bug report

Issue: Random visual glitch artifacts (green/magenta tearing and horizontal macroblocking) appear at unpredictable timestamps on exported videos when rendering HEVC 10-bit 4:2:2 footage on a dual heterogeneous GPU setup (Intel Arc A380 + NVIDIA RTX 4070 Ti). Disabling Intel hardware-accelerated decoding in Adobe Media Encoder resolves the issue completely.

Steps to Reproduce:

1. Configure a Windows 11 system with an AMD Ryzen CPU (Ryzen 9 5950X), an Intel Arc discrete GPU (A380) for QuickSync decode, and an NVIDIA GPU (RTX 4070 Ti) set as the primary Mercury Playback Engine (CUDA) renderer.

2. Ensure Preferences > Media > Enable hardware-accelerated decoding (Intel) is checked in both Premiere Pro and Adobe Media Encoder.

3. Import Sony FX3 footage shot in XAVC HS 4K (HEVC 4:2:2 10-bit Long-GOP, 24p) into a sequence.

4. Apply basic Lumetri color grading and queue the sequence to Adobe Media Encoder.

5. Export to any master format (e.g., Apple ProRes 422 MOV or H.264/HEVC MP4).

6. Inspect the exported file.

Expected Result: The export completes with frame-accurate rendering, free of visual glitches or dropped frame buffers across the entire timeline.

Actual Result: Intermittent, random green/magenta pixel artifacts and macroblock tearing are baked into the rendered file. The glitch timestamps are non-deterministic and shift positions on subsequent exports of the exact same timeline.

Premiere Version: Premiere Pro 26.5 / Adobe Media Encoder 26.5

Operating System: Windows 11 Pro 24H2

GPU Driver (Windows only):

• NVIDIA: Studio Driver 616.92 (RTX 4070 Ti)

• Intel: Arc Graphics Driver 32.0.101.8993  (Arc A380)

Video Format: Sony FX3 XAVC HS 4K (HEVC / H.265, 10-bit 4:2:2, 24.000 fps, Long-GOP)

Helpful Context & Technical Findings:

• System Configuration: AMD Ryzen 9 5950X (no iGPU), 64GB DDR4 RAM, Intel Arc A380 (installed specifically for hardware decoding 10-bit 4:2:2 HEVC, which NVIDIA NVDEC does not support), NVIDIA GeForce RTX 4070 Ti (CUDA render/NVENC encode).

• Scope: Affects all projects utilizing 10-bit 4:2:2 HEVC footage when decoded via the secondary Intel Arc GPU while the primary CUDA device handles rendering. It is not limited to a single clip or corrupted source file.

• Timeline vs. Export Behavior: Timeline scrubbing and real-time playback inside Premiere Pro work smoothly with Intel Arc hardware decoding enabled. The glitch only occurs during batch export/rendering where frame throughput is maximized.

• Verified Workaround: In Adobe Media Encoder, unchecking Intel under Preferences > Media > Hardware-accelerated decoding forces AME to fall back to CPU software decoding (via the 16-core 5950X). With CPU decoding, 100% of the exported files render flawlessly with zero artifacts across multiple passes.

• Suspected Root Cause: Cross-adapter memory synchronization failure (Race Condition). When the Intel Arc QuickSync engine uncompresses 10-bit 4:2:2 frames into its VRAM and transfers the uncompressed YUV/RGB buffers across the PCIe bus/system memory into the NVIDIA RTX 4070 Ti VRAM for CUDA processing, buffer underruns or frame packet drops occur under sustained export workloads, baking corrupted frame data into the output stream.