I am attempting to use the IMFSourceReader to read and decode a .mp4 file. I have configured the source reader to decode to MFVideoFormat_NV12 by setting a partial media type and calling IMFSourceReader::SetCurrentMediaType and loaded a video with dimensions of 1266x544.
While processing I receive the MF_SOURCE_READERF_CURRENTMEDIATYPECHANGED flag with a new dimension of 1280x544 and a MF_MT_MINIMUM_DISPLAY_APERTURE of 1266x544.
I believe the expectation is to then use either the video resizer dsp or video processor mft. However it is my understanding that the video processor mft requires windows 8.1 while I am on windows 7, and the video resizer dsp does not support MFVideoFormat_NV12.
What is the correct way to crop out the extra data added by the source reader to display only the data within the minimum display aperture for MFVideoFormat_NV12?
New media type says this: "video is 1266x544 and you expected/requested, but I have to carry it in 1280x544 textures because this is how GPU wanted it to work".
Generally speaking this does not require further scaling or cropping you already have the frames you need. If you are reading them out of sample objects - which is what I believe you are trying to do - just use increased stride (1280 bytes between consecutive rows).
If you are using this as a texture, presenting it somewhere or using it as a part of rendering, you would just use adjusted coordinates (0, 0) - (1266, 544) ignoring the remainder, as opposed to using full texture.