oss-nvjpg

The Tegra X1 provides a hardware module dedicated to JPEG encoding/decoding (NVJPG).

Using this library, images can be rendered to an RGB or YUV (triplanar) surface. YUV➝RGB conversion is handled in hardware. In addition, images can be downscaled to up to 8, also done in hardware.

Note: only baseline JPEGs are supported. Progressive and arithmetic coded files will return an error.

Performance

Decoding times are largely faster than those obtained by software rendering, even with SIMD optimizations. The results below were obtained on an Aarch64 Cortex-A57 clocked at max 2.091GHz, by decoding the same image to an RGB surface, averaging 1000 iterations:

Library	70Kib 720x1080	1.6Mib 3200x1800
NVJPG	2.036ms	15.997ms
libjpeg-turbo	6.127ms	66.341ms
stb_image (with NEON routines)	16.512ms	158.474ms
Python-pillow	11.688ms	114.918ms
nanoJPEG	48.299ms	531.575ms

Building

Requires C++20 support.

Linux

meson build && meson compile -C build

Additionally, run meson compile -C build examples to build the examples.

devkitA64

make -j$(nproc)

Additionally, run make examples to build the examples.

Credits

• The Ryujinx project for extensive documentation of the Host1x interface