Not sure if this is the correct place to report this, but I was following the example on https://libspng.org/docs/usage/ and trying to figure out why it didn't work before I realized the parameters were in the wrong order. spng_decode_image(ctx, SPNG_FMT_RGBA8, out, out_size, 0); should be spng_decode_image(ctx, out, out_size, SPNG_FMT_RGBA8, 0);

I just wanted to be sure somebody was aware of it!