[FFmpeg-user] Image extraction broken with ffmpeg, but not with mencoder. How can I fix this?

[Paul B Mahol]

On 9/4/13, James Board <jpboard2 at yahoo.com> wrote:
>>If input frame rate is smaller than output frame rate, ffmpeg will create
>
>>extra frames by default.
>>
>>If input is vfr and output is cfr than it may duplicate and/or remove
>> frames.
>
> Everyone keeps mentioning vfr and cfr.  I know what vfr and cfr mean but
> I don't see how that has anything to do with my issue, because I'm not
> creating a video as output.  I'm only creating images for every frame in
> the input.  So, can someone explain why this matters?
>
> I understand the fact that if the output is cfr and the input is vfr, then
> some frames may need to be duplicated or dropped.  But if the output is
> merely a sequence of images, why does this matter?  There's no frame rate
> in a sequence of images,

Except it is. What you are using is not simple & dumb frame extraction tool.
So before making such assumptions consult documentation.