doc: GitBook - added about page

doc/en/SUMMARY.md

@@ -10,6 +10,9 @@
 ## Architecure
 
 * [Overview](architecure/overview.md)
+* [Database Structure](architecure/database-structure/README.md)
+  * [Type of Song](architecure/database-structure/type-of-song.md)
+* [Artificial Intelligence](architecure/artificial-intelligence.md)
 
 ## API Doc
 

doc/en/about/scope-of-inclusion.md

@@ -1,2 +1,19 @@
 # Scope of Inclusion
 
+CVSA contains many aspects of Chinese Vocal Synthesis, including songs, albums, artists (publisher, manipulators, arranger, etc), singers and voice engines / voicebanks. 
+
+For a **song**, it must meet the following conditions to be included in CVSA:
+
+### Category 30
+
+In principle, the songs featured in CVSA must be included in a video categorized under VOCALOID·UTAU (ID 30) that is posted on Bilibili. In some special cases, this rule may not be enforced. 
+
+### At Leats One Line of Chinese
+
+The lyrics of the song must contain at least one line in Chinese. This means that even if a voicebank that only supports Chinese is used, if the lyrics of the song do not contain Chinese, it will not be included in the CVSA.
+
+### Using Vocal Synthesizer
+
+To be included in CVSA, at least one line of the song must be produced by a Vocal Synthesizer (including harmony vocals).
+
+We define a vocal synthesizer as a software or system that generates synthesized singing voices by algorithmically modeling vocal characteristics and producing audio from input parameters such as lyrics, pitch, and dynamics, encompassing both waveform-concatenation-based (e.g., VOCALOID, UTAU) and AI-based (e.g., Synthesizer V, ACE Studio) approaches, **but excluding voice conversion tools that solely alter the timbre of pre-existing recordings** (e.g., [so-vits svc](https://github.com/svc-develop-team/so-vits-svc)).

doc/en/about/this-project.md

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 # About CVSA Project
 
+CVSA (Chinese Vocal Synthesis Archive) aims to collect as much content as possible about the Chinese Vocal Synthesis community in a highly automation-assisted way. 
+
+Unlike existing projects such as [VocaDB](https://vocadb.net), CVSA collects and displays the following content in an automated and manually edited way:
+
+* Metadata of songs (name, duration, publisher, singer, etc.)
+* Descriptive information of songs (content introduction, creation background, lyrics, etc.)
+* Engagement data snapshots of songs, i.e. historical snapshots of their engagement data (including views, favorites, likes, etc.) on the [Bilibili](https://en.wikipedia.org/wiki/Bilibili) website.
+* Information about artists, albums, vocal synthesizers, and voicebanks.
+

doc/en/api-doc/songs.md

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 # Songs
 
+Not implemented yet.

doc/en/architecure/artificial-intelligence.md

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+# Artificial Intelligence
+
+CVSA's automated workflow relies heavily on artificial intelligence for information extraction and classification.
+
+The AI ​​systems we currently use are:
+
+### The Filter
+
+Located at `/filter/` under project root dir, it classifies a video in the [category 30](../about/scope-of-inclusion.md#category-30) into the following categories:
+
+* 0: Not related to Chinese vocal synthesis
+* 1: A original song with Chinese vocal synthesis
+* 2: A cover/remix song with Chinese vocal synthesis

doc/en/architecure/database-structure/README.md

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+# Database Structure
+
+CVSA uses [PostgreSQL](https://www.postgresql.org/) as our database.
+
+All public data of CVSA (excluding users' personal data) is stored in a database named `cvsa_main`, which contains the following tables:
+
+* songs: stores the main information of songs
+* bili\_user: stores snapshots of Bilibili user information
+* all\_data: metadata of all videos in [category 30](../../about/scope-of-inclusion.md#category-30).
+* labelling\_result: Contains label of videos in `all_data`tagged by our [AI system](../artificial-intelligence.md#the-filter).
+

doc/en/architecure/database-structure/type-of-song.md

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+# Type of Song
+
+The **Unrelated type** refers specifically to videos that are not in our [Scope of Inclusion](../../about/scope-of-inclusion.md).
+
+### Table: `songs`
+
+The `type` column used in the `songs` table.
+
+| Type | Description  |
+| ---- | ------------ |
+| 0    | Unrelated    |
+| 1    | Original     |
+| 2    | Cover        |
+| 3    | Remix        |
+| 4    | Instrumental |
+| 10   | Others       |
+
+### Table: `labelling_result`
+
+| Label | Description            |
+| ----- | ---------------------- |
+| 0     | AI tagged: Unrelated   |
+| 1     | AI tagged: Original    |
+| 2     | AI tagged: Cover/Remix |