<refentry id="vidioc-g-dv-timings">
  <refmeta>
    <refentrytitle>ioctl VIDIOC_G_DV_TIMINGS, VIDIOC_S_DV_TIMINGS</refentrytitle>
    &manvol;
  </refmeta>

  <refnamediv>
    <refname>VIDIOC_G_DV_TIMINGS</refname>
    <refname>VIDIOC_S_DV_TIMINGS</refname>
    <refpurpose>Get or set DV timings for input or output</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <funcsynopsis>
      <funcprototype>
	<funcdef>int <function>ioctl</function></funcdef>
	<paramdef>int <parameter>fd</parameter></paramdef>
	<paramdef>int <parameter>request</parameter></paramdef>
	<paramdef>struct v4l2_dv_timings *<parameter>argp</parameter></paramdef>
      </funcprototype>
    </funcsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Arguments</title>

    <variablelist>
      <varlistentry>
	<term><parameter>fd</parameter></term>
	<listitem>
	  <para>&fd;</para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term><parameter>request</parameter></term>
	<listitem>
	  <para>VIDIOC_G_DV_TIMINGS, VIDIOC_S_DV_TIMINGS</para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term><parameter>argp</parameter></term>
	<listitem>
	  <para></para>
	</listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Description</title>
    <para>To set DV timings for the input or output, applications use the
<constant>VIDIOC_S_DV_TIMINGS</constant> ioctl and to get the current timings,
applications use the <constant>VIDIOC_G_DV_TIMINGS</constant> ioctl. The detailed timing
information is filled in using the structure &v4l2-dv-timings;. These ioctls take
a pointer to the &v4l2-dv-timings; structure as argument. If the ioctl is not supported
or the timing values are not correct, the driver returns &EINVAL;.</para>
<para>The <filename>linux/v4l2-dv-timings.h</filename> header can be used to get the
timings of the formats in the <xref linkend="cea861" /> and <xref linkend="vesadmt" />
standards.</para>
  </refsect1>

  <refsect1>
    &return-value;

    <variablelist>
      <varlistentry>
	<term><errorcode>EINVAL</errorcode></term>
	<listitem>
	  <para>This ioctl is not supported, or the
<constant>VIDIOC_S_DV_TIMINGS</constant> parameter was unsuitable.</para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term><errorcode>EBUSY</errorcode></term>
	<listitem>
	  <para>The device is busy and therefore can not change the timings.</para>
	</listitem>
      </varlistentry>
    </variablelist>

    <table pgwide="1" frame="none" id="v4l2-bt-timings">
      <title>struct <structname>v4l2_bt_timings</structname></title>
      <tgroup cols="3">
	&cs-str;
	<tbody valign="top">
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>width</structfield></entry>
	    <entry>Width of the active video in pixels.</entry>
	  </row>
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>height</structfield></entry>
	    <entry>Height of the active video frame in lines. So for interlaced formats the
	    height of the active video in each field is <structfield>height</structfield>/2.</entry>
	  </row>
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>interlaced</structfield></entry>
	    <entry>Progressive (0) or interlaced (1)</entry>
	  </row>
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>polarities</structfield></entry>
	    <entry>This is a bit mask that defines polarities of sync signals.
bit 0 (V4L2_DV_VSYNC_POS_POL) is for vertical sync polarity and bit 1 (V4L2_DV_HSYNC_POS_POL) is for horizontal sync polarity. If the bit is set
(1) it is positive polarity and if is cleared (0), it is negative polarity.</entry>
	  </row>
	  <row>
	    <entry>__u64</entry>
	    <entry><structfield>pixelclock</structfield></entry>
	    <entry>Pixel clock in Hz. Ex. 74.25MHz->74250000</entry>
	  </row>
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>hfrontporch</structfield></entry>
	    <entry>Horizontal front porch in pixels</entry>
	  </row>
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>hsync</structfield></entry>
	    <entry>Horizontal sync length in pixels</entry>
	  </row>
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>hbackporch</structfield></entry>
	    <entry>Horizontal back porch in pixels</entry>
	  </row>
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>vfrontporch</structfield></entry>
	    <entry>Vertical front porch in lines. For interlaced formats this refers to the
	    odd field (aka field 1).</entry>
	  </row>
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>vsync</structfield></entry>
	    <entry>Vertical sync length in lines. For interlaced formats this refers to the
	    odd field (aka field 1).</entry>
	  </row>
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>vbackporch</structfield></entry>
	    <entry>Vertical back porch in lines. For interlaced formats this refers to the
	    odd field (aka field 1).</entry>
	  </row>
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>il_vfrontporch</structfield></entry>
	    <entry>Vertical front porch in lines for the even field (aka field 2) of
	    interlaced field formats.</entry>
	  </row>
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>il_vsync</structfield></entry>
	    <entry>Vertical sync length in lines for the even field (aka field 2) of
	    interlaced field formats.</entry>
	  </row>
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>il_vbackporch</structfield></entry>
	    <entry>Vertical back porch in lines for the even field (aka field 2) of
	    interlaced field formats.</entry>
	  </row>
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>standards</structfield></entry>
	    <entry>The video standard(s) this format belongs to. This will be filled in by
	    the driver. Applications must set this to 0. See <xref linkend="dv-bt-standards"/>
	    for a list of standards.</entry>
	  </row>
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>flags</structfield></entry>
	    <entry>Several flags giving more information about the format.
	    See <xref linkend="dv-bt-flags"/> for a description of the flags.
	    </entry>
	  </row>
	</tbody>
      </tgroup>
    </table>

    <table pgwide="1" frame="none" id="v4l2-dv-timings">
      <title>struct <structname>v4l2_dv_timings</structname></title>
      <tgroup cols="4">
	&cs-str;
	<tbody valign="top">
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>type</structfield></entry>
	    <entry></entry>
	    <entry>Type of DV timings as listed in <xref linkend="dv-timing-types"/>.</entry>
	  </row>
	  <row>
	    <entry>union</entry>
	    <entry><structfield></structfield></entry>
	    <entry></entry>
	  </row>
	  <row>
	    <entry></entry>
	    <entry>&v4l2-bt-timings;</entry>
	    <entry><structfield>bt</structfield></entry>
	    <entry>Timings defined by BT.656/1120 specifications</entry>
	  </row>
	  <row>
	    <entry></entry>
	    <entry>__u32</entry>
	    <entry><structfield>reserved</structfield>[32]</entry>
	    <entry></entry>
	  </row>
	</tbody>
      </tgroup>
    </table>

    <table pgwide="1" frame="none" id="dv-timing-types">
      <title>DV Timing types</title>
      <tgroup cols="3">
	&cs-str;
	<tbody valign="top">
	  <row>
	    <entry>Timing type</entry>
	    <entry>value</entry>
	    <entry>Description</entry>
	  </row>
	  <row>
	    <entry></entry>
	    <entry></entry>
	    <entry></entry>
	  </row>
	  <row>
	    <entry>V4L2_DV_BT_656_1120</entry>
	    <entry>0</entry>
	    <entry>BT.656/1120 timings</entry>
	  </row>
	</tbody>
      </tgroup>
    </table>
    <table pgwide="1" frame="none" id="dv-bt-standards">
      <title>DV BT Timing standards</title>
      <tgroup cols="2">
	&cs-str;
	<tbody valign="top">
	  <row>
	    <entry>Timing standard</entry>
	    <entry>Description</entry>
	  </row>
	  <row>
	    <entry></entry>
	    <entry></entry>
	  </row>
	  <row>
	    <entry>V4L2_DV_BT_STD_CEA861</entry>
	    <entry>The timings follow the CEA-861 Digital TV Profile standard</entry>
	  </row>
	  <row>
	    <entry>V4L2_DV_BT_STD_DMT</entry>
	    <entry>The timings follow the VESA Discrete Monitor Timings standard</entry>
	  </row>
	  <row>
	    <entry>V4L2_DV_BT_STD_CVT</entry>
	    <entry>The timings follow the VESA Coordinated Video Timings standard</entry>
	  </row>
	  <row>
	    <entry>V4L2_DV_BT_STD_GTF</entry>
	    <entry>The timings follow the VESA Generalized Timings Formula standard</entry>
	  </row>
	</tbody>
      </tgroup>
    </table>
    <table pgwide="1" frame="none" id="dv-bt-flags">
      <title>DV BT Timing flags</title>
      <tgroup cols="2">
	&cs-str;
	<tbody valign="top">
	  <row>
	    <entry>Flag</entry>
	    <entry>Description</entry>
	  </row>
	  <row>
	    <entry></entry>
	    <entry></entry>
	  </row>
	  <row>
	    <entry>V4L2_DV_FL_REDUCED_BLANKING</entry>
	    <entry>CVT/GTF specific: the timings use reduced blanking (CVT) or the 'Secondary
GTF' curve (GTF). In both cases the horizontal and/or vertical blanking
intervals are reduced, allowing a higher resolution over the same
bandwidth. This is a read-only flag, applications must not set this.
	    </entry>
	  </row>
	  <row>
	    <entry>V4L2_DV_FL_CAN_REDUCE_FPS</entry>
	    <entry>CEA-861 specific: set for CEA-861 formats with a framerate that is a multiple
of six. These formats can be optionally played at 1 / 1.001 speed to
be compatible with 60 Hz based standards such as NTSC and PAL-M that use a framerate of
29.97 frames per second. If the transmitter can't generate such frequencies, then the
flag will also be cleared. This is a read-only flag, applications must not set this.
	    </entry>
	  </row>
	  <row>
	    <entry>V4L2_DV_FL_REDUCED_FPS</entry>
	    <entry>CEA-861 specific: only valid for video transmitters, the flag is cleared
by receivers. It is also only valid for formats with the V4L2_DV_FL_CAN_REDUCE_FPS flag
set, for other formats the flag will be cleared by the driver.

If the application sets this flag, then the pixelclock used to set up the transmitter is
divided by 1.001 to make it compatible with NTSC framerates. If the transmitter
can't generate such frequencies, then the flag will also be cleared.
	    </entry>
	  </row>
	  <row>
	    <entry>V4L2_DV_FL_HALF_LINE</entry>
	    <entry>Specific to interlaced formats: if set, then field 1 (aka the odd field)
is really one half-line longer and field 2 (aka the even field) is really one half-line
shorter, so each field has exactly the same number of half-lines. Whether half-lines can be
detected or used depends on the hardware.
	    </entry>
	  </row>
	</tbody>
      </tgroup>
    </table>
  </refsect1>
  <refsect1>
    &return-value;
  </refsect1>
</refentry>
