* [PATCH/RFC 0/2] Propert alpha channel support in pixel formats
@ 2014-05-26 22:17 Laurent Pinchart
2014-05-26 22:17 ` [PATCH/RFC 1/2] v4l: Add ARGB and XRGB " Laurent Pinchart
` (2 more replies)
0 siblings, 3 replies; 5+ messages in thread
From: Laurent Pinchart @ 2014-05-26 22:17 UTC (permalink / raw)
To: linux-media; +Cc: Hans Verkuil
Hello,
This RFC patch series attempts to clean up the current ARGB format mess.
The core issue is that the existing ARGB formats are ill-defined. The V4L2
specification doesn't clearly document how the alpha bits should behave.
Drivers have thus used the same formats in different, incompatible ways, and
applications now rely on the driver-specific behaviours. In a word, that's a
mess.
I've discussed the issue in the #v4l channel a couple of days ago and we came
up to the conclusion that the best (or least painful) way to fix the problem
is to define new clean XRGB and ARGB formats, and consider the existing
formats as deprecated (meaning that no new driver should use them, they won't
disappear in a couple of months, as that would break userspace).
The first patch adds the new XRGB and ARGB formats and documents them. It
purposely includes no core code to handle backward compatibility for existing
drivers that may wish to move to the new formats. The reason is that I would
first like to get feedback on the proposal before working on compat code, and
I believe we should first implement the compat code in a couple of drivers and
then see how the approach could be generalized, if possible at all.
The second patch allows using the ALPHA_COMPONENT control on output devices to
support an ARGB use case documented in the first patch. One possible
shortcoming of reusing the existing control is that a mem-to-mem driver that
exposes an output and a capture queue on a single video node through the same
file handle wouldn't be able to set different alpha component values on the
two queues. I'm not sure whether that use case is real though, it seems weird
to me to set a fixed alpha value on one side to request a different fixed
alpha value on the other side.
Laurent Pinchart (2):
v4l: Add ARGB and XRGB pixel formats
DocBook: media: Document ALPHA_COMPONENT control usage on output
devices
Documentation/DocBook/media/v4l/controls.xml | 17 +-
.../DocBook/media/v4l/pixfmt-packed-rgb.xml | 415 ++++++++++++++++++++-
include/uapi/linux/videodev2.h | 8 +
3 files changed, 413 insertions(+), 27 deletions(-)
--
Regards,
Laurent Pinchart
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH/RFC 1/2] v4l: Add ARGB and XRGB pixel formats
2014-05-26 22:17 [PATCH/RFC 0/2] Propert alpha channel support in pixel formats Laurent Pinchart
@ 2014-05-26 22:17 ` Laurent Pinchart
2014-05-26 22:17 ` [PATCH/RFC 2/2] DocBook: media: Document ALPHA_COMPONENT control usage on output devices Laurent Pinchart
2014-05-27 7:18 ` [PATCH/RFC 0/2] Propert alpha channel support in pixel formats Hans Verkuil
2 siblings, 0 replies; 5+ messages in thread
From: Laurent Pinchart @ 2014-05-26 22:17 UTC (permalink / raw)
To: linux-media; +Cc: Hans Verkuil
From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
The existing RGB pixel formats are ill-defined in respect to their alpha
bits and their meaning is driver dependent. Create new standard ARGB and
XRGB variants with clearly defined meanings and make the existing
variants deprecated.
The new pixel formats 4CC values have been selected to match the DRM
4CCs for the same in-memory formats.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
---
.../DocBook/media/v4l/pixfmt-packed-rgb.xml | 415 ++++++++++++++++++++-
include/uapi/linux/videodev2.h | 8 +
2 files changed, 403 insertions(+), 20 deletions(-)
diff --git a/Documentation/DocBook/media/v4l/pixfmt-packed-rgb.xml b/Documentation/DocBook/media/v4l/pixfmt-packed-rgb.xml
index e1c4f8b..5f1602f 100644
--- a/Documentation/DocBook/media/v4l/pixfmt-packed-rgb.xml
+++ b/Documentation/DocBook/media/v4l/pixfmt-packed-rgb.xml
@@ -130,9 +130,9 @@ colorspace <constant>V4L2_COLORSPACE_SRGB</constant>.</para>
<entry>b<subscript>1</subscript></entry>
<entry>b<subscript>0</subscript></entry>
</row>
- <row id="V4L2-PIX-FMT-RGB444">
- <entry><constant>V4L2_PIX_FMT_RGB444</constant></entry>
- <entry>'R444'</entry>
+ <row id="V4L2-PIX-FMT-ARGB444">
+ <entry><constant>V4L2_PIX_FMT_ARGB444</constant></entry>
+ <entry>'AR12'</entry>
<entry></entry>
<entry>g<subscript>3</subscript></entry>
<entry>g<subscript>2</subscript></entry>
@@ -152,9 +152,31 @@ colorspace <constant>V4L2_COLORSPACE_SRGB</constant>.</para>
<entry>r<subscript>1</subscript></entry>
<entry>r<subscript>0</subscript></entry>
</row>
- <row id="V4L2-PIX-FMT-RGB555">
- <entry><constant>V4L2_PIX_FMT_RGB555</constant></entry>
- <entry>'RGBO'</entry>
+ <row id="V4L2-PIX-FMT-XRGB444">
+ <entry><constant>V4L2_PIX_FMT_XRGB444</constant></entry>
+ <entry>'XR12'</entry>
+ <entry></entry>
+ <entry>g<subscript>3</subscript></entry>
+ <entry>g<subscript>2</subscript></entry>
+ <entry>g<subscript>1</subscript></entry>
+ <entry>g<subscript>0</subscript></entry>
+ <entry>b<subscript>3</subscript></entry>
+ <entry>b<subscript>2</subscript></entry>
+ <entry>b<subscript>1</subscript></entry>
+ <entry>b<subscript>0</subscript></entry>
+ <entry></entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry>r<subscript>3</subscript></entry>
+ <entry>r<subscript>2</subscript></entry>
+ <entry>r<subscript>1</subscript></entry>
+ <entry>r<subscript>0</subscript></entry>
+ </row>
+ <row id="V4L2-PIX-FMT-ARGB555">
+ <entry><constant>V4L2_PIX_FMT_ARGB555</constant></entry>
+ <entry>'AR15'</entry>
<entry></entry>
<entry>g<subscript>2</subscript></entry>
<entry>g<subscript>1</subscript></entry>
@@ -174,6 +196,28 @@ colorspace <constant>V4L2_COLORSPACE_SRGB</constant>.</para>
<entry>g<subscript>4</subscript></entry>
<entry>g<subscript>3</subscript></entry>
</row>
+ <row id="V4L2-PIX-FMT-XRGB555">
+ <entry><constant>V4L2_PIX_FMT_XRGB555</constant></entry>
+ <entry>'XR15'</entry>
+ <entry></entry>
+ <entry>g<subscript>2</subscript></entry>
+ <entry>g<subscript>1</subscript></entry>
+ <entry>g<subscript>0</subscript></entry>
+ <entry>b<subscript>4</subscript></entry>
+ <entry>b<subscript>3</subscript></entry>
+ <entry>b<subscript>2</subscript></entry>
+ <entry>b<subscript>1</subscript></entry>
+ <entry>b<subscript>0</subscript></entry>
+ <entry></entry>
+ <entry>-</entry>
+ <entry>r<subscript>4</subscript></entry>
+ <entry>r<subscript>3</subscript></entry>
+ <entry>r<subscript>2</subscript></entry>
+ <entry>r<subscript>1</subscript></entry>
+ <entry>r<subscript>0</subscript></entry>
+ <entry>g<subscript>4</subscript></entry>
+ <entry>g<subscript>3</subscript></entry>
+ </row>
<row id="V4L2-PIX-FMT-RGB565">
<entry><constant>V4L2_PIX_FMT_RGB565</constant></entry>
<entry>'RGBP'</entry>
@@ -341,9 +385,9 @@ colorspace <constant>V4L2_COLORSPACE_SRGB</constant>.</para>
<entry>b<subscript>1</subscript></entry>
<entry>b<subscript>0</subscript></entry>
</row>
- <row id="V4L2-PIX-FMT-BGR32">
- <entry><constant>V4L2_PIX_FMT_BGR32</constant></entry>
- <entry>'BGR4'</entry>
+ <row id="V4L2-PIX-FMT-ABGR32">
+ <entry><constant>V4L2_PIX_FMT_ABGR32</constant></entry>
+ <entry>'AR24'</entry>
<entry></entry>
<entry>b<subscript>7</subscript></entry>
<entry>b<subscript>6</subscript></entry>
@@ -381,9 +425,49 @@ colorspace <constant>V4L2_COLORSPACE_SRGB</constant>.</para>
<entry>a<subscript>1</subscript></entry>
<entry>a<subscript>0</subscript></entry>
</row>
- <row id="V4L2-PIX-FMT-RGB32">
- <entry><constant>V4L2_PIX_FMT_RGB32</constant></entry>
- <entry>'RGB4'</entry>
+ <row id="V4L2-PIX-FMT-XBGR32">
+ <entry><constant>V4L2_PIX_FMT_XBGR32</constant></entry>
+ <entry>'XR24'</entry>
+ <entry></entry>
+ <entry>b<subscript>7</subscript></entry>
+ <entry>b<subscript>6</subscript></entry>
+ <entry>b<subscript>5</subscript></entry>
+ <entry>b<subscript>4</subscript></entry>
+ <entry>b<subscript>3</subscript></entry>
+ <entry>b<subscript>2</subscript></entry>
+ <entry>b<subscript>1</subscript></entry>
+ <entry>b<subscript>0</subscript></entry>
+ <entry></entry>
+ <entry>g<subscript>7</subscript></entry>
+ <entry>g<subscript>6</subscript></entry>
+ <entry>g<subscript>5</subscript></entry>
+ <entry>g<subscript>4</subscript></entry>
+ <entry>g<subscript>3</subscript></entry>
+ <entry>g<subscript>2</subscript></entry>
+ <entry>g<subscript>1</subscript></entry>
+ <entry>g<subscript>0</subscript></entry>
+ <entry></entry>
+ <entry>r<subscript>7</subscript></entry>
+ <entry>r<subscript>6</subscript></entry>
+ <entry>r<subscript>5</subscript></entry>
+ <entry>r<subscript>4</subscript></entry>
+ <entry>r<subscript>3</subscript></entry>
+ <entry>r<subscript>2</subscript></entry>
+ <entry>r<subscript>1</subscript></entry>
+ <entry>r<subscript>0</subscript></entry>
+ <entry></entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ </row>
+ <row id="V4L2-PIX-FMT-ARGB32">
+ <entry><constant>V4L2_PIX_FMT_ARGB32</constant></entry>
+ <entry>'AX24'</entry>
<entry></entry>
<entry>a<subscript>7</subscript></entry>
<entry>a<subscript>6</subscript></entry>
@@ -421,18 +505,76 @@ colorspace <constant>V4L2_COLORSPACE_SRGB</constant>.</para>
<entry>b<subscript>1</subscript></entry>
<entry>b<subscript>0</subscript></entry>
</row>
+ <row id="V4L2-PIX-FMT-XRGB32">
+ <entry><constant>V4L2_PIX_FMT_XRGB32</constant></entry>
+ <entry>'BX24'</entry>
+ <entry></entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry></entry>
+ <entry>r<subscript>7</subscript></entry>
+ <entry>r<subscript>6</subscript></entry>
+ <entry>r<subscript>5</subscript></entry>
+ <entry>r<subscript>4</subscript></entry>
+ <entry>r<subscript>3</subscript></entry>
+ <entry>r<subscript>2</subscript></entry>
+ <entry>r<subscript>1</subscript></entry>
+ <entry>r<subscript>0</subscript></entry>
+ <entry></entry>
+ <entry>g<subscript>7</subscript></entry>
+ <entry>g<subscript>6</subscript></entry>
+ <entry>g<subscript>5</subscript></entry>
+ <entry>g<subscript>4</subscript></entry>
+ <entry>g<subscript>3</subscript></entry>
+ <entry>g<subscript>2</subscript></entry>
+ <entry>g<subscript>1</subscript></entry>
+ <entry>g<subscript>0</subscript></entry>
+ <entry></entry>
+ <entry>b<subscript>7</subscript></entry>
+ <entry>b<subscript>6</subscript></entry>
+ <entry>b<subscript>5</subscript></entry>
+ <entry>b<subscript>4</subscript></entry>
+ <entry>b<subscript>3</subscript></entry>
+ <entry>b<subscript>2</subscript></entry>
+ <entry>b<subscript>1</subscript></entry>
+ <entry>b<subscript>0</subscript></entry>
+ </row>
</tbody>
</tgroup>
</table>
- <para>Bit 7 is the most significant bit. The value of the a = alpha
-bits is undefined when reading from the driver, ignored when writing
-to the driver, except when alpha blending has been negotiated for a
-<link linkend="overlay">Video Overlay</link> or <link linkend="osd">
-Video Output Overlay</link> or when the alpha component has been configured
-for a <link linkend="capture">Video Capture</link> by means of <link
-linkend="v4l2-alpha-component"> <constant>V4L2_CID_ALPHA_COMPONENT
-</constant> </link> control.</para>
+ <para>Bit 7 is the most significant bit.</para>
+
+ <para>The usage and value of the alpha bits (a) in the ARGB and ABGR formats
+ (collectively referred to as alpha formats) depend on the device type and
+ hardware operation. <link linkend="capture">Capture</link> devices
+ (including capture queues of mem-to-mem devices) fill the alpha component in
+ memory. When the device outputs an alpha channel the alpha component will
+ have a meaningful value. Otherwise, when the device doesn't output an alpha
+ channel but can set the alpha bit to a user-configurable value, the <link
+ linkend="v4l2-alpha-component"><constant>V4L2_CID_ALPHA_COMPONENT</constant>
+ </link> control is used to specify that alpha value, and the alpha component
+ of all pixels will be set to the value specified by that control. Otherwise
+ a corresponding format without an alpha component (XRGB or XBGR) must be
+ used instead of an alpha format.</para>
+
+ <para><link linkend="output">Output</link> devices (including output queues
+ of mem-to-mem devices and <link linkend="osd">video output overlay</link>
+ devices) read the alpha component from memory. When the device processes the
+ alpha channel the alpha component must be filled with meaningful values by
+ applications. Otherwise a corresponding format without an alpha component
+ (XRGB or XBGR) must be used instead of an alpha format.</para>
+
+ <para>The XRGB and XBGR formats contain undefined bits (-). Applications,
+ devices and drivers must ignore those bits, for both <link
+ linkend="capture">capture</link> and <link linkend="output">output</link>
+ devices.</para>
<example>
<title><constant>V4L2_PIX_FMT_BGR24</constant> 4 × 4 pixel
@@ -512,6 +654,239 @@ image</title>
</formalpara>
</example>
+ <para>Formats defined in <xref linkend="rgb-formats-deprecated"/> are
+ deprecated and must not be used by new drivers. They are documented here for
+ reference. The meaning of their alpha bits (a) is ill-defined and
+ interpreted as in either the corresponding ARGB or XRGB format, depending on
+ the driver.</para>
+
+ <table pgwide="1" frame="none" id="rgb-formats-deprecated">
+ <title>Deprecated Packed RGB Image Formats</title>
+ <tgroup cols="37" align="center">
+ <colspec colname="id" align="left" />
+ <colspec colname="fourcc" />
+ <colspec colname="bit" />
+
+ <colspec colnum="4" colname="b07" align="center" />
+ <colspec colnum="5" colname="b06" align="center" />
+ <colspec colnum="6" colname="b05" align="center" />
+ <colspec colnum="7" colname="b04" align="center" />
+ <colspec colnum="8" colname="b03" align="center" />
+ <colspec colnum="9" colname="b02" align="center" />
+ <colspec colnum="10" colname="b01" align="center" />
+ <colspec colnum="11" colname="b00" align="center" />
+
+ <colspec colnum="13" colname="b17" align="center" />
+ <colspec colnum="14" colname="b16" align="center" />
+ <colspec colnum="15" colname="b15" align="center" />
+ <colspec colnum="16" colname="b14" align="center" />
+ <colspec colnum="17" colname="b13" align="center" />
+ <colspec colnum="18" colname="b12" align="center" />
+ <colspec colnum="19" colname="b11" align="center" />
+ <colspec colnum="20" colname="b10" align="center" />
+
+ <colspec colnum="22" colname="b27" align="center" />
+ <colspec colnum="23" colname="b26" align="center" />
+ <colspec colnum="24" colname="b25" align="center" />
+ <colspec colnum="25" colname="b24" align="center" />
+ <colspec colnum="26" colname="b23" align="center" />
+ <colspec colnum="27" colname="b22" align="center" />
+ <colspec colnum="28" colname="b21" align="center" />
+ <colspec colnum="29" colname="b20" align="center" />
+
+ <colspec colnum="31" colname="b37" align="center" />
+ <colspec colnum="32" colname="b36" align="center" />
+ <colspec colnum="33" colname="b35" align="center" />
+ <colspec colnum="34" colname="b34" align="center" />
+ <colspec colnum="35" colname="b33" align="center" />
+ <colspec colnum="36" colname="b32" align="center" />
+ <colspec colnum="37" colname="b31" align="center" />
+ <colspec colnum="38" colname="b30" align="center" />
+
+ <spanspec namest="b07" nameend="b00" spanname="b0" />
+ <spanspec namest="b17" nameend="b10" spanname="b1" />
+ <spanspec namest="b27" nameend="b20" spanname="b2" />
+ <spanspec namest="b37" nameend="b30" spanname="b3" />
+ <thead>
+ <row>
+ <entry>Identifier</entry>
+ <entry>Code</entry>
+ <entry> </entry>
+ <entry spanname="b0">Byte 0 in memory</entry>
+ <entry spanname="b1">Byte 1</entry>
+ <entry spanname="b2">Byte 2</entry>
+ <entry spanname="b3">Byte 3</entry>
+ </row>
+ <row>
+ <entry> </entry>
+ <entry> </entry>
+ <entry>Bit</entry>
+ <entry>7</entry>
+ <entry>6</entry>
+ <entry>5</entry>
+ <entry>4</entry>
+ <entry>3</entry>
+ <entry>2</entry>
+ <entry>1</entry>
+ <entry>0</entry>
+ <entry> </entry>
+ <entry>7</entry>
+ <entry>6</entry>
+ <entry>5</entry>
+ <entry>4</entry>
+ <entry>3</entry>
+ <entry>2</entry>
+ <entry>1</entry>
+ <entry>0</entry>
+ <entry> </entry>
+ <entry>7</entry>
+ <entry>6</entry>
+ <entry>5</entry>
+ <entry>4</entry>
+ <entry>3</entry>
+ <entry>2</entry>
+ <entry>1</entry>
+ <entry>0</entry>
+ <entry> </entry>
+ <entry>7</entry>
+ <entry>6</entry>
+ <entry>5</entry>
+ <entry>4</entry>
+ <entry>3</entry>
+ <entry>2</entry>
+ <entry>1</entry>
+ <entry>0</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row id="V4L2-PIX-FMT-RGB444">
+ <entry><constant>V4L2_PIX_FMT_RGB444</constant></entry>
+ <entry>'R444'</entry>
+ <entry></entry>
+ <entry>g<subscript>3</subscript></entry>
+ <entry>g<subscript>2</subscript></entry>
+ <entry>g<subscript>1</subscript></entry>
+ <entry>g<subscript>0</subscript></entry>
+ <entry>b<subscript>3</subscript></entry>
+ <entry>b<subscript>2</subscript></entry>
+ <entry>b<subscript>1</subscript></entry>
+ <entry>b<subscript>0</subscript></entry>
+ <entry></entry>
+ <entry>a<subscript>3</subscript></entry>
+ <entry>a<subscript>2</subscript></entry>
+ <entry>a<subscript>1</subscript></entry>
+ <entry>a<subscript>0</subscript></entry>
+ <entry>r<subscript>3</subscript></entry>
+ <entry>r<subscript>2</subscript></entry>
+ <entry>r<subscript>1</subscript></entry>
+ <entry>r<subscript>0</subscript></entry>
+ </row>
+ <row id="V4L2-PIX-FMT-RGB555">
+ <entry><constant>V4L2_PIX_FMT_RGB555</constant></entry>
+ <entry>'RGBO'</entry>
+ <entry></entry>
+ <entry>g<subscript>2</subscript></entry>
+ <entry>g<subscript>1</subscript></entry>
+ <entry>g<subscript>0</subscript></entry>
+ <entry>b<subscript>4</subscript></entry>
+ <entry>b<subscript>3</subscript></entry>
+ <entry>b<subscript>2</subscript></entry>
+ <entry>b<subscript>1</subscript></entry>
+ <entry>b<subscript>0</subscript></entry>
+ <entry></entry>
+ <entry>a</entry>
+ <entry>r<subscript>4</subscript></entry>
+ <entry>r<subscript>3</subscript></entry>
+ <entry>r<subscript>2</subscript></entry>
+ <entry>r<subscript>1</subscript></entry>
+ <entry>r<subscript>0</subscript></entry>
+ <entry>g<subscript>4</subscript></entry>
+ <entry>g<subscript>3</subscript></entry>
+ </row>
+ <row id="V4L2-PIX-FMT-BGR32">
+ <entry><constant>V4L2_PIX_FMT_BGR32</constant></entry>
+ <entry>'BGR4'</entry>
+ <entry></entry>
+ <entry>b<subscript>7</subscript></entry>
+ <entry>b<subscript>6</subscript></entry>
+ <entry>b<subscript>5</subscript></entry>
+ <entry>b<subscript>4</subscript></entry>
+ <entry>b<subscript>3</subscript></entry>
+ <entry>b<subscript>2</subscript></entry>
+ <entry>b<subscript>1</subscript></entry>
+ <entry>b<subscript>0</subscript></entry>
+ <entry></entry>
+ <entry>g<subscript>7</subscript></entry>
+ <entry>g<subscript>6</subscript></entry>
+ <entry>g<subscript>5</subscript></entry>
+ <entry>g<subscript>4</subscript></entry>
+ <entry>g<subscript>3</subscript></entry>
+ <entry>g<subscript>2</subscript></entry>
+ <entry>g<subscript>1</subscript></entry>
+ <entry>g<subscript>0</subscript></entry>
+ <entry></entry>
+ <entry>r<subscript>7</subscript></entry>
+ <entry>r<subscript>6</subscript></entry>
+ <entry>r<subscript>5</subscript></entry>
+ <entry>r<subscript>4</subscript></entry>
+ <entry>r<subscript>3</subscript></entry>
+ <entry>r<subscript>2</subscript></entry>
+ <entry>r<subscript>1</subscript></entry>
+ <entry>r<subscript>0</subscript></entry>
+ <entry></entry>
+ <entry>a<subscript>7</subscript></entry>
+ <entry>a<subscript>6</subscript></entry>
+ <entry>a<subscript>5</subscript></entry>
+ <entry>a<subscript>4</subscript></entry>
+ <entry>a<subscript>3</subscript></entry>
+ <entry>a<subscript>2</subscript></entry>
+ <entry>a<subscript>1</subscript></entry>
+ <entry>a<subscript>0</subscript></entry>
+ </row>
+ <row id="V4L2-PIX-FMT-RGB32">
+ <entry><constant>V4L2_PIX_FMT_RGB32</constant></entry>
+ <entry>'RGB4'</entry>
+ <entry></entry>
+ <entry>a<subscript>7</subscript></entry>
+ <entry>a<subscript>6</subscript></entry>
+ <entry>a<subscript>5</subscript></entry>
+ <entry>a<subscript>4</subscript></entry>
+ <entry>a<subscript>3</subscript></entry>
+ <entry>a<subscript>2</subscript></entry>
+ <entry>a<subscript>1</subscript></entry>
+ <entry>a<subscript>0</subscript></entry>
+ <entry></entry>
+ <entry>r<subscript>7</subscript></entry>
+ <entry>r<subscript>6</subscript></entry>
+ <entry>r<subscript>5</subscript></entry>
+ <entry>r<subscript>4</subscript></entry>
+ <entry>r<subscript>3</subscript></entry>
+ <entry>r<subscript>2</subscript></entry>
+ <entry>r<subscript>1</subscript></entry>
+ <entry>r<subscript>0</subscript></entry>
+ <entry></entry>
+ <entry>g<subscript>7</subscript></entry>
+ <entry>g<subscript>6</subscript></entry>
+ <entry>g<subscript>5</subscript></entry>
+ <entry>g<subscript>4</subscript></entry>
+ <entry>g<subscript>3</subscript></entry>
+ <entry>g<subscript>2</subscript></entry>
+ <entry>g<subscript>1</subscript></entry>
+ <entry>g<subscript>0</subscript></entry>
+ <entry></entry>
+ <entry>b<subscript>7</subscript></entry>
+ <entry>b<subscript>6</subscript></entry>
+ <entry>b<subscript>5</subscript></entry>
+ <entry>b<subscript>4</subscript></entry>
+ <entry>b<subscript>3</subscript></entry>
+ <entry>b<subscript>2</subscript></entry>
+ <entry>b<subscript>1</subscript></entry>
+ <entry>b<subscript>0</subscript></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
<para>A test utility to determine which RGB formats a driver
actually supports is available from the LinuxTV v4l-dvb repository.
See &v4l-dvb; for access instructions.</para>
diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index 168ff50..0125f4d 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -294,7 +294,11 @@ struct v4l2_pix_format {
/* RGB formats */
#define V4L2_PIX_FMT_RGB332 v4l2_fourcc('R', 'G', 'B', '1') /* 8 RGB-3-3-2 */
#define V4L2_PIX_FMT_RGB444 v4l2_fourcc('R', '4', '4', '4') /* 16 xxxxrrrr ggggbbbb */
+#define V4L2_PIX_FMT_ARGB444 v4l2_fourcc('A', 'R', '1', '2') /* 16 aaaarrrr ggggbbbb */
+#define V4L2_PIX_FMT_XRGB444 v4l2_fourcc('X', 'R', '1', '2') /* 16 xxxxrrrr ggggbbbb */
#define V4L2_PIX_FMT_RGB555 v4l2_fourcc('R', 'G', 'B', 'O') /* 16 RGB-5-5-5 */
+#define V4L2_PIX_FMT_ARGB555 v4l2_fourcc('A', 'R', '1', '5') /* 16 ARGB-1-5-5-5 */
+#define V4L2_PIX_FMT_XRGB555 v4l2_fourcc('X', 'R', '1', '5') /* 16 XRGB-1-5-5-5 */
#define V4L2_PIX_FMT_RGB565 v4l2_fourcc('R', 'G', 'B', 'P') /* 16 RGB-5-6-5 */
#define V4L2_PIX_FMT_RGB555X v4l2_fourcc('R', 'G', 'B', 'Q') /* 16 RGB-5-5-5 BE */
#define V4L2_PIX_FMT_RGB565X v4l2_fourcc('R', 'G', 'B', 'R') /* 16 RGB-5-6-5 BE */
@@ -302,7 +306,11 @@ struct v4l2_pix_format {
#define V4L2_PIX_FMT_BGR24 v4l2_fourcc('B', 'G', 'R', '3') /* 24 BGR-8-8-8 */
#define V4L2_PIX_FMT_RGB24 v4l2_fourcc('R', 'G', 'B', '3') /* 24 RGB-8-8-8 */
#define V4L2_PIX_FMT_BGR32 v4l2_fourcc('B', 'G', 'R', '4') /* 32 BGR-8-8-8-8 */
+#define V4L2_PIX_FMT_ABGR32 v4l2_fourcc('A', 'R', '2', '4') /* 32 BGRA-8-8-8-8 */
+#define V4L2_PIX_FMT_XBGR32 v4l2_fourcc('X', 'R', '2', '4') /* 32 BGRX-8-8-8-8 */
#define V4L2_PIX_FMT_RGB32 v4l2_fourcc('R', 'G', 'B', '4') /* 32 RGB-8-8-8-8 */
+#define V4L2_PIX_FMT_ARGB32 v4l2_fourcc('B', 'A', '2', '4') /* 32 ARGB-8-8-8-8 */
+#define V4L2_PIX_FMT_XRGB32 v4l2_fourcc('B', 'X', '2', '4') /* 32 XRGB-8-8-8-8 */
/* Grey formats */
#define V4L2_PIX_FMT_GREY v4l2_fourcc('G', 'R', 'E', 'Y') /* 8 Greyscale */
--
1.8.5.5
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH/RFC 2/2] DocBook: media: Document ALPHA_COMPONENT control usage on output devices
2014-05-26 22:17 [PATCH/RFC 0/2] Propert alpha channel support in pixel formats Laurent Pinchart
2014-05-26 22:17 ` [PATCH/RFC 1/2] v4l: Add ARGB and XRGB " Laurent Pinchart
@ 2014-05-26 22:17 ` Laurent Pinchart
2014-05-27 7:18 ` [PATCH/RFC 0/2] Propert alpha channel support in pixel formats Hans Verkuil
2 siblings, 0 replies; 5+ messages in thread
From: Laurent Pinchart @ 2014-05-26 22:17 UTC (permalink / raw)
To: linux-media; +Cc: Hans Verkuil
Extend the V4L2_CID_ALPHA_COMPONENT control for use on output devices,
to set the alpha component value when the output format doesn't have an
alpha channel.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
---
Documentation/DocBook/media/v4l/controls.xml | 17 ++++++++++-------
1 file changed, 10 insertions(+), 7 deletions(-)
diff --git a/Documentation/DocBook/media/v4l/controls.xml b/Documentation/DocBook/media/v4l/controls.xml
index 47198ee..4dfea27 100644
--- a/Documentation/DocBook/media/v4l/controls.xml
+++ b/Documentation/DocBook/media/v4l/controls.xml
@@ -398,14 +398,17 @@ to work.</entry>
<row id="v4l2-alpha-component">
<entry><constant>V4L2_CID_ALPHA_COMPONENT</constant></entry>
<entry>integer</entry>
- <entry> Sets the alpha color component on the capture device or on
- the capture buffer queue of a mem-to-mem device. When a mem-to-mem
- device produces frame format that includes an alpha component
+ <entry>Sets the alpha color component. When a capture device (or
+ capture queue of a mem-to-mem device) produces a frame format that
+ includes an alpha component
(e.g. <link linkend="rgb-formats">packed RGB image formats</link>)
- and the alpha value is not defined by the mem-to-mem input data
- this control lets you select the alpha component value of all
- pixels. It is applicable to any pixel format that contains an alpha
- component.
+ and the alpha value is not defined by the device or the mem-to-mem
+ input data this control lets you select the alpha component value of
+ all pixels. When an output device (or output queue of a mem-to-mem
+ device) consumes a frame format that doesn't include an alpha
+ component and the device supports alpha channel processing this
+ control lets you set the alpha component value of all pixels for
+ further processing in the device.
</entry>
</row>
<row>
--
1.8.5.5
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH/RFC 0/2] Propert alpha channel support in pixel formats
2014-05-26 22:17 [PATCH/RFC 0/2] Propert alpha channel support in pixel formats Laurent Pinchart
2014-05-26 22:17 ` [PATCH/RFC 1/2] v4l: Add ARGB and XRGB " Laurent Pinchart
2014-05-26 22:17 ` [PATCH/RFC 2/2] DocBook: media: Document ALPHA_COMPONENT control usage on output devices Laurent Pinchart
@ 2014-05-27 7:18 ` Hans Verkuil
2014-05-27 10:36 ` Laurent Pinchart
2 siblings, 1 reply; 5+ messages in thread
From: Hans Verkuil @ 2014-05-27 7:18 UTC (permalink / raw)
To: Laurent Pinchart, linux-media; +Cc: Hans Verkuil
On 05/27/2014 12:17 AM, Laurent Pinchart wrote:
> Hello,
>
> This RFC patch series attempts to clean up the current ARGB format mess.
>
> The core issue is that the existing ARGB formats are ill-defined. The V4L2
> specification doesn't clearly document how the alpha bits should behave.
> Drivers have thus used the same formats in different, incompatible ways, and
> applications now rely on the driver-specific behaviours. In a word, that's a
> mess.
>
> I've discussed the issue in the #v4l channel a couple of days ago and we came
> up to the conclusion that the best (or least painful) way to fix the problem
> is to define new clean XRGB and ARGB formats, and consider the existing
> formats as deprecated (meaning that no new driver should use them, they won't
> disappear in a couple of months, as that would break userspace).
>
> The first patch adds the new XRGB and ARGB formats and documents them.
Question: should we add all XRGB and ARGB formats even if drivers do not use
them? Or just those that are actually used?
> It
> purposely includes no core code to handle backward compatibility for existing
> drivers that may wish to move to the new formats. The reason is that I would
> first like to get feedback on the proposal before working on compat code, and
> I believe we should first implement the compat code in a couple of drivers and
> then see how the approach could be generalized, if possible at all.
>
> The second patch allows using the ALPHA_COMPONENT control on output devices to
> support an ARGB use case documented in the first patch. One possible
> shortcoming of reusing the existing control is that a mem-to-mem driver that
> exposes an output and a capture queue on a single video node through the same
> file handle wouldn't be able to set different alpha component values on the
> two queues. I'm not sure whether that use case is real though, it seems weird
> to me to set a fixed alpha value on one side to request a different fixed
> alpha value on the other side.
I prefer a CAP_ALPHA_COMPONENT control. It's easy to add a capture-specific
control now, it's much harder to change it in the future.
Regards,
Hans
>
> Laurent Pinchart (2):
> v4l: Add ARGB and XRGB pixel formats
> DocBook: media: Document ALPHA_COMPONENT control usage on output
> devices
>
> Documentation/DocBook/media/v4l/controls.xml | 17 +-
> .../DocBook/media/v4l/pixfmt-packed-rgb.xml | 415 ++++++++++++++++++++-
> include/uapi/linux/videodev2.h | 8 +
> 3 files changed, 413 insertions(+), 27 deletions(-)
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH/RFC 0/2] Propert alpha channel support in pixel formats
2014-05-27 7:18 ` [PATCH/RFC 0/2] Propert alpha channel support in pixel formats Hans Verkuil
@ 2014-05-27 10:36 ` Laurent Pinchart
0 siblings, 0 replies; 5+ messages in thread
From: Laurent Pinchart @ 2014-05-27 10:36 UTC (permalink / raw)
To: Hans Verkuil, linux-media; +Cc: Hans Verkuil
Hi Hans,
On Tuesday 27 May 2014 09:18:23 Hans Verkuil wrote:
> On 05/27/2014 12:17 AM, Laurent Pinchart wrote:
> > Hello,
> >
> > This RFC patch series attempts to clean up the current ARGB format mess.
> >
> > The core issue is that the existing ARGB formats are ill-defined. The V4L2
> > specification doesn't clearly document how the alpha bits should behave.
> > Drivers have thus used the same formats in different, incompatible ways,
> > and applications now rely on the driver-specific behaviours. In a word,
> > that's a mess.
> >
> > I've discussed the issue in the #v4l channel a couple of days ago and we
> > came up to the conclusion that the best (or least painful) way to fix the
> > problem is to define new clean XRGB and ARGB formats, and consider the
> > existing formats as deprecated (meaning that no new driver should use
> > them, they won't disappear in a couple of months, as that would break
> > userspace).
> >
> > The first patch adds the new XRGB and ARGB formats and documents them.
>
> Question: should we add all XRGB and ARGB formats even if drivers do not use
> them? Or just those that are actually used?
The VSP1 driver is going to use them all, so we need them all.
> > It purposely includes no core code to handle backward compatibility for
> > existing drivers that may wish to move to the new formats. The reason is
> > that I would first like to get feedback on the proposal before working on
> > compat code, and I believe we should first implement the compat code in a
> > couple of drivers and then see how the approach could be generalized, if
> > possible at all.
> >
> > The second patch allows using the ALPHA_COMPONENT control on output
> > devices to support an ARGB use case documented in the first patch. One
> > possible shortcoming of reusing the existing control is that a mem-to-mem
> > driver that exposes an output and a capture queue on a single video node
> > through the same file handle wouldn't be able to set different alpha
> > component values on the two queues. I'm not sure whether that use case is
> > real though, it seems weird to me to set a fixed alpha value on one side
> > to request a different fixed alpha value on the other side.
>
> I prefer a CAP_ALPHA_COMPONENT control. It's easy to add a capture-specific
> control now, it's much harder to change it in the future.
What bothers me with this approach is the duplication of otherwise identical
controls. As we'll likely need per-pad controls at some point in the future,
wouldn't it better to implement a similar way to distinguish between capture
and output controls ?
--
Regards,
Laurent Pinchart
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2014-05-27 10:36 UTC | newest]
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2014-05-26 22:17 [PATCH/RFC 0/2] Propert alpha channel support in pixel formats Laurent Pinchart
2014-05-26 22:17 ` [PATCH/RFC 1/2] v4l: Add ARGB and XRGB " Laurent Pinchart
2014-05-26 22:17 ` [PATCH/RFC 2/2] DocBook: media: Document ALPHA_COMPONENT control usage on output devices Laurent Pinchart
2014-05-27 7:18 ` [PATCH/RFC 0/2] Propert alpha channel support in pixel formats Hans Verkuil
2014-05-27 10:36 ` Laurent Pinchart
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