audio - fscanf(文件指针， "%d\n%lg\n"，sig_length，sample_rate)；怎么解释呢？

Question

我有一个从互联网之前存在的科学音频文件类型(称为 TFD v1)的音频格式转换为未压缩的简单原始样本值数组...在 this page 上的 get_signal() 函数中，我不知道样本值的格式如何，以及为什么我需要采样率来从数组中读取 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 ，根据格式字符串从文件中读取格式化数据。

本例中的格式字符串为 "%d\n%lg\n" ，它分解为 %d (整数)、换行符、%lg(一个double)，以及另一个换行符。因此，基本上，它从文件中读取两行，第一行应包含具有样本长度的整数，第二行包含采样率。

举个例子，使用现代采样率:

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(以样本为单位)和采样率，其余行是信号值。