T.V 2.5 English

TV 2.5 Real-Time Video Coding Subjective Quality Assessment Results

For the “TV 3.0” project (see https://forumsbtvd.org.br/tv3_0), the SBTVD Forum selected Low Complexity Enhancement Video Coding (MPEG 5 Part 2 – LCEVC) as the scalable video coding technology. In the context of TV 3.0, LCEVC will be used in conjunction with Versatile Video Coding (MPEG-I VVC / H.266) as the base layer codec. But LCEVC is agnostic to the base layer video codec and could also be employed in conjunction with MPEG-4 AVC (H.264), used in TV 2.0/2.5, to provide a backward-compatible enhancement. Furthermore, LCEVC could be combined with the TV 2.5 optional HDR formats. Considering this potential application of LCEVC, the SBTVD Forum decided to investigate the possibility of including it as another optional backward-compatible video enhancement technology into TV 2.5 specifications, potentially enabling the scaling of a 1 080i / 29.97fps / 8-bit video (maximum quality possible with H.264 under TV 2.0/2.5 specifications) to 1 080p / 59.94fps / 10-bit on compatible receivers, with a relatively small overhead.


To evaluate the possible quality gain of using LCEVC in TV 2.5, as well as the possible quality loss in receivers not compatible with LCEVC as a result of reducing the bitrate of the H.264 base layer to include the LCEVC enhancement layer, the SBTVD Forum decided to perform a real-time video coding subjective quality assessment, comparing the maximum quality achievable with real-time video coding for TV 2.0 (H.264 / 1 080i / 29.97fps / 8-bit / SDR @ 14 Mbps), and TV 2.5 (H.264 / 1 080i / 29.97fps / 8-bit / SL-HDR1 @ 14 Mbps), with what would be the resulting quality if LCEVC was included in TV 2.5 specifications, both on LCEVC-compatible receivers (H.264 / 1 080i / 29.97fps / 8-bit / SL-HDR1 base layer + LCEVC / 1 080p / 59.94fps / 10-bit enhancement layer, with total bitrate of 14 Mbps) and on TV 2.0 receivers (decoding only the H.264 / 1 080i / 29.97fps / 8-bit base layer – that would be using a bitrate somewhat lower than 14 Mbps – in SDR, disregarding the SL-HDR1 dynamic metadata and the LCEVC enhancement layer).


The TV 2.5 Real-Time Video Coding Subjective Quality Assessment was carried out by the University of Brasília from June 2023 to February 2024, in parallel with the TV 3.0 Phase 3 Real-Time Video Coding Subjective Quality Assessment, under the coordination of the SBTVD Forum and funded by the Brazilian Ministry of Communications through the Brazilian National Education and Research Network (RNP, Rede Nacional de Ensino e Pesquisa).


Considering the promising results, the SBTVD Forum board decided, on 18 March 2024, to include LCEVC as an additional optional backward-compatible video enhancement technology into TV 2.5 specifications. Revisions to the TV 2.5 specifications to include LCEVC will be developed after the TV 3.0 specifications have been finalized.


The report of the TV 2.5 Real-Time Video Coding Subjective Quality Assessment is available in the link below: