[FFmpeg-user] specify duration in frames

[Tom Evans]

On Sat, May 10, 2014 at 6:43 PM, Sam Logan <shapableline at gmail.com> wrote:
> On 5/7/14, Elliott Balsley <elliottbalsley at gmail.com> wrote:
>> Is there some way to specify a duration in frames?  Using the
>> HH:MM:SS.xxx syntax seems imprecise.  It would be great to have an
>> option for HH:MM:SS:FF.
>
> The last I heard (about a year or so ago), in FFmpeg, there was no way
> to seek to specific frames with either -ss or -t, nor any similar
> options that would do so. The best you can do is to make your own
> calculations based on framerate and timestamps and hoping that
> rounding/precision errors don't ruin the results, and unfortunately,
> much of the time rounding/precision errors will indeed ruin the
> results and not get you the exact frames that you want.
>
> I have no idea why this functionality does not exist, as it is such
> basic and obvious functionality that it is one of the most glaring
> omissions in FFmpeg, something that users have asked for for years
> that the developers have never added to the best of my knowledge.

What a load of bollocks.

You can set a duration in number of frames using the -frames flag.

https://www.ffmpeg.org/ffmpeg.html

Alternatively, you can use the select filter to select out the
specific frames you want.

https://www.ffmpeg.org/ffmpeg-filters.html#select_002c-aselect


Cheers

Tom