Description & Synopsis of AAC

[chris-shaw-2011]

Bug description
If I use ffmpeg to set the metadata on an aac file like so

ffmpeg.exe -i "test.m4b" -map a:0 -c:a aac -metadata description="description" -metadata synopsis="synopsis" "test.out.m4b"

Then if I check the metadata with the following code:

import * as mm from "music-metadata"

mm.parseFile("test.out.m4b").then(metadata => {
    console.log(metadata.common.description) //outputs ["synopsis"]
    console.log(metadata.common.synopsis) //common.synopsis doesn't exist
})

Expected behavior

import * as mm from "music-metadata"

mm.parseFile("test.out.m4b").then(metadata => {
    console.log(metadata.common.description) //outputs ["description"]
    console.log(metadata.common.synopsis) //outputs "synopsis"
})

https://wiki.multimedia.cx/index.php/FFmpeg_Metadata

Audio file demonstrating the problem
files.zip

[Borewit]

Current applied mapping:

ffmpeg	ffmpeg → m4a	m4a → music-metadata	m4a → Mp3tag
description	desc (description)	subtitle	DESCRIPTION
synopsis	ldes (long description)	description	PODCASTDESC

@ozelot379 in @6d1dc00 you mapped description to subtitle. Can you explain more about this? Is subtitle not a kind of extension or clarification to a title, instead of a description. You added a specific test for mp3 & m4a for:

1. short description:

   music-metadata/test/test-pr-544.ts

   Line 297 in 5d43711

   describe('Short Description', () => {

2. long description:

   music-metadata/test/test-pr-544.ts

   Line 328 in 5d43711

   describe('Long Description', () => {

I suppose you did that for a reason.

What about the following mapping, as @chrichris-shaw-2011 proposes: ?

ffmpeg	ffmpeg → m4a	m4a → music-metadata
description	desc (description)	description
synopsis	ldes (long description)	synopsis

[ghost]

MP3Tag stores SUBTITLE in desc and PODCASTDESC in ldesc for mp4 files.
And for mp3 files it stores SUBTITLE in TIT3 and PODCASTDESC in TDES.

I think, in MP3Tag SUBTITLE means the short description and PODCASTDESC the long description.

Before my PR (#544), the desc and ldesc tags in mp4 files was mapped in the same field description and couldn't used separated, without parse the native tags self.
And for mp3 files TIT3 was mapped to subtitle and TDES was missed.

Because you already named the short description subtitle for mp3, I used the same name for mp4.

But I see, it was a bad idea to name the long description description.

It would be ok for me, if you name the short description description and the long description synopsis, like @chris-shaw-2011 proposes, for both mp3 or mp4 files.
Alternatively, may it's also sense to name it short_description and long_description.

I can adapt my code I use music-metadata, no matter how you decide.

@Borewit I hope this can answer your questions?

[Borewit]

Thanks for your reply @ozelot379, I will follow your recommendation, but I will use description instead of shortDescription for a bit more backward compatibility.

ffmpeg	ffmpeg → m4a	m4a → music-metadata
description	desc (description)	description
synopsis	ldes (long description)	longDescription