Question

我从互联网之前存在的科学音频文件类型（称为TFD v1）转换为未压缩的简单原始数组样本值...在this page上的get_signal（）函数中，我不知道样本值是如何格式化的，为什么我需要采样率从数组中读取256个点？

  fscanf (filepointer         , "%d\n%lg\n" , sig_length,  fsam         );
  fscanf (raw_audio_array_file,     ??      ,     256   ,  SRate_Float  );


    /*******************************************************
    * function get_signal reads signal data into sig_re from
    * the file pointed to by filepointer. If the file is a
    * type 2 TFD file then the imaginary part is set too.
    * If the signal is type 1, its hilbert transform is
    * returned in the imaginary part (sig_im).
    ********************************************************/


    void    get_signal (filepointer, sig_re, sig_im, fsam, sig_length)
        FILE   *filepointer;
        double  sig_re[],
                sig_im[],
               *fsam;
        int    *sig_length;

    {
        register int i; /* counter variable */
        int     sigtype; /* data file type */
        double  dummy1,
                dummy2; /* dummy temporary variables */


        fscanf (filepointer, "%d\n", &sigtype);
        if (sigtype == 1) { /* Type one TFD file */
     fscanf (filepointer, "%d\n%lg\n", sig_length, fsam);
     for (i = 0; i < *sig_length; i++) {
         fscanf (filepointer, "%lg\n", &sig_re[i]);
     }
     analytic (sig_re, sig_im, *sig_length);
        }
        else {
     if (sigtype == 2) { /* Type 2 TFD file */
         fprintf(stderr,"Complex signal.\n");    
         fscanf (filepointer, "%d\n%lg\n", sig_length, fsam);
         for (i = 0; i < *sig_length; i++) {
     fscanf (filepointer, "(%lg,%lg)\n", &sig_re[i], &sig_im[i]);
     printf("%lg\n",sig_re[i]);     
         }
     }
     else {
         fprintf (stderr, "ccg : incorrect input format.\n");
         exit (7);
     }
     fclose (filepointer);
        }
    } /* END OF FUNCTION get_signal */

Answer 1

fscanf (filepointer, "%d\n%lg\n", sig_length, fsam);调用C函数fscanf，它根据格式字符串从文件中读取格式化数据。

在这种情况下，格式字符串为"%d\n%lg\n"，其分为%d（整数），换行符，%lg（a double）和另一个换行符。所以，基本上，它从文件中读取两行，第一行应包含一个带样本长度的整数，第二行包含采样率。

例如，采用现代采样率：

1
256
44100.0
1.0
0.98
0.96
...

其中第一行是sigtype，第二行和第三行是信号长度（采样中）和采样率，其余行是信号值。

fscanf（filepointer，“％d \ n％lg \ n”，sig_length，sample_rate）;怎么解释呢？

1 个答案: