Check config files for bad settings, and explain unreadable input files

README.md

@@ -7,7 +7,7 @@ The package provides a convenient interface for FFmpeg, including a 2-pass encod
 
 ## Installation
 
-This package requires Python >= 3.9. For Windows users, ensure that Python is added to your system's PATH. I highly recommend that you use the [python.org](https://python.org) Python installation.
+This package requires Python >= 3.10. For Windows users, ensure that Python is added to your system's PATH. I highly recommend that you use the [python.org](https://python.org) Python installation.
 
 Install this package with the following command.
 
@@ -75,7 +75,7 @@ I've had a good time using this command with a Batch file on Windows. Refer to t
 | `--astreams` | all | `--astreams "0,1"` | Comma-separated list of **0-based audio stream positions** to include. When used with `--amix`, those streams will be mixed; otherwise, only the first selected stream is kept. |
 | `-v`<br>`--verbose` | false | `--verbose` | Enable verbose FFmpeg logging (useful for debugging). |
 | `--config` | off | `--config config.json` | Path to a JSON file containing a saved configuration. When a setting is provided by both JSON and CLI flags, the CLI flag wins. See [JSON Configuration](#json-configuration). |
-| `--no-config` | off | `no---config` | Disable loading any default configuration files. See [JSON Configuration](#json-configuration). |
+| `--no-config` | off | `--no-config` | Disable loading any default configuration files. See [JSON Configuration](#json-configuration). |
 | `--web` | false | `--web` | Launch the Web UI for this job. See [Web UI](#web-ui). |
 | `-p`<br>`--port` | random (when `--web`) | `-p 5333` | Run the Web UI on a specific port. If omitted, a random free port between 5000–6000 is chosen. |
 
@@ -115,7 +115,7 @@ Create a new plain text JSON file (`my-config.json`) structured like this:
 {
     "target_filesize": 10.0,
     "resolution": "1280x720",
-    "codec": "libvpx-vp9",
+    "codec": "vp9",
     "to": "00:00:40"
 }
 ```

ffmpeg4discord/__main__.py

@@ -14,6 +14,7 @@
 from textwrap import dedent
 from typing import Callable, Optional
 
+import ffmpeg
 from flask import Flask, redirect, render_template, request, send_file, url_for
 
 from ffmpeg4discord import arguments
@@ -445,7 +446,13 @@ def main() -> None:
     args["output"] = Path(args["output"])
     # the rest of the args are the encode settings
     settings = EncodeSettings(**args)
-    twopass = TwoPass(path)
+    try:
+        twopass = TwoPass(path)
+    except ffmpeg.Error as exc:
+        # ffprobe's last stderr line names the file and the problem, e.g. "clip.mp4: No such file or directory"
+        reason = exc.stderr.decode(errors="replace").strip().rsplit("\n", 1)[-1]
+        logging.error(reason or f"ffprobe couldn't read {path}")
+        raise SystemExit(1) from None
 
     if web:
         # --from and --to fill in the form's starting trim, so check them before starting the server

ffmpeg4discord/arguments.py

@@ -1,5 +1,6 @@
 """Reads ff4d's command-line flags and config files."""
 
+import difflib
 import json
 import logging
 import socket
@@ -185,6 +186,24 @@ def _search_for_default_config(args: dict) -> dict:
     return args
 
 
+def _check_config(config: dict, parser: ArgumentParser, file_path: Path) -> None:
+    """Reject config keys that match no flag and values outside a flag's choices, like argparse does on the command line."""
+    actions = {action.dest: action for action in parser._actions if action.dest != "help"}
+    for key, value in config.items():
+        if key not in actions:
+            message = f"{file_path} has an unknown setting {key!r}."
+            match = difflib.get_close_matches(key, actions, n=1)
+            if match:
+                message += f" Did you mean {match[0]!r}?"
+            parser.error(message)
+        choices = actions[key].choices
+        if choices is not None and value not in choices:
+            flags = "/".join(actions[key].option_strings)
+            parser.error(
+                f"{file_path}: argument {flags}: invalid choice: {value!r} (choose from {', '.join(map(repr, choices))})"
+            )
+
+
 def _merge_config_args(args: dict, parser: ArgumentParser, argv: list[str] | None = None) -> dict:
     """
     Make the config file's values the parser's defaults, then parse the command line again.
@@ -198,6 +217,7 @@ def _merge_config_args(args: dict, parser: ArgumentParser, argv: list[str] | Non
         if file_path not in configs:
             configs.add(file_path)
             config = load_config(file_path)
+            _check_config(config, parser, file_path)
             args["config"] = config.get("config")
             defaults = {**config, **defaults}  # a config file beats the one it points to
     if defaults:

tests/test_arguments.py

@@ -170,7 +170,7 @@ def test_merge_config_args_applies_config_values(parser, write_config):
     config = {
         "output": "mydir",
         "audio_br": 128,
-        "codec": "vp9-speed",
+        "codec": "vp9",
         "filename_times": True,
         "from": "00:00:10",
         "framerate": 60,
@@ -205,10 +205,30 @@ def test_merge_config_args_command_line_beats_config(parser, write_config, confi
     assert result[key] == expected
 
 
-def test_merge_config_args_keeps_keys_that_are_not_flags(parser, write_config):
-    argv = ["file.mp4", "--config", str(write_config({"something_else": 1}))]
-    result = _merge_config_args(vars(parser.parse_args(argv)), parser, argv)
-    assert result["something_else"] == 1
+def test_merge_config_args_rejects_unknown_key(parser, write_config, capsys):
+    path = write_config({"target-filesize": 20})
+    argv = ["file.mp4", "--config", str(path)]
+    with pytest.raises(SystemExit):
+        _merge_config_args(vars(parser.parse_args(argv)), parser, argv)
+    err = capsys.readouterr().err
+    assert f"{path.resolve()} has an unknown setting 'target-filesize'. Did you mean 'target_filesize'?" in err
+
+
+def test_merge_config_args_rejects_invalid_codec(parser, write_config, capsys):
+    path = write_config({"codec": "libvpx-vp9"})
+    argv = ["file.mp4", "--config", str(path)]
+    with pytest.raises(SystemExit):
+        _merge_config_args(vars(parser.parse_args(argv)), parser, argv)
+    err = capsys.readouterr().err
+    assert f"{path.resolve()}: argument -c/--codec: invalid choice: 'libvpx-vp9'" in err
+
+
+def test_merge_config_args_names_the_nested_file_with_the_bad_value(parser, write_config, capsys):
+    inner = write_config({"codec": "bogus"}, name="inner.json")
+    argv = ["file.mp4", "--config", str(write_config({"config": str(inner)}))]
+    with pytest.raises(SystemExit):
+        _merge_config_args(vars(parser.parse_args(argv)), parser, argv)
+    assert f"{inner.resolve()}: argument -c/--codec" in capsys.readouterr().err
 
 
 def test_merge_config_args_follows_config_key(parser, write_config):

tests/test_main.py

@@ -5,6 +5,7 @@
 from types import SimpleNamespace
 from unittest.mock import ANY, MagicMock
 
+import ffmpeg
 import pytest
 from flask import Flask
 
@@ -151,6 +152,26 @@ def test_main_shows_bad_flags_without_a_traceback(monkeypatch, caplog):
     assert "Invalid --astreams value '0,x'" in caplog.text
 
 
+@pytest.mark.parametrize(
+    ("stderr", "message"),
+    [
+        (
+            b"ffprobe version 8.0\n/clips/nope.mp4: No such file or directory\n",
+            "/clips/nope.mp4: No such file or directory",
+        ),
+        (b"", "ffprobe couldn't read"),
+    ],
+)
+def test_main_shows_unreadable_input_without_a_traceback(monkeypatch, caplog, stderr, message):
+    monkeypatch.setattr(mainmod, "check_for_update", lambda **_: VersionInfo("0.1.9", "0.1.9"))
+    monkeypatch.setattr(sys, "argv", ["ff4d", "nope.mp4", "--no-config"])
+    monkeypatch.setattr(mainmod, "TwoPass", MagicMock(side_effect=ffmpeg.Error("ffprobe", b"", stderr)))
+    with pytest.raises(SystemExit) as exc_info:
+        mainmod.main()
+    assert exc_info.value.code == 1
+    assert message in caplog.text
+
+
 def test_main_web_ignores_dry_run(run_main, monkeypatch, caplog):
     app = MagicMock()
     monkeypatch.setattr(mainmod, "Flask", MagicMock(return_value=app))