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Member "gst-plugins-good-1.20.3/gst/law/alaw-encode.c" (15 Jun 2022, 20014 Bytes) of package /linux/misc/gst-plugins-good-1.20.3.tar.xz:


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    1 /* GStreamer PCM to A-Law conversion
    2  * Copyright (C) 2000 by Abramo Bagnara <abramo@alsa-project.org>
    3  *
    4  * This library is free software; you can redistribute it and/or
    5  * modify it under the terms of the GNU Library General Public
    6  * License as published by the Free Software Foundation; either
    7  * version 2.1 of the License, or (at your option) any later version.
    8  *
    9  * This library is distributed in the hope that it will be useful,
   10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
   11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   12  * Library General Public License for more details.
   13  *
   14  * You should have received a copy of the GNU Library General Public
   15  * License along with this library; if not, write to the
   16  * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
   17  * Boston, MA 02110-1301, USA.
   18  */
   19 /**
   20  * SECTION:element-alawenc
   21  * @title: alawenc
   22  *
   23  * This element encode alaw audio. Alaw coding is also known as G.711.
   24  */
   25 
   26 #ifdef HAVE_CONFIG_H
   27 #include "config.h"
   28 #endif
   29 
   30 #include <gst/audio/audio.h>
   31 
   32 #include "alaw-encode.h"
   33 
   34 GST_DEBUG_CATEGORY_STATIC (alaw_enc_debug);
   35 #define GST_CAT_DEFAULT alaw_enc_debug
   36 
   37 extern GstStaticPadTemplate alaw_enc_src_factory;
   38 extern GstStaticPadTemplate alaw_enc_sink_factory;
   39 
   40 G_DEFINE_TYPE (GstALawEnc, gst_alaw_enc, GST_TYPE_AUDIO_ENCODER);
   41 GST_ELEMENT_REGISTER_DEFINE (alawenc, "alawenc", GST_RANK_PRIMARY,
   42     GST_TYPE_ALAW_ENC);
   43 
   44 static gboolean gst_alaw_enc_start (GstAudioEncoder * audioenc);
   45 static gboolean gst_alaw_enc_set_format (GstAudioEncoder * enc,
   46     GstAudioInfo * info);
   47 static GstFlowReturn gst_alaw_enc_handle_frame (GstAudioEncoder * enc,
   48     GstBuffer * buffer);
   49 
   50 /* some day we might have defines in gstconfig.h that tell us about the
   51  * desired cpu/memory/binary size trade-offs */
   52 #define GST_ALAW_ENC_USE_TABLE
   53 
   54 #ifdef GST_ALAW_ENC_USE_TABLE
   55 
   56 static const guint8 alaw_encode[2048 + 1] = {
   57   0xd5, 0xd4, 0xd7, 0xd6, 0xd1, 0xd0, 0xd3, 0xd2, 0xdd, 0xdc, 0xdf, 0xde,
   58   0xd9, 0xd8, 0xdb, 0xda, 0xc5, 0xc4, 0xc7, 0xc6, 0xc1, 0xc0, 0xc3, 0xc2,
   59   0xcd, 0xcc, 0xcf, 0xce, 0xc9, 0xc8, 0xcb, 0xca, 0xf5, 0xf5, 0xf4, 0xf4,
   60   0xf7, 0xf7, 0xf6, 0xf6, 0xf1, 0xf1, 0xf0, 0xf0, 0xf3, 0xf3, 0xf2, 0xf2,
   61   0xfd, 0xfd, 0xfc, 0xfc, 0xff, 0xff, 0xfe, 0xfe, 0xf9, 0xf9, 0xf8, 0xf8,
   62   0xfb, 0xfb, 0xfa, 0xfa, 0xe5, 0xe5, 0xe5, 0xe5, 0xe4, 0xe4, 0xe4, 0xe4,
   63   0xe7, 0xe7, 0xe7, 0xe7, 0xe6, 0xe6, 0xe6, 0xe6, 0xe1, 0xe1, 0xe1, 0xe1,
   64   0xe0, 0xe0, 0xe0, 0xe0, 0xe3, 0xe3, 0xe3, 0xe3, 0xe2, 0xe2, 0xe2, 0xe2,
   65   0xed, 0xed, 0xed, 0xed, 0xec, 0xec, 0xec, 0xec, 0xef, 0xef, 0xef, 0xef,
   66   0xee, 0xee, 0xee, 0xee, 0xe9, 0xe9, 0xe9, 0xe9, 0xe8, 0xe8, 0xe8, 0xe8,
   67   0xeb, 0xeb, 0xeb, 0xeb, 0xea, 0xea, 0xea, 0xea, 0x95, 0x95, 0x95, 0x95,
   68   0x95, 0x95, 0x95, 0x95, 0x94, 0x94, 0x94, 0x94, 0x94, 0x94, 0x94, 0x94,
   69   0x97, 0x97, 0x97, 0x97, 0x97, 0x97, 0x97, 0x97, 0x96, 0x96, 0x96, 0x96,
   70   0x96, 0x96, 0x96, 0x96, 0x91, 0x91, 0x91, 0x91, 0x91, 0x91, 0x91, 0x91,
   71   0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x93, 0x93, 0x93, 0x93,
   72   0x93, 0x93, 0x93, 0x93, 0x92, 0x92, 0x92, 0x92, 0x92, 0x92, 0x92, 0x92,
   73   0x9d, 0x9d, 0x9d, 0x9d, 0x9d, 0x9d, 0x9d, 0x9d, 0x9c, 0x9c, 0x9c, 0x9c,
   74   0x9c, 0x9c, 0x9c, 0x9c, 0x9f, 0x9f, 0x9f, 0x9f, 0x9f, 0x9f, 0x9f, 0x9f,
   75   0x9e, 0x9e, 0x9e, 0x9e, 0x9e, 0x9e, 0x9e, 0x9e, 0x99, 0x99, 0x99, 0x99,
   76   0x99, 0x99, 0x99, 0x99, 0x98, 0x98, 0x98, 0x98, 0x98, 0x98, 0x98, 0x98,
   77   0x9b, 0x9b, 0x9b, 0x9b, 0x9b, 0x9b, 0x9b, 0x9b, 0x9a, 0x9a, 0x9a, 0x9a,
   78   0x9a, 0x9a, 0x9a, 0x9a, 0x85, 0x85, 0x85, 0x85, 0x85, 0x85, 0x85, 0x85,
   79   0x85, 0x85, 0x85, 0x85, 0x85, 0x85, 0x85, 0x85, 0x84, 0x84, 0x84, 0x84,
   80   0x84, 0x84, 0x84, 0x84, 0x84, 0x84, 0x84, 0x84, 0x84, 0x84, 0x84, 0x84,
   81   0x87, 0x87, 0x87, 0x87, 0x87, 0x87, 0x87, 0x87, 0x87, 0x87, 0x87, 0x87,
   82   0x87, 0x87, 0x87, 0x87, 0x86, 0x86, 0x86, 0x86, 0x86, 0x86, 0x86, 0x86,
   83   0x86, 0x86, 0x86, 0x86, 0x86, 0x86, 0x86, 0x86, 0x81, 0x81, 0x81, 0x81,
   84   0x81, 0x81, 0x81, 0x81, 0x81, 0x81, 0x81, 0x81, 0x81, 0x81, 0x81, 0x81,
   85   0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
   86   0x80, 0x80, 0x80, 0x80, 0x83, 0x83, 0x83, 0x83, 0x83, 0x83, 0x83, 0x83,
   87   0x83, 0x83, 0x83, 0x83, 0x83, 0x83, 0x83, 0x83, 0x82, 0x82, 0x82, 0x82,
   88   0x82, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82,
   89   0x8d, 0x8d, 0x8d, 0x8d, 0x8d, 0x8d, 0x8d, 0x8d, 0x8d, 0x8d, 0x8d, 0x8d,
   90   0x8d, 0x8d, 0x8d, 0x8d, 0x8c, 0x8c, 0x8c, 0x8c, 0x8c, 0x8c, 0x8c, 0x8c,
   91   0x8c, 0x8c, 0x8c, 0x8c, 0x8c, 0x8c, 0x8c, 0x8c, 0x8f, 0x8f, 0x8f, 0x8f,
   92   0x8f, 0x8f, 0x8f, 0x8f, 0x8f, 0x8f, 0x8f, 0x8f, 0x8f, 0x8f, 0x8f, 0x8f,
   93   0x8e, 0x8e, 0x8e, 0x8e, 0x8e, 0x8e, 0x8e, 0x8e, 0x8e, 0x8e, 0x8e, 0x8e,
   94   0x8e, 0x8e, 0x8e, 0x8e, 0x89, 0x89, 0x89, 0x89, 0x89, 0x89, 0x89, 0x89,
   95   0x89, 0x89, 0x89, 0x89, 0x89, 0x89, 0x89, 0x89, 0x88, 0x88, 0x88, 0x88,
   96   0x88, 0x88, 0x88, 0x88, 0x88, 0x88, 0x88, 0x88, 0x88, 0x88, 0x88, 0x88,
   97   0x8b, 0x8b, 0x8b, 0x8b, 0x8b, 0x8b, 0x8b, 0x8b, 0x8b, 0x8b, 0x8b, 0x8b,
   98   0x8b, 0x8b, 0x8b, 0x8b, 0x8a, 0x8a, 0x8a, 0x8a, 0x8a, 0x8a, 0x8a, 0x8a,
   99   0x8a, 0x8a, 0x8a, 0x8a, 0x8a, 0x8a, 0x8a, 0x8a, 0xb5, 0xb5, 0xb5, 0xb5,
  100   0xb5, 0xb5, 0xb5, 0xb5, 0xb5, 0xb5, 0xb5, 0xb5, 0xb5, 0xb5, 0xb5, 0xb5,
  101   0xb5, 0xb5, 0xb5, 0xb5, 0xb5, 0xb5, 0xb5, 0xb5, 0xb5, 0xb5, 0xb5, 0xb5,
  102   0xb5, 0xb5, 0xb5, 0xb5, 0xb4, 0xb4, 0xb4, 0xb4, 0xb4, 0xb4, 0xb4, 0xb4,
  103   0xb4, 0xb4, 0xb4, 0xb4, 0xb4, 0xb4, 0xb4, 0xb4, 0xb4, 0xb4, 0xb4, 0xb4,
  104   0xb4, 0xb4, 0xb4, 0xb4, 0xb4, 0xb4, 0xb4, 0xb4, 0xb4, 0xb4, 0xb4, 0xb4,
  105   0xb7, 0xb7, 0xb7, 0xb7, 0xb7, 0xb7, 0xb7, 0xb7, 0xb7, 0xb7, 0xb7, 0xb7,
  106   0xb7, 0xb7, 0xb7, 0xb7, 0xb7, 0xb7, 0xb7, 0xb7, 0xb7, 0xb7, 0xb7, 0xb7,
  107   0xb7, 0xb7, 0xb7, 0xb7, 0xb7, 0xb7, 0xb7, 0xb7, 0xb6, 0xb6, 0xb6, 0xb6,
  108   0xb6, 0xb6, 0xb6, 0xb6, 0xb6, 0xb6, 0xb6, 0xb6, 0xb6, 0xb6, 0xb6, 0xb6,
  109   0xb6, 0xb6, 0xb6, 0xb6, 0xb6, 0xb6, 0xb6, 0xb6, 0xb6, 0xb6, 0xb6, 0xb6,
  110   0xb6, 0xb6, 0xb6, 0xb6, 0xb1, 0xb1, 0xb1, 0xb1, 0xb1, 0xb1, 0xb1, 0xb1,
  111   0xb1, 0xb1, 0xb1, 0xb1, 0xb1, 0xb1, 0xb1, 0xb1, 0xb1, 0xb1, 0xb1, 0xb1,
  112   0xb1, 0xb1, 0xb1, 0xb1, 0xb1, 0xb1, 0xb1, 0xb1, 0xb1, 0xb1, 0xb1, 0xb1,
  113   0xb0, 0xb0, 0xb0, 0xb0, 0xb0, 0xb0, 0xb0, 0xb0, 0xb0, 0xb0, 0xb0, 0xb0,
  114   0xb0, 0xb0, 0xb0, 0xb0, 0xb0, 0xb0, 0xb0, 0xb0, 0xb0, 0xb0, 0xb0, 0xb0,
  115   0xb0, 0xb0, 0xb0, 0xb0, 0xb0, 0xb0, 0xb0, 0xb0, 0xb3, 0xb3, 0xb3, 0xb3,
  116   0xb3, 0xb3, 0xb3, 0xb3, 0xb3, 0xb3, 0xb3, 0xb3, 0xb3, 0xb3, 0xb3, 0xb3,
  117   0xb3, 0xb3, 0xb3, 0xb3, 0xb3, 0xb3, 0xb3, 0xb3, 0xb3, 0xb3, 0xb3, 0xb3,
  118   0xb3, 0xb3, 0xb3, 0xb3, 0xb2, 0xb2, 0xb2, 0xb2, 0xb2, 0xb2, 0xb2, 0xb2,
  119   0xb2, 0xb2, 0xb2, 0xb2, 0xb2, 0xb2, 0xb2, 0xb2, 0xb2, 0xb2, 0xb2, 0xb2,
  120   0xb2, 0xb2, 0xb2, 0xb2, 0xb2, 0xb2, 0xb2, 0xb2, 0xb2, 0xb2, 0xb2, 0xb2,
  121   0xbd, 0xbd, 0xbd, 0xbd, 0xbd, 0xbd, 0xbd, 0xbd, 0xbd, 0xbd, 0xbd, 0xbd,
  122   0xbd, 0xbd, 0xbd, 0xbd, 0xbd, 0xbd, 0xbd, 0xbd, 0xbd, 0xbd, 0xbd, 0xbd,
  123   0xbd, 0xbd, 0xbd, 0xbd, 0xbd, 0xbd, 0xbd, 0xbd, 0xbc, 0xbc, 0xbc, 0xbc,
  124   0xbc, 0xbc, 0xbc, 0xbc, 0xbc, 0xbc, 0xbc, 0xbc, 0xbc, 0xbc, 0xbc, 0xbc,
  125   0xbc, 0xbc, 0xbc, 0xbc, 0xbc, 0xbc, 0xbc, 0xbc, 0xbc, 0xbc, 0xbc, 0xbc,
  126   0xbc, 0xbc, 0xbc, 0xbc, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf,
  127   0xbf, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf,
  128   0xbf, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf,
  129   0xbe, 0xbe, 0xbe, 0xbe, 0xbe, 0xbe, 0xbe, 0xbe, 0xbe, 0xbe, 0xbe, 0xbe,
  130   0xbe, 0xbe, 0xbe, 0xbe, 0xbe, 0xbe, 0xbe, 0xbe, 0xbe, 0xbe, 0xbe, 0xbe,
  131   0xbe, 0xbe, 0xbe, 0xbe, 0xbe, 0xbe, 0xbe, 0xbe, 0xb9, 0xb9, 0xb9, 0xb9,
  132   0xb9, 0xb9, 0xb9, 0xb9, 0xb9, 0xb9, 0xb9, 0xb9, 0xb9, 0xb9, 0xb9, 0xb9,
  133   0xb9, 0xb9, 0xb9, 0xb9, 0xb9, 0xb9, 0xb9, 0xb9, 0xb9, 0xb9, 0xb9, 0xb9,
  134   0xb9, 0xb9, 0xb9, 0xb9, 0xb8, 0xb8, 0xb8, 0xb8, 0xb8, 0xb8, 0xb8, 0xb8,
  135   0xb8, 0xb8, 0xb8, 0xb8, 0xb8, 0xb8, 0xb8, 0xb8, 0xb8, 0xb8, 0xb8, 0xb8,
  136   0xb8, 0xb8, 0xb8, 0xb8, 0xb8, 0xb8, 0xb8, 0xb8, 0xb8, 0xb8, 0xb8, 0xb8,
  137   0xbb, 0xbb, 0xbb, 0xbb, 0xbb, 0xbb, 0xbb, 0xbb, 0xbb, 0xbb, 0xbb, 0xbb,
  138   0xbb, 0xbb, 0xbb, 0xbb, 0xbb, 0xbb, 0xbb, 0xbb, 0xbb, 0xbb, 0xbb, 0xbb,
  139   0xbb, 0xbb, 0xbb, 0xbb, 0xbb, 0xbb, 0xbb, 0xbb, 0xba, 0xba, 0xba, 0xba,
  140   0xba, 0xba, 0xba, 0xba, 0xba, 0xba, 0xba, 0xba, 0xba, 0xba, 0xba, 0xba,
  141   0xba, 0xba, 0xba, 0xba, 0xba, 0xba, 0xba, 0xba, 0xba, 0xba, 0xba, 0xba,
  142   0xba, 0xba, 0xba, 0xba, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5,
  143   0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5,
  144   0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5,
  145   0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5,
  146   0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5,
  147   0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa5, 0xa4, 0xa4, 0xa4, 0xa4,
  148   0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4,
  149   0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4,
  150   0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4,
  151   0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4,
  152   0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4, 0xa4,
  153   0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7,
  154   0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7,
  155   0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7,
  156   0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7,
  157   0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7, 0xa7,
  158   0xa7, 0xa7, 0xa7, 0xa7, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6,
  159   0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6,
  160   0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6,
  161   0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6,
  162   0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6,
  163   0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa1, 0xa1, 0xa1, 0xa1,
  164   0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1,
  165   0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1,
  166   0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1,
  167   0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1,
  168   0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1, 0xa1,
  169   0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0,
  170   0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0,
  171   0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0,
  172   0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0,
  173   0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0, 0xa0,
  174   0xa0, 0xa0, 0xa0, 0xa0, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3,
  175   0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3,
  176   0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3,
  177   0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3,
  178   0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3,
  179   0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa3, 0xa2, 0xa2, 0xa2, 0xa2,
  180   0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2,
  181   0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2,
  182   0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2,
  183   0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2,
  184   0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2, 0xa2,
  185   0xad, 0xad, 0xad, 0xad, 0xad, 0xad, 0xad, 0xad, 0xad, 0xad, 0xad, 0xad,
  186   0xad, 0xad, 0xad, 0xad, 0xad, 0xad, 0xad, 0xad, 0xad, 0xad, 0xad, 0xad,
  187   0xad, 0xad, 0xad, 0xad, 0xad, 0xad, 0xad, 0xad, 0xad, 0xad, 0xad, 0xad,
  188   0xad, 0xad, 0xad, 0xad, 0xad, 0xad, 0xad, 0xad, 0xad, 0xad, 0xad, 0xad,
  189   0xad, 0xad, 0xad, 0xad, 0xad, 0xad, 0xad, 0xad, 0xad, 0xad, 0xad, 0xad,
  190   0xad, 0xad, 0xad, 0xad, 0xac, 0xac, 0xac, 0xac, 0xac, 0xac, 0xac, 0xac,
  191   0xac, 0xac, 0xac, 0xac, 0xac, 0xac, 0xac, 0xac, 0xac, 0xac, 0xac, 0xac,
  192   0xac, 0xac, 0xac, 0xac, 0xac, 0xac, 0xac, 0xac, 0xac, 0xac, 0xac, 0xac,
  193   0xac, 0xac, 0xac, 0xac, 0xac, 0xac, 0xac, 0xac, 0xac, 0xac, 0xac, 0xac,
  194   0xac, 0xac, 0xac, 0xac, 0xac, 0xac, 0xac, 0xac, 0xac, 0xac, 0xac, 0xac,
  195   0xac, 0xac, 0xac, 0xac, 0xac, 0xac, 0xac, 0xac, 0xaf, 0xaf, 0xaf, 0xaf,
  196   0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf,
  197   0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf,
  198   0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf,
  199   0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf,
  200   0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf, 0xaf,
  201   0xae, 0xae, 0xae, 0xae, 0xae, 0xae, 0xae, 0xae, 0xae, 0xae, 0xae, 0xae,
  202   0xae, 0xae, 0xae, 0xae, 0xae, 0xae, 0xae, 0xae, 0xae, 0xae, 0xae, 0xae,
  203   0xae, 0xae, 0xae, 0xae, 0xae, 0xae, 0xae, 0xae, 0xae, 0xae, 0xae, 0xae,
  204   0xae, 0xae, 0xae, 0xae, 0xae, 0xae, 0xae, 0xae, 0xae, 0xae, 0xae, 0xae,
  205   0xae, 0xae, 0xae, 0xae, 0xae, 0xae, 0xae, 0xae, 0xae, 0xae, 0xae, 0xae,
  206   0xae, 0xae, 0xae, 0xae, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9,
  207   0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9,
  208   0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9,
  209   0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9,
  210   0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9,
  211   0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa9, 0xa8, 0xa8, 0xa8, 0xa8,
  212   0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8,
  213   0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8,
  214   0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8,
  215   0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8,
  216   0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8, 0xa8,
  217   0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xab,
  218   0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xab,
  219   0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xab,
  220   0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xab,
  221   0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xab,
  222   0xab, 0xab, 0xab, 0xab, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa,
  223   0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa,
  224   0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa,
  225   0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa,
  226   0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa,
  227   0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0x2a
  228 };
  229 
  230 static inline guint8
  231 s16_to_alaw (gint16 pcm_val)
  232 {
  233   if (pcm_val >= 0)
  234     return alaw_encode[pcm_val / 16];
  235   else
  236     return (0x7F & alaw_encode[pcm_val / -16]);
  237 }
  238 
  239 #else /* GST_ALAW_ENC_USE_TABLE */
  240 
  241 /*
  242  * s16_to_alaw() - Convert a 16-bit linear PCM value to 8-bit A-law
  243  *
  244  * s16_to_alaw() accepts an 16-bit integer and encodes it as A-law data.
  245  *
  246  *              Linear Input Code       Compressed Code
  247  *      ------------------------        ---------------
  248  *      0000000wxyza                    000wxyz
  249  *      0000001wxyza                    001wxyz
  250  *      000001wxyzab                    010wxyz
  251  *      00001wxyzabc                    011wxyz
  252  *      0001wxyzabcd                    100wxyz
  253  *      001wxyzabcde                    101wxyz
  254  *      01wxyzabcdef                    110wxyz
  255  *      1wxyzabcdefg                    111wxyz
  256  *
  257  * For further information see John C. Bellamy's Digital Telephony, 1982,
  258  * John Wiley & Sons, pps 98-111 and 472-476.
  259  */
  260 
  261 static inline gint
  262 val_seg (gint val)
  263 {
  264   gint r = 1;
  265 
  266   val >>= 8;
  267   if (val & 0xf0) {
  268     val >>= 4;
  269     r += 4;
  270   }
  271   if (val & 0x0c) {
  272     val >>= 2;
  273     r += 2;
  274   }
  275   if (val & 0x02)
  276     r += 1;
  277   return r;
  278 }
  279 
  280 static inline guint8
  281 s16_to_alaw (gint pcm_val)
  282 {
  283   gint seg;
  284   guint8 mask;
  285   guint8 aval;
  286 
  287   if (pcm_val >= 0) {
  288     mask = 0xD5;
  289   } else {
  290     mask = 0x55;
  291     pcm_val = -pcm_val;
  292     if (pcm_val > 0x7fff)
  293       pcm_val = 0x7fff;
  294   }
  295 
  296   if (pcm_val < 256)
  297     aval = pcm_val >> 4;
  298   else {
  299     /* Convert the scaled magnitude to segment number. */
  300     seg = val_seg (pcm_val);
  301     aval = (seg << 4) | ((pcm_val >> (seg + 3)) & 0x0f);
  302   }
  303   return aval ^ mask;
  304 }
  305 
  306 #endif /* GST_ALAW_ENC_USE_TABLE */
  307 
  308 GstStaticPadTemplate alaw_enc_sink_factory = GST_STATIC_PAD_TEMPLATE ("sink",
  309     GST_PAD_SINK,
  310     GST_PAD_ALWAYS,
  311     GST_STATIC_CAPS ("audio/x-raw, "
  312         "format = (string) " GST_AUDIO_NE (S16) ", "
  313         "layout = (string) interleaved, "
  314         "rate = (int) [ 8000, 192000 ], " "channels = (int) [ 1, 2 ]")
  315     );
  316 
  317 GstStaticPadTemplate alaw_enc_src_factory = GST_STATIC_PAD_TEMPLATE ("src",
  318     GST_PAD_SRC,
  319     GST_PAD_ALWAYS,
  320     GST_STATIC_CAPS ("audio/x-alaw, "
  321         "rate = [ 8000 , 192000 ], " "channels = [ 1 , 2 ]")
  322     );
  323 
  324 static gboolean
  325 gst_alaw_enc_start (GstAudioEncoder * audioenc)
  326 {
  327   GstALawEnc *alawenc = GST_ALAW_ENC (audioenc);
  328 
  329   alawenc->channels = 0;
  330   alawenc->rate = 0;
  331 
  332   return TRUE;
  333 }
  334 
  335 static gboolean
  336 gst_alaw_enc_set_format (GstAudioEncoder * audioenc, GstAudioInfo * info)
  337 {
  338   GstCaps *base_caps;
  339   GstStructure *structure;
  340   GstALawEnc *alawenc = GST_ALAW_ENC (audioenc);
  341   gboolean ret;
  342 
  343   alawenc->rate = info->rate;
  344   alawenc->channels = info->channels;
  345 
  346   base_caps =
  347       gst_pad_get_pad_template_caps (GST_AUDIO_ENCODER_SRC_PAD (audioenc));
  348   g_assert (base_caps);
  349   base_caps = gst_caps_make_writable (base_caps);
  350   g_assert (base_caps);
  351 
  352   structure = gst_caps_get_structure (base_caps, 0);
  353   g_assert (structure);
  354   gst_structure_set (structure, "rate", G_TYPE_INT, alawenc->rate, NULL);
  355   gst_structure_set (structure, "channels", G_TYPE_INT, alawenc->channels,
  356       NULL);
  357 
  358   ret = gst_audio_encoder_set_output_format (audioenc, base_caps);
  359   gst_caps_unref (base_caps);
  360 
  361   return ret;
  362 }
  363 
  364 static GstFlowReturn
  365 gst_alaw_enc_handle_frame (GstAudioEncoder * audioenc, GstBuffer * buffer)
  366 {
  367   GstALawEnc *alawenc;
  368   GstMapInfo inmap, outmap;
  369   gint16 *linear_data;
  370   gsize linear_size;
  371   guint8 *alaw_data;
  372   guint alaw_size;
  373   GstBuffer *outbuf;
  374   GstFlowReturn ret;
  375   gint i;
  376 
  377   if (!buffer) {
  378     ret = GST_FLOW_OK;
  379     goto done;
  380   }
  381 
  382   alawenc = GST_ALAW_ENC (audioenc);
  383 
  384   if (!alawenc->rate || !alawenc->channels)
  385     goto not_negotiated;
  386 
  387   gst_buffer_map (buffer, &inmap, GST_MAP_READ);
  388   linear_data = (gint16 *) inmap.data;
  389   linear_size = inmap.size;
  390 
  391   alaw_size = linear_size / 2;
  392 
  393   outbuf = gst_audio_encoder_allocate_output_buffer (audioenc, alaw_size);
  394 
  395   g_assert (outbuf);
  396 
  397   gst_buffer_map (outbuf, &outmap, GST_MAP_WRITE);
  398   alaw_data = outmap.data;
  399 
  400   for (i = 0; i < alaw_size; i++) {
  401     alaw_data[i] = s16_to_alaw (linear_data[i]);
  402   }
  403 
  404   gst_buffer_unmap (outbuf, &outmap);
  405   gst_buffer_unmap (buffer, &inmap);
  406 
  407   ret = gst_audio_encoder_finish_frame (audioenc, outbuf, -1);
  408 
  409 done:
  410   return ret;
  411 
  412 not_negotiated:
  413   {
  414     GST_DEBUG_OBJECT (alawenc, "no format negotiated");
  415     ret = GST_FLOW_NOT_NEGOTIATED;
  416     goto done;
  417   }
  418 }
  419 
  420 static void
  421 gst_alaw_enc_class_init (GstALawEncClass * klass)
  422 {
  423   GstElementClass *element_class = GST_ELEMENT_CLASS (klass);
  424   GstAudioEncoderClass *audio_encoder_class = GST_AUDIO_ENCODER_CLASS (klass);
  425 
  426   audio_encoder_class->start = GST_DEBUG_FUNCPTR (gst_alaw_enc_start);
  427   audio_encoder_class->set_format = GST_DEBUG_FUNCPTR (gst_alaw_enc_set_format);
  428   audio_encoder_class->handle_frame =
  429       GST_DEBUG_FUNCPTR (gst_alaw_enc_handle_frame);
  430 
  431   gst_element_class_add_static_pad_template (element_class,
  432       &alaw_enc_src_factory);
  433   gst_element_class_add_static_pad_template (element_class,
  434       &alaw_enc_sink_factory);
  435 
  436   gst_element_class_set_static_metadata (element_class,
  437       "A Law audio encoder", "Codec/Encoder/Audio",
  438       "Convert 16bit PCM to 8bit A law",
  439       "Zaheer Abbas Merali <zaheerabbas at merali dot org>");
  440   GST_DEBUG_CATEGORY_INIT (alaw_enc_debug, "alawenc", 0, "A Law audio encoder");
  441 }
  442 
  443 static void
  444 gst_alaw_enc_init (GstALawEnc * alawenc)
  445 {
  446   GST_PAD_SET_ACCEPT_TEMPLATE (GST_AUDIO_ENCODER_SINK_PAD (alawenc));
  447 }