(七) 爬虫之爬取视频和音频文件
之前都是爬取网页中的文本信息，没有爬取过视频和音频文件，所以爬取了下b站和网易云音乐，记录下整个过程，留着学习。
1. 爬取b站视频
1.1 网页分析
最近python机器学习比较火热，那就爬取点机器学习的视频吧。首先打开b站网页，输入“python机器”进行搜索，返回页面中，审查元素可以发现每个视频系列都有一个唯一的ID，如下图所示： av28879057, 即为当前视频的一个ID值。
得知每个视频对应的唯一ID后，点击视频进去查看下，发现视频url主要有这下面这两种：
1：https://www.bilibili.com/video/av28879057 （视频只有一集，url即为上面我们观察到的ID值）
2. https://www.bilibili.com/video/av30292394/?p=3 （视频为一个系列，后面参数p=3，表示该ID下的第三集）
至此我们基本上对于每个视频界面的url构造清楚了，接下来就是寻找视频的下载地址了。刷新下网页，点击播放，查看下网络请求，对结果按大小排序，可以发现一个x-flv格式的大文件的传输请求，应该就是视频的下载地址，如下图所示，可以看到请求需要7个参数，研究了下别的视频后发现，有两个参数是动态变化的：ssig和trid。查看了下其他的json返回请求，并没有发现这两个参数，最后只能去网页源码里搜索下，看看有没有相关的动态生成函数，却发现网页源码中直接包含视频的下载地址，存在于一个window.__playinfo__={} 的字典json中，只需对其正则匹配就行了，这下就简单了。
将这个字典匹配后进行查看，结果如下：可以发现整个视频被拆分成了多个小的视频，按顺序进行了编号，order为序号，url即为视频下载地址，因此只需要分别对这些视频进行下载，最后再拼接就可以了。
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1.2 视频下载
根据上面的分析过程，视频爬取步骤如下：
1，根据视频的ID，构造该视频的url
2，访问视频url，对返回的网页进行正则匹配，拿到所有的视频下载地址和编号
3，根据视频下载地址，将视频保存到本地 （请求头中注意加入Referer和Origin，否则会返回Http 458）
代码如下：
#coding:utf-8 import requests import re import json import os import time import subprocess #传入视频的url def down_video(video_url,path="temp_videos"): """ video_url 待下载的video的url path 下载的视频保存地址 """ #video_url = "https://www.bilibili.com/video/av30292394?p=3" #video_url = "https://www.bilibili.com/video/av28879057" headers = { "User-Agent":"Mozilla/5.0 (Windows NT 6.1; r…) Gecko/20100101 Firefox/66.0", } response = requests.get(video_url,headers=headers) #在网页源码中匹配视频地址信息 match_text = re.search(r'<script>window.__playinfo__=(\{.*?\})</script>',response.text,re.S) #re.S,将字符窜中有换行时，将字符窜作为一个整体进行匹配；（否则一行匹配不到时，再匹配下一行） json_data = json.loads(match_text.group(1),encoding="utf-8") #match_text.group(1)为unicode字符窜 urls = json_data["data"]["durl"] #视频包括多个部分，拿到包括各个部分url的列表 content_size = sum([item["size"] for item in urls]) #视频总大小 print("视频总大小为：%0.2f Mb"%(content_size/(1024*1024))) if not os.path.exists(path): os.mkdir(path) header={ "Origin":"https://www.bilibili.com", "Referer":video_url, #请求头必须添加referer } headers.update(header) size=0 start = time.time() for i,item in enumerate(urls): url = item["url"] try: result = requests.get(url,headers=headers,stream=True,verify=False) print result.status_code video_path = os.path.join(path,"{}.mp4".format(i)) with open(video_path,"wb") as f: for chunk in result.iter_content(1024): f.write(chunk) f.flush() #清空缓存 size = size+len(chunk) #print("已下载：%0.2f Mb"%(size/(1024*1024))) except Exception as e: print("url下载错误：%s"%url) print(e) stop = time.time() print("下载完成，耗时：%0.2f秒"%(stop-start))
1.3 视频拼接
上面下载下来的视频也可以直接播放，但逐个播放比较麻烦，可以利用ffmpeg进行拼接。
首先需要下载ffmpeg（https://ffmpeg.zeranoe.com/builds/），解压将其拷贝到相应的文件夹，然后将bin目录下的ffmpeg.exe加入到环境变量，命令行输入ffmpeg -version， 返回提示信息即安装成功
ffmpeg拼接视频的命令语句为： ffmpeg -f concat -safe 0 -i path.txt -c copy output.mp4
其中path.txt包含需要拼接的视频的路径，格式如下：（表示video路径下的v_1.mp4）
file 'video/v_1.mp4' file 'video/v_2.mp4' file 'video/v_3.mp4'
output.mp4表示拼接后的视频存放地址，也可以写成 video/output.mp4，即保存到video文件夹下。
最终拼接的代码如下：
#将下载的多个视频拼接成一个完整的视频 def concatenate(path,title,output="vidoes"): """ path 为待拼接的视频的保存地址 title 为拼接后视频的名称 output 为拼接后视频保存的地址 """ with open("path.txt",'w') as f: for root,dirs,files in os.walk(path): for file in files: if os.path.splitext(file)[1] in [".flv",".mkv",".mp4"]: v_path = os.path.join(root,file) f.write("file '{}'\n".format(v_path)) if os.path.exists("path.txt"): if not os.path.exists(output): os.mkdir(output) try: print("开始合并视频") path_name = os.path.join(output,title+".mp4") ffmpeg_command = r"D:\ffmpeg-win32-static\bin\ffmpeg -f concat -safe 0 -i path.txt -c copy %s"%(path_name) #若将D:\ffmpeg-win32-static\bin\ffmpeg.exe路径加入环境变量，可以用"ffmpeg -f concat -safe 0 -i path.txt -c copy %s"%(path_name) #print ffmpeg_command subprocess.call(ffmpeg_command) subprocess.call("rmdir /s %s"%path) #windows 删除目录 subprocess.call("del path.txt") #windows 删除文件 except Exception as e: print(e)
完整的代码如下：
#coding:utf-8 import requests import re import json import os import time import subprocess #传入视频的url def down_video(video_url,path="temp_videos"): """ video_url 待下载的video的url path 下载的视频保存地址 """ #video_url = "https://www.bilibili.com/video/av30292394?p=3" #video_url = "https://www.bilibili.com/video/av28879057" headers = { "User-Agent":"Mozilla/5.0 (Windows NT 6.1; r…) Gecko/20100101 Firefox/66.0", } response = requests.get(video_url,headers=headers) #在网页源码中匹配视频地址信息 match_text = re.search(r'<script>window.__playinfo__=(\{.*?\})</script>',response.text,re.S) #re.S,将字符窜中有换行时，将字符窜作为一个整体进行匹配；（否则一行匹配不到时，再匹配下一行） json_data = json.loads(match_text.group(1),encoding="utf-8") #match_text.group(1)为unicode字符窜 urls = json_data["data"]["durl"] #视频包括多个部分，拿到包括各个部分url的列表 content_size = sum([item["size"] for item in urls]) #视频总大小 print("视频总大小为：%0.2f Mb"%(content_size/(1024*1024))) if not os.path.exists(path): os.mkdir(path) header={ "Origin":"https://www.bilibili.com", "Referer":video_url, #请求头必须添加referer } headers.update(header) size=0 start = time.time() for i,item in enumerate(urls): url = item["url"] try: result = requests.get(url,headers=headers,stream=True,verify=False) print result.status_code video_path = os.path.join(path,"{}.mp4".format(i)) with open(video_path,"wb") as f: for chunk in result.iter_content(1024): f.write(chunk) f.flush() #清空缓存 size = size+len(chunk) #print("已下载：%0.2f Mb"%(size/(1024*1024))) except Exception as e: print("url下载错误：%s"%url) print(e) stop = time.time() print("下载完成，耗时：%0.2f秒"%(stop-start)) #将下载的多个视频拼接成一个完整的视频 def concatenate(path,title,output="vidoes"): """ path 为待拼接的视频的保存地址 title 为拼接后视频的名称 output 为拼接后视频保存的地址 """ with open("path.txt",'w') as f: for root,dirs,files in os.walk(path): for file in files: if os.path.splitext(file)[1] in [".flv",".mkv",".mp4"]: v_path = os.path.join(root,file) f.write("file '{}'\n".format(v_path)) if os.path.exists("path.txt"): if not os.path.exists(output): os.mkdir(output) try: print("开始合并视频") path_name = os.path.join(output,title+".mp4") ffmpeg_command = r"D:\ffmpeg-win32-static\bin\ffmpeg -f concat -safe 0 -i path.txt -c copy %s"%(path_name) #若将D:\ffmpeg-win32-static\bin\ffmpeg.exe路径加入环境变量，可以用"ffmpeg -f concat -safe 0 -i path.txt -c copy %s"%(path_name) #print ffmpeg_command subprocess.call(ffmpeg_command) subprocess.call("rmdir /s %s"%path) #windows 删除目录 subprocess.call("del path.txt") #windows 删除文件 except Exception as e: print(e) if __name__=="__main__": # down_video("https://www.bilibili.com/video/av28879057") # concatenate("temp_videos",title="python") down_video("https://www.bilibili.com/video/av30292394?p=3") concatenate("temp_videos",title="python机器学习与量化分析")
参考：
https://amberwest.github.io/2018/09/11/%E7%94%A8python%E4%B8%8B%E8%BD%BD%E5%93%94%E5%93%A9%E5%93%94%E5%93%A9%E8%A7%86%E9%A2%91/
https://github.com/Henryhaohao/Bilibili_video_download
2. 爬取网易云音乐
2.1 网页分析
查看了下网页版的网易云音乐，也是每首歌有一个ID，如下，对应的网址组成为 https://music.163.com/song?id=1353372483（请求时网易自动添加了一个“#”，从而变成了https://music.163.com/#/song?id=1352541009）
接着刷新网页，看下网络请求，同样按大小排序，可以发现一个较大的mp3传输请求，如下图所示：该url即为音乐的下载url，直接发送请求就能下载该视频，剩下就是如何获得每首歌的下载url。
查看了下其他xhr请求的返回值，发现了如下的返回值，可以看到其包含了歌曲的相关信息，从中可以拿到我们需要的url。观察这个请求，发现是一个post请求，需要提交表单数据，主要是两个参数'params' 和'encSecKey', 但是是加密后的数据，如下第二张图所示，因此需要对加密方法进行解析。
整理下思路，下载音乐的整个流程可以分为三步，如下：
1.通过get请求，访问https://music.163.com/song?id=1353372483，能拿到歌曲的名字，歌词等基本信息
2.通过post请求，提交两个参数'params' 和'encSecKey'，访问https://music.163.com/weapi/song/enhance/player/url/v1?csrf_token=，从返回的json 数据中能拿到歌曲的下载地址和大小等信息
3. 访问歌曲的下载地址（http://m10.music.126.net/20190407154531/74f897c9d014dede19a0905644433907/ymusic/035c/5458/530f/46ebf59083c2f04cc090de3b1e0beaf0.mp3），将其写到本地，即完成下载信息
因此，剩下的就是如何构造加密后的两个参数'params' 和'encSecKey'。点击浏览器的source选项，在每个js文件下搜索下encSecKey（或者直接ctrl+shift +f 全局搜索），在如下js文件中找到了相关的代码，正好包括了我们需要的两个参数。
对上面的代码进行分析，主要是var bYl2x = window.asrsea()这个函数完成具体的工作，搜索这个函数发现了如下的语句 window.asrsea = d, 即该函数是d函数，而d函数中调用了一次a函数，两次b函数和一次c函数
其中a函数主要是产生一组随机的字符窜，这里是a(16)产生一个包含16个字符的随机字符窜，上面js代码和对应的python实现如下：
#a 函数 function a(a) { var d, e, b = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789", c = ""; for (d = 0; a > d; d += 1) e = Math.random() * b.length, e = Math.floor(e), c += b.charAt(e); return c } #对应python产生随机字符窜代码 def random_str(size): return binascii.hexlify(os.urandom(size))[:16] #binascii.hexlify()接受byte字符窜，返回ascii字符窜
b函数是对数据进行AES对称加密，js代码和对应的python实现如下：
python需要用到Crypto模块，pip install crypto安装会有问题，通过如下方式安装：（windows 7和python2.7环境安装成功）
python -m pip install pycrypto
#b函数 function b(a, b) { var c = CryptoJS.enc.Utf8.parse(b) , d = CryptoJS.enc.Utf8.parse("0102030405060708") , e = CryptoJS.enc.Utf8.parse(a) , f = CryptoJS.AES.encrypt(e, c, { iv: d, mode: CryptoJS.mode.CBC }); return f.toString() } #python 实现b函数 from Crypto.Cipher import AES import base64 def get_params(text,key): #AES对称加密 iv = '0102030405060708' pad = 16 - len(text)%16 text = text + pad * chr(pad) encryptor = AES.new(key, AES.MODE_CBC, iv) result = encryptor.encrypt(text) result_str = base64.b64encode(result).decode('utf-8') return result_str
c函数是对数据进行RSA不对称加密，s代码和对应的python实现如下：
#c函数 function c(a, b, c) { var d, e; return setMaxDigits(131), d = new RSAKeyPair(b,"",c), e = encryptedString(d, a) } #python实现c函数 def get_encSecKey(text,pubkey,modulus): #rsa不对称加密 text = text[::-1] rs = pow(int(binascii.hexlify(text),16),int(pubkey,16),int(modulus,16)) return format(rs,'x').zfill(256)
接下来就该分析下window.asrsea()传入的四个参数了，需要插入断点，如图所示，点击某一行插入断点，然后点击播放音乐，执行到断点处后，点击右边红圈处的两个按钮（第一个向下执行一个过程，第二个向下执行一句），当我们选中四个参数中的某一个时（复制时那样选中），即能看到该参数的值。
如下图是选中第二个参数时，显示的值为“010001”，说明第二个参数为一个常量，查看其它参数后发现第二三四个参数都为常量，第一个参数为与id相关的json数据。四个参数的示例可以见下面：
四个参数示例：
first_param = {"ids":"[1353194608]","level":"standard","encodeType":"aac","csrf_token":""}
second_param = "010001"
third_param = "00e0b509f6259df8642dbc35662901477df22677ec152b5ff68ace615bb7b725152b3ab17a876aea8a5aa76d2e417629ec4ee341f56135fccf695280104e0312ecbda92557c93870114af6c9d05c4f7f0c3685b7a46bee255932575cce10b424d813cfe4875d3e82047b97ddef52741d546b8e289dc6935b3ece0462db0a22b8e7"
fourth_param = "0CoJUm6Qyw8W8jud"
上面整个过程只需要利用歌曲的ID值和上面三个常量参数，就可以构造最终的加密数据了，剩下的就是写代码了
2.2 歌曲下载
根据上面的分析过程，代码书写流程如下：
1，根据歌曲id值，访问https://music.163.com/song?id=1353372483，利用正则表达式匹配网页内容，获得歌曲名称
2，计算加密后的参数'params' 和'encSecKey'，post请求访问https://music.163.com/weapi/song/enhance/player/url/v1?csrf_token=，拿到歌曲url和size
3. 访问歌曲的下载地址，将结果写到本地
完整代码如下：
#coding:utf-8 import os import binascii from Crypto.Cipher import AES import base64 import json import requests import re first_param = {"ids":"[1353194608]","level":"standard","encodeType":"aac","csrf_token":""} second_param = "010001" third_param = "00e0b509f6259df8642dbc35662901477df22677ec152b5ff68ace615bb7b725152b3ab17a876aea8a5aa76d2e417629ec4ee341f56135fccf695280104e0312ecbda92557c93870114af6c9d05c4f7f0c3685b7a46bee255932575cce10b424d813cfe4875d3e82047b97ddef52741d546b8e289dc6935b3ece0462db0a22b8e7" fourth_param = "0CoJUm6Qyw8W8jud" headers={ "Referer":"https://music.163.com/", "User-Agent":"Mozilla/5.0 (Linux; Android 6.0; Nexus 5 Build/MRA58N) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.81 Mobile Safari/537.36" } def random_str(size): return binascii.hexlify(os.urandom(size))[:16] #binascii.hexlify()接受byte字符窜，返回ascii字符窜 def get_params(text,key): #AES对称加密 iv = '0102030405060708' pad = 16 - len(text)%16 text = text + pad * chr(pad) encryptor = AES.new(key, AES.MODE_CBC, iv) result = encryptor.encrypt(text) result_str = base64.b64encode(result).decode('utf-8') return result_str def get_encSecKey(text,pubkey,modulus): #rsa不对称加密 text = text[::-1] rs = pow(int(binascii.hexlify(text),16),int(pubkey,16),int(modulus,16)) return format(rs,'x').zfill(256) def encrypt_data(first_param,second_param,third_param,fourth_param): data={} i = random_str(16) temp = get_params(json.dumps(first_param),fourth_param) params = get_params(temp,i) encSecKey = get_encSecKey(i,second_param,third_param) data['params']=params.encode("utf-8") data['encSecKey']=encSecKey return data #获取歌曲名称 def get_song_title(id): url = "https://music.163.com/song?id=%s"%(id) response = requests.get(url,headers=headers) title = re.search(r'<title>(.*?)\s-',response.text).group(1) #匹配歌曲标题 #print(title) return title #获取歌曲的下载地址，大小等信息 def get_song_info(id): first_param['ids'] = "[%s]"%id data = encrypt_data(first_param,second_param,third_param,fourth_param) url="https://music.163.com/weapi/song/enhance/player/url/v1?csrf_token=" response = requests.post(url,headers=headers,data=data) #print response.status_code json_data = json.loads(response.text) return json_data #下载歌曲 def down_song(id,down_url,song_title,size): filename = song_title+str(id)+".mp3" print("歌曲大小为：%0.2f Mb"%(size/(1024*1024))) try: result = requests.get(down_url,headers=headers) with open(filename,"wb") as f: for chunk in result.iter_content(1024): f.write(chunk) f.flush() except Exception as e: print("下载失败,id值为：%s"%id) print(e) print("下载完成") if __name__=="__main__": id=input("请输入歌曲的id值，如：1353194608 ") song_title = get_song_title(id) song_info=get_song_info(id) down_url = song_info["data"][0]["url"] size = song_info["data"][0]["size"] #print down_url,size down_song(id,down_url,song_title,size)
参考：
https://blog.csdn.net/qq_38282706/article/details/80251666
https://github.com/Jack-Cherish/python-spider/blob/master/Netease/Netease.py
