Ok, I see that there are not many VP9 enthusiasts 
But maybe you can help me with my questions.
1) If I have a video in 1080p with a bit rate of say 2.0 kb/s, if I encode it in ABR 2.5 kb/s, is that really useful?
2) The videos are in BT.709. At the level of Voucoder there is the option, in the "colorspace" filters, the BT.709 option with other settings "Matrix, Primaries and Transfer". Does it change anything if I turn it on?
3) Do you have any advice for me? I work in 1080p and 4K.
For 4K videos, almost all of them encode the following code:
Vidéo
ID : 1
Format : VP9
Identifiant du codec : V_VP9
Durée : 5 min 5s
Largeur : 3 840 pixels
Hauteur : 2 160 pixels
Format à l'écran : 16/9
Type d'images/s : Constant
Images par seconde : 29,970 (30000/1001) Im/s
Espace de couleurs : YUV
Default : Oui
Forced : Non
Gamme de couleurs : Limited
Coordonnées de chromaticité : BT.709
Caractéristiques du transfert : BT.709
Coefficients de la matrice : BT.709
DURATION : 00:05:05,271000000
Audio
ID : 2
Format : AAC LC
Format/Info : Advanced Audio Codec Low Complexity
Identifiant du codec : A_AAC-2
Durée : 5 min 5s
Canaux : 2 canaux
Channel layout : L R
Echantillonnage : 44,1 kHz
Images par seconde : 43,066 Im/s (1024 SPF)
Mode de compression : Avec perte
Default : Oui
Forced : Non
DURATION : 00:05:05,319000000I am sorry for his questions which may seem stupid to you but I am trying to understand the operation and possibilities of Voucoder.
Thanks in advance