crossfade between 2 videos using ffmpeg

Question

I've been trying to achieve a crossfade transition between 2 video clips using ffmpeg but have failed so far. I'm new to ffmpeg and am mostly relying on tweaking what I can find in the documentation and existing examples online. From what I read so far, using either the blend or overlay filter should help in achieving what I'm after but I can't figure out the command line details to get it to work.

The fade and concat filters are great for fade-out of video 1, fade-in to video 2 and concat the 2 into 1 clip type transitions but I'd appreciate help in getting a command to transition from video 1 to video 2 without any going to black in between. I couldn't find any examples for exactly this problem anywhere, maybe I'm looking for the wrong keywords...?

More speficially, my videos are mp4s (h264 video, no sound, in case that matters), each is 5 seconds long and I'm after a transition from approx. 4.5s of video 1 to 0.5s of video 2.

Similar to what this tutorial does using MLT and frames (see 2:25 for an example fade), though I'm looking for a way to do this just in ffmpeg without calling any other progs. http://www.youtube.com/watch?v=3PRZ9L_KLdI

Any pointers or maybe a command line to get a fade like this would be much appreciated, thanks very much!

Answer 1

I suggest to do that way:

• Create black background with the same duration and resolution as output video should be
• Add alpha channel to each video
• Add fade to alpha effect to each video
• Use overlay on each video with black background

So the command for adding crossfade to 2 video (5 sec) each should be:

ffmpeg -i 1.mp4 -i 2.mp4 -f lavfi -i color=black -filter_complex \
"[0:v]format=pix_fmts=yuva420p,fade=t=out:st=4:d=1:alpha=1,setpts=PTS-STARTPTS[va0];\
[1:v]format=pix_fmts=yuva420p,fade=t=in:st=0:d=1:alpha=1,setpts=PTS-STARTPTS+4/TB[va1];\
[2:v]scale=960x720,trim=duration=9[over];\
[over][va0]overlay[over1];\
[over1][va1]overlay=format=yuv420[outv]" \
-vcodec libx264 -map [outv] out.mp4

This will fade out first video to alpha at 4th second (st=4) during 1 second (d=1), fade in the second one at 0 second (st=0) during 1 second (d=1) and moves it's display time forward to 4 sec (+4/TB). Then we just cut 9 second of black color, scale it to output video size and overlay the stuff.

Hope it helps.

Answer 2

This is how I did :

• ffmpeg version N-77197-gdf2ce13
• 2 videos of 4 seconds each.
• Need to join it with fade between them.
• videos are 25 fps.

1) Add fade out (light to dark) at the end of the 1st and fade in (dark to light) at the beggining of the 2nd:

ffmpeg -i 1.mp4 -y -vf fade=out:76:24 1f.mp4

ffmpeg -i 2.mp4 -y -vf fade=in:0:25 2f.mp4

76:24 mean the fade out will start frame 76 and will finish 24 frames later = 1s fade out.

0:25 mean the fade in will start frame 0 and will finish 25 frames later.

2) Merge the 2 videos

Convert all to TS

ffmpeg -i 1f.mp4 -c copy -bsf:v h264_mp4toannexb -f mpegts 1f.ts

ffmpeg -i 2f.mp4 -c copy -bsf:v h264_mp4toannexb -f mpegts 2f.ts

Merge

ffmpeg -i "concat:1f.ts|2f.ts" -bsf:a aac_adtstoasc -c copy output.mp4

Thanks to:

http://www.bogotobogo.com/FFMpeg/ffmpeg_fade_in_fade_out_transitions_effects_filters.php

Answer 3

ffmpeg-concat is the easiest way to accomplish what you want and allows you to use a bunch of sexy OpenGL transitions, with the default being crossfade.

ffmpeg-gl-transition is a custom ffmpeg filter which allows you to use GLSL to smoothly transition between two video streams. This filter is significantly easier to use and customize than the alternatives listed here.

This filter supports a large list of transition types, with the default being crossfade.

./ffmpeg -i 0.mp4 -i 1.mp4 -filter_complex "gltransition=duration=4:offset=1.5" out.mp4