Sample code

This section shows sample code for encoding and decoding speech using the Speex API. The commands can be used to encode and decode a file by calling: 
% sampleenc in_file.sw | sampledec out_file.sw
where both files are raw (no header) files encoded at 16 bits per sample (in the machine natural endianness).

sampleenc.c

sampleenc takes a raw 16 bits/sample file, encodes it and outputs a Speex stream to stdout. Note that the packing used is NOT compatible with that of speexenc/speexdec.

#include <speex/speex.h>
#include <stdio.h>

/*The frame size in hardcoded for this sample code but it doesn't have to be*/
#define FRAME_SIZE 160
int main(int argc, char **argv)
{
   char *inFile;
   FILE *fin;
   short in[FRAME_SIZE];
   float input[FRAME_SIZE];
   char cbits[200];
   int nbBytes;
   /*Holds the state of the encoder*/
   void *state;
   /*Holds bits so they can be read and written to by the Speex routines*/
   SpeexBits bits;
   int i, tmp;

   /*Create a new encoder state in narrowband mode*/
   state = speex_encoder_init(&speex_nb_mode);

   /*Set the quality to 8 (15 kbps)*/
   tmp=8;
   speex_encoder_ctl(state, SPEEX_SET_QUALITY, &tmp);

   inFile = argv[1];
   fin = fopen(inFile, "r");

   /*Initialization of the structure that holds the bits*/
   speex_bits_init(&bits);
   while (1)
   {
      /*Read a 16 bits/sample audio frame*/
      fread(in, sizeof(short), FRAME_SIZE, fin);
      if (feof(fin))
         break;
      /*Copy the 16 bits values to float so Speex can work on them*/
      for (i=0;i<FRAME_SIZE;i++)
         input[i]=in[i];

      /*Flush all the bits in the struct so we can encode a new frame*/
      speex_bits_reset(&bits);

      /*Encode the frame*/
      speex_encode(state, input, &bits);
      /*Copy the bits to an array of char that can be written*/
      nbBytes = speex_bits_write(&bits, cbits, 200);

      /*Write the size of the frame first. This is what sampledec expects but
       it's likely to be different in your own application*/
      fwrite(&nbBytes, sizeof(int), 1, stdout);
      /*Write the compressed data*/
      fwrite(cbits, 1, nbBytes, stdout);
      
   }
   
   /*Destroy the encoder state*/
   speex_encoder_destroy(state);
   /*Destroy the bit-packing struct*/
   speex_bits_destroy(&bits);
   fclose(fin);
   return 0;
}

sampledec.c

sampledec reads a Speex stream from stdin, decodes it and outputs it to a raw 16 bits/sample file. Note that the packing used is NOT compatible with that of speexenc/speexdec.

#include <speex/speex.h>
#include <stdio.h>

/*The frame size in hardcoded for this sample code but it doesn't have to be*/
#define FRAME_SIZE 160
int main(int argc, char **argv)
{
   char *outFile;
   FILE *fout;
   /*Holds the audio that will be written to file (16 bits per sample)*/
   short out[FRAME_SIZE];
   /*Speex handle samples as float, so we need an array of floats*/
   float output[FRAME_SIZE];
   char cbits[200];
   int nbBytes;
   /*Holds the state of the decoder*/
   void *state;
   /*Holds bits so they can be read and written to by the Speex routines*/
   SpeexBits bits;
   int i, tmp;

   /*Create a new decoder state in narrowband mode*/
   state = speex_decoder_init(&speex_nb_mode);

   /*Set the perceptual enhancement on*/
   tmp=1;
   speex_decoder_ctl(state, SPEEX_SET_ENH, &tmp);

   outFile = argv[1];
   fout = fopen(outFile, "w");

   /*Initialization of the structure that holds the bits*/
   speex_bits_init(&bits);
   while (1)
   {
      /*Read the size encoded by sampleenc, this part will likely be 
        different in your application*/
      fread(&nbBytes, sizeof(int), 1, stdin);
      fprintf (stderr, "nbBytes: %d\n", nbBytes);
      if (feof(stdin))
         break;
      
      /*Read the "packet" encoded by sampleenc*/
      fread(cbits, 1, nbBytes, stdin);
      /*Copy the data into the bit-stream struct*/
      speex_bits_read_from(&bits, cbits, nbBytes);

      /*Decode the data*/
      speex_decode(state, &bits, output);

      /*Copy from float to short (16 bits) for output*/
      for (i=0;i<FRAME_SIZE;i++)
         out[i]=output[i];

      /*Write the decoded audio to file*/
      fwrite(out, sizeof(short), FRAME_SIZE, fout);
   }
   
   /*Destroy the decoder state*/
   speex_decoder_destroy(state);
   /*Destroy the bit-stream truct*/
   speex_bits_destroy(&bits);
   fclose(fout);
   return 0;
}