TheRock/rocm-systems/projects/rocprofiler-systems/examples/videodecode/README.md

Video Decode

Overview

This example benchmarks video decoding performance using the AMD rocDecode library with VCN (Video Core Next) hardware acceleration. It uses a thread pool to decode video files in parallel batches, leveraging FFmpeg for demuxing and the rocDecode API for GPU-accelerated frame decoding. The benchmark measures decoding throughput and is useful for profiling hardware video decoder utilization, GPU memory management during media workloads, and multi-threaded decode pipeline performance.

Source Files

• videodecodebatch.cpp - Thread pool implementation with job queue for parallel video decoding, worker thread management, and performance measurement.
• roc_video_dec.cpp / roc_video_dec.h - rocDecode video decoder wrapper with GPU memory management.
• video_demuxer.h - FFmpeg-based video demuxing utilities.
• common.h - Shared definitions and helpers.

Prerequisites

• CMake 3.25+
• HIP runtime
• rocDecode library
• FFmpeg libraries (libavcodec, libavformat, libavutil)
• Sample video files (copied from ROCm installation at build time)

Building

Standalone build:

cmake -B <build_dir> -S <project_root>/examples/videodecode -DCMAKE_PREFIX_PATH=/opt/rocm
cmake --build <build_dir>

As part of the examples suite:

cmake -B <build_dir> -S <project_root>/examples/ -DCMAKE_PREFIX_PATH=/opt/rocm
cmake --build <build_dir> --target videodecode

Running

# Decode a video file
./videodecode -i /path/to/video.mp4

# Specify GPU and thread count
./videodecode -i /path/to/video.mp4 -d 0

VA drivers (LIBVA_DRIVERS_PATH) — only if decode fails

rocDecode uses the VA stack for hardware decode. On a typical desktop, libva finds a driver under the distro’s default paths, so you often need no extra variables.

Set LIBVA_DRIVERS_PATH when decode fails or no VA driver is found. For example, when building with TheRock, point libva at the vendored sysdeps directory:

export LIBVA_DRIVERS_PATH="${ROCM_PATH}/lib/rocm_sysdeps/lib"

Profiling with rocprofiler-systems

rocprof-sys-run -- ./videodecode -i /path/to/video.mp4

Recommended Configuration

Variable	Value	Purpose
ROCPROFSYS_ROCM_DOMAINS	hip_runtime_api,kernel_dispatch,memory_copy	Trace HIP API and GPU operations
ROCPROFSYS_TRACE	true	Generate Perfetto trace for timeline analysis
ROCPROFSYS_PROFILE	true	Generate call-stack profile

rocprof-sys-run \
    -e ROCPROFSYS_ROCM_DOMAINS=hip_runtime_api,kernel_dispatch,memory_copy \
    -e ROCPROFSYS_TRACE=true \
    -- ./videodecode -i /path/to/video.mp4