[FFmpeg-user] Avoid yadif auto format for progressive bgra

Tim Nicholson nichot20 at yahoo.com
Tue May 8 09:16:47 CEST 2012

On 07/05/12 07:55, Robert Nagy wrote:
> I have a problem with yadif where a progressive bgra video stream is
> converted to yadif supported formats even though yadif does not do anything
> to the stream (auto_enable==true).

I would hazard a guess that in order for YADIF to decide to do nothing
it has to be able to understand the stream first.

> My question is whether I can solve this using a split and some form of
> "conditional" filter? e.g.
>                       /-> if interlaced   -> auto-format -> yadif ->\
> source->split ->
>  -> merge -> sink
>                       \-> if progressive ->                              ->/
> Is this possible? And will it work as I assume it would? I guess it would
> not work for streams with both interlaced and progressive frames, but does
> such stream exist?

In terms of flagging hopefully not. In terms of content, often. Which
begs the question, how do you determine the whether or not material is
interlaced or not?

The idet filter makes a good stab at content based analysis *but* it
doesn't work on bgra sources as it auto inserts a scale 0 filter to
convert to YUV first and any auto inserted filter seems to stuff its

Or do you trust the interlace flag. this requires that material is both
flagged correctly by the coding system, *and* the flag is correctly
interpreted by ffmpeg. Currently results suggest that this is not nearly
good enough to be relied upon.

> [...]


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