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• How to get a list of video devices with a particular VendorID and/or ProductID using FFmpeg (on Mac OS)

  26 mai 2020, par mcgregor94086

  The master task :

  



  I am writing software for a multiple USB camera array. The camera may be connected to a CPU that has other USB cameras builtin or attached. I need to capture one 1920x1080 JPG image from EACH of MY array's cameras into a directory of images - but I need to EXCLUDE any OTHER cameras when taking pictures.

  



  Right now I am trying to implement for MacOS, but in the future I will be implementing for Windows, Linux, iOS and Android.

  



  What is known :

  



  I know the VendorID, ProductID and UniqueID (reported by the MacOS USB system System Hardware Report) for each of the cameras in the camera array.

  



  UNIQUESKY_CAR_CAMERA #5:

  Model ID: UVC Camera VendorID_7119 ProductID_2825
  Unique ID:    0x143400001bcf0b09

UNIQUESKY_CAR_CAMERA #6:

  Model ID: UVC Camera VendorID_7119 ProductID_2825
  Unique ID:    0x143300001bcf0b09


  



  The problem code :

  



  I made the following call to FFmpeg

  



  ffmpeg -nostdin -hide_banner -an -sn -dn  -f avfoundation -list_devices true -I 1


  



  I received the following result in stderr :

  



      [AVFoundation indev @ 0x7fc870e21800] AVFoundation video devices:
    [AVFoundation indev @ 0x7fc870e21800] [0] FaceTime HD Camera (Built-in)
    [AVFoundation indev @ 0x7fc870e21800] [1] UNIQUESKY_CAR_CAMERA #5
    [AVFoundation indev @ 0x7fc870e21800] [2] UNIQUESKY_CAR_CAMERA #6
    [AVFoundation indev @ 0x7fc870e21800] [3] Capture screen 0
    [AVFoundation indev @ 0x7fc870e21800] [4] Capture screen 1
    [AVFoundation indev @ 0x7fc870e21800] AVFoundation audio devices:
    [AVFoundation indev @ 0x7fc870e21800] [0] MacBook Pro Microphone
    1: Input/output error


  



  Of these devices listed in the output, I happen to know (in this particular TEST CASE) that the cameras in my test array, are only these two :

  



  [1] UNIQUESKY_CAR_CAMERA #5
[2] UNIQUESKY_CAR_CAMERA #6


  



  With this knowledge, I can select the indices (1 2) that I need, and then use the following code to capture an image from each :

  



  for i in 1 2; 
do
    ffmpeg  -y -hide_banner  -f avfoundation  -r 15 -video_size 1920x1080 -i 1  -f image2 -qscale:v 1 -qmin 1 -qmax 1 -frames:v 1 img$i.jpg;
done



  



  Unfortunately, in production use (i.e. outside of this test case), I CAN NOT rely on cameras all identifying themselves with the same TEXT "name" prefix (e.g. "UNIQUESKY_CAR_CAMERA"), so I can't just use grep to select the ones I want.

  



  But I CAN be sure that I will know their VendorID, ProductID and UniqueIDs.

  



  So, IF I could get

  



  ffmpeg  -nostdin -hide_banner -an -sn -dn  -f avfoundation -list_devices true -I 1


  



  to also list the VendorID and ProductID, then I could grep for those values.

  



  Is this solution possible ? I can't find syntax in the documentation or examples for how to set such limits.

  



  ALTERNATIVELY : if I could specify to FFmpeg -list_devices to limit the output list to just those with my specified VendorID and ProductIDs then I could easily get the list of device indices I will need for the succeeding image extraction.

  



  Is this solution possible ? I can't find syntax in the documentation or examples for how to set such limits.

  



  Special Note :
  
The cameras I am using are all 1920x1080, and that resolution is necessary for my application. As has been noted by many Mac users on the web, other image capture programs (such as imagesnap) sometimes capture images at lower resolution (1024x720) than the cameras are capable of, and will not capture images at higher resolutions such as (1920x1080). For this reason, and because it is available on ALL the OS platforms of interest to us, I chose to use FFmpeg.

  


• Why Do Some of the Codecs in FFMPEG's Supported Codec List Show "encoders :" or "decoders :" in Parenthesis ?

  4 mai 2020, par spaceman

  If you open the Command Prompt, and run ffmpeg -codecs,
  
you will get a long list of Codecs that FFMPEG supports.

  



  Here's a small sample of the list :

  



   DEV.L. h261                 H.261
 DEV.L. h263                 H.263 / H.263-1996, H.263+ / H.263-1998 / H.263 version 2
 D.V.L. h263i                Intel H.263
 DEV.L. h263p                H.263+ / H.263-1998 / H.263 version 2
 DEV.LS h264                 H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 (encoders: libx264 libx264rgb)
 D.V.LS hevc                 H.265 / HEVC


  



  Now If you briefly go over the whole list,
  
you see that most Codecs in this list appear with their Name and Description,
  
but some of the Codecs also include parenthesis in the Description, and in the parenthesis,
  
they specify "encoders :" or "decoders :".

  



  For example :

  



  1)

  



   DEV.LS h264                 H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 (encoders: libx264 libx264rgb)


  



  2)

  



   DEVILS jpeg2000             JPEG 2000 (decoders: jpeg2000 libopenjpeg) (encoders: jpeg2000 libopenjpeg)


  



  3)

  



   DEV.L. msmpeg4v3            MPEG-4 part 2 Microsoft variant version 3 (decoders: msmpeg4) (encoders: msmpeg4)


  



  4)

  



   DEA.L. aac                  AAC (Advanced Audio Coding) (encoders: aac libvo_aacenc)


  



  5)

  



   DEA.L. amr_nb               AMR-NB (Adaptive Multi-Rate NarrowBand) (decoders: amrnb libopencore_amrnb) (encoders: libopencore_amrnb)
 DEA.L. amr_wb               AMR-WB (Adaptive Multi-Rate WideBand) (decoders: amrwb libopencore_amrwb) (encoders: libvo_amrwbenc)


  



  My question :

  



  Why do some Codecs have those parenthesis, specifying Encoders/Decoders,
  
while other (in fact : most) codecs don't have these parenthesis ?

  


• Unrecognized option '-enable-libx264'. Error splitting the argument list : Option not found

  9 mars 2020, par DigM

  I’m trying to stream MP4 videos from my server to YouTube and so I installed FFMPEG version. When I then look at the configuration of FFMPEG, I am then presented with the following :

  ffmpeg version 3.3.6 Copyright (c) 2000-2017 the FFmpeg developers
  
    built with gcc 4.9.2 (Debian 4.9.2-10)
  
    configuration: --enable-cross-compile --arch=i686 --target-os=linux --disable-yasm --disable-static --enable-shared --enable-gpl --enable-libmp3lame --enable-libx264 --enable-libsoxr --enable-version3 --enable-nonfree --enable-openssl --disable-decoder=ac3 --disable-decoder=ac3_fixed --disable-decoder=eac3 --disable-decoder=dca --disable-decoder=truehd --disable-encoder=ac3 --disable-encoder=ac3_fixed --disable-encoder=eac3 --disable-encoder=dca --disable-decoder=hevc --disable-decoder=hevc_cuvid --disable-encoder=hevc_nvenc --disable-encoder=nvenc_hevc --extra-ldflags='-L/root/daily_build/64_05/4.4.1/LinkFS/usr/lib -L/root/daily_build/64_05/4.4.1/Model/TS-X72/build/RootFS/usr/local/medialibrary/lib -Wl,--rpath -Wl,/usr/local/medialibrary/lib' --extra-cflags='-I/root/daily_build/64_05/4.4.1/LinkFS/usr/include -I/root/daily_build/64_05/4.4.1/Model/TS-X72/build/RootFS/usr/local/medialibrary/include -D_GNU_SOURCE -DQNAP' --prefix=/root/daily_build/64_05/4.4.1/Model/TS-X72/build/RootFS/usr/local/medialibrary
  
    libavutil      55. 58.100 / 55. 58.100
  
    libavcodec     57. 89.100 / 57. 89.100
  
    libavformat    57. 71.100 / 57. 71.100
  
    libavdevice    57.  6.100 / 57.  6.100
  
    libavfilter     6. 82.100 /  6. 82.100
  
    libswscale      4.  6.100 /  4.  6.100
  
    libswresample   2.  7.100 /  2.  7.100
  
    libpostproc    54.  5.100 / 54.  5.100

  However, when I then try

  ffmpeg ---enable-libx264

  I then get an error saying :

  Unrecognized option '--enable-libx264'.
  
  Error splitting the argument list: Option not found

  Do I need to change the configuaration of FFMPEG somehow or run another configuration option first or is there just something wrong with my call to enable libx264 ?