`panic` when converting to YUV420 to RGB

[mfreeborn]

I have a raw buffer of bytes which is a YUV420 format frame from a camera, which I am trying to convert to RGB (well, ultimately to a JPEG).

My code, however, panics when I try to do the conversion, looking something like this:

let frame_data: Vec<u8> = ...; // a 1920x1080 resolution YUV420 frame, 3110400 bytes long
let view = Image::<Yuv<u8>, _>::from_buf(&frame_data, 1920, 1080).unwrap();
let mut rgb_buf = Image::<Rgb<u8>, _>::new(0, 0, 0u8);
view.convert(&mut rgb_buf); 

And then I get a really long panic message:

thread '<unnamed>' panicked at 'range end index 3116160 out of range for slice of length 3110400', /home/michael/.cargo/registry/src/github.com-1ecc6299db9ec823/ffimage-0.9.0/src/packed/convert/rayon.rs:86:27
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
thread '<unnamed>' panicked at 'range end index 3306240 out of range for slice of length 3110400', /home/michael/.cargo/registry/src/github.com-1ecc6299db9ec823/ffimage-0.9.0/src/packed/convert/rayon.rs:86:27
... repeated absolutely loads of times with an incrementing "range end index"

Is YUV420 conversion supported?

[raymanfx]

Hi, YUV420 is not supported right now. We currently only have conversion support for the packed/interleaved YUV formats, i.e. YUYV and UYVY.

YUV420 looks like a planar format - can you confirm this is the case for your image? There's a helpful format description in the VLC wiki: https://wiki.videolan.org/YUV#UYVY.

[mfreeborn]

Thanks for the reply - that VLC article has clarified things significantly. Yes, my format is I420 - planar.

I understand the functionality of this crate now and can make some progress.

[raymanfx]

Would you be interested in adding this functionality to this crate? Planar image support is something I‘ve wanted to tackle for some time now, but never really got to it.

I can draft a first implementation for you to test if you don’t want to handle it. Should not take more than a week or two - there’s some smaller fish to fry first.

[raymanfx]

I just pushed preliminiary YUV 420p support to the next branch: https://github.com/raymanfx/ffimage/commit/e133a7dcfd89df030a873b0168f643e13126e206. It's untested though.

next is a major rework of the code that's in master right now, but the benchmark code in the commit should give you an idea how to use it.