[FFmpeg-user] Forcing ffmpeg to detect duration reliably

[Robert Krüger]

On Fri, Mar 1, 2013 at 10:51 AM, Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:
> Robert Krüger <krueger <at> lesspain.de> writes:
>
>> I assumed that if I make probesize large enough
>> (larger than the entire file in my case, which is a
>> bit over 4 MB) that ffmpeg would be able to detect
>> the accurate duration
>
> Just in case this is not clear:
> -analyzeduration has nothing to do with analyzing the
> duration of the input file, it means the duration (ms)
> used to analyze the sample.
yes, I saw stefano's commit with the respective documentation change
and should have left it out of the command line.

>
> You can use "ffmpeg -i input -f null -" to determine
> the actual duration of input.
> (In your sample case, the input video is vbr, meaning
> there is no way of knowing the duration without
> going through the whole file as in decoding. You can
> speed up this operation but you have to invoke the
> decoder.)
OK, thank you for that information. Just to be sure, by decoding you
mean bitstream parsing as in av_parser_parse2 (see other thread on
libav-user) , not necessarily decoding any picture data, right?

Regards,

Robert