Thanks,
I am finding that some of your files are damaged. For example,
Mar 18, 2019 23:38:14.202 [0x7f4a677ff700] DEBUG - [MI] Opening input file: "/media/share/Films/scary movie/Scary Movie 4.avi"
Mar 18, 2019 23:38:14.203 [0x7f4a677ff700] DEBUG - [FFMPEG] - Opening '/media/share/Films/scary movie/Scary Movie 4.avi' for reading
Mar 18, 2019 23:38:14.203 [0x7f4a677ff700] DEBUG - [FFMPEG] - Setting default whitelist 'file,crypto'
Mar 18, 2019 23:38:14.217 [0x7f4a677ff700] DEBUG - [FFMPEG] - Format avi probed with size=2048 and score=100
Mar 18, 2019 23:38:14.217 [0x7f4a677ff700] DEBUG - [FFMPEG] - use odml:1
Mar 18, 2019 23:38:14.217 [0x7f4a677ff700] DEBUG - [FFMPEG] - st:0 removing common factor 80 from timebase
Mar 18, 2019 23:38:14.217 [0x7f4a677ff700] DEBUG - [FFMPEG] - st:1 removing common factor 384 from timebase
Mar 18, 2019 23:38:14.398 [0x7f4a677ff700] DEBUG - [FFMPEG] - Before avformat_find_stream_info() pos: 10252 bytes read:4830362 seeks:5 nb_streams:2
Mar 18, 2019 23:38:14.423 [0x7f4a677ff700] ERROR - [FFMPEG] - Header missing
Mar 18, 2019 23:38:14.433 [0x7f4a677ff700] DEBUG - [FFMPEG] - Format yuv420p chosen by get_format().
Mar 18, 2019 23:38:14.434 [0x7f4a677ff700] DEBUG - [FFMPEG] - All info found
Mar 18, 2019 23:38:14.434 [0x7f4a677ff700] DEBUG - [FFMPEG] - After avformat_find_stream_info() pos: 32022 bytes read:4830362 seeks:5 frames:21
Mar 18, 2019 23:38:40.907 [0x7f4a677ff700] DEBUG - [MI] Opening input file: “/media/share/Films/■■■■■■ Tu braques ou tu raques/■■■■■■ Tu braques ou tu raques (2000).mkv”
Mar 18, 2019 23:38:40.978 [0x7f4a677ff700] DEBUG - [FFMPEG] - Format yuv420p chosen by get_format().
Mar 18, 2019 23:38:40.978 [0x7f4a677ff700] DEBUG - [FFMPEG] - Frame num gap 5 -1
Mar 18, 2019 23:38:40.980 [0x7f4a677ff700] DEBUG - [FFMPEG] - Frame num gap 5 0
Mar 18, 2019 23:38:40.981 [0x7f4a677ff700] DEBUG - [FFMPEG] - Frame num gap 5 1
Mar 18, 2019 23:38:40.983 [0x7f4a677ff700] DEBUG - [FFMPEG] - Frame num gap 5 2
Mar 18, 2019 23:38:40.985 [0x7f4a677ff700] DEBUG - [FFMPEG] - Frame num gap 5 3
Mar 18, 2019 23:38:40.988 [0x7f4a677ff700] DEBUG - [FFMPEG] - no picture
Mar 18, 2019 23:38:41.008 [0x7f4a677ff700] DEBUG - [FFMPEG] - nal_unit_type: 1, nal_ref_idc: 2
Mar 18, 2019 23:38:41.009 [0x7f4a677ff700] DEBUG - [FFMPEG] - no picture
Mar 18, 2019 23:38:41.020 [0x7f4a677ff700] ERROR - [FFMPEG] - mmco: unref short failure
Mar 18, 2019 23:38:41.020 [0x7f4a677ff700] ERROR - [FFMPEG] - mmco: unref short failure
Mar 18, 2019 23:38:41.020 [0x7f4a677ff700] ERROR - [FFMPEG] - mmco: unref short failure
Mar 18, 2019 23:38:41.020 [0x7f4a677ff700] ERROR - [FFMPEG] - mmco: unref short failure
Mar 18, 2019 23:38:41.020 [0x7f4a677ff700] DEBUG - [FFMPEG] - nal_unit_type: 1, nal_ref_idc: 2
Mar 18, 2019 23:38:41.063 [0x7f4a677ff700] DEBUG - Loaded memory image of size 1280x688.
Mar 18, 2019 23:38:41.122 [0x7f4a677ff700] DEBUG - [FFMPEG] - nal_unit_type: 7, nal_ref_idc: 3
Mar 18, 2019 23:38:41.122 [0x7f4a677ff700] DEBUG - [FFMPEG] - nal_unit_type: 8, nal_ref_idc: 3
Mar 18, 2019 23:38:41.149 [0x7f4a677ff700] DEBUG - [FFMPEG] - nal_unit_type: 7, nal_ref_idc: 3
Mar 18, 2019 23:38:41.149 [0x7f4a677ff700] DEBUG - [FFMPEG] - nal_unit_type: 8, nal_ref_idc: 3
You will need to either mkvtoolnix or HandBrake (with high enough bitrate to avoid quality loss) to rewrite the missing header / information.
I recommend mkvtoolnix. It does not re-encode where handbrake is a full re-encode and quality is always lost.