问题
I have a video clip that has some issues on default install of Win7: video plays without sound. The video clip comes from a mobile phone, it's a 3gp (mp4) file format with H264 video and AMR audio. I wanted to find out what I can do to add playback support for AMR audio on that machine. VLC or klite/ffdshow codec packs are out of the question here. I tried to use AMR dshow decoder from MonoGram but it doesn't solve the problem. When I tried to see the graph in MonoGram graph studio it doesn't show me the graph how win7 at all is able to play the video. Seems like it doesn't use dshow filters/decoders in case of this video clip. So the questions is: how does it play the clip and how can I extend default os functionality to make my clip playable.
来源：https://stackoverflow.com/questions/11812670/video-playback-on-win7-vista-dshow-dmo