doc/encoders: very basic FFv1 documentation

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

doc/encoders.texi

@@ -529,6 +529,44 @@ Selected by Encoder (default)
 
 @end table
 
+@anchor{ffv1}
+@section ffv1
+
+FFv1 Encoder
+
+@subsection Options
+
+The following options are supported by FFmpeg's FFv1 encoder.
+
+@table @option
+@item context
+Sets the context size, 0 (default) is small, 1 is big.
+
+@item coder
+Set the coder,
+@table @samp
+@item rice
+Golomb rice coder
+@item range_def
+Range coder with default table
+@item range_tab
+Range coder with custom table
+@end table
+
+@item slicecrc
+-1 (default, automatic), 1 use crc with zero initial and final state, 2 use crc with non zero initial and final state
+
+@item qtable
+@table @samp
+@item default
+default, automatic
+@item 8bit
+use 8bit default
+@item greater8bit
+use >8bit default
+@end table
+@end table
+
 @anchor{flac}
 @section flac