From patchwork Thu Aug 31 23:46:51 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Mauro Carvalho Chehab X-Patchwork-Id: 9933157 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id C832060362 for ; Thu, 31 Aug 2017 23:51:46 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B6BCA26E3A for ; Thu, 31 Aug 2017 23:51:46 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id ABA7926E51; Thu, 31 Aug 2017 23:51:46 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4933E26E3A for ; Thu, 31 Aug 2017 23:51:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752153AbdHaXvo (ORCPT ); Thu, 31 Aug 2017 19:51:44 -0400 Received: from ec2-52-27-115-49.us-west-2.compute.amazonaws.com ([52.27.115.49]:44948 "EHLO osg.samsung.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751874AbdHaXrK (ORCPT ); Thu, 31 Aug 2017 19:47:10 -0400 Received: from localhost (localhost [127.0.0.1]) by osg.samsung.com (Postfix) with ESMTP id ED192A0D58; Thu, 31 Aug 2017 23:47:37 +0000 (UTC) X-Virus-Scanned: amavisd-new at osg.samsung.com X-Amavis-Alert: BAD HEADER SECTION, Duplicate header field: "References" Received: from osg.samsung.com ([127.0.0.1]) by localhost (s-opensource.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id G7HL-xwove4s; Thu, 31 Aug 2017 23:47:37 +0000 (UTC) Received: from smtp.s-opensource.com (unknown [189.61.49.22]) by osg.samsung.com (Postfix) with ESMTPSA id 37B3BA0D59; Thu, 31 Aug 2017 23:47:35 +0000 (UTC) Received: from mchehab by smtp.s-opensource.com with local (Exim 4.89) (envelope-from ) id 1dnZAt-0001tY-C9; Thu, 31 Aug 2017 20:47:03 -0300 From: Mauro Carvalho Chehab To: Linux Doc Mailing List , Linux Media Mailing List Cc: Mauro Carvalho Chehab , Mauro Carvalho Chehab , linux-kernel@vger.kernel.org, Jonathan Corbet Subject: [PATCH 04/15] media: dvb/intro: adjust the notices about optional hardware Date: Thu, 31 Aug 2017 20:46:51 -0300 Message-Id: <85e534750c29d2d7eb1051b310da3e434cd97732.1504222628.git.mchehab@s-opensource.com> X-Mailer: git-send-email 2.13.5 In-Reply-To: References: MIME-Version: 1.0 In-Reply-To: References: Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Both CA and decoders are optional. Also, the presence or absence has nothing to do on being a PCI card or not. Nowadays, most hardware leaves the decoders to either the GPU or to some ISP inside the SoC, instead of implementing it inside the Digital TV part of the device. So, change the wording to reflect the hardware changes. Signed-off-by: Mauro Carvalho Chehab --- Documentation/media/uapi/dvb/intro.rst | 29 +++++++++++++++++------------ 1 file changed, 17 insertions(+), 12 deletions(-) diff --git a/Documentation/media/uapi/dvb/intro.rst b/Documentation/media/uapi/dvb/intro.rst index 4e1594816ef4..aeafc9ab96c1 100644 --- a/Documentation/media/uapi/dvb/intro.rst +++ b/Documentation/media/uapi/dvb/intro.rst @@ -71,8 +71,7 @@ Overview A Digital TV card or set-top-box (STB) usually consists of the following main hardware components: -- Frontend consisting of tuner and digital TV demodulator - +Frontend consisting of tuner and digital TV demodulator Here the raw signal reaches the digital TV hardware from a satellite dish or antenna or directly from cable. The frontend down-converts and demodulates this signal into an MPEG transport stream (TS). In case @@ -80,34 +79,40 @@ following main hardware components: equipment control (SEC), which allows control of LNB polarization, multi feed switches or dish rotors. -- Conditional Access (CA) hardware like CI adapters and smartcard slots - +Conditional Access (CA) hardware like CI adapters and smartcard slots The complete TS is passed through the CA hardware. Programs to which the user has access (controlled by the smart card) are decoded in real time and re-inserted into the TS. -- Demultiplexer which filters the incoming DVB stream + .. note:: + Not every digital TV hardware provides conditional access hardware. + +Demultiplexer which filters the incoming DVB stream The demultiplexer splits the TS into its components like audio and video streams. Besides usually several of such audio and video streams it also contains data streams with information about the programs offered in this or other streams of the same provider. -- MPEG2 audio and video decoder - +MPEG2 audio and video decoder The main targets of the demultiplexer are the MPEG2 audio and video decoders. After decoding they pass on the uncompressed audio and video to the computer screen or (through a PAL/NTSC encoder) to a TV set. + .. note:: + + Modern hardware usually doesn't have a separate decoder hardware, as + such functionality can be provided by the main CPU, by the graphics + adapter of the system or by a signal processing hardware embedded on + a Systems on a Chip (SoC) integrated circuit. + + It may also not be needed for certain usages (e.g. for data-only + uses like “internet over satellite”). + :ref:`stb_components` shows a crude schematic of the control and data flow between those components. -On a DVB PCI card not all of these have to be present since some -functionality can be provided by the main CPU of the PC (e.g. MPEG -picture and sound decoding) or is not needed (e.g. for data-only uses -like “internet over satellite”). Also not every card or STB provides -conditional access hardware. .. _dvb_devices: