Hi, On Mon, 11 Mar 2013 19:23:12 -0400, Keith Lawson <[email protected]> wrote: > > > Hello, > > I'm attempting "mask" a time selection of a video using the > split, select and delogo filters but I just can't seem to get my head > around the split filter. Looking at the start of the example[1] at the > start of the libav documentation it certainly appears that what I want > to do is possible but I'm struggling to build the proper filter. > > For > example I would like to mask the entire video of a 640x480 video from 0 > - 10 seconds. Based on the example in the docs and this[2] stackoverflow > posting I've tried things like: > > ./avconv -i input -vf "[in] split > [T1], fifo, [T2] overlay [out]; [T1] > fifo,select='gte(t,0)*lte(t,10)',delogo=x=0:y=0:w=640:h=480 [T2]" > output > > Hoping that would do something like : > > input --> split --> fifo > -----------------------------------------------------> overlay --> > output > | ^ > | | > +------> fifo --> select 0-10 seconds --> delogo > --------+ > > But I'm either completely unable to get the command to run or > when I do I don't get the desired results. Any help or suggestions for a > more appropriate approach would be greatly appreciated. >
First of all, when you ask for help with avconv, please always attach full commandlines that you tried and the output avconv printed. That eliminates a lot of pointless guessing on our part. Secondly, I'm afraid those docs are a little obsolete. For one thing, you should never insert the fifo filter manually. It is always done automatically when needed. Also in those complex situations when you deal with filters with multiple inputs or outputs, it's better to explicitly label everything and not rely on automatic mappings, as it's more clear what's going on. In any case, i think that -vf '[in] split [split_main][split_delogo]; [split_main][delogoed]overlay[out]; [split_delogo] select=gte(t\,0)*lte(t\,10),delogo=<delogo params>[delogoed];' should do roughly what you want EXCEPT for a problem with overlay. In its current form, after overlay gets an EOF on its secondary input, it will continue overlaying the last image from it. That is useful e.g. when you want to overlay a single-picture logo on a video, but in this case you want it to stop overlaying once the secondary stream ends. That cannot be done currently, but should be quite easy to implement. I will look into it soonish. -- Anton Khirnov _______________________________________________ libav-tools mailing list [email protected] https://lists.libav.org/mailman/listinfo/libav-tools
