Digital Image Analyzer

Inspect, understand and play H.264/AVC and H.265/HEVC bitstreams.

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Digital Image Analyzer is a desktop tool for video engineers, students and anyone curious about what is inside a compressed video. It opens raw Annex B streams and MP4/MOV/MKV/TS containers, decodes every NAL unit, parameter set, slice header and SEI message, and pairs that structural view with frame-accurate playback.

The NAL table and the player are linked in both directions: scrub the timeline and the NAL units of the current frame are highlighted; click a NAL unit and the player jumps to the frame that contains it.

Screenshot

Highlights

• Decode order vs display order — every access unit is listed with its DTS and PTS, making B-frame reordering easy to follow.
• Complete parameter-set parsing — SPS/PPS (plus VPS for HEVC) decoded field by field: profile, level, chroma format, bit depth, cropping, VUI timing, POC type, slice groups, 8x8 transform and more.
• SEI messages — user data (encoder name and options), recovery points, mastering display colour volume, content light level and alternative transfer characteristics.
• Built for large files — memory-mapped parsing, an MP4 sample-table fast path and lazy frame decoding keep multi-GB files responsive.
• Frame-accurate playback — play/pause, speed control, configurable frame stepping, fullscreen and audio with PTS-driven A/V sync.

Supported input

Type	Formats
Raw bitstreams	.h264, .264, .h265, .265, .hevc (Annex B)
Containers	MP4, MOV, M4V, MKV, TS
Video codecs	H.264/AVC, H.265/HEVC
Audio playback	AAC, MP3, AC-3 and other FFmpeg decoders

Features

Bitstream analysis

• NAL unit table with type, name, size, file offset, frame type, DTS and PTS
• Slice header details: first MB, slice type, POC, reference index
• Stream statistics: resolution, frame rate, frame count, I/P/B distribution, bitrate, GOP size and NAL size distribution
• Detailed view for SPS/PPS/VPS fields, SEI payloads and slice information
• Frame-type colour coding and linked highlighting between table and player

Playback

• Play/pause, stop, previous/next frame and a configurable step of 1–1000
• Playback speed from 0.25x to 3x
• Fullscreen via double-click or the toolbar button (Esc to leave)
• Ring-buffered audio output with PTS-driven A/V sync

Large files

• Memory-mapped I/O: NAL metadata is parsed without loading the whole file
• MP4 sample-table fast path and on-demand frame decoding
• Loading progress with cancel, plus per-stage timings in the status bar

Requirements

• CMake 3.21+ and a C++17 compiler
• Qt 6.4+ with the Widgets and Multimedia modules
• FFmpeg 5+ (libavformat, libavcodec, libavutil, libswscale, libswresample)
• pkg-config

Building

macOS

brew install cmake ninja qt ffmpeg pkg-config
cmake -B build -G Ninja -DCMAKE_BUILD_TYPE=Release -DCMAKE_PREFIX_PATH="$(brew --prefix)"
cmake --build build

Debian / Ubuntu

sudo apt install cmake ninja-build pkg-config \
    qt6-base-dev qt6-multimedia-dev \
    libavformat-dev libavcodec-dev libavutil-dev \
    libswscale-dev libswresample-dev
cmake -B build -G Ninja -DCMAKE_BUILD_TYPE=Release
cmake --build build

Windows (MSYS2, MINGW64 shell)

pacman -S mingw-w64-x86_64-cmake mingw-w64-x86_64-ninja mingw-w64-x86_64-gcc \
          mingw-w64-x86_64-pkgconf mingw-w64-x86_64-qt6-base \
          mingw-w64-x86_64-qt6-multimedia mingw-w64-x86_64-ffmpeg
cmake -B build -G Ninja -DCMAKE_BUILD_TYPE=Release -DCMAKE_PREFIX_PATH=/mingw64
cmake --build build

Helper tools

The build also produces small utilities under build/test/:

# generate a synthetic raw stream (width height fps frames keyint codec output)
./build/test/gen 1280 720 30 120 30 libx264 /tmp/test.h264

# print H.264 slice headers (frame_num / POC) for the bundled sample
./build/test/test_poc

# verify NAL grouping and PTS ordering
./build/test/test_map test/output.h264

Usage

Action	Shortcut / control
Open a file	Ctrl+O (File → Open)
Play / pause	Space
Previous / next frame	← / → (uses the Step value)
Fullscreen	double-click the video or the fullscreen button; Esc to exit
Seek	drag the timeline slider
Playback speed	toolbar combo box
Inspect a NAL unit	click its row in the NAL table
Jump to a frame	scrub the timeline; matching NAL rows are highlighted

The Step spin box sets how many frames the arrow keys and the previous/next buttons jump (1–1000).

Release artifacts

Prebuilt binaries are attached to the releases page:

• macOS (Apple Silicon and Intel)
• Linux (AppImage)
• Windows (x64)

Third-party components

This project bundles Qt and FFmpeg at runtime. See THIRD_PARTY_NOTICES.md for the exact licenses and source locations.

License

Distributed under the GNU General Public License v3.0 or later (GPL-3.0-or-later). See LICENSE.

Contributing

Issues and pull requests are welcome at https://github.com/blocksmith314/DigitalImageAnalyzer. When reporting a problem with a specific file, please include the codec, container and a short description of what the analyzer shows (profile/level and frame count help a lot).