Netflix rolls out AV1 Film Grain Synthesis for classic movies

Netflix has begun rolling out AV1 Film Grain Synthesis (FGS) streams across its catalogue, a move the platform says will allow it to preserve the artistic integrity of film grain while optimising data efficiency.

FGS has been part of the AV1 standard since its inception, but Netflix only enabled it for a limited number of titles during its initial launch of the AV1 codec in 2021.

2. Netflix.png — (L-R) Regular AV1 stream, AV1 FGS stream without grain synthesis during decoding, and AV1 FGS stream with grain synthesis

A key part of the look of classic movies, film grain’s random nature makes it notoriously difficult to compress. Traditional compression algorithms struggle to manage it, often forcing a choice between preserving the grain and reducing file size.

AV1 Film Grain Synthesis tool preserves the artistic integrity of film grain while making the content “easier to compress” by denoising the source video prior to encoding.

The move was announced in a Netflix Technology Blog post, which concluded: “Enabling AV1 Film Grain Synthesis has led to significant bitrate reduction, allowing us to deliver high-quality video with less data while preserving the artistic integrity of film grain.”

To evaluate the impact of AV1 Film Grain Synthesis, Netflix selected approximately 300 titles from its catalogue, each with varying levels of graininess. Netflix reported a 36% reduction in average bitrate for resolutions of 1080p and above when AV1 film grain synthesis is enabled.

For resolutions below 1080p, the reduction in bitrate is relatively small, reaching only a 10% decrease, likely because noise is filtered out during the downscaling process.