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[media] Documentation: v4l: Add hw_seek spacing and two TUNER_RDS_CAP flags
Add a couple of words about the spacing field in the HW seek struct, also a few words about the new RDS tuner capability flags V4L2_TUNER_CAP_RDS_BLOCK-IO and V4L2_TUNER_CAP_RDS_CONTROLS. Signed-off-by: Matti J. Aaltonen <matti.j.aaltonen@nokia.com> Acked-by: Hans Verkuil <hverkuil@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Matti Aaltonen
Mauro Carvalho Chehab
parent
a682d4cb76
commit
eb8942e9b6
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@ -3,15 +3,16 @@
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<para>The Radio Data System transmits supplementary
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information in binary format, for example the station name or travel
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information, on an inaudible audio subcarrier of a radio program. This
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interface is aimed at devices capable of receiving and decoding RDS
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interface is aimed at devices capable of receiving and/or transmitting RDS
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information.</para>
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<para>For more information see the core RDS standard <xref linkend="en50067" />
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and the RBDS standard <xref linkend="nrsc4" />.</para>
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<para>Note that the RBDS standard as is used in the USA is almost identical
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to the RDS standard. Any RDS decoder can also handle RBDS. Only some of the fields
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have slightly different meanings. See the RBDS standard for more information.</para>
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to the RDS standard. Any RDS decoder/encoder can also handle RBDS. Only some of the
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fields have slightly different meanings. See the RBDS standard for more
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information.</para>
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<para>The RBDS standard also specifies support for MMBS (Modified Mobile Search).
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This is a proprietary format which seems to be discontinued. The RDS interface does not
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@ -21,16 +22,25 @@ be needed, then please contact the linux-media mailing list: &v4l-ml;.</para>
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<section>
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<title>Querying Capabilities</title>
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<para>Devices supporting the RDS capturing API
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set the <constant>V4L2_CAP_RDS_CAPTURE</constant> flag in
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<para>Devices supporting the RDS capturing API set
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the <constant>V4L2_CAP_RDS_CAPTURE</constant> flag in
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the <structfield>capabilities</structfield> field of &v4l2-capability;
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returned by the &VIDIOC-QUERYCAP; ioctl.
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Any tuner that supports RDS will set the
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<constant>V4L2_TUNER_CAP_RDS</constant> flag in the <structfield>capability</structfield>
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field of &v4l2-tuner;.
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Whether an RDS signal is present can be detected by looking at
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the <structfield>rxsubchans</structfield> field of &v4l2-tuner;: the
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<constant>V4L2_TUNER_SUB_RDS</constant> will be set if RDS data was detected.</para>
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returned by the &VIDIOC-QUERYCAP; ioctl. Any tuner that supports RDS
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will set the <constant>V4L2_TUNER_CAP_RDS</constant> flag in
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the <structfield>capability</structfield> field of &v4l2-tuner;. If
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the driver only passes RDS blocks without interpreting the data
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the <constant>V4L2_TUNER_SUB_RDS_BLOCK_IO</constant> flag has to be
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set, see <link linkend="reading-rds-data">Reading RDS data</link>.
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For future use the
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flag <constant>V4L2_TUNER_SUB_RDS_CONTROLS</constant> has also been
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defined. However, a driver for a radio tuner with this capability does
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not yet exist, so if you are planning to write such a driver you
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should discuss this on the linux-media mailing list: &v4l-ml;.</para>
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<para> Whether an RDS signal is present can be detected by looking
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at the <structfield>rxsubchans</structfield> field of &v4l2-tuner;:
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the <constant>V4L2_TUNER_SUB_RDS</constant> will be set if RDS data
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was detected.</para>
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<para>Devices supporting the RDS output API
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set the <constant>V4L2_CAP_RDS_OUTPUT</constant> flag in
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@ -40,16 +50,31 @@ Any modulator that supports RDS will set the
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<constant>V4L2_TUNER_CAP_RDS</constant> flag in the <structfield>capability</structfield>
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field of &v4l2-modulator;.
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In order to enable the RDS transmission one must set the <constant>V4L2_TUNER_SUB_RDS</constant>
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bit in the <structfield>txsubchans</structfield> field of &v4l2-modulator;.</para>
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bit in the <structfield>txsubchans</structfield> field of &v4l2-modulator;.
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If the driver only passes RDS blocks without interpreting the data
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the <constant>V4L2_TUNER_SUB_RDS_BLOCK_IO</constant> flag has to be set. If the
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tuner is capable of handling RDS entities like program identification codes and radio
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text, the flag <constant>V4L2_TUNER_SUB_RDS_CONTROLS</constant> should be set,
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see <link linkend="writing-rds-data">Writing RDS data</link> and
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<link linkend="fm-tx-controls">FM Transmitter Control Reference</link>.</para>
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</section>
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<section>
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<section id="reading-rds-data">
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<title>Reading RDS data</title>
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<para>RDS data can be read from the radio device
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with the &func-read; function. The data is packed in groups of three bytes,
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with the &func-read; function. The data is packed in groups of three bytes.</para>
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</section>
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<section id="writing-rds-data">
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<title>Writing RDS data</title>
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<para>RDS data can be written to the radio device
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with the &func-write; function. The data is packed in groups of three bytes,
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as follows:</para>
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</section>
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<section>
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<table frame="none" pgwide="1" id="v4l2-rds-data">
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<title>struct
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<structname>v4l2_rds_data</structname></title>
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@ -111,48 +136,57 @@ as follows:</para>
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<tbody valign="top">
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<row>
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<entry>V4L2_RDS_BLOCK_MSK</entry>
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<entry> </entry>
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<entry>7</entry>
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<entry>Mask for bits 0-2 to get the block ID.</entry>
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</row>
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<row>
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<entry>V4L2_RDS_BLOCK_A</entry>
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<entry> </entry>
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<entry>0</entry>
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<entry>Block A.</entry>
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</row>
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<row>
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<entry>V4L2_RDS_BLOCK_B</entry>
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<entry> </entry>
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<entry>1</entry>
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<entry>Block B.</entry>
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</row>
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<row>
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<entry>V4L2_RDS_BLOCK_C</entry>
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<entry> </entry>
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<entry>2</entry>
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<entry>Block C.</entry>
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</row>
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<row>
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<entry>V4L2_RDS_BLOCK_D</entry>
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<entry> </entry>
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<entry>3</entry>
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<entry>Block D.</entry>
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</row>
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<row>
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<entry>V4L2_RDS_BLOCK_C_ALT</entry>
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<entry> </entry>
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<entry>4</entry>
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<entry>Block C'.</entry>
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</row>
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<row>
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<entry>V4L2_RDS_BLOCK_INVALID</entry>
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<entry>read-only</entry>
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<entry>7</entry>
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<entry>An invalid block.</entry>
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</row>
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<row>
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<entry>V4L2_RDS_BLOCK_CORRECTED</entry>
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<entry>read-only</entry>
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<entry>0x40</entry>
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<entry>A bit error was detected but corrected.</entry>
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</row>
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<row>
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<entry>V4L2_RDS_BLOCK_ERROR</entry>
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<entry>read-only</entry>
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<entry>0x80</entry>
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<entry>An incorrectable error occurred.</entry>
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<entry>An uncorrectable error occurred.</entry>
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</row>
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</tbody>
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</tgroup>
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@ -51,7 +51,8 @@
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<para>Start a hardware frequency seek from the current frequency.
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To do this applications initialize the <structfield>tuner</structfield>,
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<structfield>type</structfield>, <structfield>seek_upward</structfield> and
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<structfield>type</structfield>, <structfield>seek_upward</structfield>,
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<structfield>spacing</structfield> and
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<structfield>wrap_around</structfield> fields, and zero out the
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<structfield>reserved</structfield> array of a &v4l2-hw-freq-seek; and
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call the <constant>VIDIOC_S_HW_FREQ_SEEK</constant> ioctl with a pointer
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@ -89,7 +90,12 @@ field and the &v4l2-tuner; <structfield>index</structfield> field.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>reserved</structfield>[8]</entry>
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<entry><structfield>spacing</structfield></entry>
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<entry>If non-zero, defines the hardware seek resolution in Hz. The driver selects the nearest value that is supported by the device. If spacing is zero a reasonable default value is used.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>reserved</structfield>[7]</entry>
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<entry>Reserved for future extensions. Drivers and
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applications must set the array to zero.</entry>
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</row>
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