On Mon, 2009-03-09 at 08:25 +0100, Hans Verkuil wrote:
> On Monday 09 March 2009 05:30:54 Mauro Carvalho Chehab wrote:
> > On Sat, 7 Mar 2009 09:49:30 +0100
> >
> > Hans Verkuil <hverkuil@xxxxxxxxx> wrote:
> > > On Saturday 07 March 2009 02:31:41 Andy Walls wrote:
> > > > On Fri, 2009-03-06 at 15:41 +0100, Hans Verkuil wrote:
> > > > > On Friday 06 March 2009 04:39:34 Andy Walls wrote:
> > > > > > Yes, they should be exported to userspace as well, so apps like
> > > > > > MythTV don't have to keep their own copies as well. I'm going to
> > > > > > work on a V4L2 spec change to add structures and defines for the
> > > > > > packets indicated by V4L2_MPEG_STREAM_VBI_FMT_IVTV, and then add
> > > > > > it to some API header. Maybe in linux/include/linux/videodev2.h
> > > > > > with all the other VBI data formats.
> > > > > >
> > > > > > Unless someone really disagrees.
> > > > >
> > > > > These VBI defines should be moved to videodev2.h. In hindsight this
> > > > > should never have been added to ivtv.h. Originally only ivtv used
> > > > > this, but now cx18 does as well, and in theory any MPEG encoder
> > > > > device can use it.
> > > >
> > > > Hans, Mauro, and whoever:
> > > >
> > > > Before I get too far down the road of writing the spec modifications
> > > > and perhaps modifying drivers, in the diff below:
> > > >
> > > > 1. Are the modifications to the headers acceptable?
> > > >
> > > > 2. Are they correct? (I *think* they are.)
> > >
> > > Acked-by: Hans Verkuil <hverkuil@xxxxxxxxx>
> > >
> > > Very nice. I was also toying with the idea to rename 'IVTV' in these
> > > defines to something different, but that makes too much of a mess. I
> > > think it is sufficient to add a sentence to the spec along the lines
> > > of:
> > >
> > > "This format was first introduced in the ivtv driver, hence the use of
> > > IVTV in these defines. It is however not limited to the ivtv driver,
> > > any MPEG encoder can use it."
> > >
> > > And I think that it also doesn't hurt if some of my explanations from
> > > my earlier email are added to the spec as well. The format looks really
> > > weird if you do not understand the PVR350 (cx23415) limitation.
> >
> > IMO, it is better to remove the IVTV from the name or to replace to
> > something else, since it is meant to be used by other drivers.
> >
> > > +#define V4L2_MPEG_VBI_IVTV_MAGIC0 "itv0"
> > > +#define V4L2_MPEG_VBI_IVTV_MAGIC1 "ITV0"
> >
> > Hmm... maybe we could just name it as format ITV0, as marked at the magic
> > values above. What do you think?
>
> I don't really see much of an improvement here. I think it is better to put
> a note in the spec (and perhaps in videodev2.h) that while it originated
> with ivtv it is not specific to that driver.
>
> But I do not have a really strong opinion here.
I don't have a terribly strong opinion either. I'm almost done the spec
changes (see the diff inline below), but I can easily change things.
I don't particularly want to purge IVTV from the
V4L2_CID_MPEG_STREAM_VBI_FMT MPEG control enumeration:
enum v4l2_mpeg_stream_vbi_fmt {
[...]
V4L2_MPEG_STREAM_VBI_FMT_IVTV = 1,
};
as that would be a specification change vs. an addition. Also adding a
new ...FMT_ITV0 symbol to the enumeration, that overlaps with a value of
1, creates problems for the controls code. IMO, IVTV is there to stay in
that enumeration.
I can change every other IVTV reference to ITV0 in a sensible way (I
think). Let me know, if you really want this. I won't be finishing it
and posting it for final draft review for a day or two.
Regards,
Andy
diff -r 5361470b10f4 linux/include/linux/ivtv.h
--- a/linux/include/linux/ivtv.h Sun Mar 01 21:10:07 2009 -0500
+++ b/linux/include/linux/ivtv.h Mon Mar 09 16:42:40 2009 -0400
@@ -60,10 +60,10 @@
#define IVTV_IOC_DMA_FRAME _IOW ('V', BASE_VIDIOC_PRIVATE+0, struct ivtv_dma_frame)
-/* These are the VBI types as they appear in the embedded VBI private packets. */
-#define IVTV_SLICED_TYPE_TELETEXT_B (1)
-#define IVTV_SLICED_TYPE_CAPTION_525 (4)
-#define IVTV_SLICED_TYPE_WSS_625 (5)
-#define IVTV_SLICED_TYPE_VPS (7)
+/* Deprecated defines: applications should use the defines from videodev2.h */
+#define IVTV_SLICED_TYPE_TELETEXT_B V4L2_MPEG_VBI_IVTV_TELETEXT_B
+#define IVTV_SLICED_TYPE_CAPTION_525 V4L2_MPEG_VBI_IVTV_CAPTION_525
+#define IVTV_SLICED_TYPE_WSS_625 V4L2_MPEG_VBI_IVTV_WSS_625
+#define IVTV_SLICED_TYPE_VPS V4L2_MPEG_VBI_IVTV_VPS
#endif /* _LINUX_IVTV_H */
diff -r 5361470b10f4 linux/include/linux/videodev2.h
--- a/linux/include/linux/videodev2.h Sun Mar 01 21:10:07 2009 -0500
+++ b/linux/include/linux/videodev2.h Mon Mar 09 16:42:40 2009 -0400
@@ -1348,6 +1348,53 @@
};
/*
+ * Sliced VBI data inserted into MPEG Streams
+ */
+
+/*
+ * V4L2_MPEG_STREAM_VBI_FMT_IVTV:
+ *
+ * Structure of payload contained in an MPEG 2 Private Stream 1 PES Packet in an
+ * MPEG-2 Program Pack that contains V4L2_MPEG_STREAM_VBI_FMT_IVTV Sliced VBI
+ * data
+ *
+ * Note, the MPEG-2 Program Pack and Private Stream 1 PES packet header
+ * definitions are not included here. See the MPEG-2 specifications for details
+ * on these headers.
+ */
+
+/* Line type IDs */
+#define V4L2_MPEG_VBI_IVTV_TELETEXT_B (1)
+#define V4L2_MPEG_VBI_IVTV_CAPTION_525 (4)
+#define V4L2_MPEG_VBI_IVTV_WSS_625 (5)
+#define V4L2_MPEG_VBI_IVTV_VPS (7)
+
+struct v4l2_mpeg_vbi_itv0_line {
+ __u8 id; /* One of V4L2_MPEG_VBI_IVTV_* above */
+ __u8 data[42]; /* Sliced VBI data for the line */
+} __attribute__ ((packed));
+
+struct v4l2_mpeg_vbi_itv0 {
+ __u32 linemask[2]; /* Bitmasks of which VBI service lines are present */
+ struct v4l2_mpeg_vbi_itv0_line line[35];
+} __attribute__ ((packed));
+
+struct v4l2_mpeg_vbi_ITV0 {
+ struct v4l2_mpeg_vbi_itv0_line line[36];
+} __attribute__ ((packed));
+
+#define V4L2_MPEG_VBI_IVTV_MAGIC0 "itv0"
+#define V4L2_MPEG_VBI_IVTV_MAGIC1 "ITV0"
+
+struct v4l2_mpeg_vbi_fmt_ivtv {
+ __u8 magic[4];
+ union {
+ struct v4l2_mpeg_vbi_itv0 itv0;
+ struct v4l2_mpeg_vbi_ITV0 ITV0;
+ };
+} __attribute__ ((packed));
+
+/*
* A G G R E G A T E S T R U C T U R E S
*/
diff -r 5361470b10f4 v4l2-spec/Makefile
--- a/v4l2-spec/Makefile Sun Mar 01 21:10:07 2009 -0500
+++ b/v4l2-spec/Makefile Mon Mar 09 16:42:40 2009 -0400
@@ -274,6 +274,7 @@
v4l2_input \
v4l2_jpegcompression \
v4l2_modulator \
+ v4l2_mpeg_vbi_fmt_ivtv \
v4l2_output \
v4l2_outputparm \
v4l2_pix_format \
diff -r 5361470b10f4 v4l2-spec/dev-sliced-vbi.sgml
--- a/v4l2-spec/dev-sliced-vbi.sgml Sun Mar 01 21:10:07 2009 -0500
+++ b/v4l2-spec/dev-sliced-vbi.sgml Mon Mar 09 16:42:40 2009 -0400
@@ -48,7 +48,7 @@
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 +386,278 @@
</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>comment</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>comment</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. Line
+masks are provided in this form of the payload indicating which VBI
+lines are provided.</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 VBI lines are provided. 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-itv0">
+ <title>struct <structname>v4l2_mpeg_vbi_itv0</structname>
+ </title>
+ <tgroup cols="3">
+ &cs-str;
+ <tbody valign="top">
+ <row>
+ <entry>__u32</entry>
+ <entry><structfield>linemask</structfield>[2]</entry>
+ <entry>comment</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>comment: up to 35 lines</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>comment: all 36 lines</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>comment</entry>
+ </row>
+ <row>
+ <entry>__u8</entry>
+ <entry><structfield>data</structfield>[42]</entry>
+ <entry>comment</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></entry>
+ </row>
+ <row>
+ <entry><constant>V4L2_MPEG_VBI_IVTV_CAPTION_525</constant>
+ </entry>
+ <entry>4</entry>
+ <entry></entry>
+ </row>
+ <row>
+ <entry><constant>V4L2_MPEG_VBI_IVTV_WSS_625</constant>
+ </entry>
+ <entry>5</entry>
+ <entry></entry>
+ </row>
+ <row>
+ <entry><constant>V4L2_MPEG_VBI_IVTV_VPS</constant>
+ </entry>
+ <entry>7</entry>
+ <entry></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ </section>
+ </section>
+
+
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