# FFmpeg / iOS Video Taming

## General Options:

# These settings may be applied to both the INPUT and the OUTPUT
# of the FFmpeg command.

-r 30 # set the frame rate of the video to Apple's recommended 30 fps

-pix_fmt yuv420p # set the output video's pixel format
                 # QuickTime uniquely cannot handle any
                 # format other than yuv420p and it will
                 # complain if anything else is found
                 # in the container metadata

## Output Options:

# Only add these arguments to the OUTPUT settings
# of your FFmpeg command.

-copyinkf  # By default, FFmpeg does not copy the non-key frames
           # found at the beginning of most iOS-created QT media
           # when doing a stream-copy mux.
           # This option will essentially re-create the unique
           # quicktime transport feature that causes video playback
           # to hang right at the beginning of the file, so that AV
           # sync can catch up

-vsync 2   # '2' == 'vfr'. Don't let FFmpeg sync the video stream any other way!

-async 1   # Putting '1' here will tell FFmpeg to attempt to stretch/squeeze the
           # start of the audio stream such that it will need no further treatment
           # later on in the presentation of the media container's content
           
-vf setpts=PTS-STARTPTS # This is the best way to ensure that the video's PTS is 
                        # correctly transferred to the new container file without 
                        # nudging back out of sync with the audio stream.

-bsf:v h264_mp4toannexb # A bitstream filter that will
                        # allow iOS MP4s to successfully
                        # convert to MPEG-2 TS for HLS creation.