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authorHans Verkuil <hverkuil@xs4all.nl>2010-03-27 17:10:37 (GMT)
committerMauro Carvalho Chehab <mchehab@redhat.com>2010-05-19 15:58:09 (GMT)
commit37089368c1b1bea3c71217163e6d5d3b01ef1f19 (patch)
tree59bc5047fae96e5d55aff71848cddfcedf60f741 /Documentation/DocBook
parent092501936fc128992456a086193746cf34642815 (diff)
V4L/DVB: v4l spec: document what odd and even fields are
Document that odd == top and even == bottom. I can never remember this, so it is probably worth documenting. Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Diffstat (limited to 'Documentation/DocBook')
-rw-r--r--Documentation/DocBook/v4l/io.xml8
1 files changed, 4 insertions, 4 deletions
diff --git a/Documentation/DocBook/v4l/io.xml b/Documentation/DocBook/v4l/io.xml
index e870330..bb685ed 100644
--- a/Documentation/DocBook/v4l/io.xml
+++ b/Documentation/DocBook/v4l/io.xml
@@ -918,8 +918,8 @@ order</emphasis>.</para>
<para>When the driver provides or accepts images field by field
rather than interleaved, it is also important applications understand
-how the fields combine to frames. We distinguish between top and
-bottom fields, the <emphasis>spatial order</emphasis>: The first line
+how the fields combine to frames. We distinguish between top (aka odd) and
+bottom (aka even) fields, the <emphasis>spatial order</emphasis>: The first line
of the top field is the first line of an interlaced frame, the first
line of the bottom field is the second line of that frame.</para>
@@ -972,12 +972,12 @@ between <constant>V4L2_FIELD_TOP</constant> and
<row>
<entry><constant>V4L2_FIELD_TOP</constant></entry>
<entry>2</entry>
- <entry>Images consist of the top field only.</entry>
+ <entry>Images consist of the top (aka odd) field only.</entry>
</row>
<row>
<entry><constant>V4L2_FIELD_BOTTOM</constant></entry>
<entry>3</entry>
- <entry>Images consist of the bottom field only.
+ <entry>Images consist of the bottom (aka even) field only.
Applications may wish to prevent a device from capturing interlaced
images because they will have "comb" or "feathering" artefacts around
moving objects.</entry>

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