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diff --git a/v4l2-spec/vidioc-g-fbuf.sgml b/v4l2-spec/vidioc-g-fbuf.sgml deleted file mode 100644 index f70170626..000000000 --- a/v4l2-spec/vidioc-g-fbuf.sgml +++ /dev/null @@ -1,456 +0,0 @@ -<refentry id="vidioc-g-fbuf"> - <refmeta> - <refentrytitle>ioctl VIDIOC_G_FBUF, VIDIOC_S_FBUF</refentrytitle> - &manvol; - </refmeta> - - <refnamediv> - <refname>VIDIOC_G_FBUF</refname> - <refname>VIDIOC_S_FBUF</refname> - <refpurpose>Get or set frame buffer overlay parameters</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_framebuffer *<parameter>argp</parameter></paramdef> - </funcprototype> - </funcsynopsis> - <funcsynopsis> - <funcprototype> - <funcdef>int <function>ioctl</function></funcdef> - <paramdef>int <parameter>fd</parameter></paramdef> - <paramdef>int <parameter>request</parameter></paramdef> - <paramdef>const struct v4l2_framebuffer *<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_FBUF, VIDIOC_S_FBUF</para> - </listitem> - </varlistentry> - <varlistentry> - <term><parameter>argp</parameter></term> - <listitem> - <para></para> - </listitem> - </varlistentry> - </variablelist> - </refsect1> - - <refsect1> - <title>Description</title> - - <para>Applications can use the <constant>VIDIOC_G_FBUF</constant> and -<constant>VIDIOC_S_FBUF</constant> ioctl to get and set the -framebuffer parameters for a <link linkend="overlay">Video -Overlay</link> or <link linkend="osd">Video Output Overlay</link> -(OSD). The type of overlay is implied by the device type (capture or -output device) and can be determined with the &VIDIOC-QUERYCAP; ioctl. -One <filename>/dev/videoN</filename> device must not support both -kinds of overlay.</para> - - <para>The V4L2 API distinguishes destructive and non-destructive -overlays. A destructive overlay copies captured video images into the -video memory of a graphics card. A non-destructive overlay blends -video images into a VGA signal or graphics into a video signal. -<wordasword>Video Output Overlays</wordasword> are always -non-destructive.</para> - - <para>To get the current parameters applications call the -<constant>VIDIOC_G_FBUF</constant> ioctl with a pointer to a -<structname>v4l2_framebuffer</structname> structure. The driver fills -all fields of the structure or returns an &EINVAL; when overlays are -not supported.</para> - - <para>To set the parameters for a <wordasword>Video Output -Overlay</wordasword>, applications must initialize the -<structfield>flags</structfield> field of a struct -<structname>v4l2_framebuffer</structname>. Since the framebuffer is -implemented on the TV card all other parameters are determined by the -driver. When an application calls <constant>VIDIOC_S_FBUF</constant> -with a pointer to this structure, the driver prepares for the overlay -and returns the framebuffer parameters as -<constant>VIDIOC_G_FBUF</constant> does, or it returns an error -code.</para> - - <para>To set the parameters for a <wordasword>non-destructive -Video Overlay</wordasword>, applications must initialize the -<structfield>flags</structfield> field, the -<structfield>fmt</structfield> substructure, and call -<constant>VIDIOC_S_FBUF</constant>. Again the driver prepares for the -overlay and returns the framebuffer parameters as -<constant>VIDIOC_G_FBUF</constant> does, or it returns an error -code.</para> - - <para>For a <wordasword>destructive Video Overlay</wordasword> -applications must additionally provide a -<structfield>base</structfield> address. Setting up a DMA to a -random memory location can jeopardize the system security, its -stability or even damage the hardware, therefore only the superuser -can set the parameters for a destructive video overlay.</para> - - <!-- NB v4l2_pix_format is also specified in pixfmt.sgml.--> - - <table pgwide="1" frame="none" id="v4l2-framebuffer"> - <title>struct <structname>v4l2_framebuffer</structname></title> - <tgroup cols="4"> - &cs-ustr; - <tbody valign="top"> - <row> - <entry>__u32</entry> - <entry><structfield>capability</structfield></entry> - <entry></entry> - <entry>Overlay capability flags set by the driver, see -<xref linkend="framebuffer-cap" />.</entry> - </row> - <row> - <entry>__u32</entry> - <entry><structfield>flags</structfield></entry> - <entry></entry> - <entry>Overlay control flags set by application and -driver, see <xref linkend="framebuffer-flags" /></entry> - </row> - <row> - <entry>void *</entry> - <entry><structfield>base</structfield></entry> - <entry></entry> - <entry>Physical base address of the framebuffer, -that is the address of the pixel in the top left corner of the -framebuffer.<footnote><para>A physical base address may not suit all -platforms. GK notes in theory we should pass something like PCI device -+ memory region + offset instead. If you encounter problems please -discuss on the linux-media mailing list: &v4l-ml;.</para></footnote></entry> - </row> - <row> - <entry></entry> - <entry></entry> - <entry></entry> - <entry>This field is irrelevant to -<wordasword>non-destructive Video Overlays</wordasword>. For -<wordasword>destructive Video Overlays</wordasword> applications must -provide a base address. The driver may accept only base addresses -which are a multiple of two, four or eight bytes. For -<wordasword>Video Output Overlays</wordasword> the driver must return -a valid base address, so applications can find the corresponding Linux -framebuffer device (see <xref linkend="osd" />).</entry> - </row> - <row> - <entry>&v4l2-pix-format;</entry> - <entry><structfield>fmt</structfield></entry> - <entry></entry> - <entry>Layout of the frame buffer. The -<structname>v4l2_pix_format</structname> structure is defined in <xref -linkend="pixfmt" />, for clarification the fields and acceptable values - are listed below:</entry> - </row> - <row> - <entry></entry> - <entry>__u32</entry> - <entry><structfield>width</structfield></entry> - <entry>Width of the frame buffer in pixels.</entry> - </row> - <row> - <entry></entry> - <entry>__u32</entry> - <entry><structfield>height</structfield></entry> - <entry>Height of the frame buffer in pixels.</entry> - </row> - <row> - <entry></entry> - <entry>__u32</entry> - <entry><structfield>pixelformat</structfield></entry> - <entry>The pixel format of the -framebuffer.</entry> - </row> - <row> - <entry></entry> - <entry></entry> - <entry></entry> - <entry>For <wordasword>non-destructive Video -Overlays</wordasword> this field only defines a format for the -&v4l2-window; <structfield>chromakey</structfield> field.</entry> - </row> - <row> - <entry></entry> - <entry></entry> - <entry></entry> - <entry>For <wordasword>destructive Video -Overlays</wordasword> applications must initialize this field. For -<wordasword>Video Output Overlays</wordasword> the driver must return -a valid format.</entry> - </row> - <row> - <entry></entry> - <entry></entry> - <entry></entry> - <entry>Usually this is an RGB format (for example -<link linkend="V4L2-PIX-FMT-RGB565"><constant>V4L2_PIX_FMT_RGB565</constant></link>) -but YUV formats (only packed YUV formats when chroma keying is used, -not including <constant>V4L2_PIX_FMT_YUYV</constant> and -<constant>V4L2_PIX_FMT_UYVY</constant>) and the -<constant>V4L2_PIX_FMT_PAL8</constant> format are also permitted. The -behavior of the driver when an application requests a compressed -format is undefined. See <xref linkend="pixfmt" /> for information on -pixel formats.</entry> - </row> - <row> - <entry></entry> - <entry>&v4l2-field;</entry> - <entry><structfield>field</structfield></entry> - <entry>Drivers and applications shall ignore this field. -If applicable, the field order is selected with the &VIDIOC-S-FMT; -ioctl, using the <structfield>field</structfield> field of -&v4l2-window;.</entry> - </row> - <row> - <entry></entry> - <entry>__u32</entry> - <entry><structfield>bytesperline</structfield></entry> - <entry>Distance in bytes between the leftmost pixels in -two adjacent lines.</entry> - </row> - <row> - <entry spanname="hspan"><para>This field is irrelevant to -<wordasword>non-destructive Video -Overlays</wordasword>.</para><para>For <wordasword>destructive Video -Overlays</wordasword> both applications and drivers can set this field -to request padding bytes at the end of each line. Drivers however may -ignore the requested value, returning <structfield>width</structfield> -times bytes-per-pixel or a larger value required by the hardware. That -implies applications can just set this field to zero to get a -reasonable default.</para><para>For <wordasword>Video Output -Overlays</wordasword> the driver must return a valid -value.</para><para>Video hardware may access padding bytes, therefore -they must reside in accessible memory. Consider for example the case -where padding bytes after the last line of an image cross a system -page boundary. Capture devices may write padding bytes, the value is -undefined. Output devices ignore the contents of padding -bytes.</para><para>When the image format is planar the -<structfield>bytesperline</structfield> value applies to the largest -plane and is divided by the same factor as the -<structfield>width</structfield> field for any smaller planes. For -example the Cb and Cr planes of a YUV 4:2:0 image have half as many -padding bytes following each line as the Y plane. To avoid ambiguities -drivers must return a <structfield>bytesperline</structfield> value -rounded up to a multiple of the scale factor.</para></entry> - </row> - <row> - <entry></entry> - <entry>__u32</entry> - <entry><structfield>sizeimage</structfield></entry> - <entry><para>This field is irrelevant to -<wordasword>non-destructive Video Overlays</wordasword>. For -<wordasword>destructive Video Overlays</wordasword> applications must -initialize this field. For <wordasword>Video Output -Overlays</wordasword> the driver must return a valid -format.</para><para>Together with <structfield>base</structfield> it -defines the framebuffer memory accessible by the -driver.</para></entry> - </row> - <row> - <entry></entry> - <entry>&v4l2-colorspace;</entry> - <entry><structfield>colorspace</structfield></entry> - <entry>This information supplements the -<structfield>pixelformat</structfield> and must be set by the driver, -see <xref linkend="colorspaces" />.</entry> - </row> - <row> - <entry></entry> - <entry>__u32</entry> - <entry><structfield>priv</structfield></entry> - <entry>Reserved for additional information about custom -(driver defined) formats. When not used drivers and applications must -set this field to zero.</entry> - </row> - </tbody> - </tgroup> - </table> - - <table pgwide="1" frame="none" id="framebuffer-cap"> - <title>Frame Buffer Capability Flags</title> - <tgroup cols="3"> - &cs-def; - <tbody valign="top"> - <row> - <entry><constant>V4L2_FBUF_CAP_EXTERNOVERLAY</constant></entry> - <entry>0x0001</entry> - <entry>The device is capable of non-destructive overlays. -When the driver clears this flag, only destructive overlays are -supported. There are no drivers yet which support both destructive and -non-destructive overlays.</entry> - </row> - <row> - <entry><constant>V4L2_FBUF_CAP_CHROMAKEY</constant></entry> - <entry>0x0002</entry> - <entry>The device supports clipping by chroma-keying the -images. That is, image pixels replace pixels in the VGA or video -signal only where the latter assume a certain color. Chroma-keying -makes no sense for destructive overlays.</entry> - </row> - <row> - <entry><constant>V4L2_FBUF_CAP_LIST_CLIPPING</constant></entry> - <entry>0x0004</entry> - <entry>The device supports clipping using a list of clip -rectangles.</entry> - </row> - <row> - <entry><constant>V4L2_FBUF_CAP_BITMAP_CLIPPING</constant></entry> - <entry>0x0008</entry> - <entry>The device supports clipping using a bit mask.</entry> - </row> - <row> - <entry><constant>V4L2_FBUF_CAP_LOCAL_ALPHA</constant></entry> - <entry>0x0010</entry> - <entry>The device supports clipping/blending using the -alpha channel of the framebuffer or VGA signal. Alpha blending makes -no sense for destructive overlays.</entry> - </row> - <row> - <entry><constant>V4L2_FBUF_CAP_GLOBAL_ALPHA</constant></entry> - <entry>0x0020</entry> - <entry>The device supports alpha blending using a global -alpha value. Alpha blending makes no sense for destructive overlays.</entry> - </row> - <row> - <entry><constant>V4L2_FBUF_CAP_LOCAL_INV_ALPHA</constant></entry> - <entry>0x0040</entry> - <entry>The device supports clipping/blending using the -inverted alpha channel of the framebuffer or VGA signal. Alpha -blending makes no sense for destructive overlays.</entry> - </row> - </tbody> - </tgroup> - </table> - - <table pgwide="1" frame="none" id="framebuffer-flags"> - <title>Frame Buffer Flags</title> - <tgroup cols="3"> - &cs-def; - <tbody valign="top"> - <row> - <entry><constant>V4L2_FBUF_FLAG_PRIMARY</constant></entry> - <entry>0x0001</entry> - <entry>The framebuffer is the primary graphics surface. -In other words, the overlay is destructive. [?]</entry> - </row> - <row> - <entry><constant>V4L2_FBUF_FLAG_OVERLAY</constant></entry> - <entry>0x0002</entry> - <entry>The frame buffer is an overlay surface the same -size as the capture. [?]</entry> - </row> - <row> - <entry spanname="hspan">The purpose of -<constant>V4L2_FBUF_FLAG_PRIMARY</constant> and -<constant>V4L2_FBUF_FLAG_OVERLAY</constant> was never quite clear. -Most drivers seem to ignore these flags. For compatibility with the -<wordasword>bttv</wordasword> driver applications should set the -<constant>V4L2_FBUF_FLAG_OVERLAY</constant> flag.</entry> - </row> - <row> - <entry><constant>V4L2_FBUF_FLAG_CHROMAKEY</constant></entry> - <entry>0x0004</entry> - <entry>Use chroma-keying. The chroma-key color is -determined by the <structfield>chromakey</structfield> field of -&v4l2-window; and negotiated with the &VIDIOC-S-FMT; ioctl, see <xref - linkend="overlay" /> -and - <xref linkend="osd" />.</entry> - </row> - <row> - <entry spanname="hspan">There are no flags to enable -clipping using a list of clip rectangles or a bitmap. These methods -are negotiated with the &VIDIOC-S-FMT; ioctl, see <xref - linkend="overlay" /> and <xref linkend="osd" />.</entry> - </row> - <row> - <entry><constant>V4L2_FBUF_FLAG_LOCAL_ALPHA</constant></entry> - <entry>0x0008</entry> - <entry>Use the alpha channel of the framebuffer to clip or -blend framebuffer pixels with video images. The blend -function is: output = framebuffer pixel * alpha + video pixel * (1 - -alpha). The actual alpha depth depends on the framebuffer pixel -format.</entry> - </row> - <row> - <entry><constant>V4L2_FBUF_FLAG_GLOBAL_ALPHA</constant></entry> - <entry>0x0010</entry> - <entry>Use a global alpha value to blend the framebuffer -with video images. The blend function is: output = (framebuffer pixel -* alpha + video pixel * (255 - alpha)) / 255. The alpha value is -determined by the <structfield>global_alpha</structfield> field of -&v4l2-window; and negotiated with the &VIDIOC-S-FMT; ioctl, see <xref - linkend="overlay" /> -and <xref linkend="osd" />.</entry> - </row> - <row> - <entry><constant>V4L2_FBUF_FLAG_LOCAL_INV_ALPHA</constant></entry> - <entry>0x0020</entry> - <entry>Like -<constant>V4L2_FBUF_FLAG_LOCAL_ALPHA</constant>, use the alpha channel -of the framebuffer to clip or blend framebuffer pixels with video -images, but with an inverted alpha value. The blend function is: -output = framebuffer pixel * (1 - alpha) + video pixel * alpha. The -actual alpha depth depends on the framebuffer pixel format.</entry> - </row> - </tbody> - </tgroup> - </table> - </refsect1> - - <refsect1> - &return-value; - - <variablelist> - <varlistentry> - <term><errorcode>EPERM</errorcode></term> - <listitem> - <para><constant>VIDIOC_S_FBUF</constant> can only be called -by a privileged user to negotiate the parameters for a destructive -overlay.</para> - </listitem> - </varlistentry> - <varlistentry> - <term><errorcode>EBUSY</errorcode></term> - <listitem> - <para>The framebuffer parameters cannot be changed at this -time because overlay is already enabled, or capturing is enabled -and the hardware cannot capture and overlay simultaneously.</para> - </listitem> - </varlistentry> - <varlistentry> - <term><errorcode>EINVAL</errorcode></term> - <listitem> - <para>The ioctl is not supported or the -<constant>VIDIOC_S_FBUF</constant> parameters are unsuitable.</para> - </listitem> - </varlistentry> - </variablelist> - </refsect1> -</refentry> - -<!-- -Local Variables: -mode: sgml -sgml-parent-document: "v4l2.sgml" -indent-tabs-mode: nil -End: ---> |