diff options
Diffstat (limited to 'Documentation/DocBook/media/v4l/selection-api.xml')
-rw-r--r-- | Documentation/DocBook/media/v4l/selection-api.xml | 22 |
1 files changed, 11 insertions, 11 deletions
diff --git a/Documentation/DocBook/media/v4l/selection-api.xml b/Documentation/DocBook/media/v4l/selection-api.xml index e7ed5077834d..4c238ce068b0 100644 --- a/Documentation/DocBook/media/v4l/selection-api.xml +++ b/Documentation/DocBook/media/v4l/selection-api.xml | |||
@@ -40,6 +40,7 @@ cropping and composing rectangles have the same size.</para> | |||
40 | <section> | 40 | <section> |
41 | <title>Selection targets</title> | 41 | <title>Selection targets</title> |
42 | 42 | ||
43 | <para> | ||
43 | <figure id="sel-targets-capture"> | 44 | <figure id="sel-targets-capture"> |
44 | <title>Cropping and composing targets</title> | 45 | <title>Cropping and composing targets</title> |
45 | <mediaobject> | 46 | <mediaobject> |
@@ -52,12 +53,12 @@ cropping and composing rectangles have the same size.</para> | |||
52 | </textobject> | 53 | </textobject> |
53 | </mediaobject> | 54 | </mediaobject> |
54 | </figure> | 55 | </figure> |
56 | </para> | ||
55 | 57 | ||
58 | <para>See <xref linkend="v4l2-selection-targets" /> for more | ||
59 | information.</para> | ||
56 | </section> | 60 | </section> |
57 | 61 | ||
58 | See <xref linkend="v4l2-selection-targets" /> for more | ||
59 | information. | ||
60 | |||
61 | <section> | 62 | <section> |
62 | 63 | ||
63 | <title>Configuration</title> | 64 | <title>Configuration</title> |
@@ -216,18 +217,17 @@ composing and cropping operations by setting the appropriate targets. The V4L2 | |||
216 | API lacks any support for composing to and cropping from an image inside a | 217 | API lacks any support for composing to and cropping from an image inside a |
217 | memory buffer. The application could configure a capture device to fill only a | 218 | memory buffer. The application could configure a capture device to fill only a |
218 | part of an image by abusing V4L2 API. Cropping a smaller image from a larger | 219 | part of an image by abusing V4L2 API. Cropping a smaller image from a larger |
219 | one is achieved by setting the field <structfield> | 220 | one is achieved by setting the field |
220 | &v4l2-pix-format;::bytesperline </structfield>. Introducing an image offsets | 221 | &v4l2-pix-format;<structfield>::bytesperline</structfield>. Introducing an image offsets |
221 | could be done by modifying field <structfield> &v4l2-buffer;::m:userptr | 222 | could be done by modifying field &v4l2-buffer;<structfield>::m_userptr</structfield> |
222 | </structfield> before calling <constant> VIDIOC_QBUF </constant>. Those | 223 | before calling <constant> VIDIOC_QBUF </constant>. Those |
223 | operations should be avoided because they are not portable (endianness), and do | 224 | operations should be avoided because they are not portable (endianness), and do |
224 | not work for macroblock and Bayer formats and mmap buffers. The selection API | 225 | not work for macroblock and Bayer formats and mmap buffers. The selection API |
225 | deals with configuration of buffer cropping/composing in a clear, intuitive and | 226 | deals with configuration of buffer cropping/composing in a clear, intuitive and |
226 | portable way. Next, with the selection API the concepts of the padded target | 227 | portable way. Next, with the selection API the concepts of the padded target |
227 | and constraints flags are introduced. Finally, <structname> &v4l2-crop; | 228 | and constraints flags are introduced. Finally, &v4l2-crop; and &v4l2-cropcap; |
228 | </structname> and <structname> &v4l2-cropcap; </structname> have no reserved | 229 | have no reserved fields. Therefore there is no way to extend their functionality. |
229 | fields. Therefore there is no way to extend their functionality. The new | 230 | The new &v4l2-selection; provides a lot of place for future |
230 | <structname> &v4l2-selection; </structname> provides a lot of place for future | ||
231 | extensions. Driver developers are encouraged to implement only selection API. | 231 | extensions. Driver developers are encouraged to implement only selection API. |
232 | The former cropping API would be simulated using the new one. </para> | 232 | The former cropping API would be simulated using the new one. </para> |
233 | 233 | ||