- __u32
- - ``start``\ [2]
+ - ``start``\ [2]_
- This is the scanning system line number associated with the first
line of the VBI image, of the first and the second field
- __u32
- - ``count``\ [2]
+ - ``count``\ [2]_
- The number of lines in the first and second field image,
respectively.
- __u32
- - ``reserved``\ [2]
+ - ``reserved``\ [2]_
- This array is reserved for future extensions. Drivers and
applications must set it to zero.
:alt: vbi_hsync.pdf / vbi_hsync.gif
:align: center
- Line synchronization
-
- Line synchronization diagram
-
-
+ **Figure 4.1. Line synchronization**
.. _vbi-525:
:alt: vbi_525.pdf / vbi_525.gif
:align: center
- ITU-R 525 line numbering (M/NTSC and M/PAL)
-
- NTSC field synchronization diagram
-
+ **Figure 4.2. ITU-R 525 line numbering (M/NTSC and M/PAL)**
:alt: vbi_625.pdf / vbi_625.gif
:align: center
- ITU-R 625 line numbering
-
- PAL/SECAM field synchronization diagram
+ **Figure 4.3. ITU-R 625 line numbering**
.. code-block:: c
- (count[0] + count[1]) *
- samples_per_line * sample size in bytes
+ (count[0] + count[1]) * samples_per_line * sample size in bytes
The sample size is most likely always one byte, applications must check
the ``sample_format`` field though, to function properly with other
The latter bears the possibility of synchronizing video and VBI data by
using buffer timestamps.
-Remember the :ref:`VIDIOC_STREAMON` ioctl and the
-first read(), write() and select() call can be resource allocation
+Remember the :ref:`VIDIOC_STREAMON <VIDIOC_STREAMON>` ioctl and the
+first :ref:`read() <func-read>`, :ref:`write() <func-write>` and
+:ref:`select() <func-select>` call can be resource allocation
points returning an ``EBUSY`` error code if the required hardware resources
are temporarily unavailable, for example the device is already in use by
another process.