1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>Digital Video (DV) Timings</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"><link rel="home" href="index.html" title="LINUX MEDIA INFRASTRUCTURE API"><link rel="up" href="common.html" title="Chapter 1. Common API Elements"><link rel="prev" href="standard.html" title="Video Standards"><link rel="next" href="control.html" title="User Controls"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Digital Video (DV) Timings</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="standard.html">Prev</a> </td><th width="60%" align="center">Chapter 1. Common API Elements</th><td width="20%" align="right"> <a accesskey="n" href="control.html">Next</a></td></tr></table><hr></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="dv-timings"></a>Digital Video (DV) Timings</h2></div></div></div><p> 2 The video standards discussed so far have been dealing with Analog TV and the 3corresponding video timings. Today there are many more different hardware interfaces 4such as High Definition TV interfaces (HDMI), VGA, DVI connectors etc., that carry 5video signals and there is a need to extend the API to select the video timings 6for these interfaces. Since it is not possible to extend the <a class="link" href="vidioc-enumstd.html#v4l2-std-id" title="Table A.48. typedef v4l2_std_id">v4l2_std_id</a> due to 7the limited bits available, a new set of ioctls was added to set/get video timings at 8the input and output.</p><p>These ioctls deal with the detailed digital video timings that define 9each video format. This includes parameters such as the active video width and height, 10signal polarities, frontporches, backporches, sync widths etc. The <code class="filename">linux/v4l2-dv-timings.h</code> 11header can be used to get the timings of the formats in the <a class="xref" href="bi01.html#cea861" title="A DTV Profile for Uncompressed High Speed Digital Interfaces">[<abbr class="abbrev">CEA-861-E</abbr>]</a> and 12<a class="xref" href="bi01.html#vesadmt" title="VESA and Industry Standards and Guidelines for Computer Display Monitor Timing (DMT)">[<abbr class="abbrev">VESA DMT</abbr>]</a> standards. 13 </p><p>To enumerate and query the attributes of the DV timings supported by a device 14 applications use the <a class="link" href="vidioc-enum-dv-timings.html" title="ioctl VIDIOC_ENUM_DV_TIMINGS, VIDIOC_SUBDEV_ENUM_DV_TIMINGS"><code class="constant">VIDIOC_ENUM_DV_TIMINGS</code></a> and <a class="link" href="vidioc-dv-timings-cap.html" title="ioctl VIDIOC_DV_TIMINGS_CAP, VIDIOC_SUBDEV_DV_TIMINGS_CAP"><code class="constant">VIDIOC_DV_TIMINGS_CAP</code></a> ioctls. 15 To set DV timings for the device applications use the 16<a class="link" href="vidioc-g-dv-timings.html" title="ioctl VIDIOC_G_DV_TIMINGS, VIDIOC_S_DV_TIMINGS"><code class="constant">VIDIOC_S_DV_TIMINGS</code></a> ioctl and to get current DV timings they use the 17<a class="link" href="vidioc-g-dv-timings.html" title="ioctl VIDIOC_G_DV_TIMINGS, VIDIOC_S_DV_TIMINGS"><code class="constant">VIDIOC_G_DV_TIMINGS</code></a> ioctl. To detect the DV timings as seen by the video receiver applications 18use the <a class="link" href="vidioc-query-dv-timings.html" title="ioctl VIDIOC_QUERY_DV_TIMINGS"><code class="constant">VIDIOC_QUERY_DV_TIMINGS</code></a> ioctl.</p><p>Applications can make use of the <a class="xref" href="vidioc-enuminput.html#input-capabilities" title="Table A.42. Input capabilities">Table A.42, “Input capabilities”</a> and 19<a class="xref" href="vidioc-enumoutput.html#output-capabilities" title="Table A.45. Output capabilities">Table A.45, “Output capabilities”</a> flags to determine whether the digital video ioctls 20can be used with the given input or output.</p></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="standard.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="common.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="control.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Video Standards </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> User Controls</td></tr></table></div></body></html> 21