Last image of the sequence is not shown in the generated video in case it is monochrome and goes after colored image

[Andriy]

Summary of the bug:
I'm generating the video using concat demuxer with a sequence of images. Video has a fade out in the end and each image has a duration specified (4.189 sec and 0.03214 for fade in/out transitions).
In the end of the video, there goes colored image, then monochrome image and then the fade out.
So the main issue is that this colored image is showed not 4.189 but 8.378 seconds and the monochrome image is not shown at all. The colored image is shown instead of the monochrome right till the ending fade out (It can be seen in the attached video).

Is reproducible only with the monochrome image going after colored and fps set to 30 (is not reproducible when fps is not set). Two colored is fine, two monochrome is fine, monochrome and then colored is fine.

Hard to say if it is a regression because it worked fine in the ffmpeg version 2.8. But after this version, we went straight to the latest 3.4.1

Attached required files to reproduce the issue (Put images_sequence.txt file and images folder into the same directory).
Full execution report attached.

How to reproduce:

% ffmpeg -f concat -i images_sequence.txt -vf fps=30 -vcodec h264 -pix_fmt yuv420p -preset slower -crf 24 missing_last_image.mp4
ffmpeg version - 3.4.1
built on Debain Jessy x64

[Andriy]

generated video with last image missing

[Andriy]

Full report of the command execution

[Andriy]

Data required for the concat demuxer

[Andriy]

Was not able to upload files to FTP (was not able to connect, the host was unreachable ) or to Videolan (it just hang). So I put all the images in Dropbox.

​https://www.dropbox.com/sh/1hibeo24je3t7tl/AADIa-w3KiJfk8l3-yt-RR4Ia?dl=0

Simply download the images folder.

[Carl Eugen Hoyos]

For future tickets: Please remember to always test current FFmpeg git head before reporting an issue.

Regression since 9f6d48d696d679de77e8cb513d5f64cd708ed86f, related to tickets #1578 and #4119.

Work-around is to use -r 30.