Export first frame for poster video

[GuilhemBarboux]

Hi,

i try to export first frame for poster image, except i have problem with video codec :

... transcode: chain => {
          let mutableChain = chain
          
          if (codec !== "jpeg") {
            mutableChain = chain.videoCodec(codec);
          }
...

i try with this workaround, but i think maybe you have a better solution. Maybe choose another codec for jpg export, something like that.

Ty for the plugin