[FFmpeg-user] Problem in concatenation

[Gabriele Greco]

I've problem with certain mp4 files (and I cannot find exactly what kind of
mp4) in concatenation without re encoding with the ffmpeg concat demuxer.

The video of the second fragment is "broken". I cannot find differences
with ffprobe to detect when I am in such a situation, being able to detect
these unconcatenable mp4s will let me to force a re encoding...

The problem occurs with all the ffmpeg versions I tried (3.1.x to 3.3.x),
here are a small cut of a couple of files that trigger this behaviour:

https://www.dropbox.com/s/jluqga0qldn01wq/samp01.mp4?dl=0
https://www.dropbox.com/s/674jnozulee5tkr/samp02.mp4?dl=0

concat.txt:
file 'samp01.mp4'
file 'samp02.mp4'

ffmpeg -f concat -i concat.txt -c copy test.mp4


ffprobe report the samples to be of the same format/level/resolution (as
they should be since they are two videos taken with the same camera):

samp01:
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv,
bt709), 1280x720 [SAR 1:1 DAR 16:9], 7241 kb/s, 23.98 fps, 23.98 tbr, 24k
tbn, 50 tbc (default)
samp02:
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv,
bt709), 1280x720 [SAR 1:1 DAR 16:9], 7244 kb/s, 23.98 fps, 23.98 tbr, 24k
tbn, 48k tbc (default)

-- 
*Bye,*
* Gabriele Greco*