From H.265 to H.266: evaluating our new fluh266enc

At Fluendo, we have been working with VVC/H.266 encoding as part of our STREAM – Scalable Telepresence with Real-time EnhAnced Multimedia project, one of the winners of the SPIRIT - Scalable Platform for Innovations on Real-time Immersive Telepresence Open Call 1.

Building on what we previously shared in our engineering update, we recently released fluh266enc and fluh266dec, our new GStreamer elements for H.266 software encoding and decoding, based on the state-of-the-art Fraunhofer open-source library (vvenc)

In this blog post we’re going to compare our H.266 encoder, fluh266enc, with the reference H.265 software encoder, x265enc, to evaluate the quality achieved at same levels of compression. For measuring visual quality, we chose VMAF, and we mapped the compression performance of both codecs using a standard rate-distortion graph.

Our dataset consisted of several videos with varying content types, including natural real-world recordings typically seen in movies, as well as desktop screen-casts representing diverse remote collaboration scenarios.

Rate distortion

In this evaluation, we plotted the requested target bitrate against the resulting visual quality (VMAF) to evaluate compression efficiency.

Average rate distortion

The metrics showed that, on average, fluh266enc produced significantly higher visual quality than x265enc for the same requested bitrate. Viewed the other way around, fluh266enc uses substantially less bandwidth without compromising the quality.

Rate distortion per preset

When choosing an encoder profile or preset, we selected specific configuration parameters that determined the speed-to-compression ratio. A fast preset prioritized processing speed with lower compression, whereas a slow preset maximized compression efficiency at the cost of processing time.

Our benchmarking revealed that x265 required its slowest, most computationally intensive profile to match the raw performance and quality that we achieved using the fastest configuration profile of fluh266enc.

Example

To visualize these data points in a practical scenario, we extracted and evaluated identical individual frames. Below is a direct visual comparison between two frames from the open-source movie Sintel, both encoded at a restricted target bitrate of 500 kbps using a standard “medium” preset with fluh266enc and x265enc.

fluh266enc (H.266)	x265enc (H.265)

As observed in the side-by-side comparison, the frame encoded with fluh266enc achieved significantly higher visual fidelity, successfully preserving fine details and reducing compression artifacts that were visible in the x265enc output at the same bitrate constraint.

Conclusions

The collected data demonstrates that our new fluh266enc software encoder delivers a superior compression-to-quality ratio compared to H.265. Across our entire testing dataset, the H.266 pipeline achieved identical objective visual quality scores while demanding significantly less bitrate, yielding substantial bandwidth savings without sacrificing video fidelity.

Curious how fluh266enc can benefit your workflow or have questions about integrating our H.266 solutions? Get in touch with us through here. We’re excited to connect!