> ## Documentation Index > Fetch the complete documentation index at: https://docs.decktalk.ai/llms.txt > Use this file to discover all available pages before exploring further. # Requirements and costs > What DeckTalk needs, what install downloads, and which commands spend ElevenLabs credits. This page lists what DeckTalk needs, what `decktalk install` downloads, and which commands spend ElevenLabs credits. Read it before you set up a new machine or a CI runner, and before your first voiced build. ## Software DeckTalk needs Python 3.12 or later. It runs on Linux, macOS, and Windows. * DeckTalk has one Python dependency, Playwright. Your installer adds it. * Playwright includes its own browser driver, so you do not need Node. * `decktalk install` downloads Chromium and ffmpeg. KaTeX ships inside the wheel, and you install nothing else by hand. The [quickstart](/quickstart) installs DeckTalk with uv, pipx, or pip. ## Accounts A build without voice needs no account and no API key. A voiced build needs two values from ElevenLabs. | Variable | Value | Needed by | | --------------------- | ------------------- | --------------------------------------------------------- | | `ELEVENLABS_API_KEY` | your API key | a voiced build, `decktalk narrate`, `decktalk soundscape` | | `ELEVENLABS_VOICE_ID` | the id of the voice | a voiced build, `decktalk narrate` | Put both values in `.env` in the project directory, or set them in the environment. A value that starts with `<`, such as ``, counts as unset. [Part 3 of the quickstart](/quickstart#part-3-add-your-voice-and-change-a-sentence) shows where the values go. ## What spends credits Only two parts of DeckTalk call ElevenLabs. The `narrate` stage calls the text-to-speech endpoint, and `decktalk soundscape` calls the sound effects and music endpoints. | Command or change | When it spends credits | | ---------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------- | | `decktalk build` without `--no-voice` | It voices each section whose text, title, or voice changed since the last voiced build. It voices every section when the narration cache is empty. | | `decktalk narrate` without `--no-voice` | It voices the same sections as a build. `--only` limits it to the sections you name. | | `--force` on `build` or `narrate` | It voices every section again, even if nothing changed. | | A new voice id, model, output format, or `[voice]` setting | The next voiced build voices every section again, because the cache key includes all of them. | | `decktalk soundscape` | It generates each part whose request changed or whose file is missing. `--force` generates every part again. | A voiced section costs the characters of its whole text. An edit therefore costs every changed section in full, not only the changed sentences. A ten-minute narration is about 9,000 characters. A build without voice stops when the project has voiced takes. With `--force`, it empties the narration cache, so the next voiced build voices every section again. [A build without voice and a voiced build](/guides/rebuild-one-section#a-build-without-voice-and-a-voiced-build) explains the cache. To see a run before it spends credits, use `--dry-run` or `preflight`. None of these commands calls the API: * `decktalk narrate --dry-run` prints the text of each section, and which sections a voiced run would voice, with their characters. * `decktalk preflight` prints the same plan, resolves every cue, and estimates each reveal from frozen frames. * `decktalk soundscape --dry-run` prints every request. These commands never spend credits: a build without voice, `install`, `init`, `doctor`, `preflight`, `align`, `record`, `assemble`, `verify`, `screenshots`, `words`, `clip`, `serve`, and `status`. ### ElevenLabs plans Every ElevenLabs plan can call the API, including the free plan. The free plan has three limits for a video you publish: * It has no commercial license. * The title of published content must include "elevenlabs.io" or "11.ai". * It cannot use Voice Library voices through the API. For a video you publish, start with the Starter plan. ## What install downloads `decktalk install` makes two downloads, one time per machine. `decktalk doctor` then reports on each download. | Download | How `install` gets it | | ------------------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Chromium | `install` runs `playwright install chromium`. | | ffmpeg and ffprobe | `install` downloads one pinned GPL build, checks each archive against the SHA-256 DeckTalk records for it, and unpacks it into `ffmpeg/-` in DeckTalk's cache. | KaTeX is not downloaded. The pinned release ships inside the wheel, and `decktalk init` copies it into `deck/katex/`, so a project typesets its equations with no network and no CDN tag. | Cache | Linux | macOS | Windows | | ---------- | ---------------------------------------------------- | -------------------------------- | ------------------------------ | | Playwright | `~/.cache/ms-playwright` | `~/Library/Caches/ms-playwright` | `%LOCALAPPDATA%\ms-playwright` | | DeckTalk | `$XDG_CACHE_HOME/decktalk`, else `~/.cache/decktalk` | `~/Library/Caches/decktalk` | `%LOCALAPPDATA%\decktalk` | To move DeckTalk's cache, set `DECKTALK_CACHE_DIR`. ### Linux system libraries On Linux, `install` passes `--with-deps` to Playwright, and Playwright installs Chromium's system libraries with apt-get. 1. Playwright runs apt-get through sudo. 2. If sudo is missing, it uses `su root -c`. 3. If `install` runs as root, it uses neither. If the distribution has no apt-get, this download fails. `install` then stops before it downloads ffmpeg. ### If a download is missing * **The wheel's KaTeX copy is incomplete.** `doctor` prints `MISSING` in the `katex` row and names each absent file. Reinstall DeckTalk. * **`install` never ran.** DeckTalk downloads the pinned build the first time it needs ffmpeg. * **DeckTalk pins no build for your platform, or the download cannot run.** DeckTalk uses the ffmpeg on your PATH. A download whose digest does not match is discarded and never falls back. `DECKTALK_FFMPEG` and `DECKTALK_FFPROBE` override every ffmpeg source above. ## Install on a managed machine A machine with no admin rights, an index mirror, or an intercepting proxy can still record. Five settings cover the cases that come up, and none of them needs a change to the project. | What the machine blocks | What to set | | ----------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | The package index | Point your installer at your mirror, the way uv, pipx, or pip already does it. DeckTalk needs one runtime dependency, Playwright. | | The Chromium download host | Set `PLAYWRIGHT_DOWNLOAD_HOST` to your mirror before `decktalk install`, as Playwright documents. | | A shared browser directory, or a read-only home | Set `PLAYWRIGHT_BROWSERS_PATH` to a directory you can write. Playwright reads it on the download and on every launch, so set it in both places. | | The ffmpeg download | Put an approved `ffmpeg` and `ffprobe` on the machine and name them in `DECKTALK_FFMPEG` and `DECKTALK_FFPROBE`. Those two override every other ffmpeg source, so `install` reports them and downloads no build. | | A write to the default cache | Set `DECKTALK_CACHE_DIR` to a directory you can write. Everything DeckTalk downloads goes under it. | If the machine already has an approved Chrome or Chromium, record with it instead of the downloaded build. Name its executable in `[record] browser_path`. ```toml decktalk.toml theme={null} [record] browser_path = "/Applications/Google Chrome.app/Contents/MacOS/Google Chrome" ``` The pinned Playwright build is the reference build, and DeckTalk's timing limits are measured against it. A browser of your own is supported and unverified, so check a first video's reveals with `decktalk verify` before you trust the limits. A proxy needs no rule of its own. `record`, `screenshots`, and `preflight` open every page at `http://project.localhost/` and answer each request from your project directory through Playwright's request routing, which runs before the network stack. No proxy ever sees that host, and every other request a recorded page makes goes the way the machine sends it. `decktalk serve` binds 127.0.0.1 and picks a free port, and `--host` and `--port` move it. `decktalk doctor` prints the Chromium revision and the ffmpeg build a run would use, so the machine's owner can read what a recording will launch before it runs. ## Time Recording runs in real time, one section after another. A first build without voice of the starter took about 64 seconds on a MacBook Pro with Apple M5 Pro and 64 GB memory. The video it made is 44.88 seconds long, so most of the time is the recording and the encode. A slower machine takes longer. [Rebuild one section](/guides/rebuild-one-section) shows how to record only the sections that changed. ## The ffmpeg license The ffmpeg builds that `install` downloads are GPL builds. DeckTalk runs ffmpeg as a separate process and does not link against it. [THIRD\_PARTY\_NOTICES.md](https://github.com/jacobcbeaudin/decktalk/blob/main/THIRD_PARTY_NOTICES.md) lists the license of each build. To use an ffmpeg build of your own, set `DECKTALK_FFMPEG` and `DECKTALK_FFPROBE` to its two executables. ## Next * **Install and build your first video:** [Quickstart](/quickstart) * **Build in CI or with no network:** [Build in CI and offline](/guides/ci-and-offline) * **Understand the costs of an edit:** [Rebuild one section](/guides/rebuild-one-section)