SamyGO

It's like trying to play Quake with calculators CPU.
You are talking from custom image processing, such a thing could be possible with multi Gigaherts & Multi-core CPU processors.
But If we are talking with ARM 600 mhz thing, you are out of luck.

Maybe it's easier to recognize the audio stream for channel's own "commercial break theme". It should be doable with 600Mhz ARM. The question is how to identify the break reliably enough.

Yes, sound approach will be more easier than logo thing.
We can capture sound by digital tuner output, after, we could extract the audio data.
Since tuner is digital, it's more easy to recognize ring tone.
Looks possible to do now. But things became too simple if we have open sourced exeDSP. But we have not