I have many video files in my ubuntu server and I wish to stream them one by one without interruption. I just run ffmpeg with segment function.The problem is some files have different DAR-SAR-resolution values so when a video finished, the next one is not playing or giving green screen.In case I classify video files in accordance with the same resolution,fps,DAR,SAR, no problem occurs. I encoded some files to change DAR and SAR to 16:9 and 1:1 but ffmpeg is not changing encoded file with correct SAR-DAR values. Maybe I am lack of information about Sar and DarI read many answers in different forums and a bit tired of desperately searching on internet and reading same threads again and again.I'd appreciate if you could redirect me to the right direction to get rid of this problem. 
How to FFmpeg videos with different SAR DAR values
ffmpeg