mirror of https://gitee.com/openkylin/linux.git
219 lines
6.5 KiB
ReStructuredText
219 lines
6.5 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
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The ivtv driver
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===============
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Author: Hans Verkuil <hverkuil@xs4all.nl>
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This is a v4l2 device driver for the Conexant cx23415/6 MPEG encoder/decoder.
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The cx23415 can do both encoding and decoding, the cx23416 can only do MPEG
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encoding. Currently the only card featuring full decoding support is the
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Hauppauge PVR-350.
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.. note::
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#) This driver requires the latest encoder firmware (version 2.06.039, size
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376836 bytes). Get the firmware from here:
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https://linuxtv.org/downloads/firmware/#conexant
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#) 'normal' TV applications do not work with this driver, you need
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an application that can handle MPEG input such as mplayer, xine, MythTV,
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etc.
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The primary goal of the IVTV project is to provide a "clean room" Linux
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Open Source driver implementation for video capture cards based on the
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iCompression iTVC15 or Conexant CX23415/CX23416 MPEG Codec.
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Features
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--------
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* Hardware mpeg2 capture of broadcast video (and sound) via the tuner or
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S-Video/Composite and audio line-in.
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* Hardware mpeg2 capture of FM radio where hardware support exists
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* Supports NTSC, PAL, SECAM with stereo sound
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* Supports SAP and bilingual transmissions.
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* Supports raw VBI (closed captions and teletext).
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* Supports sliced VBI (closed captions and teletext) and is able to insert
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this into the captured MPEG stream.
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* Supports raw YUV and PCM input.
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Additional features for the PVR-350 (CX23415 based)
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---------------------------------------------------
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* Provides hardware mpeg2 playback
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* Provides comprehensive OSD (On Screen Display: ie. graphics overlaying the
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video signal)
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* Provides a framebuffer (allowing X applications to appear on the video
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device)
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* Supports raw YUV output.
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IMPORTANT: In case of problems first read this page:
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https://help.ubuntu.com/community/Install_IVTV_Troubleshooting
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See also
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--------
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https://linuxtv.org
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IRC
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---
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irc://irc.freenode.net/#v4l
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----------------------------------------------------------
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Devices
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-------
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A maximum of 12 ivtv boards are allowed at the moment.
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Cards that don't have a video output capability (i.e. non PVR350 cards)
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lack the vbi8, vbi16, video16 and video48 devices. They also do not
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support the framebuffer device /dev/fbx for OSD.
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The radio0 device may or may not be present, depending on whether the
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card has a radio tuner or not.
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Here is a list of the base v4l devices:
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.. code-block:: none
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crw-rw---- 1 root video 81, 0 Jun 19 22:22 /dev/video0
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crw-rw---- 1 root video 81, 16 Jun 19 22:22 /dev/video16
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crw-rw---- 1 root video 81, 24 Jun 19 22:22 /dev/video24
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crw-rw---- 1 root video 81, 32 Jun 19 22:22 /dev/video32
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crw-rw---- 1 root video 81, 48 Jun 19 22:22 /dev/video48
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crw-rw---- 1 root video 81, 64 Jun 19 22:22 /dev/radio0
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crw-rw---- 1 root video 81, 224 Jun 19 22:22 /dev/vbi0
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crw-rw---- 1 root video 81, 228 Jun 19 22:22 /dev/vbi8
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crw-rw---- 1 root video 81, 232 Jun 19 22:22 /dev/vbi16
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Base devices
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------------
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For every extra card you have the numbers increased by one. For example,
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/dev/video0 is listed as the 'base' encoding capture device so we have:
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- /dev/video0 is the encoding capture device for the first card (card 0)
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- /dev/video1 is the encoding capture device for the second card (card 1)
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- /dev/video2 is the encoding capture device for the third card (card 2)
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Note that if the first card doesn't have a feature (eg no decoder, so no
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video16, the second card will still use video17. The simple rule is 'add
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the card number to the base device number'. If you have other capture
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cards (e.g. WinTV PCI) that are detected first, then you have to tell
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the ivtv module about it so that it will start counting at 1 (or 2, or
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whatever). Otherwise the device numbers can get confusing. The ivtv
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'ivtv_first_minor' module option can be used for that.
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- /dev/video0
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The encoding capture device(s).
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Read-only.
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Reading from this device gets you the MPEG1/2 program stream.
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Example:
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.. code-block:: none
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cat /dev/video0 > my.mpg (you need to hit ctrl-c to exit)
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- /dev/video16
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The decoder output device(s)
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Write-only. Only present if the MPEG decoder (i.e. CX23415) exists.
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An mpeg2 stream sent to this device will appear on the selected video
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display, audio will appear on the line-out/audio out. It is only
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available for cards that support video out. Example:
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.. code-block:: none
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cat my.mpg >/dev/video16
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- /dev/video24
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The raw audio capture device(s).
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Read-only
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The raw audio PCM stereo stream from the currently selected
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tuner or audio line-in. Reading from this device results in a raw
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(signed 16 bit Little Endian, 48000 Hz, stereo pcm) capture.
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This device only captures audio. This should be replaced by an ALSA
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device in the future.
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Note that there is no corresponding raw audio output device, this is
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not supported in the decoder firmware.
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- /dev/video32
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The raw video capture device(s)
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Read-only
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The raw YUV video output from the current video input. The YUV format
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is non-standard (V4L2_PIX_FMT_HM12).
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Note that the YUV and PCM streams are not synchronized, so they are of
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limited use.
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- /dev/video48
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The raw video display device(s)
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Write-only. Only present if the MPEG decoder (i.e. CX23415) exists.
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Writes a YUV stream to the decoder of the card.
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- /dev/radio0
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The radio tuner device(s)
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Cannot be read or written.
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Used to enable the radio tuner and tune to a frequency. You cannot
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read or write audio streams with this device. Once you use this
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device to tune the radio, use /dev/video24 to read the raw pcm stream
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or /dev/video0 to get an mpeg2 stream with black video.
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- /dev/vbi0
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The 'vertical blank interval' (Teletext, CC, WSS etc) capture device(s)
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Read-only
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Captures the raw (or sliced) video data sent during the Vertical Blank
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Interval. This data is used to encode teletext, closed captions, VPS,
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widescreen signalling, electronic program guide information, and other
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services.
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- /dev/vbi8
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Processed vbi feedback device(s)
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Read-only. Only present if the MPEG decoder (i.e. CX23415) exists.
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The sliced VBI data embedded in an MPEG stream is reproduced on this
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device. So while playing back a recording on /dev/video16, you can
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read the embedded VBI data from /dev/vbi8.
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- /dev/vbi16
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The vbi 'display' device(s)
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Write-only. Only present if the MPEG decoder (i.e. CX23415) exists.
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Can be used to send sliced VBI data to the video-out connector.
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