4. HEVC exploite une méthode de découpage des trames dite « Coded Tree Unit » variable
(trois tailles) et sur trois niveaux. Par rapport aux macro blocs de taille fixe de l'AVC, cette
méthode présente l'intérêt de mieux s'adapter au contenu, en traitant très différemment
les aplats des zones les plus détaillées.
16. Outre l’augmentation du nombre
de pixels et l’augmentation de la
fréquence image (24, 50, 60,
120Hz), l’UHD propose également
un nouvel espace colorimétrique.
Ici, l’espace UHD de la REC 2020
correspond au large triangle
extérieur, tandis que l’espace HD
de la Rec 709 correspond au
triangle intérieur
20. Number of national full-time TV channels
(video + audio + associated data, including interactive data)
Dimensioning hypotheses
(1/3 Ultra HD channels envisaged around 2022)
Number of fixed national multiplexes
needed at the end of the migration
towards DVBT-2/HEVC
(envisaged around 2022)
(95% of the French metropolitan population)
Low
(30 TV channels)
20 full-HD 10 4K 7
Medium
(35 TV channels)
23 full-HD 12 4K 8
High
(40 TV channels)
26 full-HD 14 4K 9
For fixed reception, if UHD is introduced and full HD (1080p) generalized, a scenario after transition to DVB-
T2/HEVC (e.g. 2022/2023) could assume two thirds of TV channels being full-HD (1080p) and one third of TV
channels being ultra HD (4K).
For mobility, the objective of providing TV programmes towards smart-phones and tablets may require the
introduction of mobile SFN DVB-T2 multiplex, although it is difficult to assume a specific number.
In a nut shell, with the previous hypotheses, 8 national multiplexes would be necessary to support these
scenarios (assuming a full DVB-T2/HEVC landscape by 2022).
If it is not possible to maintain 8 multiplexes (e.g. if the 700 MHz is allocated to mobile service in France), then
this would imply a reduction of the DTT platform service offering at that horizon, in terms of UHD/4K TV
channels availability and/or the ability to migrate all national TV channels towards full HD and/or the ability of
the DTT platform to evolve towards mobility. Moreover, there is a risk that, with limited incentive for the end
user, the transition towards DVB-T2/HEVC would be more complex and lengthy. (Extrait de la réponse à la question 11, mai 2012)
21. Source : CTEN / GT2 du 13 avril 2013
On peut donc mettre 3 chaînes UHD (ou 8 HD) par mux DVB-T2