gstreamer/gst/law/alaw-decode.c

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