Zend certified PHP/Magento developer

Change video from 30 FPS to 1 FPS keeping duration and keeping audio in sync [duplicate]

Which FFMPEG command line could I use to:

  • change FPS from 30 to 1 FPS
  • keeping original video duration
  • keeping original audio in sync
  • if it goes – then without re-encoding
  • It MUST drop frames

The video is a slide show of book texts that accompany audio. My idea is to reduce its size while keeping te possibility to seek, keeping still picture quality and keeping original audio quality.