[FFmpeg-devel] Correct use of zoompan filter in combination with other filters.

[Paul B Mahol]

On 12/11/15, Ryan Williams <ryan at ryanwilliams.id.au> wrote:
> Hoping a developer can enlighten me as to why I'm having problems chaining
> the zoompan filter to the overlay filter.
>
> When I take a single jpg, feed it into zoompan and conjure 250 frames of
> output it works fine.
> But when I attempt to take those 250 frames and use them as an input to the
> overlay filter I get dropped frames during the encoding process.
>
>
> I posted this on the users list but didn't get a response.
> http://ffmpeg.org/pipermail/ffmpeg-user/2015-December/029508.html
>
> I suspect this has something to do with the zoompan filter outputting more
> frames than it consumed as I've also encountered this problem when using the
> fps filter to increase the framerate.

Other filters may not like pts the zoompan filter returns.

>
> I can work around this problem by using intermediate files, named pipes or
> the 'fifo' filter but I'd love to know is there something I'm missing or at
> the least a little more understanding of why this problem occurs.
>
>
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