[Libav-user] Getting pixel value at each x, y position of a given frame

[NDJORE BORIS]

Le ven. 5 avr. 2019 à 13:20, Simon Brown <simon.k.brown at gmail.com> a écrit :

> On Fri, 5 Apr 2019 at 12:08, NDJORE BORIS <ndjoreboris at gmail.com> wrote:
>
>> Hello,
>>
>> Can someone help me to find the value of each pixel on a given frame,
>> please.
>> I use frame.data[] and frame.linesize[].
>> Then I do this :
>>
>> for(int i = 0; i< height; i++)
>> {
>>
>>           for(int j=0 ;j<width; j++)
>>          {
>>                xy = height*stride + width
>>                   int pix_i,j = frame.data[xy][frame.linesize[xy]].
>>           }
>> }
>> where width and height are the dimension of the frame.
>>
>> I don't know if what I do is right
>>
>> I've done it in an older version of FFMpeg, so not sure if it still
> applies, but I used:
> for (yy=0 ; yy<frame->height ; yy++) {
> memcpy(bufs[0]+720*yy, frame->data[0]+(frame->linesize[0])*yy, 720);
> }
> for (yy=0 ; yy<frame->height/2 ; yy++) {
> memcpy(bufs[1]+360*yy, frame->data[1]+(frame->linesize[1])*yy, 360);
> memcpy(bufs[2]+360*yy, frame->data[2]+(frame->linesize[2])*yy, 360);
> }
> I was decoding YUV 422 data, and assuming a width of 720 pixels, copying
> it into my own buffers.
> The point is that frame->data has arrays for each plane of the decoded
> video, and then each plane buffer can get you a pixel value for that plane.
> Ultimately you'll probably need more than one value for each pixel, be it
> RGB or YUV.
>
> Simon
>

Ok, Thanks!

But can you tell me how to get the frame pixel format, please?
I use frame->format   but the output is only zero (0) value.

Regards

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