Matching [] characters with regex

[Kerndog73]

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I'm using the --metadata-from-title flag with regex and I would like to match the [ character. This is the full regex pattern.

(\[(?P<genre>.+?)\] -)?(?P<artist>.+?) - (?P<track>.+?)( \[[\w ]+\])?

I'm surrounding the pattern in 'single quotes' in the shell (bash). I'm not sure if I should be using "double quotes". I'm not really familiar with the difference between the two.

This URL has a sufficiently complex title for testing (although it doesn't have a multi-word genre).

These are some URLs that I've been testing with.

https://www.youtube.com/watch?v=5tAsUGEqob4
[Electro] - Sound Remedy & Nitro Fun - Turbo Penguin [Monstercat Release]

No genre
https://www.youtube.com/watch?v=YnwsMEabmSo
Marshmello - Alone [Monstercat Official Music Video]

No genre or [Ignored part]
https://www.youtube.com/watch?v=eOofWzI3flA
Skrillex - Rock n Roll (Will Take You to the Mountain)

I would like to match this title. For the first one, genre should be set to Electro, artist should be set to Sound Remedy & Nitro Fun and the track should be set to Turbo Penguin. [Monstercat Release] should not be included in the track. [Electro] - and [Monstercat Release] are optional.

This is how the title is parsed with the current regex

[fromtitle] parsed genre: Electro
[fromtitle] parsed track: T
[fromtitle] parsed artist: Sound Remedy & Nitro Fun

The problem I'm having is with the track. The part that is supposed to match anything within [] seems to be matching some of the track characters. With some variations of the pattern, the track is parsed as Turbo but I can't seem to get it to parse as Turbo Penguin. I think my problem has something to do with []. Also, I've never used ? in regex before. Nor have I used named capture groups (didn't even know they existed).

My full youtube-dl invokation is this:

youtube-dl --extract-audio --audio-format mp3 --audio-quality 320K --format bestaudio --add-metadata --metadata-from-title '(\[(?P<genre>.+?)\] - )?(?P<artist>.+?) - (?P<track>[\w ]+?)( \[[\w ]+\])?' --output 'song.%(ext)s' "https://www.youtube.com/watch?v=5tAsUGEqob4"

I'm fiddled around with the regex for a while and I can't seem to figure it out. Maybe bash or youtube-dl are doing something funky with []? I don't know.

[rautamiekka]

Some info:

The single quotes tell the shell to not scan and potentially mangle the string, so you should always use it when you can. That way you also introduce some additional speed to the processing.

Use (?: ) instead of full ( ) to both

• not introduce an unnamed capture group
• introduce some RAM savings.

You're doing the brackets correctly since you're escaping them.

[Kerndog73]

@rautamiekka I changed the pattern to this:

(?:\[(?P<genre>.+?)\] - )?(?P<artist>.+?) - (?P<track>.+?)(?: \[[\w ]+\])?

Are you sure I'm doing the [] correctly? How can (?: \[[\w ]+\])? match urbo Penguin? It should match a space and then a [. I don't understand.

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Maybe (?P<track>.+?) is matching T and then the rest is just ignored??? I must be doing something wrong.

[dstftw]

Invalid regex. Must be something like (?P<track>.+?)(?:\s*\[|$),

[Kerndog73]

Final regex is this:

(?:\[(?P<genre>.+?)\]\s*-\s*)?(?P<artist>.+?)\s*-\s*(?P<track>.+?)(?:\s*\[|$)

Works on all the tests I could find. I thought the regex had to match the whole title but apparently not. We can just find the [ and ignore everything after it.

I'm really happy with this! Thank you for your help!