[mkaufmann]

For x264 that is true, HEVC which is also mentioned is much slower. For a 4k source transcoding can take more than a second per frame. For a normal movie this can quickly result in encoding times of more than a day.

Another problem is that you have to encode the movie for each codec profile times the number of different bitrates per profile. The article mentions four profiles (VC1, H.264/AVC Baseline, H.264/AVC Main and HEVC) and bitrates ranging from 100 kbps to 16 Mbps. Assuming now there are 20 different bitrates per code you already get 4*20 => 80 encoded copies per source. But of course this can be solved by parallelism.

[sorenjan]

Are there any codecs that can output multiple versions of an input at the same time? Seems like a lot of the encoding process (like motion estimation) is the same every time, so why do it once for every output instead of reusing it?

[JustSomeNobody]

That would be interesting to know. A lot of transcoders can make multiple passes over the source, so being able to reuse the meta data generated for subsequent passes at different output qualities might help speed up the process. I dunno, not my forte, just thinking out loud.

[astrange]

It's not worth it, because every single decision ends up depending on your output targets anyway.

(You can't afford accurate motion estimation at low bitrates because you can't fit the accurate info in your budget anyway. Except for when you can.)