Media graph element type과 flag

범위와 entity function anchor

이 문서는 Media Controller API가 graph element를 표현할 때 사용하는 entity function, entity flag, interface type, pad flag, link flag와 link type을 정의합니다.

Entity function은 graph 안에서 component가 수행하는 주 역할을 나타냅니다. 같은 물리 장치 안에서도 sensor, tuner, decoder, scaler, interface bridge처럼 역할이 다른 block은 서로 다른 entity와 function으로 표현될 수 있습니다.

.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later

.. _media-controller-types:

Types and flags used to represent the media graph elements
==========================================================

..  tabularcolumns:: |p{8.2cm}|p{9.3cm}|

.. _media-entity-functions:
.. _MEDIA-ENT-F-UNKNOWN:
.. _MEDIA-ENT-F-V4L2-SUBDEV-UNKNOWN:
.. _MEDIA-ENT-F-IO-V4L:
.. _MEDIA-ENT-F-IO-VBI:
.. _MEDIA-ENT-F-IO-SWRADIO:
.. _MEDIA-ENT-F-IO-DTV:
.. _MEDIA-ENT-F-DTV-DEMOD:
.. _MEDIA-ENT-F-TS-DEMUX:
.. _MEDIA-ENT-F-DTV-CA:
.. _MEDIA-ENT-F-DTV-NET-DECAP:
.. _MEDIA-ENT-F-CONN-RF:
.. _MEDIA-ENT-F-CONN-SVIDEO:
.. _MEDIA-ENT-F-CONN-COMPOSITE:
.. _MEDIA-ENT-F-CAM-SENSOR:
.. _MEDIA-ENT-F-FLASH:
.. _MEDIA-ENT-F-LENS:
.. _MEDIA-ENT-F-ATV-DECODER:
.. _MEDIA-ENT-F-TUNER:
.. _MEDIA-ENT-F-IF-VID-DECODER:
.. _MEDIA-ENT-F-IF-AUD-DECODER:
.. _MEDIA-ENT-F-AUDIO-CAPTURE:
.. _MEDIA-ENT-F-AUDIO-PLAYBACK:
.. _MEDIA-ENT-F-AUDIO-MIXER:
.. _MEDIA-ENT-F-PROC-VIDEO-COMPOSER:
.. _MEDIA-ENT-F-PROC-VIDEO-PIXEL-FORMATTER:
.. _MEDIA-ENT-F-PROC-VIDEO-PIXEL-ENC-CONV:
.. _MEDIA-ENT-F-PROC-VIDEO-LUT:
.. _MEDIA-ENT-F-PROC-VIDEO-SCALER:
.. _MEDIA-ENT-F-PROC-VIDEO-STATISTICS:
.. _MEDIA-ENT-F-PROC-VIDEO-ENCODER:
.. _MEDIA-ENT-F-PROC-VIDEO-DECODER:
.. _MEDIA-ENT-F-PROC-VIDEO-ISP:
.. _MEDIA-ENT-F-VID-MUX:
.. _MEDIA-ENT-F-VID-IF-BRIDGE:
.. _MEDIA-ENT-F-DV-DECODER:
.. _MEDIA-ENT-F-DV-ENCODER:

.. cssclass:: longtable

Media entity function: 입출력, broadcast와 analog front end

첫 번째 function 묶음은 streaming I/O, DTV 처리, connector, camera 주변 장치와 analog tuner front end를 설명합니다.

구형 analog 구성에서는 tuner PLL, IF video decoder, IF audio decoder가 서로 다른 I2C address와 entity를 가질 수 있습니다. Application은 하나의 통합 tuner block이라고 가정하지 말고 graph 관계를 따라야 합니다.

.. flat-table:: Media entity functions
    :header-rows:  0
    :stub-columns: 0

    *  -  ``MEDIA_ENT_F_UNKNOWN`` and
	  ``MEDIA_ENT_F_V4L2_SUBDEV_UNKNOWN``
       -  Unknown entity. That generally indicates that a driver didn't
	  initialize properly the entity, which is a Kernel bug

    *  -  ``MEDIA_ENT_F_IO_V4L``
       -  Data streaming input and/or output entity.

    *  -  ``MEDIA_ENT_F_IO_VBI``
       -  V4L VBI streaming input or output entity

    *  -  ``MEDIA_ENT_F_IO_SWRADIO``
       -  V4L Software Digital Radio (SDR) streaming input or output entity

    *  -  ``MEDIA_ENT_F_IO_DTV``
       -  DVB Digital TV streaming input or output entity

    *  -  ``MEDIA_ENT_F_DTV_DEMOD``
       -  Digital TV demodulator entity.

    *  -  ``MEDIA_ENT_F_TS_DEMUX``
       -  MPEG Transport stream demux entity. Could be implemented on
	  hardware or in Kernelspace by the Linux DVB subsystem.

    *  -  ``MEDIA_ENT_F_DTV_CA``
       -  Digital TV Conditional Access module (CAM) entity

    *  -  ``MEDIA_ENT_F_DTV_NET_DECAP``
       -  Digital TV network ULE/MLE desencapsulation entity. Could be
	  implemented on hardware or in Kernelspace

    *  -  ``MEDIA_ENT_F_CONN_RF``
       -  Connector for a Radio Frequency (RF) signal.

    *  -  ``MEDIA_ENT_F_CONN_SVIDEO``
       -  Connector for a S-Video signal.

    *  -  ``MEDIA_ENT_F_CONN_COMPOSITE``
       -  Connector for a RGB composite signal.

    *  -  ``MEDIA_ENT_F_CAM_SENSOR``
       -  Camera video sensor entity.

    *  -  ``MEDIA_ENT_F_FLASH``
       -  Flash controller entity.

    *  -  ``MEDIA_ENT_F_LENS``
       -  Lens controller entity.

    *  -  ``MEDIA_ENT_F_ATV_DECODER``
       -  Analog video decoder, the basic function of the video decoder is
	  to accept analogue video from a wide variety of sources such as
	  broadcast, DVD players, cameras and video cassette recorders, in
	  either NTSC, PAL, SECAM or HD format, separating the stream into
	  its component parts, luminance and chrominance, and output it in
	  some digital video standard, with appropriate timing signals.

    *  -  ``MEDIA_ENT_F_TUNER``
       -  Digital TV, analog TV, radio and/or software radio tuner, with
	  consists on a PLL tuning stage that converts radio frequency (RF)
	  signal into an Intermediate Frequency (IF). Modern tuners have
	  internally IF-PLL decoders for audio and video, but older models
	  have those stages implemented on separate entities.

    *  -  ``MEDIA_ENT_F_IF_VID_DECODER``
       -  IF-PLL video decoder. It receives the IF from a PLL and decodes
	  the analog TV video signal. This is commonly found on some very
	  old analog tuners, like Philips MK3 designs. They all contain a
	  tda9887 (or some software compatible similar chip, like tda9885).
	  Those devices use a different I2C address than the tuner PLL.

    *  -  ``MEDIA_ENT_F_IF_AUD_DECODER``
       -  IF-PLL sound decoder. It receives the IF from a PLL and decodes
	  the analog TV audio signal. This is commonly found on some very
	  old analog hardware, like Micronas msp3400, Philips tda9840,
	  tda985x, etc. Those devices use a different I2C address than the
	  tuner PLL and should be controlled together with the IF-PLL video
	  decoder.

Media entity function: audio와 video processing

두 번째 function 묶음은 audio endpoint와 video composition, format conversion, scaling, codec, ISP, mux, bus bridge와 digital video encode/decode block을 정의합니다.

Pad 개수 조건은 function을 식별하는 구조적 요구 사항입니다. 예를 들어 composer와 mux는 여러 sink가 필요하지만 LUT와 statistics block은 정확히 하나의 sink와 하나의 source를 요구합니다.

Pixel formatter는 memory read/write 주변의 packing 작업을 포함하고, pixel encoding converter는 색 공간이나 Bayer 표현처럼 pixel 의미의 encoding을 바꾼다는 점에서 구분됩니다.

    *  -  ``MEDIA_ENT_F_AUDIO_CAPTURE``
       -  Audio Capture Function Entity.

    *  -  ``MEDIA_ENT_F_AUDIO_PLAYBACK``
       -  Audio Playback Function Entity.

    *  -  ``MEDIA_ENT_F_AUDIO_MIXER``
       -  Audio Mixer Function Entity.

    *  -  ``MEDIA_ENT_F_PROC_VIDEO_COMPOSER``
       -  Video composer (blender). An entity capable of video
	  composing must have at least two sink pads and one source
	  pad, and composes input video frames onto output video
	  frames. Composition can be performed using alpha blending,
	  color keying, raster operations (ROP), stitching or any other
	  means.

    *  -  ``MEDIA_ENT_F_PROC_VIDEO_PIXEL_FORMATTER``
       -  Video pixel formatter. An entity capable of pixel formatting
	  must have at least one sink pad and one source pad. Read
	  pixel formatters read pixels from memory and perform a subset
	  of unpacking, cropping, color keying, alpha multiplication
	  and pixel encoding conversion. Write pixel formatters perform
	  a subset of dithering, pixel encoding conversion and packing
	  and write pixels to memory.

    *  -  ``MEDIA_ENT_F_PROC_VIDEO_PIXEL_ENC_CONV``
       -  Video pixel encoding converter. An entity capable of pixel
	  encoding conversion must have at least one sink pad and one
	  source pad, and convert the encoding of pixels received on
	  its sink pad(s) to a different encoding output on its source
	  pad(s). Pixel encoding conversion includes but isn't limited
	  to RGB to/from HSV, RGB to/from YUV and CFA (Bayer) to RGB
	  conversions.

    *  -  ``MEDIA_ENT_F_PROC_VIDEO_LUT``
       -  Video look-up table. An entity capable of video lookup table
	  processing must have one sink pad and one source pad. It uses
	  the values of the pixels received on its sink pad to look up
	  entries in internal tables and output them on its source pad.
	  The lookup processing can be performed on all components
	  separately or combine them for multi-dimensional table
	  lookups.

    *  -  ``MEDIA_ENT_F_PROC_VIDEO_SCALER``
       -  Video scaler. An entity capable of video scaling must have
	  at least one sink pad and one source pad, and scale the
	  video frame(s) received on its sink pad(s) to a different
	  resolution output on its source pad(s). The range of
	  supported scaling ratios is entity-specific and can differ
	  between the horizontal and vertical directions (in particular
	  scaling can be supported in one direction only). Binning and
	  sub-sampling (occasionally also referred to as skipping) are
	  considered as scaling.

    *  -  ``MEDIA_ENT_F_PROC_VIDEO_STATISTICS``
       -  Video statistics computation (histogram, 3A, etc.). An entity
	  capable of statistics computation must have one sink pad and
	  one source pad. It computes statistics over the frames
	  received on its sink pad and outputs the statistics data on
	  its source pad.

    *  -  ``MEDIA_ENT_F_PROC_VIDEO_ENCODER``
       -  Video (MPEG, HEVC, VPx, etc.) encoder. An entity capable of
          compressing video frames. Must have one sink pad and at least
	  one source pad.

    *  -  ``MEDIA_ENT_F_PROC_VIDEO_DECODER``
       -  Video (MPEG, HEVC, VPx, etc.) decoder. An entity capable of
          decompressing a compressed video stream into uncompressed video
	  frames. Must have one sink pad and at least one source pad.

    *  -  ``MEDIA_ENT_F_PROC_VIDEO_ISP``
       -  An Image Signal Processor (ISP) device. ISPs generally are one of a
	  kind devices that have their specific control interfaces using a
	  combination of custom V4L2 controls and IOCTLs, and parameters
	  supplied in a metadata buffer.

    *  -  ``MEDIA_ENT_F_VID_MUX``
       - Video multiplexer. An entity capable of multiplexing must have at
         least two sink pads and one source pad, and must pass the video
         frame(s) received from the active sink pad to the source pad.

    *  -  ``MEDIA_ENT_F_VID_IF_BRIDGE``
       - Video interface bridge. A video interface bridge entity must have at
         least one sink pad and at least one source pad. It receives video
         frames on its sink pad from an input video bus of one type (HDMI, eDP,
         MIPI CSI-2, etc.), and outputs them on its source pad to an output
         video bus of another type (eDP, MIPI CSI-2, parallel, etc.).

    *  -  ``MEDIA_ENT_F_DV_DECODER``
       -  Digital video decoder. The basic function of the video decoder is
	  to accept digital video from a wide variety of sources
	  and output it in some digital video standard, with appropriate
	  timing signals.

    *  -  ``MEDIA_ENT_F_DV_ENCODER``
       -  Digital video encoder. The basic function of the video encoder is
	  to accept digital video from some digital video standard with
	  appropriate timing signals (usually a parallel video bus with sync
	  signals) and output this to a digital video output connector such
	  as HDMI or DisplayPort.

Media entity flag

Entity flag는 function과 별도로 default 선택과 connector 표현을 표시합니다.

`MEDIA_ENT_FL_DEFAULT`는 graph에서 유일한 영구 ID를 제공하는 flag가 아니라 특정 type의 기본 선택을 알려주는 metadata입니다.

..  tabularcolumns:: |p{5.5cm}|p{12.0cm}|

.. _media-entity-flag:
.. _MEDIA-ENT-FL-DEFAULT:
.. _MEDIA-ENT-FL-CONNECTOR:

.. flat-table:: Media entity flags
    :header-rows:  0
    :stub-columns: 0

    *  -  ``MEDIA_ENT_FL_DEFAULT``
       -  Default entity for its type. Used to discover the default audio,
	  VBI and video devices, the default camera sensor, etc.

    *  -  ``MEDIA_ENT_FL_CONNECTOR``
       -  The entity represents a connector.

Media interface type과 device node

Interface type은 entity에 연결된 userspace device node의 API family와 역할을 나타냅니다. 표의 path는 일반적인 이름이며 `?`는 adapter, card, device 번호처럼 system이 정하는 숫자 자리입니다.

Device node 이름만 추측해 interface를 분류하지 말고 topology가 제공하는 `MEDIA_INTF_T_*` 값과 `media_v2_intf_devnode`의 major/minor를 기준으로 연결해야 합니다.

..  tabularcolumns:: |p{6.5cm}|p{6.0cm}|p{4.8cm}|

.. _media-intf-type:
.. _MEDIA-INTF-T-DVB-FE:
.. _MEDIA-INTF-T-DVB-DEMUX:
.. _MEDIA-INTF-T-DVB-DVR:
.. _MEDIA-INTF-T-DVB-CA:
.. _MEDIA-INTF-T-DVB-NET:
.. _MEDIA-INTF-T-V4L-VIDEO:
.. _MEDIA-INTF-T-V4L-VBI:
.. _MEDIA-INTF-T-V4L-RADIO:
.. _MEDIA-INTF-T-V4L-SUBDEV:
.. _MEDIA-INTF-T-V4L-SWRADIO:
.. _MEDIA-INTF-T-V4L-TOUCH:
.. _MEDIA-INTF-T-ALSA-PCM-CAPTURE:
.. _MEDIA-INTF-T-ALSA-PCM-PLAYBACK:
.. _MEDIA-INTF-T-ALSA-CONTROL:
.. _MEDIA-INTF-T-ALSA-COMPRESS:
.. _MEDIA-INTF-T-ALSA-RAWMIDI:
.. _MEDIA-INTF-T-ALSA-HWDEP:
.. _MEDIA-INTF-T-ALSA-SEQUENCER:
.. _MEDIA-INTF-T-ALSA-TIMER:

.. flat-table:: Media interface types
    :header-rows:  0
    :stub-columns: 0

    *  -  ``MEDIA_INTF_T_DVB_FE``
       -  Device node interface for the Digital TV frontend
       -  typically, /dev/dvb/adapter?/frontend?

    *  -  ``MEDIA_INTF_T_DVB_DEMUX``
       -  Device node interface for the Digital TV demux
       -  typically, /dev/dvb/adapter?/demux?

    *  -  ``MEDIA_INTF_T_DVB_DVR``
       -  Device node interface for the Digital TV DVR
       -  typically, /dev/dvb/adapter?/dvr?

    *  -  ``MEDIA_INTF_T_DVB_CA``
       -  Device node interface for the Digital TV Conditional Access
       -  typically, /dev/dvb/adapter?/ca?

    *  -  ``MEDIA_INTF_T_DVB_NET``
       -  Device node interface for the Digital TV network control
       -  typically, /dev/dvb/adapter?/net?

    *  -  ``MEDIA_INTF_T_V4L_VIDEO``
       -  Device node interface for video (V4L)
       -  typically, /dev/video?

    *  -  ``MEDIA_INTF_T_V4L_VBI``
       -  Device node interface for VBI (V4L)
       -  typically, /dev/vbi?

    *  -  ``MEDIA_INTF_T_V4L_RADIO``
       -  Device node interface for radio (V4L)
       -  typically, /dev/radio?

    *  -  ``MEDIA_INTF_T_V4L_SUBDEV``
       -  Device node interface for a V4L subdevice
       -  typically, /dev/v4l-subdev?

    *  -  ``MEDIA_INTF_T_V4L_SWRADIO``
       -  Device node interface for Software Defined Radio (V4L)
       -  typically, /dev/swradio?

    *  -  ``MEDIA_INTF_T_V4L_TOUCH``
       -  Device node interface for Touch device (V4L)
       -  typically, /dev/v4l-touch?

    *  -  ``MEDIA_INTF_T_ALSA_PCM_CAPTURE``
       -  Device node interface for ALSA PCM Capture
       -  typically, /dev/snd/pcmC?D?c

    *  -  ``MEDIA_INTF_T_ALSA_PCM_PLAYBACK``
       -  Device node interface for ALSA PCM Playback
       -  typically, /dev/snd/pcmC?D?p

    *  -  ``MEDIA_INTF_T_ALSA_CONTROL``
       -  Device node interface for ALSA Control
       -  typically, /dev/snd/controlC?

    *  -  ``MEDIA_INTF_T_ALSA_COMPRESS``
       -  Device node interface for ALSA Compress
       -  typically, /dev/snd/compr?

    *  -  ``MEDIA_INTF_T_ALSA_RAWMIDI``
       -  Device node interface for ALSA Raw MIDI
       -  typically, /dev/snd/midi?

    *  -  ``MEDIA_INTF_T_ALSA_HWDEP``
       -  Device node interface for ALSA Hardware Dependent
       -  typically, /dev/snd/hwC?D?

    *  -  ``MEDIA_INTF_T_ALSA_SEQUENCER``
       -  Device node interface for ALSA Sequencer
       -  typically, /dev/snd/seq

    *  -  ``MEDIA_INTF_T_ALSA_TIMER``
       -  Device node interface for ALSA Timer
       -  typically, /dev/snd/timer

Media pad flag

Pad flag는 entity를 기준으로 data가 들어오는 sink인지 나가는 source인지와 streaming을 위한 필수 연결 여부를 나타냅니다.

`MEDIA_PAD_FL_MUST_CONNECT`가 없다고 해서 enable된 link가 절대 필요 없다는 뜻은 아닙니다. Device configuration 같은 일시적 조건 때문에 flag 없이도 연결이 필요할 수 있습니다.

각 pad에는 `MEDIA_PAD_FL_SINK`와 `MEDIA_PAD_FL_SOURCE` 중 하나만 반드시 설정되어야 하며 둘 다 설정하거나 둘 다 비우는 것은 올바른 표현이 아닙니다.

.. tabularcolumns:: |p{5.5cm}|p{12.0cm}|

.. _media-pad-flag:
.. _MEDIA-PAD-FL-SINK:
.. _MEDIA-PAD-FL-SOURCE:
.. _MEDIA-PAD-FL-MUST-CONNECT:

.. flat-table:: Media pad flags
    :header-rows:  0
    :stub-columns: 0

    *  -  ``MEDIA_PAD_FL_SINK``
       -  Input pad, relative to the entity. Input pads sink data and are
	  targets of links.

    *  -  ``MEDIA_PAD_FL_SOURCE``
       -  Output pad, relative to the entity. Output pads source data and
	  are origins of links.

    *  -  ``MEDIA_PAD_FL_MUST_CONNECT``
       -  If this flag is set, then for this pad to be able to stream, it must
	  be connected by at least one enabled link. There could be temporary
	  reasons (e.g. device configuration dependent) for the pad to need
	  enabled links even when this flag isn't set; the absence of the flag
	  doesn't imply there is none.


One and only one of ``MEDIA_PAD_FL_SINK`` and ``MEDIA_PAD_FL_SOURCE``
must be set for every pad.

Media link flag와 link type

Link flag는 data 전송 가능 상태, runtime 변경 가능성, streaming 중 변경 가능성과 link가 나타내는 관계 종류를 표현합니다.

같은 sink pad로 향하는 enabled data link는 한 번에 하나만 허용됩니다. Link 설정 시 driver가 다른 link를 자동으로 끄지 않으므로 application이 충돌을 해결해야 합니다.

`MEDIA_LNK_FL_DYNAMIC`은 application이 쓰는 요청 bit가 아니라 driver가 제공하는 capability flag입니다. 이 flag가 없는 link는 streaming을 멈춘 상태에서만 enable 상태를 변경할 수 있습니다.

.. tabularcolumns:: |p{5.5cm}|p{12.0cm}|

.. _media-link-flag:
.. _MEDIA-LNK-FL-ENABLED:
.. _MEDIA-LNK-FL-IMMUTABLE:
.. _MEDIA-LNK-FL-DYNAMIC:
.. _MEDIA-LNK-FL-LINK-TYPE:

.. flat-table:: Media link flags
    :header-rows:  0
    :stub-columns: 0

    *  -  ``MEDIA_LNK_FL_ENABLED``
       -  The link is enabled and can be used to transfer media data. When
	  two or more links target a sink pad, only one of them can be
	  enabled at a time.

    *  -  ``MEDIA_LNK_FL_IMMUTABLE``
       -  The link enabled state can't be modified at runtime. An immutable
	  link is always enabled.

    *  -  ``MEDIA_LNK_FL_DYNAMIC``
       -  The link enabled state can be modified during streaming. This flag
	  is set by drivers and is read-only for applications.

    *  -  ``MEDIA_LNK_FL_LINK_TYPE``
       -  This is a bitmask that defines the type of the link. The following
	  link types are currently supported:

	  .. _MEDIA-LNK-FL-DATA-LINK:

	  ``MEDIA_LNK_FL_DATA_LINK`` for links that represent a data connection
	  between two pads.

	  .. _MEDIA-LNK-FL-INTERFACE-LINK:

	  ``MEDIA_LNK_FL_INTERFACE_LINK`` for links that associate an entity to its
	  interface.

	  .. _MEDIA-LNK-FL-ANCILLARY-LINK:

	  ``MEDIA_LNK_FL_ANCILLARY_LINK`` for links that represent a physical
	  relationship between two entities. The link may or may not be
	  immutable, so applications must not assume either case.