[FFmpeg-user] Issue with split filter

Dave Cleal dmc at vyclone.com
Thu Jan 24 19:02:01 CET 2013


Oops, sorry, accident :(

- Dave

On Thu, Jan 24, 2013 at 1:02 PM, Paul B Mahol <onemda at gmail.com> wrote:
> On 1/24/13, Dave Cleal <dmc at vyclone.com> wrote:
>> Hi,
>>
>> I'm trying to use a complex filter to replace severeal existing ffmpeg
>> steps with one, to get the job done faster (we do this a lot).
>>
>> This
>>
>> ffmpeg -y -i bottom.mp4 -i top.mp4 -i filler.mp4 -filter_complex
>> "[2:0]split=4[f1][f2][f3][f4];[0:0]setsar=0:1[video0];
>> [f1]select=lt(n\,125)[leader0]; [f2]select=lt(n\,78)[trailer0];
>> [leader0][video0][trailer0]concat=n=3[filled0];
>> [1:0]setsar=0:1[video1]; [f3]select=lt(n\,0)[leader1];
>> [f4]select=lt(n\,45)[trailer1];
>> [leader1][video1][trailer1]concat=n=3[filled1];
>> [filled0]pad=240:360:0:180 [large]; [large][filled1]
>> overlay=0:0,setsar=1:1" -r 30 -b:v 600k -vcodec libx264 looksbad.mp4
>>
>> does something different to
>>
>> ffmpeg -y -i bottom.mp4 -i top.mp4 -i filler.mp4 -i filler.mp4 -i
>> filler.mp4 -i filler.mp4 -filter_complex "[0:0]setsar=0:1[video0];
>> [2:0]select=lt(n\,125)[leader0]; [3:0]select=lt(n\,78)[trailer0];
>> [leader0][video0][trailer0]concat=n=3[filled0];
>> [1:0]setsar=0:1[video1]; [4:0]select=lt(n\,0)[leader1];
>> [5:0]select=lt(n\,45)[trailer1];
>> [leader1][video1][trailer1]concat=n=3[filled1];
>> [filled0]pad=240:360:0:180 [large]; [large][filled1]
>> overlay=0:0,setsar=1:1" -r 30 -b:v 600k -vcodec libx264 looksgood.mp4
>>
>> As far as I can tell, the only difference between these is that the
>> first uses split to get four copies of an input stream, and the second
>> just adds it as an input four times. My understanding is that these
>> two should be equivalent: is there supposed to be a difference?
>>
>> It seems that the second does what I expect: the first drops frames,
>> freezes here and there, and is 77 frames shorter than I expect it to
>> be.
>>
>> Not too fussed as I do have a workaround, but in some realistic (and
>> more complex) examples, I will end up with an awful lot of "-i..."s! So
>> it'd be nice to use split if I can.
>>
>> Thanks in advance for any advice
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>>
>
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