png_uint_32 png_set_acTl(png_structp png_ptr, png_infop info_ptr, png_uint_32 num_frames, png_uint_32 num_plays);

Sets the number of frames and the number of iterations in the animated image.


void png_set_next_frame_fcTl(png_structp png_ptr, png_infop info_ptr, png_uint_32 width, png_uint_32 height, png_uint_32 x_offset, png_uint_32 y_offset, png_uint_16 delay_num, png_uint_16 delay_den, png_byte dispose_op, png_byte blend_op);

This function is probably useless and will be removed in a future version. It works but does the same thing as write_frame_head()