Below is the ffmpeg command to convert still images into video with the delay of 5 seconds to each image.
ffmpeg -f image2 -r 1/5 -i img%03d.png -vcodec libx264 out.mp4
This command is working fine. I just wanted to know, whether it is possible to put two parameters for -vcodec, as along with libx264, I also want to use H264, to make that video work even on i-phone.