[FFmpeg-user] When to determine frames are progressive or interlaced ?
Carl Eugen Hoyos
cehoyos at ag.or.at
Mon Jan 7 17:05:01 CET 2013
Christian Ebert <blacktrash <at> gmx.net> writes:
> * James Darnley on Wednesday, December 19, 2012 at 14:50:06 +0100
> > On 2012-12-19 13:12, Christian Ebert wrote:
> >> Hm, a vob file for instance is in all probability interlaced, and
I own a few dvd's, they are all progressive (they are all movies
or television series that usually cannot be interlaced), only
very few samples in our database are interlaced DVD, typically
music or live television recordings (or both).
But perhaps you mean telecined?
> >> at least it "looks" like in this case for once mediainfo gives
> >> more meaningful info:
> >> $ mediainfo --Inform='Video;%ScanType%' test.vob
> >> Interlaced
> >> $ mediainfo --Inform='Video;%ScanOrder%' test.vob
> >> TFF
> > This tells you absolutely nothing about the *content* and is of no more
> > use than ffmpeg's flags about the manner in which a video was encoded.
> Fair enough. It's very useful though when I want to know whether
> I need to apply a deinterlace filter or not. The idet filter does
> not help then.
I wonder what you mean here.
I suspect (and it is what James writes above) that mediainfo
only tells you if the video was encoded using an encoder
setting "interlaced" or not. It does not tell anything about
the actual content.
If you use a deinterlacer on progressive content (no matter
if it was encoded as "interlaced" or not), you permanently
damage the frames. Otoh, you can encode interlaced material
as "progressive" (or use an encoder that does not support
"interlaced") and only visual inspection or a filter like
idet will tell you if you should use a deinterlacer or not.
So I really don't see in which situation "the idet filter
does not help" - actually it is exactly the other way round.
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