<structfield>capabilities</structfield> field of &v4l2-capability;
returned by the &VIDIOC-QUERYCAP; ioctl. That flag means the device has an
Analog to Digital Converter (ADC), which is a mandatory element for the SDR receiver.
+ </para>
+ <para>
+Devices supporting the SDR transmitter interface set the
+<constant>V4L2_CAP_SDR_OUTPUT</constant> and
+<constant>V4L2_CAP_MODULATOR</constant> flag in the
+<structfield>capabilities</structfield> field of &v4l2-capability;
+returned by the &VIDIOC-QUERYCAP; ioctl. That flag means the device has an
+Digital to Analog Converter (DAC), which is a mandatory element for the SDR transmitter.
+ </para>
+ <para>
At least one of the read/write, streaming or asynchronous I/O methods must
be supported.
</para>
<para>
SDR devices can support <link linkend="control">controls</link>, and must
support the <link linkend="tuner">tuner</link> ioctls. Tuner ioctls are used
-for setting the ADC sampling rate (sampling frequency) and the possible RF tuner
-frequency.
+for setting the ADC/DAC sampling rate (sampling frequency) and the possible
+radio frequency (RF).
</para>
<para>
-The <constant>V4L2_TUNER_SDR</constant> tuner type is used for SDR tuners, and
-the <constant>V4L2_TUNER_RF</constant> tuner type is used for RF tuners. The
-tuner index of the RF tuner (if any) must always follow the SDR tuner index.
+The <constant>V4L2_TUNER_SDR</constant> tuner type is used for setting SDR
+device ADC/DAC frequency, and the <constant>V4L2_TUNER_RF</constant>
+tuner type is used for setting radio frequency.
+The tuner index of the RF tuner (if any) must always follow the SDR tuner index.
Normally the SDR tuner is #0 and the RF tuner is #1.
</para>
<title>Data Format Negotiation</title>
<para>
-The SDR capture device uses the <link linkend="format">format</link> ioctls to
-select the capture format. Both the sampling resolution and the data streaming
-format are bound to that selectable format. In addition to the basic
+The SDR device uses the <link linkend="format">format</link> ioctls to
+select the capture and output format. Both the sampling resolution and the data
+streaming format are bound to that selectable format. In addition to the basic
<link linkend="format">format</link> ioctls, the &VIDIOC-ENUM-FMT; ioctl
must be supported as well.
</para>
<para>
To use the <link linkend="format">format</link> ioctls applications set the
<structfield>type</structfield> field of a &v4l2-format; to
-<constant>V4L2_BUF_TYPE_SDR_CAPTURE</constant> and use the &v4l2-sdr-format;
+<constant>V4L2_BUF_TYPE_SDR_CAPTURE</constant> or
+<constant>V4L2_BUF_TYPE_SDR_OUTPUT</constant> and use the &v4l2-sdr-format;
<structfield>sdr</structfield> member of the <structfield>fmt</structfield>
union as needed per the desired operation.
Currently there is two fields, <structfield>pixelformat</structfield> and
<row>
<entry><constant>V4L2_BUF_TYPE_SDR_CAPTURE</constant></entry>
<entry>11</entry>
- <entry>Buffer for Software Defined Radio (SDR), see <xref
- linkend="sdr" />.</entry>
+ <entry>Buffer for Software Defined Radio (SDR) capture stream, see
+ <xref linkend="sdr" />.</entry>
+ </row>
+ <row>
+ <entry><constant>V4L2_BUF_TYPE_SDR_OUTPUT</constant></entry>
+ <entry>12</entry>
+ <entry>Buffer for Software Defined Radio (SDR) output stream, see
+ <xref linkend="sdr" />.</entry>
</row>
</tbody>
</tgroup>