message: videoio: fix capture modes
diff: @@ -70,7 +70,7 @@ static const struct VideoBackendInfo builtin_backends[] =
  // Windows
  #ifdef WINRT_VIDEO
  - DECLARE_BACKEND(CAP_WINRT, "WINRT", MODE_CAPTURE_BY_FILENAME),
  + DECLARE_BACKEND(CAP_WINRT, "WINRT", MODE_CAPTURE_BY_INDEX),
  #endif
  #ifdef HAVE_MSMF
  DECLARE_BACKEND(CAP_MSMF, "MSMF", MODE_CAPTURE_ALL | MODE_WRITER),
  @@ -79,7 +79,7 @@ static const struct VideoBackendInfo builtin_backends[] =
  DECLARE_BACKEND(CAP_VFW, "VFW", MODE_CAPTURE_ALL | MODE_WRITER),
  #endif
  #ifdef HAVE_DSHOW
  - DECLARE_BACKEND(CAP_DSHOW, "DSHOW", MODE_CAPTURE_ALL),
  + DECLARE_BACKEND(CAP_DSHOW, "DSHOW", MODE_CAPTURE_BY_INDEX),
  #endif
  // Linux, some Unix
  @@ -98,7 +98,7 @@ static const struct VideoBackendInfo builtin_backends[] =
  DECLARE_BACKEND(CAP_OPENNI2, "OPENNI2", MODE_CAPTURE_ALL),
  #endif
  #ifdef HAVE_INTELPERC
  - DECLARE_BACKEND(CAP_INTELPERC, "INTEL_PERC", MODE_CAPTURE_ALL),
  + DECLARE_BACKEND(CAP_INTELPERC, "INTEL_PERC", MODE_CAPTURE_BY_INDEX),
  #endif
  // OpenCV file-based only
  @@ -107,23 +107,23 @@ static const struct VideoBackendInfo builtin_backends[] =
  // special interfaces / stereo cameras / other SDKs
  #if defined(HAVE_DC1394_2) || defined(HAVE_DC1394) || defined(HAVE_CMU1394)
  - DECLARE_BACKEND(CAP_FIREWIRE, "FIREWIRE", MODE_CAPTURE_ALL),
  + DECLARE_BACKEND(CAP_FIREWIRE, "FIREWIRE", MODE_CAPTURE_BY_INDEX),
  #endif
  // GigE
  #ifdef HAVE_PVAPI
  - DECLARE_BACKEND(CAP_PVAPI, "PVAPI", MODE_CAPTURE_ALL),
  + DECLARE_BACKEND(CAP_PVAPI, "PVAPI", MODE_CAPTURE_BY_INDEX),
  #endif
  #ifdef HAVE_XIMEA
  DECLARE_BACKEND(CAP_XIAPI, "XIMEA", MODE_CAPTURE_ALL),
  #endif
  #ifdef HAVE_GIGE_API
  - DECLARE_BACKEND(CAP_GIGANETIX, "GIGANETIX", MODE_CAPTURE_ALL),
  + DECLARE_BACKEND(CAP_GIGANETIX, "GIGANETIX", MODE_CAPTURE_BY_INDEX),
  #endif
  #ifdef HAVE_ARAVIS_API
  - DECLARE_BACKEND(CAP_ARAVIS, "ARAVIS", MODE_CAPTURE_ALL),
  + DECLARE_BACKEND(CAP_ARAVIS, "ARAVIS", MODE_CAPTURE_BY_INDEX),
  #endif
  #ifdef HAVE_UNICAP
  - DECLARE_BACKEND(CAP_UNICAP, "UNICAP", MODE_CAPTURE_BY_FILENAME),
  + DECLARE_BACKEND(CAP_UNICAP, "UNICAP", MODE_CAPTURE_BY_INDEX),
  #endif
  #ifdef HAVE_GPHOTO2
  