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Diffstat (limited to 'Documentation/media/uapi/v4l/pixfmt-002.rst')
| -rw-r--r-- | Documentation/media/uapi/v4l/pixfmt-002.rst | 298 |
1 files changed, 116 insertions, 182 deletions
diff --git a/Documentation/media/uapi/v4l/pixfmt-002.rst b/Documentation/media/uapi/v4l/pixfmt-002.rst index fd73f4697878..0d9e697f5d4e 100644 --- a/Documentation/media/uapi/v4l/pixfmt-002.rst +++ b/Documentation/media/uapi/v4l/pixfmt-002.rst @@ -15,185 +15,119 @@ Single-planar format structure :stub-columns: 0 :widths: 1 1 2 - - - .. row 1 - - - __u32 - - - ``width`` - - - Image width in pixels. - - - .. row 2 - - - __u32 - - - ``height`` - - - Image height in pixels. If ``field`` is one of ``V4L2_FIELD_TOP``, - ``V4L2_FIELD_BOTTOM`` or ``V4L2_FIELD_ALTERNATE`` then height - refers to the number of lines in the field, otherwise it refers to - the number of lines in the frame (which is twice the field height - for interlaced formats). - - - .. row 3 - - - :cspan:`2` Applications set these fields to request an image - size, drivers return the closest possible values. In case of - planar formats the ``width`` and ``height`` applies to the largest - plane. To avoid ambiguities drivers must return values rounded up - to a multiple of the scale factor of any smaller planes. For - example when the image format is YUV 4:2:0, ``width`` and - ``height`` must be multiples of two. - - - .. row 4 - - - __u32 - - - ``pixelformat`` - - - The pixel format or type of compression, set by the application. - This is a little endian - :ref:`four character code <v4l2-fourcc>`. V4L2 defines standard - RGB formats in :ref:`rgb-formats`, YUV formats in - :ref:`yuv-formats`, and reserved codes in - :ref:`reserved-formats` - - - .. row 5 - - - enum :c:type::`v4l2_field` - - - ``field`` - - - Video images are typically interlaced. Applications can request to - capture or output only the top or bottom field, or both fields - interlaced or sequentially stored in one buffer or alternating in - separate buffers. Drivers return the actual field order selected. - For more details on fields see :ref:`field-order`. - - - .. row 6 - - - __u32 - - - ``bytesperline`` - - - Distance in bytes between the leftmost pixels in two adjacent - lines. - - - .. row 7 - - - :cspan:`2` - - Both applications and drivers can set this field to request - padding bytes at the end of each line. Drivers however may ignore - the value requested by the application, returning ``width`` times - bytes per pixel or a larger value required by the hardware. That - implies applications can just set this field to zero to get a - reasonable default. - - Video hardware may access padding bytes, therefore they must - reside in accessible memory. Consider cases where padding bytes - after the last line of an image cross a system page boundary. - Input devices may write padding bytes, the value is undefined. - Output devices ignore the contents of padding bytes. - - When the image format is planar the ``bytesperline`` value applies - to the first plane and is divided by the same factor as the - ``width`` field for the other planes. For example the Cb and Cr - planes of a YUV 4:2:0 image have half as many padding bytes - following each line as the Y plane. To avoid ambiguities drivers - must return a ``bytesperline`` value rounded up to a multiple of - the scale factor. - - For compressed formats the ``bytesperline`` value makes no sense. - Applications and drivers must set this to 0 in that case. - - - .. row 8 - - - __u32 - - - ``sizeimage`` - - - Size in bytes of the buffer to hold a complete image, set by the - driver. Usually this is ``bytesperline`` times ``height``. When - the image consists of variable length compressed data this is the - maximum number of bytes required to hold an image. - - - .. row 9 - - - enum :c:type:`v4l2_colorspace` - - - ``colorspace`` - - - This information supplements the ``pixelformat`` and must be set - by the driver for capture streams and by the application for - output streams, see :ref:`colorspaces`. - - - .. row 10 - - - __u32 - - - ``priv`` - - - This field indicates whether the remaining fields of the - struct :c:type:`v4l2_pix_format`, also called the - extended fields, are valid. When set to - ``V4L2_PIX_FMT_PRIV_MAGIC``, it indicates that the extended fields - have been correctly initialized. When set to any other value it - indicates that the extended fields contain undefined values. - - Applications that wish to use the pixel format extended fields - must first ensure that the feature is supported by querying the - device for the :ref:`V4L2_CAP_EXT_PIX_FORMAT <querycap>` - capability. If the capability isn't set the pixel format extended - fields are not supported and using the extended fields will lead - to undefined results. - - To use the extended fields, applications must set the ``priv`` - field to ``V4L2_PIX_FMT_PRIV_MAGIC``, initialize all the extended - fields and zero the unused bytes of the - struct :c:type:`v4l2_format` ``raw_data`` field. - - When the ``priv`` field isn't set to ``V4L2_PIX_FMT_PRIV_MAGIC`` - drivers must act as if all the extended fields were set to zero. - On return drivers must set the ``priv`` field to - ``V4L2_PIX_FMT_PRIV_MAGIC`` and all the extended fields to - applicable values. - - - .. row 11 - - - __u32 - - - ``flags`` - - - Flags set by the application or driver, see :ref:`format-flags`. - - - .. row 12 - - - enum :c:type:`v4l2_ycbcr_encoding` - - - ``ycbcr_enc`` - - - This information supplements the ``colorspace`` and must be set by - the driver for capture streams and by the application for output - streams, see :ref:`colorspaces`. - - - .. row 13 - - - enum :c:type:`v4l2_quantization` - - - ``quantization`` - - - This information supplements the ``colorspace`` and must be set by - the driver for capture streams and by the application for output - streams, see :ref:`colorspaces`. - - - .. row 14 - - - enum :c:type:`v4l2_xfer_func` - - - ``xfer_func`` - - - This information supplements the ``colorspace`` and must be set by - the driver for capture streams and by the application for output - streams, see :ref:`colorspaces`. + * - __u32 + - ``width`` + - Image width in pixels. + * - __u32 + - ``height`` + - Image height in pixels. If ``field`` is one of ``V4L2_FIELD_TOP``, + ``V4L2_FIELD_BOTTOM`` or ``V4L2_FIELD_ALTERNATE`` then height + refers to the number of lines in the field, otherwise it refers to + the number of lines in the frame (which is twice the field height + for interlaced formats). + * - :cspan:`2` Applications set these fields to request an image + size, drivers return the closest possible values. In case of + planar formats the ``width`` and ``height`` applies to the largest + plane. To avoid ambiguities drivers must return values rounded up + to a multiple of the scale factor of any smaller planes. For + example when the image format is YUV 4:2:0, ``width`` and + ``height`` must be multiples of two. + * - __u32 + - ``pixelformat`` + - The pixel format or type of compression, set by the application. + This is a little endian + :ref:`four character code <v4l2-fourcc>`. V4L2 defines standard + RGB formats in :ref:`rgb-formats`, YUV formats in + :ref:`yuv-formats`, and reserved codes in + :ref:`reserved-formats` + * - enum :c:type::`v4l2_field` + - ``field`` + - Video images are typically interlaced. Applications can request to + capture or output only the top or bottom field, or both fields + interlaced or sequentially stored in one buffer or alternating in + separate buffers. Drivers return the actual field order selected. + For more details on fields see :ref:`field-order`. + * - __u32 + - ``bytesperline`` + - Distance in bytes between the leftmost pixels in two adjacent + lines. + * - :cspan:`2` + + Both applications and drivers can set this field to request + padding bytes at the end of each line. Drivers however may ignore + the value requested by the application, returning ``width`` times + bytes per pixel or a larger value required by the hardware. That + implies applications can just set this field to zero to get a + reasonable default. + + Video hardware may access padding bytes, therefore they must + reside in accessible memory. Consider cases where padding bytes + after the last line of an image cross a system page boundary. + Input devices may write padding bytes, the value is undefined. + Output devices ignore the contents of padding bytes. + + When the image format is planar the ``bytesperline`` value applies + to the first plane and is divided by the same factor as the + ``width`` field for the other planes. For example the Cb and Cr + planes of a YUV 4:2:0 image have half as many padding bytes + following each line as the Y plane. To avoid ambiguities drivers + must return a ``bytesperline`` value rounded up to a multiple of + the scale factor. + + For compressed formats the ``bytesperline`` value makes no sense. + Applications and drivers must set this to 0 in that case. + * - __u32 + - ``sizeimage`` + - Size in bytes of the buffer to hold a complete image, set by the + driver. Usually this is ``bytesperline`` times ``height``. When + the image consists of variable length compressed data this is the + maximum number of bytes required to hold an image. + * - enum :c:type:`v4l2_colorspace` + - ``colorspace`` + - This information supplements the ``pixelformat`` and must be set + by the driver for capture streams and by the application for + output streams, see :ref:`colorspaces`. + * - __u32 + - ``priv`` + - This field indicates whether the remaining fields of the + struct :c:type:`v4l2_pix_format`, also called the + extended fields, are valid. When set to + ``V4L2_PIX_FMT_PRIV_MAGIC``, it indicates that the extended fields + have been correctly initialized. When set to any other value it + indicates that the extended fields contain undefined values. + + Applications that wish to use the pixel format extended fields + must first ensure that the feature is supported by querying the + device for the :ref:`V4L2_CAP_EXT_PIX_FORMAT <querycap>` + capability. If the capability isn't set the pixel format extended + fields are not supported and using the extended fields will lead + to undefined results. + + To use the extended fields, applications must set the ``priv`` + field to ``V4L2_PIX_FMT_PRIV_MAGIC``, initialize all the extended + fields and zero the unused bytes of the + struct :c:type:`v4l2_format` ``raw_data`` field. + + When the ``priv`` field isn't set to ``V4L2_PIX_FMT_PRIV_MAGIC`` + drivers must act as if all the extended fields were set to zero. + On return drivers must set the ``priv`` field to + ``V4L2_PIX_FMT_PRIV_MAGIC`` and all the extended fields to + applicable values. + * - __u32 + - ``flags`` + - Flags set by the application or driver, see :ref:`format-flags`. + * - enum :c:type:`v4l2_ycbcr_encoding` + - ``ycbcr_enc`` + - This information supplements the ``colorspace`` and must be set by + the driver for capture streams and by the application for output + streams, see :ref:`colorspaces`. + * - enum :c:type:`v4l2_quantization` + - ``quantization`` + - This information supplements the ``colorspace`` and must be set by + the driver for capture streams and by the application for output + streams, see :ref:`colorspaces`. + * - enum :c:type:`v4l2_xfer_func` + - ``xfer_func`` + - This information supplements the ``colorspace`` and must be set by + the driver for capture streams and by the application for output + streams, see :ref:`colorspaces`. |