v4l2-spec: Added data formats used for Sliced VBI data in MPEG streams

From: Andy Walls <awalls@radix.net>

Document existing data formats used for inserting sliced VBI data into
MPEG streams.  V4L2_CID_MPEG_STREAM_VBI_FMT's V4L2_MPEG_STREAM_VBI_FMT_NONE &
V4L2_MPEG_STREAM_VBI_FMT_IVTV data were already existing and implemented, but
not documented in the V4L2 spec.

Priority: normal

Signed-off-by: Andy Walls <awalls@radix.net>

3 files changed, 330 insertions, 3 deletions

diff --git a/v4l2-spec/Makefile b/v4l2-spec/Makefile
index d0dde12f4..41dba1cdd 100644
--- a/v4l2-spec/Makefile
+++ b/v4l2-spec/Makefile
@@ -274,6 +274,7 @@ STRUCTS = \
 	v4l2_input \
 	v4l2_jpegcompression \
 	v4l2_modulator \
+	v4l2_mpeg_vbi_fmt_ivtv \
 	v4l2_output \
 	v4l2_outputparm \
 	v4l2_pix_format \
diff --git a/v4l2-spec/dev-sliced-vbi.sgml b/v4l2-spec/dev-sliced-vbi.sgml
index 5560650a6..3c260e3e3 100644
--- a/v4l2-spec/dev-sliced-vbi.sgml
+++ b/v4l2-spec/dev-sliced-vbi.sgml
@@ -48,7 +48,7 @@ vital to program a sliced VBI device, therefore must be
 supported.</para>
   </section>
 
-  <section>
+  <section id="sliced-vbi-format-negotitation">
     <title>Sliced VBI Format Negotiation</title>
 
     <para>To find out which data services are supported by the
@@ -386,6 +386,319 @@ video and VBI data by using buffer timestamps.</para>
 
   </section>
 
+  <section>
+    <title>Sliced VBI Data in MPEG Streams</title>
+
+    <para>If a device can produce an MPEG output stream, it may be
+capable of providing <link
+linkend="sliced-vbi-format-negotitation">negotiated sliced VBI
+services</link> as data embedded in the MPEG stream.  Users or
+applications control this sliced VBI data insertion with the <link
+linkend="v4l2-mpeg-stream-vbi-fmt">V4L2_CID_MPEG_STREAM_VBI_FMT</link>
+control.</para>
+
+    <para>If the driver does not provide the <link
+linkend="v4l2-mpeg-stream-vbi-fmt">V4L2_CID_MPEG_STREAM_VBI_FMT</link>
+control, or only allows that control to be set to <link
+linkend="v4l2-mpeg-stream-vbi-fmt"><constant>
+V4L2_MPEG_STREAM_VBI_FMT_NONE</constant></link>, then the device
+cannot embed sliced VBI data in the MPEG stream.</para>
+
+    <para>The <link linkend="v4l2-mpeg-stream-vbi-fmt">
+V4L2_CID_MPEG_STREAM_VBI_FMT</link> control does not implicitly set
+the device driver to capture nor cease capturing sliced VBI data.  The
+control only indicates to embed sliced VBI data in the MPEG stream, if
+an application has negotiated sliced VBI service be captured.</para>
+
+    <para>It may also be the case that a device can embed sliced VBI
+data in only certain types of MPEG streams: for example in an MPEG-2
+PS but not an MPEG-2 TS.  In this situation, if sliced VBI data
+insertion is requested, the sliced VBI data will be embedded in MPEG
+stream types when supported, and silently omitted from MPEG stream
+types where sliced VBI data insertion is not supported by the device.
+</para>
+
+    <para>The following subsections specify the format of the
+embedded sliced VBI data.</para>
+
+  <section>
+    <title>MPEG Stream Embedded, Sliced VBI Data Format: NONE</title>
+    <para>The <link linkend="v4l2-mpeg-stream-vbi-fmt"><constant>
+V4L2_MPEG_STREAM_VBI_FMT_NONE</constant></link> embedded sliced VBI
+format shall be interpreted by drivers as a control to cease
+embedding sliced VBI data in MPEG streams.  Neither the device nor
+driver shall insert "empty" embedded sliced VBI data packets in the
+MPEG stream when this format is set.  No MPEG stream data structures
+are specified for this format.</para>
+  </section>
+
+  <section>
+    <title>MPEG Stream Embedded, Sliced VBI Data Format: IVTV</title>
+    <para>The <link linkend="v4l2-mpeg-stream-vbi-fmt"><constant>
+V4L2_MPEG_STREAM_VBI_FMT_IVTV</constant></link> embedded sliced VBI
+format, when supported, indicates to the driver to embed up to 36
+lines of sliced VBI data per frame in an MPEG-2 <emphasis>Private
+Stream 1 PES</emphasis> packet encapsulated in an MPEG-2 <emphasis>
+Program Pack</emphasis> in the MPEG stream.</para>
+
+    <para><emphasis>Historical context</emphasis>: This format
+specification originates from a custom, embedded, sliced VBI data
+format used by the <filename>ivtv</filename> driver.  This format
+has already been informally specified in the kernel sources in the
+file <filename>Documentation/video4linux/cx2341x/README.vbi</filename>
+.  The maximum size of the payload and other aspects of this format
+are driven by the CX23415 MPEG decoder's capabilities and limitations
+with respect to extracting, decoding, and displaying sliced VBI data
+embedded within an MPEG stream.</para>
+
+    <para>This format's use is <emphasis>not</emphasis> exclusive to
+the <filename>ivtv</filename> driver <emphasis>nor</emphasis>
+exclusive to CX2341x devices, as the sliced VBI data packet insertion
+into the MPEG stream is implemented in driver software.  At least the
+<filename>cx18</filename> driver provides sliced VBI data insertion
+into an MPEG-2 PS in this format as well.</para>
+
+    <para>The following definitions specify the payload of the
+MPEG-2 <emphasis>Private Stream 1 PES</emphasis> packets that contain
+sliced VBI data when <link linkend="v4l2-mpeg-stream-vbi-fmt">
+<constant>V4L2_MPEG_STREAM_VBI_FMT_IVTV</constant></link> is set.
+(The MPEG-2 <emphasis>Private Stream 1 PES</emphasis> packet header
+and encapsulating MPEG-2 <emphasis>Program Pack</emphasis> header are
+not detailed here.  Please refer to the MPEG-2 specifications for
+details on those packet headers.)</para>
+
+    <para>The payload of the MPEG-2 <emphasis>Private Stream 1 PES
+</emphasis> packets that contain sliced VBI data is specified by
+&v4l2-mpeg-vbi-fmt-ivtv;.  The payload is variable
+length, depending on the actual number of lines of sliced VBI data
+present in a video frame.  The payload may be padded at the end with
+unspecified fill bytes to align the end of the payload to a 4-byte
+boundary.  The payload shall never exceed 1552 bytes (2 fields with
+18 lines/field with 43 bytes of data/line and a 4 byte magic number).
+</para>
+
+    <table frame="none" pgwide="1" id="v4l2-mpeg-vbi-fmt-ivtv">
+      <title>struct <structname>v4l2_mpeg_vbi_fmt_ivtv</structname>
+      </title>
+      <tgroup cols="4">
+	&cs-ustr;
+	<tbody valign="top">
+	  <row>
+	    <entry>__u8</entry>
+	    <entry><structfield>magic</structfield>[4]</entry>
+	    <entry></entry>
+	    <entry>A "magic" constant from <xref
+	    linkend="v4l2-mpeg-vbi-fmt-ivtv-magic"> that indicates
+this is a valid sliced VBI data payload and also indicates which
+member of the anonymous union, <structfield>itv0</structfield> or
+<structfield>ITV0</structfield>, to use for the payload data.</entry>
+	  </row>
+	  <row>
+	    <entry>union</entry>
+	    <entry>(anonymous)</entry>
+	  </row>
+	  <row>
+	    <entry></entry>
+	    <entry>struct <link linkend="v4l2-mpeg-vbi-itv0">
+	      <structname>v4l2_mpeg_vbi_itv0</structname></link>
+	    </entry>
+	    <entry><structfield>itv0</structfield></entry>
+	    <entry>The primary form of the sliced VBI data payload
+that contains anywhere from 1 to 35 lines of sliced VBI data.
+Line masks are provided in this form of the payload indicating
+which VBI lines are provided.</entry>
+	  </row>
+	  <row>
+	    <entry></entry>
+	    <entry>struct <link linkend="v4l2-mpeg-vbi-ITV0-1">
+	      <structname>v4l2_mpeg_vbi_ITV0</structname></link>
+	    </entry>
+	    <entry><structfield>ITV0</structfield></entry>
+	    <entry>An alternate form of the sliced VBI data payload
+used when 36 lines of sliced VBI data are present.  No line masks are
+provided in this form of the payload; all valid line mask bits are
+implcitly set.</entry>
+	  </row>
+	</tbody>
+      </tgroup>
+    </table>
+
+    <table frame="none" pgwide="1" id="v4l2-mpeg-vbi-fmt-ivtv-magic">
+      <title>Magic Constants for &v4l2-mpeg-vbi-fmt-ivtv;
+	<structfield>magic</structfield> field</title>
+      <tgroup cols="3">
+	&cs-def;
+	<thead>
+	  <row>
+	    <entry align="left">Defined Symbol</entry>
+	    <entry align="left">Value</entry>
+	    <entry align="left">Description</entry>
+	  </row>
+	</thead>
+	<tbody valign="top">
+	  <row>
+	    <entry><constant>V4L2_MPEG_VBI_IVTV_MAGIC0</constant>
+	    </entry>
+	    <entry>"itv0"</entry>
+	    <entry>Indicates the <structfield>itv0</structfield>
+member of the union in &v4l2-mpeg-vbi-fmt-ivtv; is valid.</entry>
+	  </row>
+	  <row>
+	    <entry><constant>V4L2_MPEG_VBI_IVTV_MAGIC1</constant>
+	    </entry>
+	    <entry>"ITV0"</entry>
+	    <entry>Indicates the <structfield>ITV0</structfield>
+member of the union in &v4l2-mpeg-vbi-fmt-ivtv; is valid and
+that 36 lines of sliced VBI data are present.</entry>
+	  </row>
+	</tbody>
+      </tgroup>
+    </table>
+
+    <table frame="none" pgwide="1" id="v4l2-mpeg-vbi-itv0">
+      <title>struct <structname>v4l2_mpeg_vbi_itv0</structname>
+      </title>
+      <tgroup cols="3">
+	&cs-str;
+	<tbody valign="top">
+	  <row>
+	    <entry>__le32</entry>
+	    <entry><structfield>linemask</structfield>[2]</entry>
+	    <entry><para>Bitmasks indicating the VBI service lines
+present.  These <structfield>linemask</structfield> values are stored
+in little endian byte order in the MPEG stream.  Some reference
+<structfield>linemask</structfield> bit positions with their
+corresponding VBI line number and video field are given below.
+b<subscript>0</subscript> indicates the least significant bit of a
+<structfield>linemask</structfield> value:<screen>
+<structfield>linemask</structfield>[0] b<subscript>0</subscript>:		line  6		first field
+<structfield>linemask</structfield>[0] b<subscript>17</subscript>:		line 23		first field
+<structfield>linemask</structfield>[0] b<subscript>18</subscript>:		line  6		second field
+<structfield>linemask</structfield>[0] b<subscript>31</subscript>:		line 19		second field
+<structfield>linemask</structfield>[1] b<subscript>0</subscript>:		line 20		second field
+<structfield>linemask</structfield>[1] b<subscript>3</subscript>:		line 23		second field
+<structfield>linemask</structfield>[1] b<subscript>4</subscript>-b<subscript>31</subscript>:	unused and set to 0</screen></para></entry>
+	  </row>
+	  <row>
+	    <entry>struct <link linkend="v4l2-mpeg-vbi-itv0-line">
+	      <structname>v4l2_mpeg_vbi_itv0_line</structname></link>
+	    </entry>
+	    <entry><structfield>line</structfield>[35]</entry>
+	    <entry>This is a variable length array that holds from 1
+to 35 lines of sliced VBI data.  The sliced VBI data lines present
+correspond to the bits set in the <structfield>linemask</structfield>
+array, starting from b<subscript>0</subscript> of <structfield>
+linemask</structfield>[0] up through b<subscript>31</subscript> of
+<structfield>linemask</structfield>[0], and from b<subscript>0
+</subscript> of <structfield>linemask</structfield>[1] up through b
+<subscript>3</subscript> of <structfield>linemask</structfield>[1].
+<structfield>line</structfield>[0] corresponds to the first bit
+found set in the <structfield>linemask</structfield> array,
+<structfield>line</structfield>[1] corresponds to the second bit
+found set in the <structfield>linemask</structfield> array, etc.
+If no <structfield>linemask</structfield> array bits are set, then
+<structfield>line</structfield>[0] may contain one line of
+unspecified data that should be ignored by applications.</entry>
+	  </row>
+	</tbody>
+      </tgroup>
+    </table>
+
+    <table frame="none" pgwide="1" id="v4l2-mpeg-vbi-ITV0-1">
+      <title>struct <structname>v4l2_mpeg_vbi_ITV0</structname>
+      </title>
+      <tgroup cols="3">
+	&cs-str;
+	<tbody valign="top">
+	  <row>
+	    <entry>struct <link linkend="v4l2-mpeg-vbi-itv0-line">
+	      <structname>v4l2_mpeg_vbi_itv0_line</structname></link>
+	    </entry>
+	    <entry><structfield>line</structfield>[36]</entry>
+	    <entry>A fixed length array of 36 lines of sliced VBI
+data.  <structfield>line</structfield>[0] through <structfield>line
+</structfield>[17] correspond to lines 6 through 23 of the
+first field.  <structfield>line</structfield>[18] through
+<structfield>line</structfield>[35] corresponds to lines 6
+through 23 of the second field.</entry>
+	  </row>
+	</tbody>
+      </tgroup>
+    </table>
+
+    <table frame="none" pgwide="1" id="v4l2-mpeg-vbi-itv0-line">
+      <title>struct <structname>v4l2_mpeg_vbi_itv0_line</structname>
+      </title>
+      <tgroup cols="3">
+	&cs-str;
+	<tbody valign="top">
+	  <row>
+	    <entry>__u8</entry>
+	    <entry><structfield>id</structfield></entry>
+	    <entry>A line identifier value from
+<xref linkend="ITV0-Line-Identifier-Constants"> that indicates
+the type of sliced VBI data stored on this line.</entry>
+	  </row>
+	  <row>
+	    <entry>__u8</entry>
+	    <entry><structfield>data</structfield>[42]</entry>
+	    <entry>The sliced VBI data for the line.</entry>
+	  </row>
+	</tbody>
+      </tgroup>
+    </table>
+
+    <table frame="none" pgwide="1" id="ITV0-Line-Identifier-Constants">
+      <title>Line Identifiers for struct <link
+      linkend="v4l2-mpeg-vbi-itv0-line"><structname>
+v4l2_mpeg_vbi_itv0_line</structname></link> <structfield>id
+</structfield> field</title>
+      <tgroup cols="3">
+	&cs-def;
+	<thead>
+	  <row>
+	    <entry align="left">Defined Symbol</entry>
+	    <entry align="left">Value</entry>
+	    <entry align="left">Description</entry>
+	  </row>
+	</thead>
+	<tbody valign="top">
+	  <row>
+	    <entry><constant>V4L2_MPEG_VBI_IVTV_TELETEXT_B</constant>
+	    </entry>
+	    <entry>1</entry>
+	    <entry>Refer to <link linkend="vbi-services2">
+Sliced VBI services</link> for a description of the line payload.</entry>
+	  </row>
+	  <row>
+	    <entry><constant>V4L2_MPEG_VBI_IVTV_CAPTION_525</constant>
+	    </entry>
+	    <entry>4</entry>
+	    <entry>Refer to <link linkend="vbi-services2">
+Sliced VBI services</link> for a description of the line payload.</entry>
+	  </row>
+	  <row>
+	    <entry><constant>V4L2_MPEG_VBI_IVTV_WSS_625</constant>
+	    </entry>
+	    <entry>5</entry>
+	    <entry>Refer to <link linkend="vbi-services2">
+Sliced VBI services</link> for a description of the line payload.</entry>
+	  </row>
+	  <row>
+	    <entry><constant>V4L2_MPEG_VBI_IVTV_VPS</constant>
+	    </entry>
+	    <entry>7</entry>
+	    <entry>Refer to <link linkend="vbi-services2">
+Sliced VBI services</link> for a description of the line payload.</entry>
+	  </row>
+	</tbody>
+      </tgroup>
+    </table>
+
+  </section>
+  </section>
+
+
 <!--
 Local Variables:
 mode: sgml
diff --git a/v4l2-spec/v4l2.sgml b/v4l2-spec/v4l2.sgml
index 9f43b6d1e..a6cbae2bf 100644
--- a/v4l2-spec/v4l2.sgml
+++ b/v4l2-spec/v4l2.sgml
@@ -77,6 +77,19 @@ API.</contrib>
 	<contrib>Designed and documented the VIDIOC_ENUM_FRAMESIZES
 and VIDIOC_ENUM_FRAMEINTERVALS ioctls.</contrib>
       </author>
+
+      <author>
+	<firstname>Andy</firstname>
+	<surname>Walls</surname>
+	<contrib>Documented the fielded V4L2_MPEG_STREAM_VBI_FMT_IVTV
+MPEG stream embedded, sliced VBI data format in this specification.
+</contrib>
+	<affiliation>
+	  <address>
+	    <email>awalls@radix.net</email>
+	  </address>
+	</affiliation>
+      </author>
     </authorgroup>
 
     <copyright>
@@ -92,12 +105,12 @@ and VIDIOC_ENUM_FRAMEINTERVALS ioctls.</contrib>
       <year>2008</year>
       <year>2009</year>
       <holder>Bill Dirks, Michael H. Schimek, Hans Verkuil, Martin
-Rubli</holder>
+Rubli, Andy Walls</holder>
     </copyright>
 
     <legalnotice>
       <para>This document is copyrighted &copy; 1999-2009 by Bill
-Dirks, Michael H. Schimek, Hans Verkuil and Martin Rubli.</para>
+Dirks, Michael H. Schimek, Hans Verkuil, Martin Rubli, and Andy Walls.</para>
 
       <para>Permission is granted to copy, distribute and/or modify
 this document under the terms of the GNU Free Documentation License,