Viewing YV12 images and videos, cutting a frame

[Festivas]

How can I cut a frame from YV12 video? I am new to video processing, so I do not even know what program should I use to open/view YV12 videos and images, please advise Also, where can I find a small YV12 video sample? Thanks!

[manono]

Also, where can I find a small YV12 video sample? Thanks!

Any DVD. Any XviD or DivX AVI.

How can I cut a frame from YV12 video?

I use MPC-HC, File->Save Image.

[Festivas]

I have installed Media Player Classic and DirectX, but still no luck. When I choose File->Save Image, the only available options to save are .jpg, .png and .bmp. Nothing like .yuv, not to mention YV12...

All video samples I can find on internet are .flv, .avi, .wmv or .mpg. Are these all wrong formats? Will "DVD. Any XviD or DivX AVI" really make any difference? How can I make sure the video has correct format for YV12 image, what extensions should it have?

[Festivas]

Hmmm, it looks like I have solved my problem, I have downloaded a .yuv player from http://www.fileinfo.com/extension/yuv, and I had a set of .yuv images that appear to be frames of the same video. The yuv player says that these images have format yuv420, which i think is the same as yu12, right?

Thanks!

[jagabo]

What exactly are you looking for? Raw (no container) YV12 video? You need to differentiate between containers (AVI, MPG, M2TS, MKV, MP4, MOV) and the format of what's in them (uncompressed YUY2, uncompressed YV12, uncompressed RGB24, uncompressed RGB32, many different compression codecs).

Most high compression video codecs use YUV 4:2:0 chroma subsampling internally and will output uncompressed YV12 (a specific arrangement of that 4:2:0 data) frames to an editor. If you open such a file in VirtualDub and save without compression you will get an AVI with uncompressed YV12 frames.

This site:

http://media.xiph.org/ldv/pub/test_sequences/

Has some test videos in raw (no header data, no metadata, etc.) I420 format. That's the same as YV12 except the two chroma channels are reversed:

http://fourcc.org/yuv.php#YV12
http://fourcc.org/yuv.php#IYUV

You can open those with AviSynth's RawSource(). For example, the 720p stockholm video can be opened with this command:

RawSource("720p5994_stockholm_ter.yuv", 1280, 720, "I420")

Attached is an AVI file (ZIP'd, the first non-gray frame of that 720p stockholm file) with a single 1280x720 uncompressed YV12 frame. If you are writing software to access YV12 data you can skip past all the AVI header info and access the 1280x720 Y image data (1280x720) as 921600 bytes at offset 8212 bytes into the file. The V plane (640x360) follows immediately after that, 230400 bytes at offset 929812, then the U plane (640x360) at offset 1160212.