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

[Paul B Mahol]

On 9/2/13, James Board <jpboard2 at yahoo.com> wrote:
>>> Please tell me I didn't waste 4 hours because of an ffmpeg bug.
>
>>
>>You never mentioned what you are actually doing.
>
> I'm converting a video file to a sequence of image files.  I used both
> ffmpeg and
> mencoder (actually, mplayer) (I mentioned this is the first line).  Here is
> an example:
>
>     ffmpeg -i IN.avi -q:v 4 -f image2 %08d.jpg
>
>>For image demuxer you need to set input frame rate or default one
>>will be used, which may not be what you want.
>
> The image2 muxer documentation doesn't mention this.  How do I
> specify an input frame rate (24000/1001) for the above command?

You need it for whatever reads images not for creating them....

So it is needed for DEmuxer, not for muxer (unless you want to
dupe/remove random frames).

>
> Also, I have a huge edit list which took 4 hours to generate.  Is there
> some formula I can use which will convert the frame numbers that ffmpeg
> used as output for the jpeg images to the  equivalent frame numbers that
> ffmpeg
> will use as input to the select filter?

Use same frame rate for input as for output, its simple enough.