diff options
Diffstat (limited to 'Documentation/DocBook/media/v4l/selection-api.xml')
-rw-r--r-- | Documentation/DocBook/media/v4l/selection-api.xml | 30 |
1 files changed, 12 insertions, 18 deletions
diff --git a/Documentation/DocBook/media/v4l/selection-api.xml b/Documentation/DocBook/media/v4l/selection-api.xml index 46cb47ab8e3b..2f0bdb4d5551 100644 --- a/Documentation/DocBook/media/v4l/selection-api.xml +++ b/Documentation/DocBook/media/v4l/selection-api.xml | |||
@@ -84,9 +84,7 @@ configure the cropping targets before to the composing targets.</para> | |||
84 | areas that can be sampled is given by the <constant> V4L2_SEL_TGT_CROP_BOUNDS | 84 | areas that can be sampled is given by the <constant> V4L2_SEL_TGT_CROP_BOUNDS |
85 | </constant> target. It is recommended for the driver developers to put the | 85 | </constant> target. It is recommended for the driver developers to put the |
86 | top/left corner at position <constant> (0,0) </constant>. The rectangle's | 86 | top/left corner at position <constant> (0,0) </constant>. The rectangle's |
87 | coordinates are expressed in driver dependant units, although the coordinate | 87 | coordinates are expressed in pixels.</para> |
88 | system guarantees that if sizes of the active cropping and the active composing | ||
89 | rectangles are equal then no scaling is performed. </para> | ||
90 | 88 | ||
91 | <para>The top left corner, width and height of the source rectangle, that is | 89 | <para>The top left corner, width and height of the source rectangle, that is |
92 | the area actually sampled, is given by the <constant> V4L2_SEL_TGT_CROP_ACTIVE | 90 | the area actually sampled, is given by the <constant> V4L2_SEL_TGT_CROP_ACTIVE |
@@ -103,10 +101,10 @@ not later.</para> | |||
103 | 101 | ||
104 | <para>The composing targets refer to a memory buffer. The limits of composing | 102 | <para>The composing targets refer to a memory buffer. The limits of composing |
105 | coordinates are obtained using <constant> V4L2_SEL_TGT_COMPOSE_BOUNDS | 103 | coordinates are obtained using <constant> V4L2_SEL_TGT_COMPOSE_BOUNDS |
106 | </constant>. All coordinates are expressed in natural unit for given formats. | 104 | </constant>. All coordinates are expressed in pixels. The rectangle's top/left |
107 | Pixels are highly recommended. The rectangle's top/left corner must be located | 105 | corner must be located at position <constant> (0,0) </constant>. The width and |
108 | at position <constant> (0,0) </constant>. The width and height are equal to the | 106 | height are equal to the image size set by <constant> VIDIOC_S_FMT </constant>. |
109 | image size set by <constant> VIDIOC_S_FMT </constant>.</para> | 107 | </para> |
110 | 108 | ||
111 | <para>The part of a buffer into which the image is inserted by the hardware is | 109 | <para>The part of a buffer into which the image is inserted by the hardware is |
112 | controlled by the <constant> V4L2_SEL_TGT_COMPOSE_ACTIVE </constant> target. | 110 | controlled by the <constant> V4L2_SEL_TGT_COMPOSE_ACTIVE </constant> target. |
@@ -145,10 +143,9 @@ the cropping targets.</para> | |||
145 | <para>The cropping targets refer to the memory buffer that contains an image to | 143 | <para>The cropping targets refer to the memory buffer that contains an image to |
146 | be inserted into a video signal or graphical screen. The limits of cropping | 144 | be inserted into a video signal or graphical screen. The limits of cropping |
147 | coordinates are obtained using <constant> V4L2_SEL_TGT_CROP_BOUNDS </constant>. | 145 | coordinates are obtained using <constant> V4L2_SEL_TGT_CROP_BOUNDS </constant>. |
148 | All coordinates are expressed in natural units for a given format. Pixels are | 146 | All coordinates are expressed in pixels. The top/left corner is always point |
149 | highly recommended. The top/left corner is always point <constant> (0,0) | 147 | <constant> (0,0) </constant>. The width and height is equal to the image size |
150 | </constant>. The width and height is equal to the image size specified using | 148 | specified using <constant> VIDIOC_S_FMT </constant> ioctl.</para> |
151 | <constant> VIDIOC_S_FMT </constant> ioctl.</para> | ||
152 | 149 | ||
153 | <para>The top left corner, width and height of the source rectangle, that is | 150 | <para>The top left corner, width and height of the source rectangle, that is |
154 | the area from which image date are processed by the hardware, is given by the | 151 | the area from which image date are processed by the hardware, is given by the |
@@ -163,13 +160,10 @@ limitations.</para> | |||
163 | bounding rectangle.</para> | 160 | bounding rectangle.</para> |
164 | 161 | ||
165 | <para>The part of a video signal or graphics display where the image is | 162 | <para>The part of a video signal or graphics display where the image is |
166 | inserted by the hardware is controlled by <constant> V4L2_SEL_TGT_COMPOSE_ACTIVE | 163 | inserted by the hardware is controlled by <constant> |
167 | </constant> target. The rectangle's coordinates are expressed in driver | 164 | V4L2_SEL_TGT_COMPOSE_ACTIVE </constant> target. The rectangle's coordinates |
168 | dependant units. The only exception are digital outputs where the units are | 165 | are expressed in pixels. The composing rectangle must lie completely inside the |
169 | pixels. For other types of devices, the coordinate system guarantees that if | 166 | bounds rectangle. The driver must adjust the area to fit to the bounding |
170 | sizes of the active cropping and the active composing rectangles are equal then | ||
171 | no scaling is performed. The composing rectangle must lie completely inside | ||
172 | the bounds rectangle. The driver must adjust the area to fit to the bounding | ||
173 | limits. Moreover, the driver can perform other adjustments according to | 167 | limits. Moreover, the driver can perform other adjustments according to |
174 | hardware limitations. </para> | 168 | hardware limitations. </para> |
175 | 169 | ||