Ao usar o ffplay para visualizar uma webcam USB usando o filtro DirectShow no Windows 10 Pro, aparece uma tela preta.
Tentei CamDiag32 e CamDiag64, ambos mostram quartz.dll ausente, mas aparece um "erro de acesso negado" quando clico com o botão direito e escolho corrigir. CamDiag64 ainda pode visualizar a webcam, mas CamDiag32 apresenta tela preta. Eu tentei regsvr32 no prompt de comando com privilégios de administrador para quartzo em System32 e SysWOW64, parece registrado com sucesso, mas CamDiagXX ainda reclama dos problemas de quartz.dll.
Também tentei o GraphEdit fixando o pino de captura na renderização do vídeo e também exibindo uma tela preta.
Não tenho certeza da causa raiz do problema.
C:\Temp>ffplay.exe -f dshow -i "video=Vimicro USB Camera (Altair)"
ffplay version N-94129-g098ab93257 Copyright (c) 2003-2019 the FFmpeg developers
built with gcc 9.1.1 (GCC) 20190621
configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libmfx --enable-amf --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt
libavutil 56. 29.100 / 56. 29.100
libavcodec 58. 53.100 / 58. 53.100
libavformat 58. 28.101 / 58. 28.101
libavdevice 58. 7.100 / 58. 7.100
libavfilter 7. 55.100 / 7. 55.100
libswscale 5. 4.101 / 5. 4.101
libswresample 3. 4.100 / 3. 4.100
libpostproc 55. 4.100 / 55. 4.100
Input #0, dshow, from 'video=Vimicro USB Camera (Altair)':B f=0/0
Duration: N/A, start: 2664.043000, bitrate: N/A
Stream #0:0: Video: rawvideo (YUY2 / 0x32595559), yuyv422, 640x480, 30 fps, 30 tbr, 10000k tbn, 10000k tbc
2734.21 M-V: 0.000 fd= 0 aq= 0KB vq= 0KB sq= 0B f=0/0
C:\Temp>ffplay.exe -list_devices true -f dshow -i dummy
ffmpeg version N-94129-g098ab93257 Copyright (c) 2000-2019 the FFmpeg developers
built with gcc 9.1.1 (GCC) 20190621
configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libmfx --enable-amf --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt
libavutil 56. 29.100 / 56. 29.100
libavcodec 58. 53.100 / 58. 53.100
libavformat 58. 28.101 / 58. 28.101
libavdevice 58. 7.100 / 58. 7.100
libavfilter 7. 55.100 / 7. 55.100
libswscale 5. 4.101 / 5. 4.101
libswresample 3. 4.100 / 3. 4.100
libpostproc 55. 4.100 / 55. 4.100
[dshow @ 0000022188bb8a00] DirectShow video devices (some may be both video and audio devices)
[dshow @ 0000022188bb8a00] "Vimicro USB Camera (Altair)"
[dshow @ 0000022188bb8a00] Alternative name "@device_pnp_\\?\usb#vid_0ac8&pid_3450&mi_00#6&22d596c2&0&0000#{65e8773d-8f56-11d0-a3b9-00a0c9223196}\global"
dummy: Immediate exit requested
C:\Temp>ffplay.exe -f dshow -i "video=Vimicro USB Camera (Altair)" -list_options true
ffplay version N-94129-g098ab93257 Copyright (c) 2003-2019 the FFmpeg developers
built with gcc 9.1.1 (GCC) 20190621
configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libmfx --enable-amf --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt
libavutil 56. 29.100 / 56. 29.100
libavcodec 58. 53.100 / 58. 53.100
libavformat 58. 28.101 / 58. 28.101
libavdevice 58. 7.100 / 58. 7.100
libavfilter 7. 55.100 / 7. 55.100
libswscale 5. 4.101 / 5. 4.101
libswresample 3. 4.100 / 3. 4.100
libpostproc 55. 4.100 / 55. 4.100
[dshow @ 000001b0b698ca40] DirectShow video device options (from video devices)
[dshow @ 000001b0b698ca40] Pin "Capture" (alternative pin name "0")
[dshow @ 000001b0b698ca40] pixel_format=yuyv422 min s=640x480 fps=30 max s=640x480 fps=30
[dshow @ 000001b0b698ca40] pixel_format=yuyv422 min s=640x480 fps=30 max s=640x480 fps=30
[dshow @ 000001b0b698ca40] pixel_format=yuyv422 min s=352x288 fps=30 max s=352x288 fps=30
[dshow @ 000001b0b698ca40] pixel_format=yuyv422 min s=352x288 fps=30 max s=352x288 fps=30
[dshow @ 000001b0b698ca40] pixel_format=yuyv422 min s=320x240 fps=30 max s=320x240 fps=30
[dshow @ 000001b0b698ca40] pixel_format=yuyv422 min s=320x240 fps=30 max s=320x240 fps=30
[dshow @ 000001b0b698ca40] pixel_format=yuyv422 min s=176x144 fps=30 max s=176x144 fps=30
[dshow @ 000001b0b698ca40] pixel_format=yuyv422 min s=176x144 fps=30 max s=176x144 fps=30
[dshow @ 000001b0b698ca40] pixel_format=yuyv422 min s=160x120 fps=30 max s=160x120 fps=30
[dshow @ 000001b0b698ca40] pixel_format=yuyv422 min s=160x120 fps=30 max s=160x120 fps=30
video=Vimicro USB Camera (Altair): Immediate exit requested f=0/0
nan : 0.000 fd= 0 aq= 0KB vq= 0KB sq= 0B f=0/0
Responder1
Erro de sintaxe, aqui está a correção
ffplay.exe -f dshow -i vídeo="Câmera USB Vimicro (Altar)"