probe: add check for jpeg/mpeg type of inputs

[emranemran]

Any single jpeg input file may get classified as an mjpeg in the probing logic. These inputs are not supported currently. This change adds a check for mjpeg type of inputs and fails the probe check.

[codecov]

Codecov Report

Merging #451 (18add64) into main (31e8bd8) will increase coverage by 0.27351%.
The diff coverage is 100.00000%.

@@                 Coverage Diff                 @@
##                main        #451         +/-   ##
===================================================
+ Coverage   55.40114%   55.67465%   +0.27351%     
===================================================
  Files             39          39                 
  Lines           3166        3172          +6     
===================================================
+ Hits            1754        1766         +12     
+ Misses          1266        1260          -6     
  Partials         146         146                 

Impacted Files	Coverage Δ
video/probe.go	13.48315% <100.00000%> (+13.48315%)	⬆️

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Impacted Files	Coverage Δ
video/probe.go	13.48315% <100.00000%> (+13.48315%)	⬆️

[thomshutt]

@emranemran Looks good, I also added some unit tests (and from running them noticed that we'd also return the mjpeg error if the source video codec string was empty, so changed it to an equality rather than Contains check)

[emranemran]

@emranemran Looks good, I also added some unit tests (and from running them noticed that we'd also return the mjpeg error if the source video codec string was empty, so changed it to an equality rather than Contains check)

Got it. Nice catch.