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227 lines
7 KiB
C
227 lines
7 KiB
C
/* GStreamer A-Law to PCM conversion
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* Copyright (C) 2000 by Abramo Bagnara <abramo@alsa-project.org>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
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* Boston, MA 02110-1301, USA.
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*/
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/**
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* SECTION:element-alawdec
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*
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* This element decodes alaw audio. Alaw coding is also known as G.711.
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*/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include "alaw-decode.h"
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extern GstStaticPadTemplate alaw_dec_src_factory;
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extern GstStaticPadTemplate alaw_dec_sink_factory;
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GST_DEBUG_CATEGORY_STATIC (alaw_dec_debug);
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#define GST_CAT_DEFAULT alaw_dec_debug
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static gboolean gst_alaw_dec_set_format (GstAudioDecoder * dec, GstCaps * caps);
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static GstFlowReturn gst_alaw_dec_handle_frame (GstAudioDecoder * dec,
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GstBuffer * buffer);
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#define gst_alaw_dec_parent_class parent_class
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G_DEFINE_TYPE (GstALawDec, gst_alaw_dec, GST_TYPE_AUDIO_DECODER);
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/* some day we might have defines in gstconfig.h that tell us about the
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* desired cpu/memory/binary size trade-offs */
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#define GST_ALAW_DEC_USE_TABLE
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#ifdef GST_ALAW_DEC_USE_TABLE
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static const gint alaw_to_s16_table[256] = {
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-5504, -5248, -6016, -5760, -4480, -4224, -4992, -4736,
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-7552, -7296, -8064, -7808, -6528, -6272, -7040, -6784,
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-2752, -2624, -3008, -2880, -2240, -2112, -2496, -2368,
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-3776, -3648, -4032, -3904, -3264, -3136, -3520, -3392,
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-22016, -20992, -24064, -23040, -17920, -16896, -19968, -18944,
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-30208, -29184, -32256, -31232, -26112, -25088, -28160, -27136,
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-11008, -10496, -12032, -11520, -8960, -8448, -9984, -9472,
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-15104, -14592, -16128, -15616, -13056, -12544, -14080, -13568,
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-344, -328, -376, -360, -280, -264, -312, -296,
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-472, -456, -504, -488, -408, -392, -440, -424,
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-88, -72, -120, -104, -24, -8, -56, -40,
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-216, -200, -248, -232, -152, -136, -184, -168,
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-1376, -1312, -1504, -1440, -1120, -1056, -1248, -1184,
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-1888, -1824, -2016, -1952, -1632, -1568, -1760, -1696,
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-688, -656, -752, -720, -560, -528, -624, -592,
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-944, -912, -1008, -976, -816, -784, -880, -848,
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5504, 5248, 6016, 5760, 4480, 4224, 4992, 4736,
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7552, 7296, 8064, 7808, 6528, 6272, 7040, 6784,
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2752, 2624, 3008, 2880, 2240, 2112, 2496, 2368,
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3776, 3648, 4032, 3904, 3264, 3136, 3520, 3392,
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22016, 20992, 24064, 23040, 17920, 16896, 19968, 18944,
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30208, 29184, 32256, 31232, 26112, 25088, 28160, 27136,
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11008, 10496, 12032, 11520, 8960, 8448, 9984, 9472,
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15104, 14592, 16128, 15616, 13056, 12544, 14080, 13568,
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344, 328, 376, 360, 280, 264, 312, 296,
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472, 456, 504, 488, 408, 392, 440, 424,
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88, 72, 120, 104, 24, 8, 56, 40,
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216, 200, 248, 232, 152, 136, 184, 168,
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1376, 1312, 1504, 1440, 1120, 1056, 1248, 1184,
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1888, 1824, 2016, 1952, 1632, 1568, 1760, 1696,
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688, 656, 752, 720, 560, 528, 624, 592,
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944, 912, 1008, 976, 816, 784, 880, 848
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};
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static inline gint
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alaw_to_s16 (guint8 a_val)
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{
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return alaw_to_s16_table[a_val];
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}
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#else /* GST_ALAW_DEC_USE_TABLE */
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static inline gint
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alaw_to_s16 (guint8 a_val)
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{
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gint t;
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gint seg;
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a_val ^= 0x55;
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t = a_val & 0x7f;
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if (t < 16)
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t = (t << 4) + 8;
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else {
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seg = (t >> 4) & 0x07;
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t = ((t & 0x0f) << 4) + 0x108;
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t <<= seg - 1;
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}
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return ((a_val & 0x80) ? t : -t);
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}
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#endif /* GST_ALAW_DEC_USE_TABLE */
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static gboolean
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gst_alaw_dec_set_format (GstAudioDecoder * dec, GstCaps * caps)
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{
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GstALawDec *alawdec = GST_ALAW_DEC (dec);
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GstStructure *structure;
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int rate, channels;
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GstAudioInfo info;
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structure = gst_caps_get_structure (caps, 0);
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if (!structure) {
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GST_ERROR_OBJECT (dec, "failed to get structure from caps");
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return FALSE;
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}
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if (!gst_structure_get_int (structure, "rate", &rate)) {
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GST_ERROR_OBJECT (dec, "failed to find field rate in input caps");
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return FALSE;
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}
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if (!gst_structure_get_int (structure, "channels", &channels)) {
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GST_ERROR_OBJECT (dec, "failed to find field channels in input caps");
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return FALSE;
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}
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gst_audio_info_init (&info);
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gst_audio_info_set_format (&info, GST_AUDIO_FORMAT_S16, rate, channels, NULL);
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GST_DEBUG_OBJECT (alawdec, "rate=%d, channels=%d", rate, channels);
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return gst_audio_decoder_set_output_format (dec, &info);
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}
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static GstFlowReturn
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gst_alaw_dec_handle_frame (GstAudioDecoder * dec, GstBuffer * buffer)
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{
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GstMapInfo inmap, outmap;
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gint16 *linear_data;
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guint8 *alaw_data;
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gsize alaw_size, linear_size;
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GstBuffer *outbuf;
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gint i;
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if (!buffer) {
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return GST_FLOW_OK;
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}
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if (!gst_buffer_map (buffer, &inmap, GST_MAP_READ)) {
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GST_ERROR_OBJECT (dec, "failed to map input buffer");
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goto error_failed_map_input_buffer;
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}
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alaw_data = inmap.data;
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alaw_size = inmap.size;
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linear_size = alaw_size * 2;
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outbuf = gst_audio_decoder_allocate_output_buffer (dec, linear_size);
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if (!gst_buffer_map (outbuf, &outmap, GST_MAP_WRITE)) {
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GST_ERROR_OBJECT (dec, "failed to map input buffer");
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goto error_failed_map_output_buffer;
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}
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linear_data = (gint16 *) outmap.data;
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for (i = 0; i < alaw_size; i++) {
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linear_data[i] = alaw_to_s16 (alaw_data[i]);
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}
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gst_buffer_unmap (outbuf, &outmap);
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gst_buffer_unmap (buffer, &inmap);
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return gst_audio_decoder_finish_frame (dec, outbuf, -1);
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error_failed_map_output_buffer:
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gst_buffer_unref (outbuf);
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error_failed_map_input_buffer:
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return GST_FLOW_ERROR;
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}
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static gboolean
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gst_alaw_dec_start (GstAudioDecoder * dec)
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{
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gst_audio_decoder_set_estimate_rate (dec, TRUE);
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return TRUE;
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}
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static void
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gst_alaw_dec_class_init (GstALawDecClass * klass)
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{
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GstElementClass *element_class = (GstElementClass *) klass;
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GstAudioDecoderClass *audiodec_class = GST_AUDIO_DECODER_CLASS (klass);
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gst_element_class_add_pad_template (element_class,
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gst_static_pad_template_get (&alaw_dec_src_factory));
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gst_element_class_add_pad_template (element_class,
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gst_static_pad_template_get (&alaw_dec_sink_factory));
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audiodec_class->start = GST_DEBUG_FUNCPTR (gst_alaw_dec_start);
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audiodec_class->set_format = GST_DEBUG_FUNCPTR (gst_alaw_dec_set_format);
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audiodec_class->handle_frame = GST_DEBUG_FUNCPTR (gst_alaw_dec_handle_frame);
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gst_element_class_set_static_metadata (element_class, "A Law audio decoder",
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"Codec/Decoder/Audio",
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"Convert 8bit A law to 16bit PCM",
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"Zaheer Abbas Merali <zaheerabbas at merali dot org>");
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GST_DEBUG_CATEGORY_INIT (alaw_dec_debug, "alawdec", 0, "A Law audio decoder");
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}
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static void
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gst_alaw_dec_init (GstALawDec * alawdec)
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{
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gst_audio_decoder_set_needs_format (GST_AUDIO_DECODER (alawdec), TRUE);
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}
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