How well can AMD GPU’s Hardware transcode?

I went out and bought an RX580 naively thinking it might have similar performance to the P2000 without the price tag. On paper things look very similar and in some cases slightly better for the RX580:

On paper these two cards are similar and even if I were to have gotten half the performance out of the rx580 I would have been very satisfied with the purchase since it is about half the price of the P2000; however, that was not the case. The RX580 with its 3rd generation of AMD’s Video Coding Engine (AMD’s video encoding ASIC Implementation similar to NVIDIA NVENC) should have performed better than it did. I was very disappointed with the results I saw from the card.

The tests I ran were H265 and H264 transcoding in Plex. For video games these cards perform fairly well, but when transcoding media its a whole different story.

The first test I ran was H265 1080p transcoded down to H264 1080p. I wanted to eliminate any potential bottlenecks so i threw the P2000 in a computer with an i5-8600k overclocked to ~4.8ghz.

The P2000 got to 100% after 28 h265 transcodes with only 50% CPU utilization so this was the real limit of the P2000 and since plex doesn’t allow you to use Quicksync AND NVENC simultaneously that’s where the story ended for the P2000.

Immediately after launching my first transcode with the RX580 I realized it was not going to end well, the GPU utilization with a single h265 transcode shot up to 70% and stayed there for several minutes. I had to open new streams very slowly with the RX580 to get it to its absolute limit as far as how many transcode jobs it could run simultaneously. Ultimately that number was 7. I only got 7 transcodes running simultaneously before the RX580 was at 100% utilization and was completely out of steam. This was incredibly disappointing as I had high hopes for this GPU and with its price tag as it is it seemed like a good deal. That is not the case. H264 seemed to be fairly decent on the card and I got to about 14 transcodes before I stopped testing.. if it can’t do H265 very well I don’t want to use it in my server.

 

I might revisit this and do some more thorough tests, or grab a Vega 64 in the future. Leave comments and let me know what you think.

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