plugins/codecs/G726/G726decode.c

   1 /* G726decode.c
   2  * G.726 codec
   3  *
   4  * Wireshark - Network traffic analyzer
   5  * By Gerald Combs <gerald@wireshark.org>
   6  * Copyright 1998 Gerald Combs
   7  *
   8  * SPDX-License-Identifier: GPL-2.0-or-later
   9  */
  10
  11 #include "config.h"
  12
  13 #include <glib.h>
  14
  15 #include "spandsp.h"
  16 #include "wsutil/codecs.h"
  17 #include "ws_attributes.h"
  18
  19 typedef struct _g726_codec_ctx {
  20     g726_state_t *state;
  21     int bit_rate;
  22 } g726_codec_ctx;
  23
  24 void codec_register_g726(void);
  25
  26 static void *
  27 codec_g726_init(int bit_rate, int packing)
  28 {
  29     g726_state_t *decoder = g726_init(NULL, bit_rate, G726_ENCODING_LINEAR, packing);
  30
  31     if (!decoder) {
  32         return NULL;  /* out-of-memory; */
  33     }
  34
  35     g726_codec_ctx *state = g_new(g726_codec_ctx, 1);
  36     state->state = decoder;
  37     state->bit_rate = bit_rate;
  38
  39     return state;
  40 }
  41
  42 static void *codec_g726_16_init(codec_context_t *ctx _U_) { return codec_g726_init(16000, G726_PACKING_RIGHT); }
  43 static void *codec_g726_24_init(codec_context_t *ctx _U_) { return codec_g726_init(24000, G726_PACKING_RIGHT); }
  44 static void *codec_g726_32_init(codec_context_t *ctx _U_) { return codec_g726_init(32000, G726_PACKING_RIGHT); }
  45 static void *codec_g726_40_init(codec_context_t *ctx _U_) { return codec_g726_init(40000, G726_PACKING_RIGHT); }
  46 static void *codec_aal2_g726_16_init(codec_context_t *ctx _U_) { return codec_g726_init(16000, G726_PACKING_LEFT); }
  47 static void *codec_aal2_g726_24_init(codec_context_t *ctx _U_) { return codec_g726_init(24000, G726_PACKING_LEFT); }
  48 static void *codec_aal2_g726_32_init(codec_context_t *ctx _U_) { return codec_g726_init(32000, G726_PACKING_LEFT); }
  49 static void *codec_aal2_g726_40_init(codec_context_t *ctx _U_) { return codec_g726_init(40000, G726_PACKING_LEFT); }
  50
  51 static void
  52 codec_g726_release(codec_context_t *ctx)
  53 {
  54     g726_codec_ctx *state = (g726_codec_ctx *)(ctx->priv);
  55
  56     if (!state) {
  57         return;  /* out-of-memory; */
  58     }
  59
  60     /* Note: replaces g726_release since SpanDSP 20090211 */
  61     g726_free(state->state);
  62     g_free(state);
  63 }
  64
  65 static unsigned
  66 codec_g726_get_channels(codec_context_t *ctx _U_)
  67 {
  68     return 1;
  69 }
  70
  71 static unsigned
  72 codec_g726_get_frequency(codec_context_t *ctx _U_)
  73 {
  74     return 8000;
  75 }
  76
  77 static size_t
  78 codec_g726_decode(codec_context_t *ctx, const void *inputBytes,
  79         size_t inputBytesSize, void *outputSamples, size_t *outputSamplesSize)
  80 {
  81     g726_codec_ctx *state = (g726_codec_ctx *)ctx->priv;
  82
  83     if (!state) {
  84         return 0;  /* out-of-memory; */
  85     }
  86
  87     if (!outputSamples || !outputSamplesSize) {
  88         /*
  89          * sample rate 8kHz, for bitrate 16kHz we have 16/8 = 2 bits/sample, so
  90          * 1 input byte (8 bits) will expand to four 16-bit samples. Likewise,
  91          * for bitrate 40kHz we have 40/8 = 5 bits/sample.  Alternatively:
  92          * bitsPerSample = bitRate / sampleRate (8kHz).
  93          * outputBytes = (inputBits / bitsPerSample) * sizeof(sample)
  94          */
  95         return inputBytesSize * 8 / (state->bit_rate / 8000) * 2;
  96     }
  97
  98     /* g726_decode returns the number of 16-bit samples. */
  99     *outputSamplesSize = 2 * g726_decode(state->state, (int16_t *)outputSamples, (const uint8_t *) inputBytes, (int)inputBytesSize);
 100     return *outputSamplesSize;
 101 }
 102
 103 void
 104 codec_register_g726(void)
 105 {
 106     register_codec("G726-16", codec_g726_16_init, codec_g726_release,
 107             codec_g726_get_channels, codec_g726_get_frequency, codec_g726_decode);
 108     register_codec("G726-24", codec_g726_24_init, codec_g726_release,
 109             codec_g726_get_channels, codec_g726_get_frequency, codec_g726_decode);
 110     register_codec("G726-32", codec_g726_32_init, codec_g726_release,
 111             codec_g726_get_channels, codec_g726_get_frequency, codec_g726_decode);
 112     register_codec("G726-40", codec_g726_40_init, codec_g726_release,
 113             codec_g726_get_channels, codec_g726_get_frequency, codec_g726_decode);
 114     register_codec("AAL2-G726-16", codec_aal2_g726_16_init, codec_g726_release,
 115             codec_g726_get_channels, codec_g726_get_frequency, codec_g726_decode);
 116     register_codec("AAL2-G726-24", codec_aal2_g726_24_init, codec_g726_release,
 117             codec_g726_get_channels, codec_g726_get_frequency, codec_g726_decode);
 118     register_codec("AAL2-G726-32", codec_aal2_g726_32_init, codec_g726_release,
 119             codec_g726_get_channels, codec_g726_get_frequency, codec_g726_decode);
 120     register_codec("AAL2-G726-40", codec_aal2_g726_40_init, codec_g726_release,
 121             codec_g726_get_channels, codec_g726_get_frequency, codec_g726_decode);
 122 }
 123
 124 /*
 125  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 126  *
 127  * Local variables:
 128  * c-basic-offset: 4
 129  * tab-width: 8
 130  * indent-tabs-mode: nil
 131  * End:
 132  *
 133  * vi: set shiftwidth=4 tabstop=8 expandtab:
 134  * :indentSize=4:tabSize=8:noTabs=true:
 135  */