124 lines
4.6 KiB
Markdown
124 lines
4.6 KiB
Markdown
# Video Concat
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A small, focused desktop app that **merges split stream recordings into one
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file** using ffmpeg stream-copy (`-c copy`, no re-encoding — fast and lossless).
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Built with Tauri 2 (Rust backend + TypeScript UI).
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This is a standalone spin-off of Stream Studio with the song-detection feature
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removed, so it needs **no Python and no ML model** — just ffmpeg.
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## Features
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- Drag-and-drop / browse to add videos, reorder, select which to merge.
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- Stream-copy concat with honest real-time progress. On local NVMe a merge runs
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at ~95 % of plain file-copy speed — the disk is the limit, not the app.
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- **History** tab: every merge (done, failed, stopped, or interrupted by a
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crash) with its files, size, time and MB/s. Show the output in its folder, or
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load the same files again with "Merge again".
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- BiliBili-Live filename helper (`[date][uploader][title]` → readable name).
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- Optionally delete the originals after a successful merge.
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- Optional **Web-optimize MP4 (`+faststart`)**, off by default. It moves the
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MP4 index to the front so playback can begin mid-download, but ffmpeg has to
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re-read and re-write the whole file to do it — measured at 17–56 % extra time
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locally and 60 % over a NAS. Local players don't need it.
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## Portable: everything stays in one folder
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Nothing is written outside the app folder — not to `%APPDATA%`, not to the
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registry. Copy the folder to another PC and history, theme and options come
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with it:
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```
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VideoConcat\
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Video Concat.exe
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ffmpeg.exe, ffprobe.exe
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data\
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history.jsonl <- merge history, one JSON line per job
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running.json <- only while a merge runs; left behind = "interrupted"
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webview\ <- WebView2 profile (theme, options)
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```
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`data\` is created on first run. If the folder isn't writable (say, under
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Program Files), the app still works but shows a banner and keeps no history.
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It needs the WebView2 runtime, which ships with Windows 10 and 11.
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## Build a standalone (copy-paste) version
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Double-click **`build.bat`**. It compiles the app and assembles a portable
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folder with ffmpeg bundled:
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```
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dist-portable\VideoConcat\
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Video Concat.exe <- double-click this
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ffmpeg.exe <- bundled
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ffprobe.exe <- bundled
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```
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Copy that whole `VideoConcat` folder to any Windows PC and run it — nothing else
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to install. To **upgrade** an existing copy, replace only `Video Concat.exe`
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and keep its `data\` folder; history carries over.
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### Build requirements (on the build machine only)
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- [Node.js](https://nodejs.org/)
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- [Rust](https://rustup.rs/) (`winget install Rustlang.Rustup`)
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- Visual Studio 2022 with the **Desktop development with C++** workload
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- ffmpeg: in `C:\ffmpeg\bin`, on `PATH`, or point `FFMPEG_DIR` at any folder
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holding `ffmpeg.exe` + `ffprobe.exe` (an existing portable copy works:
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`set FFMPEG_DIR=%USERPROFILE%\Documents\VideoConcat`)
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Building from a network share is slow and fragile (thousands of small files in
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`node_modules` and `target`). Copy the source to a local disk first.
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## Develop
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Double-click **`dev.bat`** (hot-reload UI + Rust). Needs ffmpeg on `PATH`.
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In dev mode the `data\` folder sits next to the debug exe in `src-tauri\target\debug\`.
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## Test
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```
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npm run build # the Rust tests embed dist/, so build the UI first
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cd src-tauri && cargo test
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```
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Covers the BiliBili rename parser, concat-list path escaping (`\\?\` and UNC
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prefixes, quotes), duration reuse, "never delete the output", and history
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crash recovery.
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## Benchmark
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`tools/bench_concat.py` times each pipeline stage with the exact ffmpeg flags
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the app uses, against the I/O floor of a plain file copy:
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```
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python tools/bench_concat.py --ffmpeg-dir <folder with ffmpeg> --make 6 --src D:\bench --dst D:\bench\out
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```
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## Icons
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The app icon lives as vector art in `src-tauri/icons/icon.svg` — a rounded-square
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gradient tile with the three-filmstrips-into-one-arrow mark. Everything else in
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`src-tauri/icons/` is generated from it:
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```
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python tools/make_icons.py
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```
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That rewrites the PNGs and `icon.ico` with 8x supersampling and a real alpha
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channel, dropping sub-pixel detail (sprocket holes below 48px, the play-triangle
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knockout below 64px) rather than smearing it. Only the Windows/desktop icons are
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regenerated; the `android/` and `ios/` subfolders are untouched.
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To fix the icon on an **already-built** exe without recompiling it:
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```
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python tools/patch_exe_icon.py "path\to\Video Concat.exe"
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```
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That rewrites only the `RT_ICON` / `RT_GROUP_ICON` resources — `.text`, `.rdata`
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and `.data` come out byte-identical — and keeps a `.bak` alongside. Explorer
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caches icons aggressively, so follow it with `ie4uinit.exe -show`.
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Both tools need `pillow` and `numpy`.
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