[FFmpeg-user] Multiple xfade in one run

[Paul B Mahol]

On Mon, Jul 4, 2022 at 11:30 PM Michael Koch <astroelectronic at t-online.de>
wrote:

> Am 04.07.2022 um 18:46 schrieb Cecil Westerhof via ffmpeg-user:
> > Paul B Mahol <onemda at gmail.com> writes:
> >
> >> On Mon, Jul 4, 2022 at 6:15 PM Cecil Westerhof via ffmpeg-user <
> >> ffmpeg-user at ffmpeg.org> wrote:
> >>
> >>> Some time ago I was experimenting with xfade. I wanted to know how to
> >>> use several in one run. Now I really needed it, so I did some digging
> >>> and found this:
> >>>       ffmpeg -y                  \
> >>>        -i input0.mkv             \
> >>>        -i input1.mkv             \
> >>>        -i input2.mkv             \
> >>>        -i input3.mkv             \
> >>>        -i input4.mkv             \
> >>>        -i input5.mkv             \
> >>>        -i input6.mkv             \
> >>>        -i input7.mkv             \
> >>>        -i input8.mkv             \
> >>>        -i input9.mkv             \
> >>>        -vcodec libx264           \
> >>>        -crf    26                \
> >>>        -preset veryfast          \
> >>>        -filter_complex "
> >>>          [0:a][1:a] acrossfade=d=4[a1];
> >>>          [0:v][1:v] xfade=transition=hlslice:
> >>>                            duration=4:
> >>>                            offset=308[v1];
> >>>
> >>>          [a1][2:a] acrossfade=d=4[a2];
> >>>          [v1][2:v] xfade=transition=vertopen:
> >>>                            duration=4:
> >>>                            offset=357[v2];
> >>>
> >>>          [a2][3:a] acrossfade=d=4[a3];
> >>>          [v2][3:v] xfade=transition=circlecrop:
> >>>                            duration=4:
> >>>                            offset=533[v3];
> >>>
> >>>          [a3][4:a] acrossfade=d=4[a4];
> >>>          [v3][4:v] xfade=transition=rectcrop:
> >>>                            duration=4:
> >>>                            offset=1016[v4];
> >>>
> >>>          [a4][5:a] acrossfade=d=4[a5];
> >>>          [v4][5:v] xfade=transition=slideup:
> >>>                            duration=4:
> >>>                            offset=1158[v5];
> >>>
> >>>          [a5][6:a] acrossfade=d=4[a6];
> >>>          [v5][6:v] xfade=transition=wiperight:
> >>>                            duration=4:
> >>>                            offset=1473[v6];
> >>>
> >>>          [a6][7:a] acrossfade=d=4[a7];
> >>>          [v6][7:v] xfade=transition=horzclose:
> >>>                            duration=4:
> >>>                            offset=1661[v7];
> >>>
> >>>          [a7][8:a] acrossfade=d=4[a8];
> >>>          [v7][8:v] xfade=transition=diagbl:
> >>>                            duration=4:
> >>>                            offset=2082[v8];
> >>>
> >>>          [a8][9:a] acrossfade=d=4[a9];
> >>>          [v8][9:v] xfade=transition=slideright:
> >>>                            duration=4:
> >>>                            offset=2211[v9]
> >>>        "                         \
> >>>        -map '[v9]' -map '[a9]'   \
> >>>        output.mkv
> >>>
> >>> I hope there are better ways, because there are some problems with it.
> >>> For example it needs a lot of memory. (24 GB)
> >>>
> >> Could use (a)movie filters and only use such filter when actually
> needed in
> >> graph.
> > I am concerning ffmpeg still a newbie. What do you mean by this?
> >
>
> I also didn't understand it.
>

Before each new input to xfade use movie filter to set input file.
Similar for audio.

Your current solution is problematic because it starts decoding everything
from start and that used lots of memory
to keep timestamps in sync when they are not really needed.

>
> Michael
>
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