Tanks for your reply Rémi.
I can use a video-filter instead of a sub-source although it seems to consume more CPU resources.
My intention is that audiobargraph_v-barWidth and audobargraph_v-barHeight use a percent instead of the size in pixels because in most cases I do not know previously the size of the image.
And another question:
In some video-filter or spu like audiobargraph_v have a Callback to update params on the fly. Previously this was done sends params with tcp packets from audio-filter to video-filter through rc and I could change parameters from an external application by sending commands TCP to the rc. Later it was changed to use vlc variable Callback for send params form audio-fiter to video-filter (commit f2092cbf8 ). It's possible to send params on the fly from extenal app using the current varialbe callback?
Edit:
I see that with the latest git versions, --video-filter does not work and return the following error:
[00007f488cac1630] blend blend error: no matching alpha blending routine (chroma: YUVA -> VAOP)
[00007f488cb15fb0] audiobargraph_v filter error: failed to blend a picture
[00007f488cac1630] blend blend error: no matching alpha blending routine (chroma: YUVA -> VAOP)
[00007f488cb15fb0] audiobargraph_v filter error: failed to blend a picture
[00007f488cac1630] blend blend error: no matching alpha blending routine (chroma: YUVA -> VAOP)
[00007f488cb15fb0] audiobargraph_v filter error: failed to blend a picture
[0.....
work fine with --sub-source