Read and write ID3v1 information for MP3 files using python

1. Causes

has been crazy fan of "Winter Wu Theory of relativity", in order to tidy up the download of his MP3 spent a lot of effort, today suddenly found that the computer's MP3 imported into itunes, the file name is not recognized. #_ * itunes automatically recognizes the contents of the MP3 information. Many times, the filename is very good. The truth is, it makes me feel imperfect. Be sure to write the file name as well as MP3 information Central.

A search on the internet, a lot of Python code, are used eyeD3 this component package. Follow the example of a simple two to come out of a version, run the discovery latin_1 what the coding problem. OK put its tag and ID3 and frames package in the code of all changed to GBK can solve. But also found that if the file originally did not id3v1, get title directly error. I found two, and no one mentioned the question. It seems that I can do it by myself. Then there is no eyeD3 package at all. Because ID3v1 is really simple.

2. Analysis

Baidu has said that I want to write this information can be stored in the tail of the mp3 file.

ID3v1 is relatively simple, it is stored at the end of the MP3 file, with a 16-input editor open a MP3 file, view its end of the 128 sequential bytes, the data structure is defined as follows:

Char header[3]; /Tag header must be "tag" otherwise think no label/

Char title[30]; Title

Char artist[30]; Author

Char album[30]; Album

Char year[4]; /Vintage/

Char comment[30]; Notes

Char Genre; Type

ID3v1 information is stored in sequence, without any identity to separate it, such as the title information less than 30 bytes, then use ' "" to make up, or will cause information errors.

3. Resolve

Fortunately, the file structure is not complex, processing is relatively simple. The idea is very simple, read the tail of the MP3 file 128 bytes, to determine that there is a tag, there is the last 128 of our own information to replace, did not add 128 bytes up.

4. Code

The best document is the source code, of course I write the comments back. Do not rely on eyeD3 such a package, pure hand-written.

#encoding=utf8

__author__ ='pcode@qq.com'import os

importstructdefGetFiles(path):"""

    Read the file of the specified directory

    """FileDic=[]

    Files=os.listdir(path)for f in files:

        f=f[:-4]FileDic.append(f)returnFileDic,files

def_GetLast128K(path,file):

    Ff1=open(os.path.join(path,file),"rb")

    Ff1.seek(-128,2)

    Id3v1data=ff1.read()

    Ff1.close()return id3v1data

def_GetAllBinData(path,file):

    Ff1=open(os.path.join(path,file),"rb")

    Data=ff1.read()

    Ff1.close()return data

defSetTag(path,file,title,artist,album,year,comment,genre):"""

    Set some parameters of mp3 ID3 v1

    Char Header[3]; /* The tag header must be "TAG" or it is considered to have no tag */

    Char Title[30]; /*title*/

    Char Artist[30]; /*Author*/

    Char Album[30]; /* specials*/

    Char Year[4]; /*production age*/

    Char Comment[30]; /*Remarks*/

    Char Genre; /*type*/

    The 128 bytes of the mp3 file are id3v1 data. If there is data, the data is read and modified. If there is no data, it is added.

    """

    Header='TAG'# combines the data content of the last 128K id3V1

    Str =struct.pack('3s30s30s30s4s30ss',header,title,artist,album,year,comment,genre)#Get all the original data

    Data=_GetAllBinData(path,file)#Get the last 128 bytes of data

    Id3v1data=_GetLast128K(path,file)#Open the original file and prepare to write

    Ff=open(os.path.join(path,file),"wb")try:#Judge whether there is id3v1 data if id3v1data[0:3]!=header:# Countdown 128 bytes is not indicated by TAG #According to the structure of id3v1

            Ff.write(data+str)else:# There are cases to change

            Ff.write(data[0:-128]+str)

        Ff.close()print"OK"+title

    Except:

        Ff.write(data)print"Error "+title

    Finally:if ff :ff.close()if __name__=="__main__":#I store the mp3 file directory

    Path=u"K:\\reading\\Read\\Relativity"#Get the file name and full file name

    Names, files=GetFiles(path)# cool code for i in range(len(files)):#Note code decoding

        Title=names[i].encode('gbk')

        Artist=u'Author'.encode('gbk')

        Album=u'relativity '.encode('gbk')

        Year=''

        Comment=''

        Genre=''#call function handles SetTag(path,files[i],title,artist,album,year,comment,genre) 

5. Follow-up

After using the information of the ID3V1 is changed by the file name, the Settag function can also be migrated to other programs to change the ID3V1 information. But write the file there, regardless of whether the tag has to rewrite all the contents of the file. The efficiency is generally like. Speed does not eyeD3 this component fast. But at that time EyeD3 can not support Chinese, and the document was not ID3V1 information will be wrong, their own more relieved. Bingo.

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