[Libav-user] How can i extract Y plane from any frame in video

Amir Rouhi-Rmit amir.rouhi at rmit.edu.au
Wed Jun 29 02:35:23 CEST 2011

Thanks for your nice reply.
in Pixel formats (-pix_fmt) we have a wide variety of output formats. I have
three question and i would be pleased if you help me the answers:

1- Would you let me know whats the difference between yuvj420p  and yuv420p?
both has same nb-channels and depth
2- whats the mean of is_alpha parameter and nb_channels in different
3- if i want to quantise the result how can i reduce the depth from 8 to 3
or 4?


On Tue, Jun 28, 2011 at 7:14 PM, Alex Cohn <alexcohn at netvision.net.il>wrote:

> Amir,
> > 1- i convert a video to yuv images (1 image per second) as below:
> > ffmpeg -i c:\test\animals.wmv -r 1 -f image2 -s 320x240 -pix_fmt yuvj420p
> c:\test\Img-%03d.yuv
> By default, -f image2 produces JPEG files. You should use -vcodec
> rawvideo to produce yuv420 images, e.g.
> ffmpeg -i c:\test\animals.wmv -r 1 -f image2 -vcodec rawvideo -pix_fmt
> yuvj420p c:\test\Img-%03d.yuv
> Note that you can skip -s if you do not resize the result.
> Sincerely,
> Alex
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Amir H. Rouhi
PhD Student/ CSIT RMIT University
Room: 14-09-04
rouhi_amirhossein at student.rmit.edu.au
amir.rouhi at rmit.edu.au
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