lektor-ai/docs/usage.md

# Usage

ComfyUI must be running before any command that generates speech
(`~/comfy-tts-app/start_comfyui.sh`). `--rebuild` is the exception — it only
touches ffmpeg and works with the backend stopped.

## Invocation

```
python3 lektor_ai_comfy.py [SRT] VIDEO [options]
```

Both positionals are optional in the argparse sense, because several modes do
not need an SRT file. The rule:

```bash
# External subtitle file — pass both, SRT first
python3 lektor_ai_comfy.py input/film.pl.srt input/film.mkv

# Subtitles inside the video — pass the video alone
python3 lektor_ai_comfy.py input/film.mkv --embedded-subs

# --rebuild and --regen also need only the video
python3 lektor_ai_comfy.py input/film.mkv --rebuild
```

When a single positional is given in a mode that needs no SRT, the script moves
it into the video slot automatically. Always quote paths containing spaces or
parentheses:

```bash
python3 lektor_ai_comfy.py "input/Star City (2026)/S01_E01 The Eyes.mkv" --embedded-subs
```

## Working modes

### Full generation (default)

Parses subtitles, generates one TTS clip per block, assembles, muxes.

```bash
python3 lektor_ai_comfy.py input/film.mkv --embedded-subs
```

Roughly real-time-ish on a 4070 Ti SUPER: a 60-minute episode of ~700 subtitle
blocks takes on the order of an hour. Each clip is saved as it completes, so a
crash never loses more than the clip in flight.

### `--embedded-subs`

Lists the video's subtitle tracks and prompts for one:

```
  Available subtitle tracks in S01_E01 The Eyes.mkv:
    [1] Stream #2: subrip [eng] — Forced
    [2] Stream #3: subrip [eng]
    [3] Stream #4: subrip [eng] — SDH
   ...
    [30] Stream #31: subrip [pol]
  Select track number: 30
```

The chosen track is extracted to `embedded_sub.srt` in the job folder and processed
exactly like an external file. Image-based tracks are listed but marked
unusable — they hold bitmaps, not text.

### `--rebuild`

Reassembles audio from existing clips and rebuilds the video, with no TTS at
all. This is the fast iteration loop — seconds to minutes rather than an hour.

```bash
python3 lektor_ai_comfy.py input/film.mkv --rebuild
python3 lektor_ai_comfy.py input/film.mkv --rebuild --orig-volume 0.5 --tts-volume 2.0
```

Use it after `--regen`, or to adjust the mix. It reads that video's job folder
(`output/clips/<video name>/`) and needs its `tts_input.srt` plus a complete set
of `clip_NNNN.flac`, reporting which are missing if any are.

If the original run used `--end`, pass it again so the same video fragment is
used.

### `--regen`

Regenerates specific clips by block number, leaving everything else alone.

```bash
python3 lektor_ai_comfy.py input/film.mkv --regen 12 22 41
python3 lektor_ai_comfy.py input/film.mkv --rebuild        # then apply
```

Block numbers match that job's `tts_input.srt` and its `clip_NNNN.flac` files.
Only the selected FLAC files are replaced — `--rebuild` afterwards is what
actually updates the video.

This is the intended fix for a bad clip. There is no automatic retry; when the
model hallucinates, mumbles, or truncates, note the number and regenerate it. A
different seed usually resolves it, and `--seed 0` (the default) randomises
every run.

### `--resume-from`

Continues a crashed run, loading clips `1..N-1` from disk and generating from
`N` onward.

```bash
python3 lektor_ai_comfy.py input/film.mkv --resume-from 47
```

The console prints `[47/693]` style progress, so the number to resume from is
the last one that completed.

**It does not reprocess the subtitles.** The blocks come from the job folder's
existing `tts_input.srt`, so the dictionary and the number normalizer are not
run again:

```
[1/4] Resuming from block 47 — reusing tts_input.srt…
      693 blocks, subtitles not reprocessed — the numbering still matches the clips on disk.
```

That is a correctness requirement, not an optimisation. `--resume-from` pairs
block *N* with `clip_NNNN.flac`, and re-deriving the text can change it — a
dictionary rule added since, a different normalizer result, a changed `--start`.
Same block count with different words is the dangerous case, because nothing
would look wrong until you listened.

It also means `--start`/`--end` need not be repeated for the block list, since
the saved file already holds the adjusted timings. If the job folder has no
`tts_input.srt`, the run says so and falls back to parsing the SRT.

### `--skip-tts`

Uses a pre-assembled audio file and goes straight to the mux.

```bash
python3 lektor_ai_comfy.py input/film.mkv --skip-tts "output/clips/film/tts_assembled.flac"
```

## Settings file

Defaults live in **`settings.ini`** next to the script, so the values you always
want no longer need to be typed on every run. Precedence:

```
command-line flag   >   settings.ini   >   built-in default
```

```ini
[tts]
voice = gudowski_short
speed = 1.2
temperature = 0.9
max_tokens = 4096
strip_leading_ms = 0
trailing_fade_ms = 80

[mix]
orig_volume = 0.60
tts_volume = 1.8

[paths]
output_dir = output
dictionary = dictionary.txt

[normalize]
numbers = yes
python = normalizer/venv/bin/python
llm = normalizer/models/PLLuM-4B-instruct-2512
timeout = 60
free_comfy_vram = yes

[comfy]
comfy_url = http://127.0.0.1:8189
```

Every one of these has a matching flag that overrides it for a single run:

```bash
# settings.ini says tts_volume = 1.8; this run uses 2.5
python3 lektor_ai_comfy.py film.mkv --embedded-subs --tts-volume 2.5
```

Each run prints which file it used, so there is never any doubt:

```
  Settings: /home/lukas/Programy/lektor_ai/settings.ini
```

**Alternative profiles** — keep per-show settings side by side and select one:

```bash
python3 lektor_ai_comfy.py film.mkv --embedded-subs --settings profiles/docu.ini
```

**Behaviour when things are missing or wrong**, none of which is fatal:

| Situation | Result |
|---|---|
| No `settings.ini` | Built-in defaults; the run says so |
| Key absent from the file | That key falls back to its built-in default |
| Value unparseable (`speed = fast`) | Warning, that key falls back, run continues |
| File is not valid INI | Warning, all built-in defaults, run continues |

Comments use `#` or `;`, inline comments included. Deleting a line is a valid
way to return it to its built-in default.

**Not in the file, by design**: `--start`, `--end`, `--seed`, `--regen`,
`--rebuild`, `--resume-from`, `--embedded-subs`, `--skip-tts`. These describe a
particular run rather than your setup, so pinning them in config would be a
trap.

## Options

Every option below can also be set in `settings.ini`, except those noted as
run-specific.

### Range

| Flag | Default | Meaning |
|---|---|---|
| `--start MM:SS` | `00:00` | Start of the range to process |
| `--end MM:SS` | *(end)* | End of the range |

With `--end`, a matching fragment is extracted to `video_fragment.mkv` in the job folder
and all TTS timestamps become relative to `--start`. Pass the same values to any
later `--rebuild`, or the audio will not line up.

`--end 01:00` is the quickest way to sanity-check a new voice or speed setting.

### Voice and model

| Flag | Default | Meaning |
|---|---|---|
| `--voice NAME\|PATH` | `gudowski_short` | Name in `voices/`, or a path to a WAV |
| `--seed N` | `0` | Base seed; `0` randomises each run |
| `--temperature T` | `0.9` | Sampling temperature |
| `--max-tokens N` | `4096` | Token ceiling per clip |

`--temperature` is worth understanding. At `1.0` the model sometimes recites the
reference transcript instead of the subtitle. `0.9` largely prevents that;
lower is more deterministic but flatter. A per-clip seed of `base_seed + index`
means a fixed `--seed` reproduces a run exactly.

Raise `--max-tokens` only if long clips are cut off mid-word.

### Timing and cleanup

| Flag | Default | Meaning |
|---|---|---|
| `--speed FACTOR` | `1.2` | Per-clip speed-up via `atempo` |
| `--strip-leading-ms MS` | `0` | Trim the start of each clip |
| `--trailing-fade-ms MS` | `80` | Fade the end of each clip |

`--speed` compresses speech so a clip is more likely to fit its subtitle window.
It is applied **per clip, before assembly** — never to the assembled track,
which would shift every timestamp by speeding up the silences too.

`--strip-leading-ms` removes an inhale artifact at clip starts; try 80–150 if
you hear one. `--trailing-fade-ms` suppresses tail pops; `0` disables it.

### Mixing

| Flag | Default | Meaning |
|---|---|---|
| `--orig-volume 0-1` | `0.60` | Original audio level inside the lektor mix |
| `--tts-volume 0-2` | `1.8` | Voiceover level inside the lektor mix |

These affect **Track 1 only**. Track 0 is always the untouched original, so
nothing is lost by mixing aggressively. Changing them needs only `--rebuild`.

Typical starting point for dialogue-heavy material: `--orig-volume 0.5
--tts-volume 2.0`. For quiet sources, `--orig-volume 1.0 --tts-volume 1.4`.

### Paths

| Flag | Default | Meaning |
|---|---|---|
| `--output-dir DIR` | `output` | Where everything is written |
| `--dictionary FILE` | `dictionary.txt` | Word/phrase replacements, `""` disables |
| `--normalize-numbers` / `--no-normalize-numbers` | on | Spell digits out in Polish |
| `--comfy-url URL` | `http://127.0.0.1:8189` | Backend address |

## Replacement dictionary

`dictionary.txt` next to the script rewrites words and phrases in the subtitles
**before** they reach the TTS engine. It exists for everything the model reads
out wrong on its own: abbreviations, units, symbols, names with an unusual
spelling.

One rule per line:

```
km/h = kilometrów na godzinę
np. = na przykład
m.in. = między innymi
/(\d+)\s*%/ = \1 procent
```

| Rule | Behaviour |
|---|---|
| Matching | **Case-sensitive**, whole words only — `np.` does not match inside `znp.`, and `Joshua` does not match `joshua` |
| Capitals | The replacement goes in exactly as written; nothing is re-cased for you |
| Priority | Longer literals win: `km/h` beats a plain `km` rule whichever order they are written in |
| Chaining | Replacement text is never rescanned, so rules cannot feed each other or loop |
| Regex | A pattern in slashes is a regular expression; `\1 \2 …` refer to its groups |
| Comments | Lines starting with `#` or `;`; `->` and `=>` also work as separators |
| Deleting | An empty replacement removes the phrase |

Each run reports what it loaded and how much it changed:

```
  Dictionary: 14 rule(s) from /home/lukas/Programy/lektor_ai/dictionary.txt
      6 dictionary replacement(s) applied.
```

The replaced text is what lands in the job folder's `tts_input.srt` — check
there when a rule is not doing what you expect. Because `--regen` and
`--rebuild` work from that file, they do **not** re-apply the dictionary: edit
`tts_input.srt` and `--regen` the affected blocks, or rerun from the SRT.

A relative name is looked for in the current directory first and then next to
the script, so one film can keep its own list without hiding the shared one.
A missing file, a line with no separator and an invalid regex are all warnings,
never fatal.

### The queue dictionary

`dictionary.txt` holds rules that are true of Polish generally. A batch often
needs its own — a character's name the model mangles, a recurring
mistranslation — and those do not belong in the shared file.

The GUI's **Queue dictionary** button opens a plain text editor with the same
format, one rule per line:

```
Joshua = Dżoszua
P12 = pozycja dwunasta
# comments work here too
```

Saving writes `queue_dictionary.txt` into the **first queued video's job
folder**, and every video in the queue is run with it. The dialog reports how
many rules parsed, so a typo shows up when you save rather than as a rule that
silently does nothing during the run. **Clear** empties the editor only —
nothing is written until you press Save.

The two files are **merged into one rule set**, not chained: a replacement made
by one still cannot be rewritten by the other, and longest-literal-wins applies
across both. A run lists them separately:

```
  Dictionary: 10 rule(s) from /home/lukas/Programy/lektor_ai/dictionary.txt
  Dictionary: 2 rule(s) from output/clips/S02E01/queue_dictionary.txt
      3 dictionary replacement(s) applied.
```

On the command line it is `--dictionary-extra FILE`, which works with any file
you like.

## Number normalization

Higgs Audio misreads long digit strings and sometimes emits garbled non-words,
so the **last** subtitle stage rewrites numbers as Polish words:

```
Wygrał 1247 złotych.   →  Wygrał tysiąc dwieście czterdzieści siedem złotych.
Mówimy o 25 psach.     →  Mówimy o dwudziestu pięciu psach.
Mam 3 koty.            →  Mam 3 koty.
```

The case matters — `25 psów` / `o 25 psach` / `z 25 psami` are three different
forms of the same numeral — which is why this is a small fine-tuned model rather
than a lookup table. Standalone single digits are left as digits: the TTS reads
those correctly, and expanding them only makes the clip longer than the subtitle
window it has to fit.

It runs **after** the dictionary, so a rule that turns `16%` into `16 procent`
feeds `szesnaście procent`, and after dialogue splitting, so the numbers are
normalized in the clip that actually says them.

| Flag | Default | Meaning |
|---|---|---|
| `--normalize-numbers` | on | Spell digits out |
| `--no-normalize-numbers` | | Leave digits alone for this run |

or in `settings.ini`:

```ini
[normalize]
numbers = no
```

### Install

The model needs `transformers >= 5`, which must not go into the ComfyUI
environment, so it lives in `normalizer/` with its own venv:

```bash
normalizer/setup.sh                             # venv + torch + transformers
HF_TOKEN=hf_... normalizer/setup.sh --model     # the weights
```

The weights are **gated**: accept the terms at
<https://huggingface.co/Folx/qwen3-0.6b-pl-text-normalization> with your Hugging
Face account, then create a token at <https://huggingface.co/settings/tokens>.
That is the only step that needs the network; runs are offline afterwards.

Full details, including the JSON-lines protocol and the deviations from the
build brief, are in [normalizer/README.md](../normalizer/README.md).

### Two models, and which one gets a block

Numbers fail in two different ways and no single model handles both:

| block contains | goes to | because |
|---|---|---|
| plain integers only (74%) | num2words → inflection model | num2words cannot miscount; the model only fixes the case |
| times, dates, decimals, `P10`, `LO 3842` (26%) | the 0.6B fine-tune | it was trained on those formats; the other leg destroys them |

The split is why `Mówili o 250000 uchodźcach.` comes out as *o dwustu
pięćdziesięciu tysiącach uchodźców* — the fine-tune alone renders that as
*o pięciu tysiącach*, losing the number — while `Teraz na P12.` still comes out
as *P dwanaście* rather than *Pdziesięć*.

Every answer is then checked before use: runaway length, repetition loops,
invalid characters, leftover digits, a lost minus sign, a changed number, a lost
word. A block that fails falls back to num2words — nominative, but never wrong
about the value. The run reports how often that happened.

Set `llm =` (empty) to use the fine-tune for everything.

### What a run prints

```
      5 block(s) contain numbers — normalizing…
      Asking ComfyUI to unload its models (7.9 GB)…
      Freed 7.9 GB.
      Normalizer ready (model on cuda:0, two models).
      5 of 5 block(s) rewritten (2 complex, 3 plain).
      1 block(s) failed a safety check and fell back (word lost x1).
```

`Normalizer ready (fallback)` means the model is missing or failed to load and
`num2words` is standing in — bare integers in the nominative case only, with
times, dates and decimals left as digits. The run says so and continues.

### Sharing the GPU with ComfyUI

Higgs stays resident between runs — about 8.4 GB of a 16 GB card — which leaves
too little for the normalizer. That failure is silent rather than loud:
`accelerate` answers a shortage by spilling layers to RAM, so the run continues
with no error and roughly **5× the time per block** (measured: 1.19 s → 5.96 s).

So before starting the normalizer the script asks ComfyUI to unload:

```
      5 block(s) contain numbers — normalizing…
      Asking ComfyUI to unload its models (7.9 GB)…
      Freed 7.9 GB.
      Normalizer ready (model on cuda:0).
```

ComfyUI reloads Higgs on the first clip of step 2 — 20–30 s, once per run. It is
a `POST /free` on ComfyUI's own API, not a restart: the server stays up, with
its custom nodes loaded. The unload is asynchronous, so the script waits until
`torch_vram_total` in `/system_stats` actually drops before continuing.

`--regen` and `--rebuild` work from `tts_input.srt`, which is already
normalized, so they never normalize and never pay the reload. On a freshly
started ComfyUI the call is a no-op and prints nothing.

Set `free_comfy_vram = no` to skip it — worth doing only if you have VRAM to
spare, or if you have turned the neural normalizer off.

Nothing about this stage is fatal. A missing venv, a worker that dies, a block
that takes longer than `timeout` — each is a warning, and the affected text goes
to the TTS with its digits intact. The worker is started once per run and exits
before TTS generation begins, so it is not holding VRAM while Higgs works.

## The backend's lifecycle

ComfyUI is normally started once and left running. The script manages it when it
has to:

| situation | what happens |
|---|---|
| not running when a clip is submitted | started via `start_comfyui.sh`, waited for, the clip resubmitted |
| running but wedged or suspended | stopped (SIGKILL if suspended) before the restart |
| dies on a clip | up to 3 retries, each with a **different seed** |
| dies 3 times on the same clip | that clip is skipped, the queue continues, all skips reported at the end |
| queue finished | models unloaded, backend left running — it reloads on the next request |
| GUI closed | backend stopped, so no idle process is left holding the GPU |

Its output goes to `comfyui.log` next to the script as well as to the terminal
window, so a crash can be diagnosed after the fact.

The GUI has a **ComfyUI** button showing the same state: `Start ComfyUI` when it
is down, `ComfyUI ●` when it is answering, `ComfyUI ◍` when it holds the port but
does not answer. Pressing it starts or restarts.

Quitting the GUI stops the backend, including one you started by hand in a
terminal — it is found by port, not by remembering what was launched. Between
runs it stays up on purpose: the queue only unloads its models, so the next job
does not pay for a cold start.

`start_comfyui.sh` ends with `exec python main.py`, so the script's PID *is*
ComfyUI's. Without that the launcher only ever sees a wrapper shell, and killing
it orphans the python still holding 8 GB of VRAM.

## Output

Everything belonging to one video is kept together in a **job folder** named
after the video file. Only the finished video is written to the top level.

```
output/
  clips/
    S01_E01 The Eyes/          job folder, named after the video file
      clip_NNNN.flac           one lossless clip per block, kept for --regen
      tts_input.srt            processed text actually sent to TTS
      tts_assembled.flac       all clips at their final positions, lossless
      embedded_sub.srt         extracted subtitle (--embedded-subs only)
      video_fragment.mkv       extracted segment (--end only)
    F1 The Movie 2025/
      ...
  S01_E01 The Eyes_lektor.mkv  the finished video
  F1 The Movie 2025_lektor.mkv
```

Each run prints the folder it is using:

```
  Job folder: output/clips/S01_E01 The Eyes
```

This is what makes `--rebuild` and `--regen` safe across films. `tts_input.srt`
and the clips are a matched pair — block *N* in the SRT is `clip_NNNN.flac` —
so both live in the job folder. They previously sat at the top level and every
new job overwrote the last one's, which meant rebuilding an older film paired
its clips with the newest film's text. Any past job can now be rebuilt at any
time.

The folder is derived from the video filename, so `--rebuild` and `--regen`
locate it automatically; just pass the same video path.

The finished file contains:

| Track | Content |
|---|---|
| Video | Stream-copied, untouched |
| Audio 0 | **Original** — stream-copied, full 5.1 if the source had it |
| Audio 1 | **Polish** — lektor mix, AAC 192k stereo, `language=pol` |
| Subtitles | Every track from the source, stream-copied |

The lektor track is stereo deliberately; see
[troubleshooting.md](troubleshooting.md#the-lektor-track-is-silent-in-the-player).

FLAC is used for every intermediate so repeated processing stays lossless. Only
the final voiceover track is ever encoded.

## Recipes

**Check a voice before committing to a full run**

```bash
python3 lektor_ai_comfy.py input/film.mkv --embedded-subs --end 02:00 --voice gudowski
```

**Tune the mix without regenerating speech**

```bash
python3 lektor_ai_comfy.py input/film.mkv --rebuild --orig-volume 0.45 --tts-volume 2.1
```

**Fix a handful of bad clips**

```bash
# read output/clips/<video name>/tts_input.srt, note the offending block numbers
python3 lektor_ai_comfy.py input/film.mkv --regen 88 91 104
python3 lektor_ai_comfy.py input/film.mkv --rebuild
```

**Reproduce a run exactly**

```bash
python3 lektor_ai_comfy.py input/film.mkv --embedded-subs --seed 123456
```

**Speech running long and overlapping the next line**

```bash
python3 lektor_ai_comfy.py input/film.mkv --embedded-subs --speed 1.35
```

## Reading the console

```
[1/4] Parsing subtitles 00:00–end…
      693 entries after dialogue splitting.
[2/4] Generating TTS (693 clips, speed 1.2×)…
  [12/693] 00:01:34,120  'Nie wiem, o czym mówisz.'
    Waiting for a3f8b201… done.
    → placed at 00:01:34,120, duration 1.84s
```

`→ placed at` reveals timing drift. A clip that overruns its window pushes the
next one forward, shown as `[+1.20s behind SRT]`. Small values are normal and
self-correct at the next natural gap in the subtitles; values that keep growing
mean `--speed` is too low for the material.

Assembly then shows a progress bar per batch (clips are assembled 500 at a time
to stay under the open-file limit), followed by the two-pass mux.