From 8d4f9d241cdbd71a882a852c6e9285de279c0f87 Mon Sep 17 00:00:00 2001 From: Hans Verkuil Date: Sun, 18 Jan 2009 13:00:12 +0100 Subject: v4l2spec: add version 0.24 of the spec From: Hans Verkuil Priority: normal Signed-off-by: Hans Verkuil --- v4l2-spec/vidioc-g-fbuf.sgml | 435 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 435 insertions(+) create mode 100644 v4l2-spec/vidioc-g-fbuf.sgml (limited to 'v4l2-spec/vidioc-g-fbuf.sgml') diff --git a/v4l2-spec/vidioc-g-fbuf.sgml b/v4l2-spec/vidioc-g-fbuf.sgml new file mode 100644 index 000000000..3e4ac2952 --- /dev/null +++ b/v4l2-spec/vidioc-g-fbuf.sgml @@ -0,0 +1,435 @@ + + + ioctl VIDIOC_G_FBUF, VIDIOC_S_FBUF + &manvol; + + + + VIDIOC_G_FBUF + VIDIOC_S_FBUF + Get or set frame buffer overlay parameters + + + + + + int ioctl + int fd + int request + struct v4l2_framebuffer *argp + + + + + int ioctl + int fd + int request + const struct v4l2_framebuffer *argp + + + + + + Arguments + + + + fd + + &fd; + + + + request + + VIDIOC_G_FBUF, VIDIOC_S_FBUF + + + + argp + + + + + + + + + Description + + Applications can use the VIDIOC_G_FBUF and +VIDIOC_S_FBUF ioctl to get and set the +framebuffer parameters for a Video +Overlay or Video Output Overlay +(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 /dev/videoN device must not support both +kinds of overlay. + + 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. +Video Output Overlays are always +non-destructive. + + To get the current parameters applications call the +VIDIOC_G_FBUF ioctl with a pointer to a +v4l2_framebuffer structure. The driver fills +all fields of the structure or returns an &EINVAL; when overlays are +not supported. + + To set the parameters for a Video Output +Overlay, applications must initialize the +flags field of a struct +v4l2_framebuffer. Since the framebuffer is +implemented on the TV card all other parameters are determined by the +driver. When an application calls VIDIOC_S_FBUF +with a pointer to this structure, the driver prepares for the overlay +and returns the framebuffer parameters as +VIDIOC_G_FBUF does, or it returns an error +code. + + To set the parameters for a non-destructive +Video Overlay, applications must initialize the +flags field, the +fmt substructure, and call +VIDIOC_S_FBUF. Again the driver prepares for the +overlay and returns the framebuffer parameters as +VIDIOC_G_FBUF does, or it returns an error +code. + + For a destructive Video Overlay +applications must additionally provide a +base 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. + + + + + struct <structname>v4l2_framebuffer</structname> + + &cs-ustr; + + + __u32 + capability + + Overlay capability flags set by the driver, see +. + + + __u32 + flags + + Overlay control flags set by application and +driver, see + + + void * + base + + Physical base address of the framebuffer, +that is the address of the pixel in the top left corner of the +framebuffer.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 Video4Linux mailing list: +&v4l-ml;.This field is irrelevant to +non-destructive Video Overlays. For +destructive Video Overlays applications must +provide a base address. The driver may accept only base addresses +which are a multiple of two, four or eight bytes. For +Video Output Overlays the driver must return +a valid base address, so applications can find the corresponding Linux +framebuffer device (see ). + + + &v4l2-pix-format; + fmt + + Layout of the frame buffer. The +v4l2_pix_format structure is defined in , for clarification the fields and acceptable values + are listed below: + + + + __u32 + width + Width of the frame buffer in pixels. + + + + __u32 + height + Height of the frame buffer in pixels. + + + + __u32 + pixelformat + The pixel format of the +framebuffer.For non-destructive Video +Overlays this field only defines a format for the +&v4l2-window; chromakey +field.For destructive Video +Overlays applications must initialize this field. For +Video Output Overlays the driver must return +a valid format.Usually this is an RGB format (for example +V4L2_PIX_FMT_RGB565) +but YUV formats (only packed YUV formats when chroma keying is used, +not including V4L2_PIX_FMT_YUYV and +V4L2_PIX_FMT_UYVY) and the +V4L2_PIX_FMT_PAL8 format are also permitted. The +behavior of the driver when an application requests a compressed +format is undefined. See for information on +pixel formats. + + + + &v4l2-field; + field + Drivers and applications shall ignore this field. +If applicable, the field order is selected with the &VIDIOC-S-FMT; +ioctl, using the field field of +&v4l2-window;. + + + + __u32 + bytesperline + Distance in bytes between the leftmost pixels in +two adjacent lines. + + + This field is irrelevant to +non-destructive Video +Overlays.For destructive Video +Overlays 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 width +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.For Video Output +Overlays the driver must return a valid +value.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.When the image format is planar the +bytesperline value applies to the largest +plane and is divided by the same factor as the +width 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 bytesperline value +rounded up to a multiple of the scale factor. + + + + __u32 + sizeimage + This field is irrelevant to +non-destructive Video Overlays. For +destructive Video Overlays applications must +initialize this field. For Video Output +Overlays the driver must return a valid +format.Together with base it +defines the framebuffer memory accessible by the +driver. + + + + &v4l2-colorspace; + colorspace + This information supplements the +pixelformat and must be set by the driver, +see . + + + + __u32 + priv + Reserved for additional information about custom +(driver defined) formats. When not used drivers and applications must +set this field to zero. + + + +
+ + + Frame Buffer Capability Flags + + &cs-def; + + + V4L2_FBUF_CAP_EXTERNOVERLAY + 0x0001 + 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. + + + V4L2_FBUF_CAP_CHROMAKEY + 0x0002 + 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. + + + V4L2_FBUF_CAP_LIST_CLIPPING + 0x0004 + The device supports clipping using a list of clip +rectangles. + + + V4L2_FBUF_CAP_BITMAP_CLIPPING + 0x0008 + The device supports clipping using a bit mask. + + + V4L2_FBUF_CAP_LOCAL_ALPHA + 0x0010 + The device supports clipping/blending using the +alpha channel of the framebuffer or VGA signal. Alpha blending makes +no sense for destructive overlays. + + + V4L2_FBUF_CAP_GLOBAL_ALPHA + 0x0020 + The device supports alpha blending using a global +alpha value. Alpha blending makes no sense for destructive overlays. + + + V4L2_FBUF_CAP_LOCAL_INV_ALPHA + 0x0040 + The device supports clipping/blending using the +inverted alpha channel of the framebuffer or VGA signal. Alpha +blending makes no sense for destructive overlays. + + + +
+ + + Frame Buffer Flags + + &cs-def; + + + V4L2_FBUF_FLAG_PRIMARY + 0x0001 + The framebuffer is the primary graphics surface. +In other words, the overlay is destructive. [?] + + + V4L2_FBUF_FLAG_OVERLAY + 0x0002 + The frame buffer is an overlay surface the same +size as the capture. [?] + + + The purpose of +V4L2_FBUF_FLAG_PRIMARY and +V4L2_FBUF_FLAG_OVERLAY was never quite clear. +Most drivers seem to ignore these flags. For compatibility with the +bttv driver applications should set the +V4L2_FBUF_FLAG_OVERLAY flag. + + + V4L2_FBUF_FLAG_CHROMAKEY + 0x0004 + Use chroma-keying. The chroma-key color is +determined by the chromakey field of +&v4l2-window; and negotiated with the &VIDIOC-S-FMT; ioctl, see +and + . + + + 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 and . + + + V4L2_FBUF_FLAG_LOCAL_ALPHA + 0x0008 + 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. + + + V4L2_FBUF_FLAG_GLOBAL_ALPHA + 0x0010 + 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 global_alpha field of +&v4l2-window; and negotiated with the &VIDIOC-S-FMT; ioctl, see +and . + + + V4L2_FBUF_FLAG_LOCAL_INV_ALPHA + 0x0020 + Like +V4L2_FBUF_FLAG_LOCAL_ALPHA, 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. + + + +
+ + + + &return-value; + + + + EPERM + + VIDIOC_S_FBUF can only be called +by a privileged user to negotiate the parameters for a destructive +overlay. + + + + EBUSY + + 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. + + + + EINVAL + + The ioctl is not supported or the +VIDIOC_S_FBUF parameters are unsuitable. + + + + + + + -- cgit v1.2.3 From 3f45ddcc291e0175fa252241002fcc915cde43d7 Mon Sep 17 00:00:00 2001 From: Hans Verkuil Date: Sun, 18 Jan 2009 16:35:57 +0100 Subject: v4l2-spec: update mailing list to linux-media. From: Hans Verkuil Priority: normal Signed-off-by: Hans Verkuil --- v4l2-spec/vidioc-g-fbuf.sgml | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'v4l2-spec/vidioc-g-fbuf.sgml') diff --git a/v4l2-spec/vidioc-g-fbuf.sgml b/v4l2-spec/vidioc-g-fbuf.sgml index 3e4ac2952..65f597100 100644 --- a/v4l2-spec/vidioc-g-fbuf.sgml +++ b/v4l2-spec/vidioc-g-fbuf.sgml @@ -136,7 +136,7 @@ that is the address of the pixel in the top left corner of the framebuffer.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 Video4Linux mailing list: +discuss on the linux-media mailing list: &v4l-ml;.This field is irrelevant to non-destructive Video Overlays. For destructive Video Overlays applications must -- cgit v1.2.3 From 8f85ebb446130d67e0b6f8a8a6ac48451843beaf Mon Sep 17 00:00:00 2001 From: Hans Verkuil Date: Thu, 22 Jan 2009 08:52:53 +0100 Subject: v4l2-spec: fix some table alignment problems From: Hans Verkuil Priority: normal Signed-off-by: Hans Verkuil --- v4l2-spec/vidioc-g-fbuf.sgml | 45 ++++++++++++++++++++++++++++++++------------ 1 file changed, 33 insertions(+), 12 deletions(-) (limited to 'v4l2-spec/vidioc-g-fbuf.sgml') diff --git a/v4l2-spec/vidioc-g-fbuf.sgml b/v4l2-spec/vidioc-g-fbuf.sgml index 65f597100..6781b5334 100644 --- a/v4l2-spec/vidioc-g-fbuf.sgml +++ b/v4l2-spec/vidioc-g-fbuf.sgml @@ -131,20 +131,25 @@ driver, see void * base - Physical base address of the framebuffer, + Physical base address of the framebuffer, that is the address of the pixel in the top left corner of the framebuffer.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;.This field is irrelevant to +discuss on the linux-media mailing list: &v4l-ml;. + + + + + + This field is irrelevant to non-destructive Video Overlays. For destructive Video Overlays applications must provide a base address. The driver may accept only base addresses which are a multiple of two, four or eight bytes. For Video Output Overlays the driver must return a valid base address, so applications can find the corresponding Linux -framebuffer device (see ). +framebuffer device (see ). &v4l2-pix-format; @@ -171,23 +176,39 @@ linkend="pixfmt">, for clarification the fields and acceptable values __u32 pixelformat - The pixel format of the -framebuffer.For non-destructive Video + The pixel format of the +framebuffer. + + + + + + For non-destructive Video Overlays this field only defines a format for the -&v4l2-window; chromakey -field.For destructive Video +&v4l2-window; chromakey field. + + + + + + For destructive Video Overlays applications must initialize this field. For Video Output Overlays the driver must return -a valid format.Usually this is an RGB format (for example -V4L2_PIX_FMT_RGB565) +a valid format. + + + + + + Usually this is an RGB format (for example +V4L2_PIX_FMT_RGB565) but YUV formats (only packed YUV formats when chroma keying is used, not including V4L2_PIX_FMT_YUYV and V4L2_PIX_FMT_UYVY) and the V4L2_PIX_FMT_PAL8 format are also permitted. The behavior of the driver when an application requests a compressed format is undefined. See for information on -pixel formats. +pixel formats. -- cgit v1.2.3