Using ffmpeg to get the actual video resolution

Question

Well, this is my first question in this community. I have asked it in SO but it was considered out of scope there.

Anyway, I am trying to decode an avi video but when I pass it through ffmpeg to check the encoding parameters I got this outcome which confused me:

$ffmpeg -i video.avi
...
Stream #0:0(und): Video: mpeg4 (Simple Profile) (mp4v / 0x7634706D), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], 2501 kb/s, 30 fps, 30 tbr, 15360 tbn, 30 tbc (default)

I guess yuv420p means something like 746x420 pixel (I made the multiplication myself, so I am not sure it's exactly this one using the ratio of 1920x1080 and 1280x720) but anyway much less than 1280x720 which is 720p. So, what does exactly means those two together? yuv420p vs 1280x720?

Can someone explain which is the actual resolution of the video (and why I get those different resolutions)?

Answer 1

In yuv420p, 1280x720 [SAR 1:1 DAR 16:9],

• yuv420p indicates the pixel format and chroma subsampling scheme.

• the video's raster resolution is simply 1280x720.

• the video's Sample Aspect Ratio (width of pixel : height of pixel ratio) is 1:1 (square pixels)

• the video's Display Aspect Ratio is 16:9