen mode I can not understand how can I control.
I found that there are at least two complex options: for VMR video and with adding overlay mixer, but is there a known way for doing this for IGraphBuilder' RenderFile video?
回答1:
When you do IGraphBuilder::RenderFile, it internally adds a video renderer filter to the graph. It is typically a VMR-7 Video Renderer Filter:
In Windows XP and later, the Video Mixing Renderer 7 (VMR-7) is the default video renderer. It is called the VMR-7 because internally it uses DirectDraw 7.
At this point you can enumerate graph's filters, locate VMR-7 and use its interfaces such as IVMRAspectRatioControl to specify mode of interest.
来源：https://stackoverflow.com/questions/6774112/controlling-the-aspect-ratio-in-directshow-full-screen-mode