Encoding complexity¶

Number of iterations¶

As for conventional codecs (e.g. HEVC or VVC), Cool-chic encoding time is variable. A longer encoding gives better compression performance while a reduced encoding time results in slightly degraded coding efficiency.

We present here the impact of the number of encoding iterations on the compression performance by comparing the results obtained through the 3 proposed configurations in cfg/enc/: fast_10k, medium_30k and slow_100k. We used the hop decoding preset.

Kodak¶

Kodak rd results

CLIC20 Pro Valid¶

CLIC20 rd results

JVET Class B¶

JVET class B rd results

JVET Class C¶

JVET class C rd results

JVET Class D¶

JVET class D rd results

JVET Class E¶

JVET class E rd results

JVET Class F¶

JVET class F rd results

JVET All Classes¶

JVET class BCDEF rd results

Encoding time¶

The actual time required to perform one encoding iteration depends on the hardware, the image resolution and… the Cool-chic version since more recent versions are usually more optimized.

Important

Starting from Cool-chic 3.4.1, torch.compile is used to significantly reduce the encoding time

Here are a comparison of the encoding time required for 3 different resolutions on different hardwares and Cool-chic versions. This is obtained with the medium_30k encoding configuration.

512x768 image¶

Encoding time on kodak

720x1280 image¶

Encoding time on JVET E

1363x2048 image¶

Encoding time on CLIC