Undo/Redo for edit scene/batch/line

Changed edit scene, edit batch and edit line to work via the command system so that they can be undone and redone. If you didn't know you could edit scenes, batches or lines try double-clicking things in the GUI 😅

Underneath the hood there was a major overhaul of the command system to better support these operations, and to improve parallelism and feedback via the status bar. Please report any new issues you encounter.

There is some additional new functionality that is activated by holding shift when clicking icons in the main toolbar:

• Shift + Load - will reload the subtitles from the source file for existing projects, in case you want to change the batch settings. Top-level settings like the movie name and description will be kept, but all translations and scene/batch descriptions will be lost. I recommend enabling "Write Backup" in the settings menu, so that you can recover the previous version by renaming the .subtrans-backup file to .subtrans, in case it turns out this wasn't really what you wanted.
• Shift + Save - This isn't new at all, but in case you didn't already know, it allows you to save the project with a different name or path. Translated subtitles will follow the project.
• Shift + Start Translating - Will restart translation from the beginning, retranslating any scenes/batches that have existing translations, instead of resuming at the first untranslated batch.
• Shift + Start Translating Fast - As above but using multiple translation threads.

Speaking of fast translation, this option is now enabled dynamically based on the provider settings - typically this means that it will be disabled if you set a rate limit for the provider, in order to respect the limit. It will also now be respected by "Translate Selection", which previously always used multiple threads if the selection spanned multiple scenes.

What's Changed

• Rework of the command queue and project actions structure by @machinewrapped in #184

Full Changelog: v0.8.1...v0.8.2

Fix for parallel translations

Minor fix for an error that could occur when stopping/aborting multiple parallel translation commands (e.g. using "Translate Selection" with multiple scenes selected).

Also includes an update to the openai module which may fix a crash that could occur in parallel translations.

Undo/Redo commands

Finally got around to implementing undo/redo for commands, which have been sitting there as a TODO since the GUI was first written. Undo/Redo is supported for:

• Merge scenes
• Merge batches
• Split scene
• Split / Auto-split batch
• Merge lines
• Delete lines (a new command, the motivation to finally implement undo)
• Reparse translation (also new)

Undo/Redo is NOT supported for the following commands, and they will clear the undo stack.

• Load project / subtitles
• Translate selection
• Start/resume translation

Undo is also not supported for these operations, as they are not technically commands. The next release will probably convert them to undoable commands.

• Edit scene/batch description
• Edit subtitle text/translation

You can hover over the undo/redo icons in the toolbar to see what type of command will be undone or redone, if in doubt.

There were a lot of technical changes to support undo/redo, so as with any major update there are bound to be new bugs. The automated test suite has been greatly expanded though and quite a few bugs were squashed, so hopefully it is pretty stable. As ever, please report an issue if something isn't working as you would expect it to.

This release also adds a pre-processor option to merge lines shorter than a given length with the previous line. This is to help with the add absurdly short lines (<0.2 seconds) Whisper generates on occasion, but it's not really possible to know whether those lines are an orphaned part of the previous line or just a random hallucination, so this is definitely not guaranteed to improve the result, so it is not enabled by default (the duration is set to 0 seconds).

What's Changed

• Processing settings by @machinewrapped in #179
• Delete line action, plus undo implemented for various commands by @machinewrapped in #180

Full Changelog: v0.7.10...v0.8.0

Detect and fix unclosed <summary> tags in last line of translation

This release fixes the problem that sometimes occurs where the last line of a batch contains the batch summary because the closing tag is not present. If the last line is implausibly long the parser checks for an opening tag in the text, and discards anything from that point.

This is mainly an issue with Gemini, and seems to be even more common with Gemini 1.5 Flash as it sometimes produces absurdly long summaries and runs out of tokens (but is otherwise a very good translator). Along with the more flexible parsing in v0.7.8 this should basically eliminate structural errors in Gemini translations.

(v0.7.10 is a bug fix replacing v0.7.9)

Full Changelog: v0.7.8...v0.7.10

Improved handling of malformed Gemini responses

Adjusted the translation parser to handle the most common problems with translations returned by Gemini, which should fix most of the errors where you see something like this in the translation:

#123
Original>
Something or other
Translation>

This should reduce the number of retranslation requests and errors when translating with Gemini.

Fix for missing context

Fixes an issue where context (e.g. the list of names) was not being passed to the translator.

• Added new Whisper-Experimental instructions, based on the new default instructions, with additional cues that the AI should attempt to identify and fix transcription errors in the source. May make things better, may make things worse - let's find out :-)

New default instructions

The default instructions have been updated for this release - the first significant revision in quite a while, done with some advice from Claude. The new instructions significantly reduce the error rate with Gemini (fewer unreadable responses or summaries getting merged with translations), and with larger batches for all models.

They also work surprisingly well when the source subtitles contain OCR or transcription errors, so consider using them instead of the custom (OCR errors) or (Whispered) instructions.

The previous default instructions can still be found as instructions (legacy) in case you run into problems - please open an issue or comment in the discussions if you find that the new instructions are producing errors or worse results.

Additionally, lines which are empty in the translation are now shown differently to lines that were not translated - this is particularly useful when using "remove filler words", as Whisper often produces lines that are just something like "Eh?" that should not be subtitled.

The simple batcher has been removed - I think the "new" batcher has proven its reliability, I haven't ever felt the need to use the old batcher since it was implemented.

Some additional bug fixes:

• Occasional crashes in the new project settings dialog should finally be fixed
• Fixed project settings being copied across from the open project when starting a new project.
• Fixed target language being blank in the new project settings dialog

Fix for batch preview in new project settings

Fixed a bug introduced in a recent update that meant the pre-processor was always active for batch previews, even if the "pre-process subtitles" option was not selected.

Please see the discussions section for some important notes about Google Gemini.

0.7.5b - very minor update, possibly improves stability for the new project settings dialog in some cases, and includes new (experimental) instructions.

Fix for first-run options

• remember last used directory

Full Changelog: v0.7.2...v0.7.4

Ensure full-width punctuation in Asian script

• Pre/post process option to ensure that punctuation in Asian script that doesn't use whitespace is full-width, ensuring that it works with line breaks/splits.
• Update batcher preview on a background thread in the new project settings dialog.
• A few other bug-fixes.

Full Changelog: v0.7.1...v0.7.2