projects / deliverable / linux.git / blame
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|---|---|---|
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1 | .. -*- coding: utf-8; mode: rst -*- |
| 2 | ||
| af4a4d0d | 3 | .. _VIDIOC_G_STD: |
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4 | |
| 5 | ******************************** | |
| 6 | ioctl VIDIOC_G_STD, VIDIOC_S_STD | |
| 7 | ******************************** | |
| 8 | ||
| 15e7d615 | 9 | Name |
| 586027ce | 10 | ==== |
| 5377d91f | 11 | |
| 586027ce | 12 | VIDIOC_G_STD - VIDIOC_S_STD - Query or select the video standard of the current input |
| 5377d91f | 13 | |
| 15e7d615 MCC |
14 | |
| 15 | Synopsis | |
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16 | ======== |
| 17 | ||
| b7e67f6c | 18 | .. cpp:function:: int ioctl( int fd, int request, v4l2_std_id *argp ) |
| 5377d91f | 19 | |
| b7e67f6c | 20 | .. cpp:function:: int ioctl( int fd, int request, const v4l2_std_id *argp ) |
| 5377d91f | 21 | |
| 586027ce | 22 | |
| 15e7d615 | 23 | Arguments |
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24 | ========= |
| 25 | ||
| 26 | ``fd`` | |
| 27 | File descriptor returned by :ref:`open() <func-open>`. | |
| 28 | ||
| 29 | ``request`` | |
| 30 | VIDIOC_G_STD, VIDIOC_S_STD | |
| 31 | ||
| 32 | ``argp`` | |
| 33 | ||
| 34 | ||
| 15e7d615 | 35 | Description |
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36 | =========== |
| 37 | ||
| 38 | To query and select the current video standard applications use the | |
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39 | :ref:`VIDIOC_G_STD <VIDIOC_G_STD>` and :ref:`VIDIOC_S_STD <VIDIOC_G_STD>` ioctls which take a pointer to a |
| 40 | :ref:`v4l2_std_id <v4l2-std-id>` type as argument. :ref:`VIDIOC_G_STD <VIDIOC_G_STD>` | |
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41 | can return a single flag or a set of flags as in struct |
| 42 | :ref:`v4l2_standard <v4l2-standard>` field ``id``. The flags must be | |
| 43 | unambiguous such that they appear in only one enumerated | |
| acf309a2 | 44 | :ref:`struct v4l2_standard <v4l2-standard>` structure. |
| 5377d91f | 45 | |
| 2212ff25 | 46 | :ref:`VIDIOC_S_STD <VIDIOC_G_STD>` accepts one or more flags, being a write-only ioctl it |
| 4e03cb76 | 47 | does not return the actual new standard as :ref:`VIDIOC_G_STD <VIDIOC_G_STD>` does. When |
| 5377d91f | 48 | no flags are given or the current input does not support the requested |
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49 | standard the driver returns an ``EINVAL`` error code. When the standard set |
| 50 | is ambiguous drivers may return ``EINVAL`` or choose any of the requested | |
| 5377d91f | 51 | standards. If the current input or output does not support standard |
| 7347081e | 52 | video timings (e.g. if :ref:`VIDIOC_ENUMINPUT` |
| cdb4af0f | 53 | does not set the ``V4L2_IN_CAP_STD`` flag), then ``ENODATA`` error code is |
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54 | returned. |
| 55 | ||
| 56 | ||
| 15e7d615 | 57 | Return Value |
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58 | ============ |
| 59 | ||
| 60 | On success 0 is returned, on error -1 and the ``errno`` variable is set | |
| 61 | appropriately. The generic error codes are described at the | |
| 62 | :ref:`Generic Error Codes <gen-errors>` chapter. | |
| 63 | ||
| 64 | EINVAL | |
| 2212ff25 | 65 | The :ref:`VIDIOC_S_STD <VIDIOC_G_STD>` parameter was unsuitable. |
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66 | |
| 67 | ENODATA | |
| 68 | Standard video timings are not supported for this input or output. |