========
-:title: ITU-T Recommendation T.81 "Information Technology --- Digital Compression and Coding of Continous-Tone Still Images --- Requirements and Guidelines"
+:title: ITU-T Recommendation T.81 "Information Technology --- Digital Compression and Coding of Continuous-Tone Still Images --- Requirements and Guidelines"
:author: International Telecommunication Union (http://www.itu.int)
The :ref:`video standard <standard>` ioctls provide information vital
to program a sliced VBI device, therefore must be supported.
-.. _sliced-vbi-format-negotitation:
+.. _sliced-vbi-format-negotiation:
Sliced VBI Format Negotiation
=============================
If a device can produce an MPEG output stream, it may be capable of
providing
-:ref:`negotiated sliced VBI services <sliced-vbi-format-negotitation>`
+:ref:`negotiated sliced VBI services <sliced-vbi-format-negotiation>`
as data embedded in the MPEG stream. Users or applications control this
sliced VBI data insertion with the
:ref:`V4L2_CID_MPEG_STREAM_VBI_FMT <v4l2-mpeg-stream-vbi-fmt>`
broadcasts speech. If the transmitter doesn't make this distinction,
then it will be set.
-``V4L2_CID_TUNE_DEEMPHASIS``
- (enum)
-
-enum v4l2_deemphasis -
+``V4L2_CID_TUNE_DEEMPHASIS (enum)``
Configures the de-emphasis value for reception. A de-emphasis filter
is applied to the broadcast to accentuate the high audio
frequencies. Depending on the region, a time constant of either 50
- or 75 useconds is used. The enum v4l2_deemphasis defines possible
- values for de-emphasis. Here they are:
-
-
+ or 75 microseconds is used. The enum v4l2_deemphasis defines possible
+ values for de-emphasis. They are:
.. flat-table::
:header-rows: 0
``V4L2_CID_AUDIO_LIMITER_RELEASE_TIME (integer)``
Sets the audio deviation limiter feature release time. Unit is in
- useconds. Step and range are driver-specific.
+ microseconds. Step and range are driver-specific.
``V4L2_CID_AUDIO_LIMITER_DEVIATION (integer)``
Configures audio frequency deviation level in Hz. The range and step
range and step are driver-specific.
``V4L2_CID_AUDIO_COMPRESSION_THRESHOLD (integer)``
- Sets the threshold level for audio compression freature. It is a dB
+ Sets the threshold level for audio compression feature. It is a dB
value. The range and step are driver-specific.
``V4L2_CID_AUDIO_COMPRESSION_ATTACK_TIME (integer)``
- Sets the attack time for audio compression feature. It is a useconds
+ Sets the attack time for audio compression feature. It is a microseconds
value. The range and step are driver-specific.
``V4L2_CID_AUDIO_COMPRESSION_RELEASE_TIME (integer)``
Sets the release time for audio compression feature. It is a
- useconds value. The range and step are driver-specific.
+ microseconds value. The range and step are driver-specific.
``V4L2_CID_PILOT_TONE_ENABLED (boolean)``
Enables or disables the pilot tone generation feature.
Configures pilot tone frequency value. Unit is in Hz. The range and
step are driver-specific.
-``V4L2_CID_TUNE_PREEMPHASIS``
- (enum)
-
-enum v4l2_preemphasis -
+``V4L2_CID_TUNE_PREEMPHASIS (enum)``
Configures the pre-emphasis value for broadcasting. A pre-emphasis
filter is applied to the broadcast to accentuate the high audio
frequencies. Depending on the region, a time constant of either 50
- or 75 useconds is used. The enum v4l2_preemphasis defines possible
- values for pre-emphasis. Here they are:
-
-
+ or 75 microseconds is used. The enum v4l2_preemphasis defines possible
+ values for pre-emphasis. They are:
.. flat-table::
:header-rows: 0
* - ``V4L2_PREEMPHASIS_75_uS``
- A pre-emphasis of 75 uS is used.
-
-
``V4L2_CID_TUNE_POWER_LEVEL (integer)``
Sets the output power level for signal transmission. Unit is in
dBuV. Range and step are driver-specific.
.. _v4l2-pix-fmt-sgrbg12p:
*******************************************************************************************************************************
-V4L2_PIX_FMT_SRGGB12P ('pRCC'), V4L2_PIX_FMT_SGRBG12P ('pgCC'), V4L2_PIX_FMT_SGBRG12P ('pGCC'), V4L2_PIX_FMT_SBGGR12P ('pBCC'),
+V4L2_PIX_FMT_SRGGB12P ('pRCC'), V4L2_PIX_FMT_SGRBG12P ('pgCC'), V4L2_PIX_FMT_SGBRG12P ('pGCC'), V4L2_PIX_FMT_SBGGR12P ('pBCC')
*******************************************************************************************************************************
These four pixel formats are packed raw sRGB / Bayer formats with 12
bits per colour. Every two consecutive samples are packed into three
bytes. Each of the first two bytes contain the 8 high order bits of
-the pixels, and the third byte contains the four least significants
+the pixels, and the third byte contains the four least significant
bits of each pixel, in the same order.
Each n-pixel row contains n/2 green samples and n/2 blue or red
bits per colour. Every four consecutive samples are packed into seven
bytes. Each of the first four bytes contain the eight high order bits
of the pixels, and the three following bytes contains the six least
-significants bits of each pixel, in the same order.
+significant bits of each pixel, in the same order.
Each n-pixel row contains n/2 green samples and n/2 blue or red samples,
with alternating green-red and green-blue rows. They are conventionally