diff options
| author | jmvalin <jmvalin@0101bb08-14d6-0310-b084-bc0e0c8e3800> | 2002-06-07 07:20:42 +0400 |
|---|---|---|
| committer | jmvalin <jmvalin@0101bb08-14d6-0310-b084-bc0e0c8e3800> | 2002-06-07 07:20:42 +0400 |
| commit | 5622ee5a1d223a2cde59242817441bfba42fdb13 (patch) | |
| tree | 46de4810efdfce730e73ce2bcc82fa3b488df62e /doc/programming.html | |
| parent | 3c8bc3d3297e5f521ded2e1691d4db89665d5738 (diff) | |
High-band (for wideband) is now a shape-sign codebook, reducing search
by a factor two
git-svn-id: http://svn.xiph.org/trunk/speex@3358 0101bb08-14d6-0310-b084-bc0e0c8e3800
Diffstat (limited to 'doc/programming.html')
| -rw-r--r-- | doc/programming.html | 157 |
1 files changed, 92 insertions, 65 deletions
diff --git a/doc/programming.html b/doc/programming.html index 6bfce96..7b5bc7a 100644 --- a/doc/programming.html +++ b/doc/programming.html @@ -2,55 +2,18 @@ <html> <head> <title>Speex Programming</title> + <meta http-equiv="content-type" content="text/html; charset=ISO-8859-1"> </head> -<body> -<div align="center"> + <body> + +<div align="center"> <h1>Speex Programming</h1> -<div align="left"> + +<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> -.<br> -<br> -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> + In order to encode speech using Speex, you first need to:<br> <blockquote> <pre><big>#include <speex.h></big></pre> @@ -63,36 +26,100 @@ In order to encode speech using Speex, you first need to:<br> and a Speex encoder state<br> <blockquote> - <pre><big>void *dec_state;</big></pre> + <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>dec_state = speex_decoder_init(&speex_nb_mode);</big></pre> + <pre><big>enc_state = speex_encoder_init(&speex_nb_mode);</big></pre> </blockquote> - For wideband decoding, <i>speex_nb_mode</i> will be replaced by <i>speex_wb_mode</i> -.<br> - <br> + 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_read_from(&bits, input_bytes, nbBytes);</big></pre> - <pre><big>speex_decode(st, &bits, output_frame, 0);</big></pre> + +<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>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> +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> -</div> -</div> +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> |