[FFmpeg-user] Deinterlace and change framerate with -vcodec copy

Andrew Berg bahamutzero8825 at gmail.com
Mon May 23 21:18:48 CEST 2011

On 2011.05.23 12:36 PM, Peter Bašista wrote:
> I have given up deinterlacing, because
> I have spotted this sentence in the manual page of ffmpeg:
> "... but deinterlacing introduces losses."
> which was enough for me to give it up.
Yadif is very good. It's also worth mentioning that deinterlacing is
necessary to display interlaced content on a progressive display. Media
players and HDTVs do this during rendering. Technically, deinterlacing
filters irreversibly alter the video, but only very poor quality filters
hurt quality, so such wording in the man page is misleading. You can
search this list (and the MEncoder-users list) for tons of discussion on
deinterlacing. In short, it's almost always a good idea to deinterlace
with a high-quality filter like Yadif.
> So, I will try to summarize and I will welcome any corrections:
> Deinterlacing:
> 1) is only possible with reencoding
Video filters require decoding; it is not necessary to reencode the
changed video. In most cases, you will want to encode the uncompressed
video, but it's an important distinction - filters can be applied
losslessly when rendering instead of encoding.
> 2) always introduces losses
High-quality filters introduce very minimal loss.

In any case, be sure to change the frame rate to 24000/1001 fps instead
of 24fps. Also, you might need to adjust the samplerate of the audio if
the original was adjusted (which I would assume is the case, but I've
never been in PAL land). It /might/ be possible to make your audio sync
up untouched with container options, but I'm not sure how to go about
doing that.

More information about the ffmpeg-user mailing list