img2: document the options available

doc/demuxers.texi

@@ -64,6 +64,19 @@ Note that the pattern must not necessarily contain "%d" or
 avconv -i img.jpeg img.png
 @end example
 
+@table @option
+@item -pixel_format @var{format}
+Set the pixel format (for raw image)
+@item -video_size   @var{size}
+Set the frame size (for raw image)
+@item -framerate    @var{rate}
+Set the frame rate
+@item -loop         @var{bool}
+Loop over the images
+@item -start_number @var{start}
+Specify the first number in the sequence
+@end table
+
 @section applehttp
 
 Apple HTTP Live Streaming demuxer.

doc/muxers.texi

@@ -168,6 +168,11 @@ Note also that the pattern must not necessarily contain "%d" or
 avconv -i in.avi -f image2 -frames:v 1 img.jpeg
 @end example
 
+@table @option
+@item -start_number @var{number}
+Start the sequence from @var{number}.
+@end table
+
 @section MOV/MP4/ISMV
 
 The mov/mp4/ismv muxer supports fragmentation. Normally, a MOV/MP4