Zerek
200 lines
4.6 KiB
Markdown
200 lines
4.6 KiB
Markdown
# bvid说明
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2020-03-23 B站推出了全新的稿件视频id“bvid”来接替之前的“avid”，其用法与性质等价于“avid”
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详见：
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1. [【升级公告】AV号全面升级至BV号（专栏）](https://www.bilibili.com/read/cv5167957)
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2. [【升级公告】AV号全面升级至BV号](https://www.bilibili.com/blackboard/activity-BV-PC.html)
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## 格式
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“bvid”恒为长度为12的字符串，前两个字母为大写“BV”，后10个为base58计算结果
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## 实质
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“bvid"为“avid”的base58编码，可通过算法进行相互转化
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## avid发放方式的变化
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从2009-09-09 09:09:09 [av2](https://www.bilibili.com/video/av2)的发布到2020-03-28 19:45:02 [av99999999](https://www.bilibili.com/video/av99999999)的发布B站结束了以投稿时间为顺序的avid发放，改为随机发放avid
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~~暗示B站东方要完？泪目~~
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## av->bv算法
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注：本算法及示例程序仅能编码及解码avid<` 29460791296 `，无法验证avid>=` 29460791296 `的正确性
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1. a=(avid⊕177451812)+8728348608
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2. 以i为循环变量循环6次b[i]=(a/58^i)%58
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3. 将b[i]中各个数字转换为以下码表中的字符
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码表：
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> fZodR9XQDSUm21yCkr6zBqiveYah8bt4xsWpHnJE7jL5VG3guMTKNPAwcF
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4. 初始化字符串b[i]=`BV1 4 1 7 `
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5. 按照以下字符顺序编码表编码并填充至b[i]
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字符顺序编码表：
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> 0 -> 11
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>
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> 1 -> 10
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>
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> 2 -> 3
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>
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> 3 -> 8
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>
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> 4 -> 4
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>
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> 5 -> 6
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算法以及程序主要参考[知乎@mcfx的回答](https://www.zhihu.com/question/381784377/answer/1099438784)
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## bv->av算法
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为以上算法的逆运算
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## 转换程序
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使用Python、C以及TypeScript作为示例，欢迎社区提交更多例程
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### python
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```python
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table = 'fZodR9XQDSUm21yCkr6zBqiveYah8bt4xsWpHnJE7jL5VG3guMTKNPAwcF' # 码表
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tr = {} # 反查码表
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# 初始化反查码表
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for i in range(58):
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tr[table[i]] = i
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s = [11, 10, 3, 8, 4, 6] # 位置编码表
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XOR = 177451812 # 固定异或值
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ADD = 8728348608 # 固定加法值
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def bv2av(x):
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r = 0
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for i in range(6):
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r += tr[x[s[i]]] * 58 ** i
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return (r - ADD) ^ XOR
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def av2bv(x):
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x = (x ^ XOR) + ADD
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r = list('BV1 4 1 7 ')
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for i in range(6):
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r[s[i]] = table[x // 58 ** i % 58]
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return ''. join(r)
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print(av2bv(170001))
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print(bv2av('BV17x411w7KC'))
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```
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输出为：
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```
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BV17x411w7KC
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170001
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```
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### C语言
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```c
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#include <stdio.h>
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#include <stdlib.h>
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#include <math.h>
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#include <string.h>
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const char table[] = "fZodR9XQDSUm21yCkr6zBqiveYah8bt4xsWpHnJE7jL5VG3guMTKNPAwcF"; // 码表
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char tr[124]; // 反查码表
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const unsigned long long XOR = 177451812; // 固定异或值
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const unsigned long long ADD = 8728348608; // 固定加法值
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const int s[] = {11, 10, 3, 8, 4, 6}; // 位置编码表
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// 初始化反查码表
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void tr_init() {
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for (int i = 0; i < 58; i++)
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tr[table[i]] = i;
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}
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unsigned long long bv2av(char bv[]) {
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unsigned long long r = 0;
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unsigned long long av;
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for (int i = 0; i < 6; i++)
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r += tr[bv[s[i]]] * (unsigned long long)pow(58, i);
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av = (r - ADD) ^ XOR;
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return av;
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}
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char *av2bv(unsigned long long av) {
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char *result = (char*)malloc(13);
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strcpy(result,"BV1 4 1 7 ");
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av = (av ^ XOR) + ADD;
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for (int i = 0; i < 6; i++)
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result[s[i]] = table[(unsigned long long)(av / (unsigned long long)pow(58, i)) % 58];
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return result;
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}
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int main() {
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tr_init();
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printf("%s\n", av2bv(170001));
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printf("%u\n", bv2av("BV17x411w7KC"));
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return 0;
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}
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```
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输出为：
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```
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BV17x411w7KC
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170001
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```
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### TypeScript
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感谢[#417](https://github.com/SocialSisterYi/bilibili-API-collect/issues/417#issuecomment-1186475063)提供
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```typescript
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export default class BvCode {
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private TABEL = 'fZodR9XQDSUm21yCkr6zBqiveYah8bt4xsWpHnJE7jL5VG3guMTKNPAwcF'; // 码表
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private TR: Record<string, number> = {}; // 反查码表
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private S = [11, 10, 3, 8, 4, 6]; // 位置编码表
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private XOR = 177451812; // 固定异或值
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private ADD = 8728348608; // 固定加法值
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constructor() {
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// 初始化反查码表
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const len = this.TABEL.length;
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for (let i = 0; i < len; i++) {
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this.TR[this.TABEL[i]] = i;
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}
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}
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av2bv(av: number): string {
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const x_ = (av ^ this.XOR) + this.ADD;
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const r = ['B', 'V', '1', , , '4', , '1', , '7'];
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for (let i = 0; i < 6; i++) {
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r[this.S[i]] = this.TABEL[Math.floor(x_ / 58 ** i) % 58];
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}
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return r.join('');
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}
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bv2av(bv: string): number {
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let r = 0;
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for (let i = 0; i < 6; i++) {
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r += this.TR[bv[this.S[i]]] * 58 ** i;
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}
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return (r - this.ADD) ^ this.XOR;
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}
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}
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const bvcode = new BvCode();
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console.log(bvcode.bv2av('BV17x411w7KC'));
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console.log(bvcode.av2bv(170001));
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```
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输出为：
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```
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BV17x411w7KC
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170001
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```
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