By Mike McCarthy

The High Efficiency Video Codec (HEVC), or H.265, is a processing-intensive codec for both encode and decode that leads to higher video quality at lower data rates. There have been both CPUs and GPUs available for years that have dedicated hardware within them to accelerate HEVC encoding and decoding. But this hardware acceleration requires specific support within software applications to use them. And unlike with software encoders, there are a finite number of supported encoding options that can be accelerated, each of which has to be explicitly supported. The newest updates to Premiere Pro have increased the number of hardware-accelerated options for HEVC workflows, greatly increasing performance with those types of files.

CPU-Based Codec Acceleration
Premiere Pro has had CUDA-based GPU acceleration for over a decade, since CS5, but it did not use Nvidia’s accelerated encode and decode hardware until recently. Adobe started with Intel’s hardware-based acceleration for H.264 and HEVC encoding in Version 13, which was limited to 4K at 8-bit on CPUs with Quick Sync video processing. This, from my perspective, was because of laptop chips. (High-end Xeon CPUs don’t support Quick Sync, including the newest W-3300 chips.)

The quality was also inferior to software encodes in the initial release, but that was fixed shortly thereafter. The next step was hardware-accelerated decoding of H.264 and HEVC, which made editing with those codecs much more doable on less powerful systems, especially when it came to scrubbing through footage, which is usually rough with long GOP compression formats.

GPU-Based Codec Acceleration
Then in June of 2020, Adobe added GPU encoding acceleration to Premiere Pro 14.2, which gave support for hardware acceleration of H.264 and HEVC encoding with both Nvidia and AMD graphics cards, regardless of your CPU. This capability was much more applicable to high-end workstations, which don’t have Intel’s consumer-level Quick Sync feature but have top-end, discrete GPUs. This is when I started using hardware acceleration for more than just testing purposes. It supported up to 8K resolution on newer hardware, but it was still limited to 8-bit color.

The Limits of Hardware Acceleration
Eight-bit color was fine for most web deliverables, which was what many of those types of encodes were geared toward at the time. But that was also about the time we started seeing more HDR workflows being developed…and HDR definitely requires at least 10-bit color. All HDR exports were still using the slower software encoding and required more processing under the hood to render the extra color detail when Max Bit Depth was enabled.

Once accelerated encoding became mainstream, my standard system benchmarking process was to encode 8K Red to 8K HEVC with hardware encoding to 8-bit Rec. 709, and with software encoding to 10-bit HDR, which took considerably longer. Those benchmarks were not really affected when Adobe added GPU decoding support for H264 and HEVC in Premiere 14.5, but that support really helped playback performance, especially when using multiple streams (like in a multicam timeline).

New, High-Quality 10-Bit 4:2:2 HEVC Recordings
What about newer, high-quality 10-bit 4:2:2 HEVC recordings? With the most recent release of its Version 22, Adobe added support for accelerated decode of 10-bit 4:2:2 HEVC files. This is specific to Intel Quick Sync because neither Nvidia nor AMD currently support 4:2:2 acceleration in their GPUs. Without hardware acceleration, these newer 4:2:2 HEVC files do not play back well at all on most systems. 4:2:2 refers to the amount of color data in a file, and it used to be much more frequently discussed when the industry was making the jump from SD to HD.

The human eye is more sensitive to brightness than chroma, so higher-resolution images could be encoded more efficiently by focusing on the luminance values over the chroma data. A 4:2:0 video file has basically half-res color detail in both dimensions, while a 4:4:4 file has full color data for every pixel. 4:2:2 sits between the two, with full-vertical but half-horizontal resolution for the color data. It is the default format for SDI connections.

Because H.264 and HEVC are designed to be delivery formats, they are targeted to carry the detail that is visible to the human eye and, for the sake of efficiency, drop anything that won’t be noticed. But now those codecs are being used in cameras for acquisition, and the lost color detail is becoming more noticeable during grading, when colorists highlight image detail that otherwise wouldn’t have been visible.

Because of this, camera manufacturers — who want the affordable efficiency of HEVC encoding but better-quality imagery — have started using HEVC encoding on 4:2:2 image data. Specifically, the Canon R5 and R6, Sony’s a7S III and other DSLRs use this new format, which is not as widely supported for hardware-accelerated playback. But users of Premiere Pro 22 who have Intel Quick Sync support on their newer CPUs (11^th-gen graphics or higher) should now see much smoother playback of files from those cameras — on the order of 10 times the frame rate for real-time playback and three times faster processing for export or transcoding tasks.

10-bit Encoding Acceleration
The most recent feature, which just appeared in the Premiere 22.1.1 beta, is 10-bit HEVC-accelerated encoding. This includes support for HDR output formats and runs on Intel CPUs or Nvidia GPUs. My initial tests showed my standard benchmarking encodes completing four times faster on my workstation (which can already encode pretty fast in software on the top-end CPU) and 16 times faster on my Razer laptop. Hardware acceleration usually makes a bigger difference on less powerful systems because the system has less spare processing power to throw at the software-encoding implementation.

This new 10-bit encoding acceleration will be a big help to those working in HDR, especially if they are using an Intel laptop — and all the more if they don’t have a discrete GPU (which I wouldn’t usually recommend editing on). HEVC export is limited to 4:2:0 color space because no one should need to output 4:2:2 HEVC for delivery, and HEVC is not a good choice for intermediate exports, even at 4:2:2. But if you have a top-end DSLR shooting 4:2:2 HEVC files, and you want to edit on a laptop and post your work to YouTube in HDR, then the playback and export of your project is going to be a whole lot better with the newest version of Premiere than it would have been before.

Mike McCarthy is a technology consultant with extensive experience in the film post production. He started posting technology info and analysis at HD4PC in 2007. He broadened his focus with TechWithMikeFirst 10 years later.