[FFmpeg-user] Cross fading of videos

Tony Mobily merc at mobily1.com
Thu Dec 17 02:16:45 CET 2015


Hi,

Question: how would you fix my command, so that it doesn't need fifos?
That is, given this command;


/tmp/ffmpeg -i segment2s.mp4 -i segment1s.mp4 -an \
-filter_complex \
"   [0:v]trim=start=0:end=9,setpts=PTS-STARTPTS[firstclip];
    [1:v]trim=start=1,setpts=PTS-STARTPTS[secondclip];
    [0:v]trim=start=9:end=10,setpts=PTS-STARTPTS[fadeoutsrc];
    [1:v]trim=start=0:end=1,setpts=PTS-STARTPTS[fadeinsrc];
    [fadeinsrc]format=pix_fmts=yuva420p,
                fade=t=in:st=0:d=1:alpha=1[fadein];
    [fadeoutsrc]format=pix_fmts=yuva420p,
                fade=t=out:st=0:d=1:alpha=1[fadeout];
    [fadein]fifo[fadeinfifo];
    [fadeout]fifo[fadeoutfifo];
    [fadeoutfifo][fadeinfifo]overlay[crossfade];
    [firstclip][crossfade][secondclip]concat=n=3[output];
    [0:a][1:a] acrossfade=d=1 [audio]
" \
-map "[output]" -map "[audio]" result.mp4

How can it be changed without using fifos, and yet getting around
https://trac.ffmpeg.org/ticket/4804 ?

Merc.
ᐧ

On 16 December 2015 at 09:25, Tony Mobily <merc at mobily1.com> wrote:

> Hi,
>
> Hopefully that bug will get fixed soon...
>
> Merc.
>>
> On 16 December 2015 at 07:47, Ryan Williams <rwilliams at busivid.com> wrote:
>
>> I discovered I could avoid using the 'fifo' filter by providing the same
>> input file multiple times rather than reading from the same input source
>> stream multiple times in the filter graph.
>>
>> -----Original Message-----
>> From: ffmpeg-user [mailto:ffmpeg-user-bounces at ffmpeg.org] On Behalf Of
>> Tony Mobily
>> Sent: Wednesday, 16 December 2015 10:44
>> To: FFmpeg user questions
>> Subject: Re: [FFmpeg-user] Cross fading of videos
>>
>> Hi,
>>
>> Is that the bug you were getting around when passing the same file name
>> multiple times?
>>
>> Merc.
>>>>
>> On 16 December 2015 at 07:37, Ryan Williams <rwilliams at busivid.com>
>> wrote:
>>
>> > Please to see you have it working, however the 'fifo' filter stores
>> > frames in memory (I believe in an uncompressed format).
>> > You should do testing with longer videos to ensure you don't run out
>> > of resources.
>> >
>> > -----Original Message-----
>> > From: ffmpeg-user [mailto:ffmpeg-user-bounces at ffmpeg.org] On Behalf Of
>> > Tony Mobily
>> > Sent: Tuesday, 15 December 2015 16:43
>> > To: FFmpeg user questions
>> > Subject: Re: [FFmpeg-user] Cross fading of videos
>> >
>> > Hi Ryan,
>> >
>> > Well, now I to know FFMpeg!
>> > But I have to say, this is what we ended up with. It's simple, it's
>> > straightforward, and it just seems to work...
>> >
>> >
>> > /tmp/ffmpeg -i segment2s.mp4 -i segment1s.mp4 -an \ -filter_complex \
>> > "   [0:v]trim=start=0:end=9,setpts=PTS-STARTPTS[firstclip];
>> >     [1:v]trim=start=1,setpts=PTS-STARTPTS[secondclip];
>> >     [0:v]trim=start=9:end=10,setpts=PTS-STARTPTS[fadeoutsrc];
>> >     [1:v]trim=start=0:end=1,setpts=PTS-STARTPTS[fadeinsrc];
>> >     [fadeinsrc]format=pix_fmts=yuva420p,
>> >                 fade=t=in:st=0:d=1:alpha=1[fadein];
>> >     [fadeoutsrc]format=pix_fmts=yuva420p,
>> >                 fade=t=out:st=0:d=1:alpha=1[fadeout];
>> >     [fadein]fifo[fadeinfifo];
>> >     [fadeout]fifo[fadeoutfifo];
>> >     [fadeoutfifo][fadeinfifo]overlay[crossfade];
>> >     [firstclip][crossfade][secondclip]concat=n=3[output];
>> >     [0:a][1:a] acrossfade=d=1 [audio]
>> > " \
>> > -map "[output]" -map "[audio]" result.mp4
>> >
>> > That was exactly my approach; I was doing my best to make it happen,
>> > doing exactly that: get the first video minus the last second, get the
>> > second video minus the initial second, get the two versions of the
>> > "middle second", and then fade them together. And voila', you have a
>> > well faded video. The audio is ridiculosly simple too.
>> >
>> > As I was banging my head against the wall making this happen, Guido
>> > found this post:
>> >
>> >
>> > http://superuser.com/questions/1001039/what-is-an-efficient-way-to-do-
>> > a-video-crossfade-with-ffmpeg
>> >
>> > All I had to do is fix the syntax a little, add the audio, and voila'!
>> >
>> > Just in case you can use it for your project -- free of charge! :D
>> >
>> > Thanks for your answer...
>> >
>> > Merc.
>> >
>> >
>> > On 11 December 2015 at 15:44, Ryan Williams <ryan at ryanwilliams.id.au>
>> > wrote:
>> >
>> > > Please note that I haven't tested any of the following suggestions.
>> > > I do however have dissolve with crossfade working a project of mine
>> > > and I have based these suggestions off working code.
>> > >
>> > > 1) Dissolve (Assuming the resolution of both videos is 1280x720 and
>> > > the audio format is identical)
>> > >
>> > > Notes:
>> > > '+9/TB' represents (length of 1st video in seconds - length of
>> > > dissolve in
>> > > seconds)
>> > > 'ns=43076’ represents (1 second at 44100 Hz sample rate - 1024
>> > > samples) to work around a bug I reported (which may've been fixed
>> > already).
>> > > The reason for including the same files multiple times is a work
>> > > around filters which "scrub" (trim, atrim, select etc) thus causing
>> > > buffering problems during encoding.
>> > >
>> > > Visuals Explained:
>> > > * Create a 1 second fade in from the start of the 2nd video to be
>> > > the transition.
>> > > * Overlay the transition onto the 1st video so that the end lines up.
>> > > * Take the remainder of the 2nd video and concatenate it on the end.
>> > >
>> > > Audios Explained:
>> > > * Cossfade the 2nd videos audio with the first with a 1 second
>> > > overlap (Allowing for the 1024 sample bug I reported)
>> > > * Truncate that new audio stream to be the same length as the first
>> > > video
>> > > * Take the remainder of the 2nd videos audio and append it to the end.
>> > >
>> > > The reason for making the audio in 2 parts is so that each part can
>> > > be resynced with the visuals in the concat filter.
>> > > If you attempt to conjure the visuals completely separate from the
>> > > audio you may get lip sync issues during playback of the 2nd clip.
>> > >
>> > > ffmpeg \
>> > >  -y \
>> > >  -i "2.mp4" \
>> > >  -i "1.mp4" \
>> > >  -i "2.mp4" \
>> > >  -i "1.mp4" \
>> > >  -i "2.mp4" \
>> > >  -i "2.mp4" \
>> > >  -filter_complex " \
>> > >    [0:a] anullsink; \
>> > >    [0:v] trim='duration=1', format='pix_fmts=yuva420p',
>> > > fade='alpha=1:d=1:t=in', setpts='PTS-STARTPTS+9/TB' [transition-v];
>> > > \
>> > >
>> > >    [1:v][transition-v] overlay='eval=init', setpts='PTS-STARTPTS'
>> > > [scene-0]; \
>> > >    [2:v] select='e=gte(t\, 1)', setpts='PTS-STARTPTS',
>> > > format='pix_fmts=yuva420p' [scene-1]; \
>> > >
>> > >    [3:a][4:a] acrossfade='ns=43076', atrim='duration=10' [track-0]; \
>> > >    [5:a] atrim='start=1', asetpts='PTS-STARTPTS' [track-1]; \
>> > >
>> > >    [scene-0][track-0] [scene-1][track-1] concat='n=2:v=1:a=1'
>> > > [output-v][output-a] \
>> > >  " \
>> > >  -map '[output-a]' \
>> > >  -strict experimental -acodec aac \
>> > >  -map '[output-v]' \
>> > >  -s 1280x720 \
>> > >  -vcodec mpeg4 \
>> > >  -pix_fmt +yuvj420p \
>> > >  -q:v 0 \
>> > >  "output.mp4"
>> > >
>> > >
>> > > 2) Slicing
>> > > ffmpeg -y -i 1.mp4 -filter_complex " \
>> > >   [0:v] trim='start=10.45:end=23.54' [trim-v]; \
>> > >   [0:a] atrim='start=10.45:end=23.54' [trim-a]; \
>> > >   [trim-v][trim-a] concat='n=1:v=1:a=1' [output] \ " \ -map '[output]'
>> > > \ -strict experimental -acodec aac \ -vcodec mpeg4 \ -q:v 0 \
>> > > output.mp4
>> > >
>> > >
>> > > 3) Overwriting
>> > > ffmpeg -y -i 1.mp4 -i 2.mp4 -filter_complex " \
>> > >   [0:v] trim='duration=31.5' [trim-v]; \
>> > >   [0:a] trim='duration=31.5' [trim-a]; \
>> > >   [trim-v][trim-a][1:v][1:a] concat='n=2:v=1:a=1' [output] \ " \
>> > > -map '[output]' \ -strict experimental -acodec aac \ -vcodec mpeg4 \
>> > > -q:v 0 \
>> > > output.mp4
>> > >
>> > > -----Original Message-----
>> > > From: ffmpeg-user [mailto:ffmpeg-user-bounces at ffmpeg.org] On Behalf
>> > > Of Tony Mobily
>> > > Sent: Friday, 11 December 2015 16:45
>> > > To: ffmpeg-user at ffmpeg.org
>> > > Subject: [FFmpeg-user] Cross fading of videos
>> > >
>> > > Hi,
>> > >
>> > > I am new to ffmpeg. I am reading through the documentation --
>> > > although there is a lot to take in!
>> > > I was wondering if you could give me a couple of hints on how to get
>> > > started.
>> > >
>> > > 1) Cross-dissolve
>> > >
>> > > I have two videos, 1.mp4 and 2.mp4, 10 seconds each. I want to
>> > > concatenate those videos, so that the first one has a cross-dissolve
>> > > with the second one when they are joined. If the effect goes on for
>> > > 1 second, this necessarily means that the resulting video will
>> > > necessarily be 19 seconds (since the last second of 1.mp4 will "blend"
>> > with the first second of 2.mp4.
>> > > Is this something that can be done with ffmpeg?
>> > >
>> > > 2) Slicing
>> > >
>> > > I have a 60 second video, and want to get a slice from the second
>> > > 10.45 to the second 23.54. Is that possible?
>> > >
>> > > 2) Overlay
>> > > I have two videos, 1.mp4 (30 seconds) and 2.mp4 (8.5 seconds). I
>> > > want to create a result video where 2.mp4 overwrites the last 8.5
>> > > seconds of
>> > 1.mp4.
>> > > Is this possible without doing cut/concatenation?
>> > >
>> > > Thank you in advance -- and I apologise if I asked silly questions!
>> > >
>> > > Merc.
>> > > ᐧ
>> > > _______________________________________________
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>> > > ffmpeg-user at ffmpeg.org
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