From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail.kapsi.fi ([217.30.184.167]:47698 "EHLO mail.kapsi.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753861Ab2F2MzN (ORCPT ); Fri, 29 Jun 2012 08:55:13 -0400 Message-ID: <4FEDA5A8.5030704@iki.fi> Date: Fri, 29 Jun 2012 15:55:04 +0300 From: Antti Palosaari MIME-Version: 1.0 To: Mauro Carvalho Chehab CC: linux-media , htl10@users.sourceforge.net Subject: Re: DVB core enhancements - comments please? References: <4FEBA656.7060608@iki.fi> <4FED2FE0.9010602@redhat.com> <4FED3714.2080901@iki.fi> <4FED9972.9090105@redhat.com> In-Reply-To: <4FED9972.9090105@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: On 06/29/2012 03:02 PM, Mauro Carvalho Chehab wrote: > Em 29-06-2012 02:03, Antti Palosaari escreveu: >> On 06/29/2012 07:32 AM, Mauro Carvalho Chehab wrote: >>> Em 27-06-2012 21:33, Antti Palosaari escreveu: >>>> SDR - Softaware Defined Radio support DVB API >>>> -------------------------------------------------- >>>> * http://comments.gmane.org/gmane.linux.drivers.video-input-infrastructure/44461 >>>> * there is existing devices that are SDR (RTL2832U "rtl-sdr") >>>> * SDR is quite near what is digital TV streaming >>>> * study what is needed >>>> * new delivery system for frontend API called SDR? >>>> * some core changes needed, like status (is locked etc) >>>> * how about demuxer? >>>> * stream conversion, inside Kernel? >>>> * what are new parameters needed for DVB API? >>> >>> Let's not mix APIs: the radio control should use the V4L2 API, as this is not >>> DVB. The V4L2 API has already everything needed for radio. The only missing >>> part ther is the audio stream. However, there are a few drivers that provide >>> audio via the radio device node, using read()/poll() syscalls, like pvrusb. >>> On this specific driver, audio comes through a MPEG stream. As SDR provides >>> audio on a different format, it could make sense to use VIDIOC_S_STD/VIDIOC_G_STD >>> to set/retrieve the type of audio stream, for SDR, but maybe it better to just >>> add capabilities flag at VIDIOC_QUERYCTL or VIDIOC_G_TUNER to indicate that >>> the audio will come though the radio node and if the format is MPEG or SDR. >> >> SDR is not a radio in mean of V4L2 analog audio radios. > > Why not? There's nothing at V4L2 API that limits it to analog, otherwise it couldn't > be used by digital cameras. > >> SDR can receive all kind of signals, analog audio, analog television, digital radio, >> digital television, cellular phones, etc. You can even receive DVB-T, but hardware I >> have is not capable to receive such wide stream. > > The V4L2 API has everything to control receivers. What it doesn't have (and it doesn't make > sense to have, as such thing would just duplicate existing features at DVB API) > are the per delivery-system specific demodulator properties and PID filtering. > >> That chip supports natively DVB-T TS but change be switched to SDR mode. Is it even possible >> to switch from DVB API (DVB-T delivery system) to V4L2 API at runtime? > > Yes. There are lots of drivers that do that. There are even a few that allow to control the > frontend and demod via DVB API and to receive streams via V4L2 mmap or read API. Could you give closest example? In that case I have RTL2832 DVB-T frontend which I want to change SDR mode. What are the those existing DVB frontend drivers look example. regards Antti -- http://palosaari.fi/