minor hack with odd height of a slide png

[broukema]

One of the png files created from a slide had size 1600x1901 . The creation of the .mp4 video file failed with the warning

[libx264 @ 0xXXXXXXXXXXXXXX] height not divisible by 2 (1600x901)
Error initializing output stream 0:0 -- Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height                                                                                                                                       
Conversion failed!

I used gimp to create an even pixel height and width sized file (1598x900), the conversion worked fine, I edited the last video time length (as per README.md) and the remainder of the steps for putting the pieces together worked fine.

I'm not sure that it's worth modifying the script to handle cases like this, but this may be useful as a hint for people who miss the red coloured warning and don't know how to look at files and check what has happened. I guess you could add a comment to README.md in the 'Notes' section such as "Check the output of the commands for warnings or errors."

Excellent script - for anyone with elementary GNU/Linux skills, this saves a huge amount of effort in trying to learn all the details of ffmpeg options. :) Thanks!