|  Guides, macOS

We Stress-Tested an M2 Pro with Plex: What It Reveals About Apple Silicon’s Media Advantage

The results reach far beyond home streaming, revealing how Apple’s Media Engine could reshape video production, broadcasting and other media-heavy industries.

Our M2 Pro MacBook Pro handled four simultaneous 4K HDR-to-1080p HEVC Plex transcodes without buffering, yet struggled with just two lower-bitrate H.264/SDR transcodes. The difference wasn’t bitrate or raw CPU/GPU power, but whether Plex could use Apple’s dedicated Media Engine. We explore what that contrast means not only for Plex servers, but also for video editors, streamers and other media professionals building workflows around Apple Silicon.

What We Tested

We didn’t pick the fastest Mac we could find. We chose the M2 Pro because it’s powerful without being ridiculously expensive, particularly on the refurbished market. You can also find the same chip in both the Mac mini and MacBook Pro, making it a more useful test than one involving a rare or top-of-the-range model.

Our test machine was a 2023 14-inch MacBook Pro with a 10-core CPU, 16-core GPU and 512GB SSD. We deliberately used the 32GB model so memory wouldn’t get in the way and distract from what we actually wanted to test: the M2 Pro’s transcoding performance. Plex ran directly in macOS.

We started with one 4K HEVC Main 10 video, added another every five minutes and worked our way up to four different films playing at once. Once all four were running, we left them going for another ten minutes. Each simulated remote device behaved like a real player, maintaining about 31 seconds of buffered video while we watched for slowdowns, stalls and dropped buffers.

The M2 Pro didn’t blink. All four streams used Apple’s hardware for both video and audio transcoding, and we recorded no stalls or rebuffering.

There is one important caveat: this was designed to test Plex, not every video workload a Mac might face. The results don’t automatically tell us how the same machine would perform in Final Cut Pro, HandBrake or with every possible combination of audio and subtitles.

The Part That Makes the Difference: Apple’s Media Engine

The Simple Explanation

The M2 Pro has dedicated video hardware that handles multiple Plex transcodes simultaneously without putting the CPU to work.

For Those Who Want the Details

Alongside its CPU and GPU, the M2 Pro has a separate Media Engine. It includes dedicated hardware for decoding and encoding H.264, HEVC, ProRes and ProRes RAW video. Because it is designed specifically for video processing, it can complete these jobs more efficiently than relying on the CPU or general GPU cores.

On macOS, Plex accesses this hardware through Apple’s VideoToolbox framework. As long as the source file and the requested output are compatible, the Media Engine handles the repetitive decoding and encoding. That is what allowed our M2 Pro to process four HEVC/HDR streams simultaneously.

Apple lists a single general video encoding engine in the M2 Pro, but that does not mean it can handle only one stream. A single engine can process several encoding sessions at once, depending on their codec, resolution, frame rate and complexity. Our result suggests that the engine can serve at least four suitable Plex transcodes.

CPU Impact: Tone Mapping Changes the Workload

The Simple Explanation

Keeping the video in HEVC and HDR was easy for the M2 Pro; converting it to H.264 and SDR made the CPU work much harder.

For Those Who Want the Detail

With four HEVC/HDR transcodes running, total CPU usage averaged just 29.2%. A single H.264/SDR stream used 55.9%—nearly twice the CPU for a quarter of the streams.

When we added a second H.264/SDR stream, average CPU usage rose to 59.2% and peaked at almost 88%. More importantly, Plex could no longer convert the videos quickly enough. Playback buffers eventually emptied, despite the network and storage having plenty of capacity left.

The difference was HDR-to-SDR tone mapping. HDR displays offer a wider range of brightness and colour than SDR displays, so Plex must convert the content to prevent the picture from looking washed out.

That CPU-heavy step became the bottleneck. The M2 Pro could still use dedicated hardware to decode and encode the video, but those parts of the pipeline were left waiting for the CPU to finish tone mapping each frame.

You might notice Plex reporting more than 100% CPU usage. Nothing has gone wrong—it’s simply how macOS adds up usage across several processor cores. To keep things straightforward, we’ve used the Mac’s overall CPU usage instead.

GPU Impact: Near Zero Does Not Mean “No Hardware Acceleration”

The Simple Explanation

Plex barely used the normal GPU cores because Apple’s separate Media Engine handled the video processing.

For Those Who Want the Detail

General GPU usage stayed close to zero throughout the successful four-stream HEVC test. That might make the M2 Pro’s 16-core GPU look irrelevant, but the monitoring data needs some context.

Apple’s Media Engine is separate from the general-purpose GPU cores, and our monitoring tool did not report its activity as normal GPU usage. At the same time, Plex confirmed that Apple’s hardware decoder and encoder were active throughout the test.

This also means a 19-core GPU should not automatically be treated as a Plex upgrade over the 16-core version. Those three extra GPU cores may help with graphics, effects and other GPU-heavy work, but Apple does not describe them as additional video encoders.

A 19-core M2 Pro might perform differently, but we would need to test it under the same conditions before claiming that it can handle more streams.

RAM Impact: Near Zero

Plex used surprisingly little memory, so the test Mac’s 32GB of RAM was never close to becoming a bottleneck.

Plex hovered around 1.1GB while all four HEVC streams were running and never exceeded 1.2GB. Even the failed two-stream H.264/SDR test only pushed it to about 1.6GB.

Storage Speed: Useful But Not Limiting

The Simple Explanation

The SSD had plenty of speed to spare. In practice, free space on the SSD and the speed of the internet connection were far more important.

For Those Who Want the Detail

The Mac’s 512GB SSD still played an important role because Plex needs somewhere to store temporary transcoding files. A nearly full drive, or one being heavily used by another application, could cause playback problems. Neither happened during our testing, and hundreds of gigabytes remained available.

Buying a faster SSD purely to improve Plex transcoding would therefore be difficult to justify. Free space and reliable access to your media are more important than headline storage speeds.

Your internet connection is much more likely to become the limit. Four streams at a nominal 15 Mbps require about 60 Mbps of upload bandwidth before accounting for overhead and normal fluctuations.

The Real Plex Bottlenecks

The Simple Explanation

Your playback device and Plex settings can matter more than the Mac itself because they determine whether Plex uses its efficient hardware path.

For Those Who Want the Detail

The biggest bottleneck may be the conversion requested by the playback device. A client that supports HEVC and HDR allows Plex to preserve the original format and use the M2 Pro’s Media Engine efficiently. If the client requires H.264 and SDR, Plex may need to tone map the picture and place far more pressure on the CPU.

Client settings can trigger this heavier route. Plex says that enabling Auto Adjust Quality on Apple devices forces transcoded video into H.264. That can help when a connection is unstable, but it reduced this server’s measured capacity from four HEVC/HDR streams to one stable H.264/SDR stream.

Reducing the H.264 bitrate from 15 to 10 Mbps does not solve the underlying problem. Plex still has to convert HDR into SDR, so a smaller output file does not necessarily mean an easier transcode.

Audio and subtitles can also change the workload. TrueHD and DTS audio converted successfully in our tests. We could not conclusively verify Plex’s handling of ASS and PGS subtitle burning, though. Styled and image-based subtitles may force Plex to process the video when it would otherwise use a simpler route. Plain text formats such as SRT are generally the safer option for remote playback.

What This Means Beyond Plex

This result is not only useful for people running a Plex server. The same Media Engine is available to video editors, production teams, streamers and businesses that regularly encode or export video.

Applications that properly support Apple’s hardware can decode and encode H.264, HEVC and ProRes without placing the entire workload on the CPU. That can mean smoother editing, faster exports and more room to continue working while a video renders in the background. It is particularly useful for agencies producing social content, videographers working with multiple camera feeds and businesses converting large media libraries.

This is also where Apple’s Max chips can offer a meaningful advantage. The M2 Pro has one video encode engine and one ProRes encode/decode engine, while the M2 Max has two of each. Those additional engines can improve performance when exporting video or processing multiple compatible streams simultaneously. However, they will not automatically double performance; this all depends on your workflow.

The M2 Pro may now be a few generations old, but for the right video workloads, its Media Engine still makes it far more capable than its age or a basic CPU benchmark might suggest.

FAQs

1. How many simultaneous 4K Plex hardware transcodes can an M2 Pro handle?

We got four running at once. Each started as a different 4K HEVC Main 10 HDR file, and Plex converted it to 1080p HEVC/HDR using the 15 Mbps remote-quality setting. We added a new stream every five minutes, then left all four playing together for another ten. None of them stalled or had to rebuffer.

That doesn’t mean every M2 Pro will always manage four streams. Change the codec, subtitles, playback device or HDR handling, and you change the amount of work Plex has to do. We saw that for ourselves when we switched to 1080p H.264/SDR at 10 Mbps: one stream worked, but two could not keep up with playback.

2. How do I turn on and confirm Plex hardware transcoding on an M2 Pro Mac?

First, you need Plex Pass on the server owner’s account. A Remote Watch Pass lets you watch remotely, but it does not unlock hardware transcoding.

In Plex Web, go to Settings, Server and then Transcoder. Switch on Use hardware acceleration when available. Open Show Advanced and enable Use hardware-accelerated video encoding as well.

To check that it is working, play a file and choose Convert rather than Direct Play. Open that session in Plex Dashboard and look for “(hw)” beside the video transcode. That is a much better check than watching the usual GPU meter, because Apple’s Media Engine does not show up as normal GPU activity.

3. Which Plex transcoder and client settings should I use on an M2 Pro Mac?

You only need to change a few Plex settings. Here is the best setup we used for the M2 Pro.

On the Plex server

  • Turn on hardware acceleration
  • Turn on hardware-accelerated video encoding
  • Set transcoder quality to Automatic
  • Turn on experimental HEVC encoding

On the player

  • Set local quality to Original
  • Set remote quality to 1080p, 15 Mbps
  • Turn off automatic quality adjustment
  • Use HEVC/HDR where available

4. Why can Plex use high CPU but show almost no GPU activity during hardware transcoding on an M2 Pro?

This catches people out because Apple’s Media Engine is not part of the normal GPU readout. Plex can be using hardware to decode and encode the video while your GPU monitor sits close to zero.

The CPU may still have work to do between those two stages. In our H.264/SDR test, HDR-to-SDR tone mapping was the costly part. One stream averaged 55.9% of the Mac’s total CPU, and two averaged about 59.2%. Four HEVC/HDR streams averaged just 29.2%.

You may also see the Plex process climb above 100%. That is normal on macOS: it adds together the work being done across several CPU cores.

5. What video tasks can the M2 Pro Media Engine accelerate besides Plex?

Plex is only one example. The M2 Pro has hardware acceleration for H.264, HEVC, ProRes, and ProRes RAW, so other software can use the same dedicated video hardware for editing, exporting, streaming, and media conversion. When an app supports it properly, less of that work is left to the CPU.

How much difference it makes depends on the app, the codec and the rest of the workflow. We only tested Plex, so our results do not indicate how much faster Final Cut Pro, HandBrake, or FFmpeg will be.

This is one area where the Max chips have an advantage. The M2 Pro has one video encode engine and one ProRes encode/decode engine; the M2 Max has two of each. That extra hardware can help with several compatible video jobs at once, although it will not automatically make every export twice as fast.