The first link was supposed to be this one https://ffmpeg.org/ffmpeg-filters.html#Text-expansion
On Thu, Apr 30, 2015 at 12:32 PM, Shlomo Morosow <[email protected]> wrote: > Sorry email was sent before complete: > > https://www.ffmpeg.org/ffmpeg-utils.html#Expression-Evaluation > > I regularly use this in many filters and it works just as expected, it's > just that I ran into an issue with the fade filter. > > Thanks, > Shlomo > > On Thu, Apr 30, 2015 at 12:31 PM, Shlomo Morosow <[email protected]> > wrote: > >> Thanks Moritz, >> The reason I need to use mathematical values is because I'd like to make >> a preset command to fade out the last second of any given video and since >> the fade filter needs to be instructed on when to begin in relation to the >> start of the video I need to be able to tell it to start at duration minus >> one second. >> >> Regarding the documentation on using expressions in filters, this can be >> found in the the text-expansion section of the ffmpeg filters documentation: >> >> https://www.ffmpeg.org/ffmpeg-utils.html#Expression-Evaluation >> >> >> To which can be applied the the expressions-evaluation found in the >> ffmpeg expression-evaluation documentation: >> >> >> >> On Thu, Apr 30, 2015 at 3:50 AM, Moritz Barsnick <[email protected]> >> wrote: >> >>> On Wed, Apr 29, 2015 at 17:57:43 -0400, Shlomo Morosow wrote: >>> > I need the ability to input mathematical values for setting the start >>> time >>> > (st) on the "fade" filter, I've attempted to use an expression and >>> this >>> > particular filter does not seem to work with expressions, nor simple >>> math >>> > as "10*1". >>> >>> As far as I can tell, you are right in saying that this filter (or at >>> least the "st" argument) does not support expressions. >>> >>> For "st", it also doesn't make much sense. Expressions are used not for >>> convenient calculation, but rather for expressing something which >>> changes over the course of a media stream, i.e. depending on frame >>> count, timestamp or the likes. "st" can only ever express a constant >>> value. >>> >>> If you need to do math, you can let your interpreter (on Unix: the >>> shell) do the math for you. I'm not sure how to do this on Windows (and >>> usually avoid it, even professionally). ;-) >>> >>> > ffmpeg.exe -y -ss "0:00:20" -t "0:00:10" -i input.avi -filter_complex >>> > "fade=out:st=%{expr\\\: (10-1)}:d=1" -f dvd -target ntsc-dvd -r 29.97 >>> > -aspect 4:3 -b:v 4500k -mbd rd -trellis 1 -flags +mv0 -cmp 0 -subcmp 2 >>> -b:a >>> > 128k output.vob >>> >>> Where is it documented that an expression is expressed as such? >>> >>> Moritz >>> _______________________________________________ >>> ffmpeg-user mailing list >>> [email protected] >>> http://ffmpeg.org/mailman/listinfo/ffmpeg-user >>> >> >> >> >> -- >> >> *Shlomo Morosow* >> >> *The Living Archive · Archive Manager* >> >> 781 East New York Ave, Brooklyn, NY 11203 >> *t *718.774.1800 x1450 *c *347.693.7196 >> > > > > -- > > *Shlomo Morosow* > > *The Living Archive · Archive Manager* > > 781 East New York Ave, Brooklyn, NY 11203 > *t *718.774.1800 x1450 *c *347.693.7196 > -- *Shlomo Morosow* *The Living Archive · Archive Manager* 781 East New York Ave, Brooklyn, NY 11203 *t *718.774.1800 x1450 *c *347.693.7196 _______________________________________________ ffmpeg-user mailing list [email protected] http://ffmpeg.org/mailman/listinfo/ffmpeg-user
