Do not upscale or multi channel stereo sound.

[matvp91]

Each output stream will be generated when matched with a particular input.

We should allow ffmpeg jobs to skip working on an input when:

• the stream requests a larger resolution (1080) and the input is of lower resolution (720).
• the audio input is 2 channels but we request 6.

BullMQ has no skipped state but we can mark a job skipped by returning with a "skip value" earlier in the chain.