The beauty of film grain is back in the digital world. The grain will be reduced before encoding and transmitted via a grain table in the AV1 bitstream. After decoding the grain is added back and now it is possible to enjoy film look even at ultra low bitrates. This AV1 encoded file was processed with the Wavelet Beam Grain & Noise Management solution using the Film Grain Synthesis technology. Please note that not all browsers are supporting this AV1 features at the moment.

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16mm 1728x1248 -10bpc (Full HD pixel count) - AV1@2Mbit/s and Film Grain Synthesis - AV1 encoder test Feb. 2022

16mm 1728x1248 -10bpc (Full HD pixel count) - AV1@1,1Mbit/s and Film Grain Synthesis - AV1 encoder test Feb. 2022

Block-based encoder technology at low bitrates is not able to carry the grain structure. The frequencies of the grain are transferred into lower frequencies. This low frequency distortion is a modulation in the time domain and cannot be measured with tools like PSNR or VMAF. H264 let the video flicker and complete areas in the video are moving against the video signal itself. Block based encoders are not able to proper carry grain information. In the decoder motion vectors are used to reconstruct the image. E.g. a 8x8 pixel block of the previous frame will be used to reconstruct the current frame at another part of the image. In the quantization process the grain amplitudes are changed. This is the reason why a grain structure is changed and moved into the time domain. This leads to a loss of resolution and blocking artefacts. These artefacts will be noticeable as a kind of noise but the frequencies of the grain shifted, the amplitudes are higher and the characteristic of grain has gone. AV1 & Film Grain Synthesis will be the future for low-bitrate and high-quality video delivery.