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[moyang628]

Hi,

I got a jpeg buff ,I want to convert it to opencv Mat for more image opration .

I have tried the Mat::from_raw 、Mat::new_rows_cols_with_data_def 、Mat::from_slice 、Mat::from_slice_rows_cols

it all got wrong,

now I have to save it as jpeg file and imread from it .

Is there a direct way to do that?

        let jpg_buff = std::slice::from_raw_parts(*p_data, (&*pst_frame_info).nFrameLen as usize);

        let mut file = File::create("camm.jpg").unwrap();
        let _ = file.write_all(jpg_buff);

        let mat = opencv::imgcodecs::imread_def("camm.jpg").unwrap();
        let _ = opencv::highgui::imshow("code jpeg", &mat);
        let _ = wait_key(0);
        let _ = destroy_all_windows();

[twistedfall]

You should use the imdecode function, but first convert the slice to Vector<u8> by calling Vector::<u8>::from_slice(jpeg_buff). If you want to avoid copying the buffer and don't mind a little bit of unsafe then instead of Vector you can use Mat:

unsafe { Mat::new_rows_cols_with_data_def(1, jpg_buff.len() as i32, u8::opencv_type(), jpg_buff.as_mut_ptr().cast::<c_void>()) }

Just make sure that you drop this Mat before you drop the jpeg_buff.

[moyang628]

thanks.

converting the slice to Vector by calling Vector::::from_slice(jpeg_buff) works

but the new_rows_cols_with_data_def dont work.
the

  unsafe { Mat::new_rows_cols_with_data_def(1, jpg_buff.len() as i32, u8::opencv_type(), jpg_buff.as_mut_ptr().cast::<c_void>()) }

You should use the imdecode function, but first convert the slice to Vector<u8> by calling Vector::<u8>::from_slice(jpeg_buff). If you want to avoid copying the buffer and don't mind a little bit of unsafe then instead of Vector you can use Mat:

unsafe { Mat::new_rows_cols_with_data_def(1, jpg_buff.len() as i32, u8::opencv_type(), jpg_buff.as_mut_ptr().cast::<c_void>()) }

Just make sure that you drop this Mat before you drop the jpeg_buff.

[twistedfall]

When you say it doesn't work what kind of error are you getting?

[twistedfall]

I'm going to close this for now with the hope that you made it work, but feel free to reopen and supply additional details if it's not the case.