在DirectShow中控制纵横比（全屏模式） [英] Controlling the aspect ratio in DirectShow (full screen mode)

问题描述

我正在通过一种简单的方法（IGraphBuilder RenderFile）使用DirectShow，并尝试通过查询补充接口来控制其他所有内容。

I'm using DirectShow with a simple approach (IGraphBuilder RenderFile) and try to control everything else with querying supplemental interfaces.

有问题的选项是宽高比。我以为默认情况下会对其进行维护，但是实际上同一程序在不同的计算机（也许是DirectX的版本）上的行为会有所不同。对于窗口中的视频来说，这不是一个大问题，因为我可以自己维护窗口的纵横比（基于视频大小），但是对于全屏模式，我无法理解如何控制。

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.

我发现至少有两个复杂的选择：用于VMR视频和添加叠加混合器，但是对于IGraphBuilder的RenderFile视频，有没有一种已知的方法？

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?

推荐答案

当您执行IGraphBuilder :: RenderFile时，它会在内部向图形添加视频渲染器过滤器。它通常是 VMR-7视频渲染器过滤器：

When you do IGraphBuilder::RenderFile, it internally adds a video renderer filter to the graph. It is typically a VMR-7 Video Renderer Filter:

在Windows XP和更高版本中，视频混合渲染器7（VMR-7）是
默认视频渲染器。之所以称为VMR-7，是因为内部
使用DirectDraw 7。

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.

此时，您可以枚举图形过滤器，找到VMR-7并使用其接口，例如 IVMRAspectRatioControl 指定兴趣模式。

At this point you can enumerate graph's filters, locate VMR-7 and use its interfaces such as IVMRAspectRatioControl to specify mode of interest.

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