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diff --git a/doc/programming.html b/doc/programming.html new file mode 100644 index 0000000..7b5bc7a --- /dev/null +++ b/doc/programming.html @@ -0,0 +1,125 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> +<html> +<head> + <title>Speex Programming</title> + + <meta http-equiv="content-type" + content="text/html; charset=ISO-8859-1"> +</head> + <body> + +<div align="center"> +<h1>Speex Programming</h1> + +<div align="left"> +<h2>Encoding</h2> + In order to encode speech using Speex, you first need to:<br> + +<blockquote> + <pre><big>#include <speex.h></big></pre> + </blockquote> + You then need to declare a Speex bit-packing struct<br> + +<blockquote> + <pre><big>SpeexBits bits;</big></pre> + </blockquote> + and a Speex encoder state<br> + +<blockquote> + <pre><big>void *enc_state;</big></pre> + </blockquote> + The two are initialized by:<br> + +<blockquote> + <pre><big>speex_bits_init(&bits);</big></pre> + + <pre><big>enc_state = speex_encoder_init(&speex_nb_mode);</big></pre> + </blockquote> + For wideband coding, <i>speex_nb_mode</i> will be replaced by <i>speex_wb_mode</i> +. In most cases, you will need to know the frame size used by the mode you +are using. You can get that value in the <i>frame_size</i> variable with:<br> +<blockquote><big><tt>speex_encoder_ctl(enc_state, SPEEX_GET_FRAME_SIZE, &frame_size);</tt></big><br> +</blockquote> + For every input frame:<br> + +<blockquote> + <pre><big>speex_bits_reset(&bits);</big></pre> + + <pre><big>speex_encode(enc_state, input_frame, &bits);</big></pre> + + <pre><big>nbBytes = speex_bits_write(&bits, byte_ptr, MAX_NB_BYTES);</big></pre> + </blockquote> + where <i>input_frame</i> is a <i>(float *)</i> pointing to the beginning +of a speech frame, byte_ptr is a <i>(char *)</i> where the encoded frame will +be written, <i>MAX_NB_BYTES</i> is the maximum number of bytes that can be +written to <i>byte_ptr</i> without causing an overflow and <i>nbBytes</i> + is the number of bytes actually written to <i>byte_ptr</i> (the encoded +size in bytes).<br> + <br> + After you're done with the encoding, free all resources with:<br> + +<blockquote> + <pre><big>speex_bits_destroy(&bits);</big></pre> + + <pre><big>speex_encoder_destroy(&enc_state);</big></pre> + </blockquote> + That's about it for the encoder.<br> + +<h2>Decoding</h2> + In order to encode speech using Speex, you first need to:<br> + +<blockquote> + <pre><big>#include <speex.h></big></pre> + </blockquote> + You then need to declare a Speex bit-packing struct<br> + +<blockquote> + <pre><big>SpeexBits bits;</big></pre> + </blockquote> + and a Speex encoder state<br> + +<blockquote> + <pre><big>void *dec_state;</big></pre> + </blockquote> + The two are initialized by:<br> + +<blockquote> + <pre><big>speex_bits_init(&bits);</big></pre> + + <pre><big>dec_state = speex_decoder_init(&speex_nb_mode);</big></pre> + </blockquote> + For wideband decoding, <i>speex_nb_mode</i> will be replaced by <i>speex_wb_mode</i> +. You can get that value in the <i>frame_size</i> variable with:<br> + +<blockquote><big><tt>speex_decoder_ctl(dec_state, SPEEX_GET_FRAME_SIZE, &frame_size);</tt></big><br> +</blockquote> + There is also a parameter that can be set for the decoder: whether or not +to use a perceptual post-filter. This can be set by:<br> +<blockquote><big><tt>speex_decoder_ctl(dec_state, SPEEX_SET_PF, &pf);</tt></big><br> +</blockquote> +where <i>pf</i> is an <i>int</i> that with value 0 to have the post-filter +disabled and 1 to have it enabled.<br> +<br> +For every input frame:<br> + +<blockquote> + <pre><big>speex_bits_read_from(&bits, input_bytes, nbBytes);</big></pre> + + <pre><big>speex_decode(st, &bits, output_frame, 0);</big></pre> + </blockquote> + where <i>input_bytes</i> is a <i>(char *)</i> containing the bit-stream +data received for a frame, <i>nbBytes</i> is the size (in bytes) of that +bit-stream, and <i>output_frame</i> is a <i>(float *)</i> and points to the +area where the decoded speech frame will be written. The last argument indicates +whether the frame we'd like to decode was lost. A value of 0 indicates the +normal case where bits points to the bit of the current frame. A value of +1 indicates that we don't have the bits for the current frame, in which case +the bits argument should be the same as the bits for the last correctly received +frame. When a frame is lost, the Speex decoder will do its best to "guess" +the sorrect signal.<br> + <br> + </div> + </div> + +</body> +</html> |