我正在尝试从以下位置捕获视频Elikliv UVC 显微镜在Linux中。
我们可以使用以下命令直接进行逐帧捕获：
v4l2-ctl --device /dev/video0 --stream-mmap --stream-to=stream.mjpg
...我可以使用这个疯狂的大命令实时查看它：
v4l2-ctl --device /dev/video0 --stream-mmap --stream-to=/proc/self/fd/1 | \
ffmpeg -i - -fflags discardcorrupt -c:v copy -f matroska - | \
mpv --profile=low-latency -
v4l2-ctl..但如果没有将其流式传输到ffmpeg然后的帮助，我无法让它直接与 V4L2 感知软件（即 MPV、VLC、OBS）一起使用mpv。
问题：
有没有一种方法可以告诉我配置 V4L2 设备以“正常”方式工作，直接从/dev/video0，而不需要一个大而疯狂的管道？
多用途车说
# mpv /dev/video0
[lavf] avformat_open_input() failed
Failed to recognize file format.
VLC 说
Your input can't be opened:
VLC is unable to open the MRL 'v4l2:///dev/video0'. Check the log for details.
[00007efbdc001120] v4l2 demux error: cannot set format: Input/output error
[00007efbdc001120] v4l2 demux error: not a radio tuner device
[00007efbdc003710] v4l2 stream error: cannot set format: Input/output error
其他杂项信息：
# dmesg
[ +0.078764] usb 1-4.3: New USB device found, idVendor=05e3, idProduct=f12b, bcdDevice= 1.00
[ +0.000019] usb 1-4.3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[ +0.000008] usb 1-4.3: Product: GENERAL - UVC
[ +0.000006] usb 1-4.3: Manufacturer: GENERAL
[ +0.002536] usb 1-4.3: Found UVC 1.00 device GENERAL - UVC (05e3:f12b)
[ +0.000287] usb 1-4.3: UVC non compliance - GET_DEF(PROBE) not supported. Enabling workaround.
[ +5.549774] retire_capture_urb: 233 callbacks suppressed
[ +5.000996] retire_capture_urb: 4991 callbacks suppressed
[ +5.000956] retire_capture_urb: 4991 callbacks suppressed
[ +5.001062] retire_capture_urb: 4991 callbacks suppressed
... <lots of these, 1000/sec> ...
[ +3.438372] uvcvideo 1-4.3:1.1: Failed to query (130) UVC probe control : -32 (exp. 26).
# v4l2-ctl --list-devices
GENERAL - UVC : GENERAL - UVC (usb-0000:00:14.0-4.3):
/dev/video0
/dev/video1
/dev/media0
# v4l2-ctl --list-formats -d /dev/video0
ioctl: VIDIOC_ENUM_FMT
Type: Video Capture
[0]: 'MJPG' (Motion-JPEG, compressed)
# v4l2-ctl --list-formats -d /dev/video1
ioctl: VIDIOC_ENUM_FMT
Type: Video Capture
# v4l2-ctl --list-formats -d /dev/media0
Unable to detect what device /dev/media0 is, exiting.
# v4l2-ctl -D -d /dev/video0
Driver Info:
Driver name : uvcvideo
Card type : GENERAL - UVC : GENERAL - UVC
Bus info : usb-0000:00:14.0-4.3
Driver version : 6.7.6
Capabilities : 0x84a00001
Video Capture
Metadata Capture
Streaming
Extended Pix Format
Device Capabilities
Device Caps : 0x04200001
Video Capture
Streaming
Extended Pix Format
Media Driver Info:
Driver name : uvcvideo
Model : GENERAL - UVC : GENERAL - UVC
Serial :
Bus info : usb-0000:00:14.0-4.3
Media version : 6.7.6
Hardware revision: 0x00000100 (256)
Driver version : 6.7.6
Interface Info:
ID : 0x03000002
Type : V4L Video
Entity Info:
ID : 0x00000001 (1)
Name : GENERAL - UVC : GENERAL - UVC
Function : V4L2 I/O
Flags : default
Pad 0x01000007 : 0: Sink
Link 0x02000010: from remote pad 0x100000a of entity 'Processing 5': Data, Enabled, Immutable
# v4l2-ctl -D -d /dev/video1
Driver Info:
Driver name : uvcvideo
Card type : GENERAL - UVC : GENERAL - UVC
Bus info : usb-0000:00:14.0-4.3
Driver version : 6.7.6
Capabilities : 0x84a00001
Video Capture
Metadata Capture
Streaming
Extended Pix Format
Device Capabilities
Device Caps : 0x04a00000
Metadata Capture
Streaming
Extended Pix Format
Media Driver Info:
Driver name : uvcvideo
Model : GENERAL - UVC : GENERAL - UVC
Serial :
Bus info : usb-0000:00:14.0-4.3
Media version : 6.7.6
Hardware revision: 0x00000100 (256)
Driver version : 6.7.6
Interface Info:
ID : 0x03000005
Type : V4L Video
Entity Info:
ID : 0x00000004 (4)
Name : GENERAL - UVC : GENERAL - UVC
Function : V4L2 I/O
MPV 详细输出：
# mpv av://v4l2:/dev/video0 --profile=low-latency --untimed --demuxer-lavf-o=video_size=1280x720,input_format=mjpeg -v -v
[cplayer] Command line options: 'av://v4l2:/dev/video0' '--profile=low-latency' '--untimed' '--demuxer-lavf-o=video_size=1280x720,input_format=mjpeg' '-v' '-v'
[cplayer] mpv 0.35.1 Copyright © 2000-2023 mpv/MPlayer/mplayer2 projects
[cplayer] built on UNKNOWN
[cplayer] FFmpeg library versions:
[cplayer] libavutil 57.28.100
[cplayer] libavcodec 59.37.100
[cplayer] libavformat 59.27.100
[cplayer] libswscale 6.7.100
[cplayer] libavfilter 8.44.100
[cplayer] libswresample 4.7.100
[cplayer] FFmpeg version: 5.1.3
[cplayer]
[cplayer] Configuration: /usr/bin/waf configure --prefix=/usr --bindir=/usr/bin --libdir=/usr/lib64 --mandir=/usr/share/man --docdir=/usr/share/doc/mpv --confdir=/etc/mpv --disable-build-date --enable-libmpv-shared --enable-sdl2 --enable-libarchive --enable-dvdnav --enable-cdda --enable-html-build --enable-dvbin --enable-gl-x11 --enable-wayland
[cplayer] List of enabled features: alsa asm av-channel-layout caca cdda cplayer cplugins cuda-hwaccel cuda-interop debug-build dmabuf-interop-gl dmabuf-interop-pl dmabuf-wayland drm drm-is-kms dvbin dvdnav egl egl-drm egl-helpers egl-x11 ffmpeg ffnvcodec gbm gbm.h gl gl-wayland gl-x11 glibc-thread-name glob glob-posix gpl iconv jack javascript jpeg jpegxl lcms2 libarchive libass libavdevice libbluray libdl libm libmpv-shared libplacebo librt linux-fstatfs linux-input-event-codes lua lua_5_1 memfd_create optimize pipewire plain-gl posix posix-or-mingw pthreads pulse rubberband rubberband-3 sdl2 sdl2-audio sdl2-gamepad sdl2-video shaderc shaderc-shared stdatomic uchardet vaapi vaapi-drm vaapi-egl vaapi-libplacebo vaapi-wayland vaapi-x-egl vaapi-x11 vapoursynth vdpau vdpau-gl-x11 vector vt.h vulkan wayland wayland-protocols wayland-protocols-1-24 x11 xv zimg zlib
[global] config path: '' -> '/root/.config/mpv'
[global] user path: '~~home/' -> '/root/.config/mpv'
[global] user path: '~~old_home/' -> '/root/.mpv'
[global] config path: 'encoding-profiles.conf' -/-> '/root/.config/mpv/encoding-profiles.conf'
[global] config path: 'encoding-profiles.conf' -/-> '/root/.mpv/encoding-profiles.conf'
[global] config path: 'encoding-profiles.conf' -> '/etc/mpv/encoding-profiles.conf'
[cplayer] Reading config file /etc/mpv/encoding-profiles.conf
[cplayer] Applying profile 'default'...
[global] config path: 'mpv.conf' -/-> '/root/.config/mpv/mpv.conf'
[global] config path: 'config' -/-> '/root/.config/mpv/config'
[global] config path: 'mpv.conf' -/-> '/root/.mpv/mpv.conf'
[global] config path: 'config' -/-> '/root/.mpv/config'
[global] config path: 'mpv.conf' -/-> '/etc/mpv/mpv.conf'
[global] config path: 'config' -/-> '/etc/mpv/config'
[cplayer] Setting option 'profile' = 'low-latency' (flags = 8)
[cplayer] Applying profile 'low-latency'...
[cplayer] Setting option 'audio-buffer' = '0' (flags = 12)
[cplayer] Setting option 'vd-lavc-threads' = '1' (flags = 12)
[cplayer] Setting option 'cache-pause' = 'no' (flags = 12)
[cplayer] Setting option 'demuxer-lavf-o-add' = 'fflags=+nobuffer' (flags = 12)
[cplayer] Setting option 'demuxer-lavf-probe-info' = 'nostreams' (flags = 12)
[cplayer] Setting option 'demuxer-lavf-analyzeduration' = '0.1' (flags = 12)
[cplayer] Setting option 'video-sync' = 'audio' (flags = 12)
[cplayer] Setting option 'interpolation' = 'no' (flags = 12)
[cplayer] Setting option 'video-latency-hacks' = 'yes' (flags = 12)
[cplayer] Setting option 'stream-buffer-size' = '4k' (flags = 12)
[cplayer] Setting option 'untimed' = '' (flags = 8)
[cplayer] Setting option 'demuxer-lavf-o' = 'video_size=1280x720,input_format=mjpeg' (flags = 8)
[cplayer] Setting option 'v' = '' (flags = 8)
[cplayer] Setting option 'v' = '' (flags = 8)
[global] config path: 'input.conf' -/-> '/root/.config/mpv/input.conf'
[global] config path: 'input.conf' -/-> '/root/.mpv/input.conf'
[global] config path: 'input.conf' -/-> '/etc/mpv/input.conf'
[osc] Loading lua script @osc.lua...
[ytdl_hook] Loading lua script @ytdl_hook.lua...
[stats] Loading lua script @stats.lua...
[console] Loading lua script @console.lua...
[osc] loading mp.defaults
[auto_profiles] Loading lua script @auto_profiles.lua...
[ytdl_hook] loading mp.defaults
[global] config path: 'scripts' -/-> '/root/.config/mpv/scripts'
[stats] loading mp.defaults
[global] config path: 'scripts' -/-> '/root/.mpv/scripts'
[global] config path: 'scripts' -/-> '/etc/mpv/scripts'
[cplayer] Waiting for scripts...
[auto_profiles] loading mp.defaults
[console] loading mp.defaults
[osc] loading @osc.lua
[stats] loading @stats.lua
[auto_profiles] loading @auto_profiles.lua
[console] loading @console.lua
[auto_profiles] Exiting...
[console] reading options for console
[global] config path: 'script-opts/console.conf' -/-> '/root/.config/mpv/script-opts/console.conf'
[global] config path: 'script-opts/console.conf' -/-> '/root/.mpv/script-opts/console.conf'
[global] config path: 'script-opts/console.conf' -/-> '/etc/mpv/script-opts/console.conf'
[console] script-opts/console.conf not found.
[global] config path: 'lua-settings/console.conf' -/-> '/root/.config/mpv/lua-settings/console.conf'
[global] config path: 'lua-settings/console.conf' -/-> '/root/.mpv/lua-settings/console.conf'
[global] config path: 'lua-settings/console.conf' -/-> '/etc/mpv/lua-settings/console.conf'
[console] lua-settings/console.conf not found.
[stats] reading options for stats
[global] config path: 'script-opts/stats.conf' -/-> '/root/.config/mpv/script-opts/stats.conf'
[global] config path: 'script-opts/stats.conf' -/-> '/root/.mpv/script-opts/stats.conf'
[global] config path: 'script-opts/stats.conf' -/-> '/etc/mpv/script-opts/stats.conf'
[stats] script-opts/stats.conf not found.
[global] config path: 'lua-settings/stats.conf' -/-> '/root/.config/mpv/lua-settings/stats.conf'
[global] config path: 'lua-settings/stats.conf' -/-> '/root/.mpv/lua-settings/stats.conf'
[global] config path: 'lua-settings/stats.conf' -/-> '/etc/mpv/lua-settings/stats.conf'
[stats] lua-settings/stats.conf not found.
[ytdl_hook] loading @ytdl_hook.lua
[global] config path: 'fonts' -/-> '/root/.config/mpv/fonts'
[global] config path: 'fonts' -/-> '/root/.mpv/fonts'
[global] config path: 'fonts' -/-> '/etc/mpv/fonts'
[osd/libass] ASS library version: 0x1701000 (runtime 0x1701000)
[osd/libass] libass API version: 0x1701000
[osd/libass] libass source: tarball: 0.17.1
[osd/libass] Shaper: FriBidi 1.0.10 (SIMPLE) HarfBuzz-ng 2.7.4 (COMPLEX)
[global] config path: 'subfont.ttf' -/-> '/root/.config/mpv/subfont.ttf'
[global] config path: 'subfont.ttf' -/-> '/root/.mpv/subfont.ttf'
[global] config path: 'subfont.ttf' -/-> '/etc/mpv/subfont.ttf'
[global] config path: 'fonts.conf' -/-> '/root/.config/mpv/fonts.conf'
[global] config path: 'fonts.conf' -/-> '/root/.mpv/fonts.conf'
[global] config path: 'fonts.conf' -/-> '/etc/mpv/fonts.conf'
[osd/libass] Setting up fonts...
[ytdl_hook] reading options for ytdl_hook
[global] config path: 'script-opts/ytdl_hook.conf' -/-> '/root/.config/mpv/script-opts/ytdl_hook.conf'
[global] config path: 'script-opts/ytdl_hook.conf' -/-> '/root/.mpv/script-opts/ytdl_hook.conf'
[global] config path: 'script-opts/ytdl_hook.conf' -/-> '/etc/mpv/script-opts/ytdl_hook.conf'
[ytdl_hook] script-opts/ytdl_hook.conf not found.
[global] config path: 'lua-settings/ytdl_hook.conf' -/-> '/root/.config/mpv/lua-settings/ytdl_hook.conf'
[global] config path: 'lua-settings/ytdl_hook.conf' -/-> '/root/.mpv/lua-settings/ytdl_hook.conf'
[global] config path: 'lua-settings/ytdl_hook.conf' -/-> '/etc/mpv/lua-settings/ytdl_hook.conf'
[ytdl_hook] lua-settings/ytdl_hook.conf not found.
[osc] reading options for osc
[global] config path: 'script-opts/osc.conf' -/-> '/root/.config/mpv/script-opts/osc.conf'
[global] config path: 'script-opts/osc.conf' -/-> '/root/.mpv/script-opts/osc.conf'
[global] config path: 'script-opts/osc.conf' -/-> '/etc/mpv/script-opts/osc.conf'
[osc] script-opts/osc.conf not found.
[global] config path: 'lua-settings/osc.conf' -/-> '/root/.config/mpv/lua-settings/osc.conf'
[global] config path: 'lua-settings/osc.conf' -/-> '/root/.mpv/lua-settings/osc.conf'
[global] config path: 'lua-settings/osc.conf' -/-> '/etc/mpv/lua-settings/osc.conf'
[osc] lua-settings/osc.conf not found.
[osd/libass] Using font provider fontconfig
[osd/libass] Done.
[cplayer] Run command: define-section, flags=64, args=[name="input_stats", contents="", flags="default"]
[cplayer] Run command: enable-section, flags=64, args=[name="input_stats", flags="allow-hide-cursor+allow-vo-dragging"]
[cplayer] Run command: define-section, flags=64, args=[name="input_forced_stats", contents="", flags="force"]
[cplayer] Run command: enable-section, flags=64, args=[name="input_forced_stats", flags="allow-hide-cursor+allow-vo-dragging"]
[cplayer] Run command: define-section, flags=64, args=[name="input_console", contents="", flags="default"]
[cplayer] Run command: enable-section, flags=64, args=[name="input_console", flags="allow-hide-cursor+allow-vo-dragging"]
[cplayer] Run command: define-section, flags=64, args=[name="input_forced_console", contents="", flags="force"]
[cplayer] Run command: enable-section, flags=64, args=[name="input_forced_console", flags="allow-hide-cursor+allow-vo-dragging"]
[cplayer] Run command: define-section, flags=64, args=[name="showhide", contents="mouse_move script-binding osc/__keybinding1\nmouse_leave script-binding osc/__keybinding2\n", flags="force"]
[cplayer] Run command: define-section, flags=64, args=[name="showhide_wc", contents="mouse_move script-binding osc/__keybinding3\nmouse_leave script-binding osc/__keybinding4\n", flags="force"]
[cplayer] Run command: enable-section, flags=64, args=[name="showhide", flags="allow-hide-cursor+allow-vo-dragging"]
[cplayer] Run command: enable-section, flags=64, args=[name="showhide_wc", flags="allow-hide-cursor+allow-vo-dragging"]
[cplayer] Run command: define-section, flags=64, args=[name="input", contents="mbtn_left script-binding osc/__keybinding5\nshift+mbtn_left script-binding osc/__keybinding6\nmbtn_right script-binding osc/__keybinding7\nmbtn_mid script-binding osc/__keybinding8\nwheel_up script-binding osc/__keybinding9\nwheel_down script-binding osc/__keybinding10\nmbtn_left_dbl ignore\nshift+mbtn_left_dbl ignore\nmbtn_right_dbl ignore\n", flags="force"]
[cplayer] Run command: enable-section, flags=64, args=[name="input", flags=""]
[cplayer] Run command: define-section, flags=64, args=[name="window-controls", contents="mbtn_left script-binding osc/__keybinding11\n", flags="force"]
[cplayer] Run command: enable-section, flags=64, args=[name="window-controls", flags=""]
[cplayer] Run command: change-list, flags=64, args=[name="shared-script-properties", operation="append", value="osc-visibility=auto"]
[cplayer] Set property: shared-script-properties -> 1
[cplayer] Run command: disable-section, flags=64, args=[name="input"]
[cplayer] Run command: disable-section, flags=64, args=[name="window-controls"]
[cplayer] Run command: change-list, flags=64, args=[name="shared-script-properties", operation="append", value="osc-margins=0.000000,0.000000,0.000000,0.000000"]
[cplayer] Set property: shared-script-properties -> 1
[cplayer] Done loading scripts.
[global] config path: 'watch_later' -> '/root/.config/mpv/watch_later'
[cplayer] Running hook: ytdl_hook/on_load
[ytdl_hook] ytdl:// hook
[ytdl_hook] not a ytdl:// url
[cplayer] Run command: change-list, flags=64, args=[name="shared-script-properties", operation="append", value="osc-margins=0.000000,0.000000,0.000000,0.000000"]
[avdevice] Opening av://v4l2:/dev/video0
[avdevice] resize stream to 4096 bytes, drop 0 bytes
[cplayer] Set property: shared-script-properties -> 1
[osc] osc_init
[avdevice] Stream opened successfully.
[demux] Trying demuxers for level=request.
[demux] Trying demuxer: lavf (force-level: request)
[cplayer] Run command: change-list, flags=64, args=[name="shared-script-properties", operation="append", value="osc-margins=0.000000,0.000000,0.000000,0.000000"]
[cplayer] Set property: shared-script-properties -> 1
[global] config path: 'fonts' -/-> '/root/.config/mpv/fonts'
[global] config path: 'fonts' -/-> '/root/.mpv/fonts'
[global] config path: 'fonts' -/-> '/etc/mpv/fonts'
[osd/libass] ASS library version: 0x1701000 (runtime 0x1701000)
[osd/libass] libass API version: 0x1701000
[osd/libass] libass source: tarball: 0.17.1
[lavf] Found 'video4linux2,v4l2' at score=100 size=0 (forced).
[osd/libass] Shaper: FriBidi 1.0.10 (SIMPLE) HarfBuzz-ng 2.7.4 (COMPLEX)
[global] config path: 'subfont.ttf' -/-> '/root/.config/mpv/subfont.ttf'
[global] config path: 'subfont.ttf' -/-> '/root/.mpv/subfont.ttf'
[global] config path: 'subfont.ttf' -/-> '/etc/mpv/subfont.ttf'
[global] config path: 'fonts.conf' -/-> '/root/.config/mpv/fonts.conf'
[global] config path: 'fonts.conf' -/-> '/root/.mpv/fonts.conf'
[global] config path: 'fonts.conf' -/-> '/etc/mpv/fonts.conf'
[osd/libass] Setting up fonts...
[ffmpeg/demuxer] video4linux2,v4l2: fd:6 capabilities:84a00001
[lavf] avformat_open_input() failed
[cplayer] Opening failed or was aborted: av://v4l2:/dev/video0
[osd/libass] Using font provider fontconfig
[osd/libass] Done.
[cplayer] Running hook: ytdl_hook/on_load_fail
[ytdl_hook] full hook
[cplayer] Run command: define-section, flags=64, args=[name="input_osc", contents="", flags="default"]
[cplayer] Run command: enable-section, flags=64, args=[name="input_osc", flags="allow-hide-cursor+allow-vo-dragging"]
[cplayer] Run command: define-section, flags=64, args=[name="input_forced_osc", contents="", flags="force"]
[cplayer] Run command: enable-section, flags=64, args=[name="input_forced_osc", flags="allow-hide-cursor+allow-vo-dragging"]
[cplayer] finished playback, unrecognized file format (reason 4)
[cplayer] Failed to recognize file format.
[cplayer]
[cplayer] Exiting... (Errors when loading file)
[ytdl_hook] Exiting...
[cplayer] Run command: change-list, flags=64, args=[name="shared-script-properties", operation="remove", value="osc-margins"]
[cplayer] Set property: shared-script-properties -> 1
[stats] Exiting...
[console] Exiting...
[osc] Exiting...
答案1
我不能说对于 VLC，但对于 mpv，新的（我不知道它何时更改）语法使用 URI 而不是普通的设备路径：
mpv av://v4l2:/dev/video0 --profile=low-latency --untimed