Trent Piepho wrote:
On Mon, 15 May 2006, Manu Abraham wrote:
Trent Piepho wrote:
I'm sorry, but I still do not understand how to do this simple task with this
new API. It seemed clear to me with version 3, but now I'm at a loss. Can
you please answer these couple of questions?
Thank for your answers. I think the task I wanted to do, find out if a
front-end supports ATSC and QAM-256, can not be done. It appears that the
only way to do this, is to tell the front-end to use QAM-256, and then see if
this fails.
I didn't follow your question.
Is this correct? The only way for an application to check if a front-end
supports a certain modulation or FEC rate or other parameter is to call
DVBFE_SET_PARAMS to change the frontend settings and then see if the ioctl
failed. Finding out if an ATSC tuner supports both 8-VSB and 256-QAM will
require re-loading the firmware and programming the demod over I2C, to change
modes with DVBFE_SET_PARAMS and then see if this fails.
You mean to have modulation as a static bitfield in dvbfe_info ?
If this is not correct, how is this done? I will write the first part of a
function to do this, but I just don't see how to do the rest.
int check_for_atsc_and_qam256(int fe)
{
struct dvbfe_info info;
ioctl(fe, DVBFE_GET_INFO, &info);
if(!(info.delivery & DVBFE_DELSYS_ATSC))
return 0; /* ATSC not supported */
/* Check if front-end supports 256 QAM modulation */
/* what goes here??? */
}
I thought ATSC tuners supported 256QAM additionally for digital cable,
alongwith VSB8/16 for OTA.
I think you imply that you would like to see the modulation bitfield in
info .. ? If that's the case we can add that bitfield into the info struct.
PS: I have a bug in the DVBFE_GET_INFO ioctl, it should be _IORW,
instead of _IOR
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