[linux-dvb] V4 Demux Point

[Rob.McConnell@Zarlink.Com]

Hi Johannes,

A while back we were in discussions on the demux V4 API.  What I was
unhappy with was the fact that you could not have multiple section filters
attached to a single fd to match the underlying h/w.  For our DTV-1 chip,
we would have to do a copy from the h/w buffer to each fd/process's kernel
buffer wasting valuable time.  Additionally, the middle-ware would have to
have more threads to deal with this architecture.  The end result is that
the CPU load is higher as you have effectively more processes running  with
greater context switching overhead and more copying being done.

There seems to be a technical conflict of interest between DTV chips that
have a single h/w output buffer per section filter and ones like ours that
allow you to attach multiple section filters on a single PID with a common
h/w output buffer.  The current V4 API is indeed clean/lean, but we are
particularly worried about the extra processor load especially as we are
running demanding applications like MHEG-5 and 8-day EPG on our h/w.

Are we at a point where the V4 API is now frozen or can we open up
negotiations on the architecture again?  I would love to see an API that
caters for both scenarios as this would be optimal.

TIA,

Rob : )