[Libav-user] Exposing -start_number

[Gonzalo Garramuño]

I would like to use the PNG reader that comes with FFMPEG in my program 
as it is multithreaded and quite fast.  However, I don't know how to set 
the starting frame number ( -start_number ) nor the length of frames to 
read.  Reading img2dec.c, I found out about VideoDemuxData.  Currently, 
the class VideoDemuxData is private to libavformat, and is located in a 
private .h file (img2.h).  So I am stumped.

My question is: is there any way in libav to set the value of 
-start_number or, more to the point, have the png reader start/end at a 
particular frame?

Thanks in advance.

-- 
Gonzalo Garramuño