[linux-dvb] Linux DVB API 4 Q's

[Rob.McConnell@Zarlink.Com]

Hi Folks,

Seen that there is work being done on the V4 API now.  Does this mean that
it is full speed ahead on V4 now, or are there other loose ends to fixup
first?

Have a few Q's about the header files in the V4 API dir in CVS:

1: I see that the "dvb_dmx_source_format" has a new format called PES.  Is
this to cover proprietary formats such as AVPES?

2:  Shouldn't the structure "dvb_dmx_source" be:

        struct dvb_dmx_source {
                enum dvb_dmx_source_type        type;
                enum dvb_dmx_source_format     format;
                unsigned int
frontend_num;
        }

3:  For the DVB_DMX_SET_PID_FILTER  syscall option 2 (not using the add/del
pid IOCTLs), if we set all the PIDs up at once then they would all have to
have the same type, output format and share the same flags.  Now the same
type and output format are OK, but if you want to prioritise one PID over
another using the HIGH/LOW priority flags, then this becomes a problem.
Basically, if you wanted to have different flag values for the PIDs then
having this single IOCTL to set all the PIDs at once would be a problem.  I
can see that it certainly simplifies the overall code, but I would favour
having the ADD/DEL IOCTLs instead as this gives more flexibility to the
user programs.

4. Why have the filter id elements of the structs "dvb_dmx_pid_filter",
"dvb_dmx_section_filter" and "dvb_dmx_sid_filter" been removed?  How do you
go about removing/changing an already instantiated section filter/sid
filter without the id field?

5. struct "dvb_video_source" should be:

      struct dvb_video_source {
            dvb_video_source_type   type;
            dvb_video_source_format format;
            int                     demux_fd;
      }

6. Same for "dvb_audio_source"

7.  For audio decoding, will there be status information for Dolby
Digital/DTS/.....  returned to user-space?  For example, will the source
format (e.g. 3/2) be returned as well as whether the program is surround
encoded (Dolby Pro Logic).  Will there be an IOCTL to select Dolby Pro
Logic decoding from a multi-channel source?  There are endless options for
audio decoding, so what stance are we to take with the user/kernel space
divide?

8. What is the current state of the V4 API in terms of available software?
Is the intention to take the existing V3 API s/w and apply the required
changes to make it V4 compatible, or are we going to start from scratching
implementing it.  IMHO, taking existing good s/w such as the section
filtering and re-writing some of the other demux s/w that was inherited
from collaboration with Nokia would be the best approach (as we have all
learnt a lot more about DTV over the years and the existing s/w certainly
has limitations).

That's all 4 now...

Cheers,

Rob : )











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