patched ffmpeg nov 2

source/patched-ffmpeg-mt/doc/indevs.texi

 @chapter Input Devices
 @c man begin INPUT DEVICES
 
 Input devices are configured elements in FFmpeg which allow to access
 the data coming from a multimedia device attached to your system.
 
 When you configure your FFmpeg build, all the supported input devices
 are enabled by default. You can list all available ones using the
 configure option "--list-indevs".
 
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 ffplay -f video4linux2 /dev/video0
 
 # Grab and record the input of a video4linux2 device, autoadjust size.
 ffmpeg -f video4linux2 -i /dev/video0 out.mpeg
 @end example
 
 @section vfwcap
 
 VfW (Video for Windows) capture input device.
 
+The filename passed as input is the capture driver number, ranging from
+0 to 9. You may use "list" as filename to print a list of drivers. Any
+other filename will be interpreted as device number 0.
+
 @section x11grab
 
 X11 video input device.
 
 This device allows to capture a region of an X11 display.
 
 The filename passed as input has the syntax:
 @example
 [@var{hostname}]:@var{display_number}.@var{screen_number}[+@var{x_offset},@var{y_offset}]
 @end example
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 For example to grab from @file{:0.0} using @file{ffmpeg}:
 @example
 ffmpeg -f x11grab -r 25 -s cif -i :0.0 out.mpg
 
 # Grab at position 10,20.
 ffmpeg -f x11grab -25 -s cif -i :0.0+10,20 out.mpg
 @end example
 
 @c man end INPUT DEVICES