Add documentation for the image2 demuxer.

Originally committed as revision 26283 to svn://svn.ffmpeg.org/ffmpeg/trunk

doc/demuxers.texi

@@ -18,4 +18,45 @@ enabled demuxers.
 
 The description of some of the currently available demuxers follows.
 
+@section image2
+
+Image file demuxer.
+
+This demuxer reads from a list of image files specified by a pattern.
+
+The filename of each file to read must contain a sequential number,
+which specifies the position of the file in the sequence.
+
+The pattern must contain the string "%d" or "%0@var{N}d", which
+specifies the position of the characters representing the seqential
+number in each filename matched by the pattern. If the form
+"%d0@var{N}d" is used, the string representing the number in each
+filename is 0-padded and @var{N} is the total number of 0-padded
+digits representing the number. The literal character '%' can be
+specified in the pattern with the string "%%".
+
+The first filename of the file sequence specified by the pattern must
+contain a number inclusively contained between 0 and 4, all the
+following numbers must be sequential.
+
+The pattern may contain a suffix which is used to automatically
+determine the format of the images contained in the files.
+
+For example the pattern "img-%03d.bmp" will match a sequence of
+filenames of the form @file{img-001.bmp}, @file{img-002.bmp}, ...,
+@file{img-010.bmp}, etc.; the pattern "i%%m%%g-%d.jpg" will match a
+sequence of filenames of the form @file{i%m%g-1.jpg},
+@file{i%m%g-2.jpg}, ..., @file{i%m%g-10.jpg}, etc.
+
+The size, the pixel format, and the format of each image must be the
+same for all the files in the sequence.
+
+The following example shows how to use @file{ffmpeg} for creating a
+video from the images in the file sequence @file{img-001.jpeg},
+@file{img-002.jpeg}, ..., assuming an input framerate of 10 frames per
+second:
+@example
+ffmpeg -r 10 -f image2 -i 'img-%03d.jpeg' out.avi
+@end example
+
 @c man end INPUT DEVICES