[FFmpeg-user] Extract image every x frames?

[Peter B.]

On 08/07/2012 12:12 AM, Nicolas George wrote:
> Le decadi 20 thermidor, an CCXX, Peter B. a écrit :
>> It outputs frame 0 (correct), frame #1500 (correct) and then infinitely
>> write frame #1500 again and again... :(
>> The duration of the source video is 45000 frames at 25fps. The command
>> below exported 100 frames (should have been 30).
>>
>> Anyone got any hint why this is happening?
> See the note on "-vsync" in the example for the "tile" filter, this is
> probably the same phenomenon.
>
I've looked up the note [1], which reads:

"The ‘-vsync 0’ is necessary to prevent |ffmpeg| from duplicating each
output frame to accomodate the originally detected frame rate. "

I've tried with:
//---------------------
$ ffmpeg -i video.avi -vf select='not(mod(n\,1500))' -f image2 -sameq
-vsync 0 delme_images/%03d.jpg
//---------------------

Same result: Gets stuck at frame #1500 and exports 100 images.

Hm...

Thanks,
Pb


== References:
[1] http://ffmpeg.org/ffmpeg.html#tile