[FFmpeg-user] ffmpeg transitions not working

[iburman at compuscience.com]

Yes, adding this parameter worked. Thanks for your suggestion, it allows me
to generate the transitions I need...
But I'm curious to understand why this parameter is required. All samples I
was able to find for transitions, nobody included it.
Also, both videos that I'm using are cut out from a larger video file, so
all their encoding parameters are the same. Shouldn't ffmpeg have all the
parameters it needs?

As for the player, I am not using anything in special, it is the default
that plays an mp4 in Windows 10. In task manager it shows up as Movies & TV
with a process name of Video.Ui.exe and a child process of
RuntimeBroker.exe. It works fine with all my mp4. Also, all videos generated
with ffmpeg, like extracting a video, concatenate videos, etc., show fine
with this player. Just the transition doesn't work.

By the way, I tried to open the bad files with Media Player and it also
shows all black. It doesn't seem to be a player issue.

An additional question - although your suggestion worked, the generation of
the file also took a long time, like with my unsuccessful trials. Are
transitions expected to take so long time? I'm wondering because everything
else I did with ffmpeg so far has been very fast. 

Please excuse my questions, the video manipulation is quite new for me...:)

Thanks for your help



-----Original Message-----
From: ffmpeg-user <ffmpeg-user-bounces at ffmpeg.org> On Behalf Of Gyan Doshi
Sent: Saturday, June 19, 2021 3:56 PM
To: ffmpeg-user at ffmpeg.org
Subject: Re: [FFmpeg-user] ffmpeg transitions not working



On 2021-06-19 18:22, iburman at compuscience.com wrote:
> I'm having problems with transitions. To be sure I am not making 
> something wrong, I simply copy/paste the example shown in 
> https://ffmpeg.org/ffmpeg-filters.html#xfade, adjusted my two video 
> file names to comply with the example, and got the same problems as 
> with my own commands.
>
>   
>
> The example on the site shows this: ffmpeg -i first.mp4 -i second.mp4 
> -filter_complex xfade=transition=fade:duration=2:offset=5 output.mp4
>
> My first and second files have 1 min each.
>
>   
>
> First I run the command without any change; obviously offset 5 isn't 
> appropriate but I gave it a try.
>
> Second I adjusted duration to 10 and offset to 55 to be appropriate 
> with my two mp4 files. The result was the same:
>
> The final output.mp4 has the right duration (1:55) but it is totally
black.
>
>   
>
> What I see during execution is that the first video is read/copied to
> output.mp4 quite fast. After that it starts reading second.mp4 and 
> works a very long time on it, probably close to one minute.

Which player?

Try

     ffmpeg -i first.mp4 -i second.mp4 -filter_complex
xfade=transition=fade:duration=2:offset=5 -pix_fmt yuv420p output.mp4


Regards,
Gyan
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