gstreamer/gst/law/alaw-decode.c

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/* GStreamer
* Copyright (C) 1999 Erik Walthinsen <omega@cse.ogi.edu>
* PCM - A-Law 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., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <gst/gst.h>
#include "alaw-decode.h"
extern GstPadTemplate *alawdec_src_template, *alawdec_sink_template;
/* Stereo signals and args */
enum
{
/* FILL ME */
LAST_SIGNAL
};
enum
{
ARG_0
};
static void gst_alawdec_class_init (GstALawDecClass * klass);
static void gst_alawdec_base_init (GstALawDecClass * klass);
static void gst_alawdec_init (GstALawDec * alawdec);
static GstFlowReturn gst_alawdec_chain (GstPad * pad, GstBuffer * buffer);
static GstElementClass *parent_class = NULL;
/*static guint gst_stereo_signals[LAST_SIGNAL] = { 0 }; */
/*
* alaw_to_s16() - Convert an A-law value to 16-bit linear PCM
*
*/
static 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);
}
static GstCaps *
alawdec_getcaps (GstPad * pad)
{
GstALawDec *alawdec;
GstPad *otherpad;
GstCaps *base_caps, *othercaps;
alawdec = GST_ALAWDEC (GST_PAD_PARENT (pad));
/* we can do what our template says */
base_caps = gst_caps_copy (gst_pad_get_pad_template_caps (pad));
if (pad == alawdec->sinkpad) {
otherpad = alawdec->srcpad;
} else {
otherpad = alawdec->sinkpad;
}
/* now intersect rate and channels from peer caps */
othercaps = gst_pad_peer_get_caps (otherpad);
if (othercaps) {
GstStructure *structure;
const GValue *orate, *ochans;
const GValue *rate, *chans;
GValue irate = { 0 }, ichans = {
0};
structure = gst_caps_get_structure (othercaps, 0);
orate = gst_structure_get_value (structure, "rate");
ochans = gst_structure_get_value (structure, "channels");
if (!rate || !chans)
goto done;
structure = gst_caps_get_structure (base_caps, 0);
rate = gst_structure_get_value (structure, "rate");
chans = gst_structure_get_value (structure, "channels");
if (!rate || !chans)
goto done;
gst_value_intersect (&irate, orate, rate);
gst_value_intersect (&ichans, ochans, chans);
/* Set the samplerate/channels on the to-be-returned caps */
structure = gst_caps_get_structure (base_caps, 0);
gst_structure_set_value (structure, "rate", &irate);
gst_structure_set_value (structure, "channels", &ichans);
gst_caps_unref (othercaps);
}
done:
return base_caps;
}
static gboolean
alawdec_setcaps (GstPad * pad, GstCaps * caps)
{
GstALawDec *alawdec;
GstPad *otherpad;
GstStructure *structure;
const GValue *rate, *chans;
GstCaps *base_caps;
alawdec = GST_ALAWDEC (GST_PAD_PARENT (pad));
/* take rate and channels */
structure = gst_caps_get_structure (caps, 0);
rate = gst_structure_get_value (structure, "rate");
chans = gst_structure_get_value (structure, "channels");
if (!rate || !chans)
return FALSE;
if (pad == alawdec->srcpad) {
otherpad = alawdec->sinkpad;
} else {
otherpad = alawdec->srcpad;
}
/* fill in values for otherpad */
base_caps = gst_caps_copy (gst_pad_get_pad_template_caps (otherpad));
structure = gst_caps_get_structure (base_caps, 0);
gst_structure_set_value (structure, "rate", rate);
gst_structure_set_value (structure, "channels", chans);
/* and set on otherpad */
gst_pad_set_caps (otherpad, base_caps);
gst_caps_unref (base_caps);
return TRUE;
}
GType
gst_alawdec_get_type (void)
{
static GType alawdec_type = 0;
if (!alawdec_type) {
static const GTypeInfo alawdec_info = {
sizeof (GstALawDecClass),
(GBaseInitFunc) gst_alawdec_base_init,
NULL,
(GClassInitFunc) gst_alawdec_class_init,
NULL,
NULL,
sizeof (GstALawDec),
0,
(GInstanceInitFunc) gst_alawdec_init,
};
alawdec_type =
g_type_register_static (GST_TYPE_ELEMENT, "GstALawDec", &alawdec_info,
0);
}
return alawdec_type;
}
static void
gst_alawdec_base_init (GstALawDecClass * klass)
{
GstElementClass *element_class = GST_ELEMENT_CLASS (klass);
GstElementDetails alawdec_details = {
"A Law to PCM conversion",
"Codec/Decoder/Audio",
"Convert 8bit A law to 16bit PCM",
"Zaheer Abbas Merali <zaheerabbas at merali dot org>"
};
gst_element_class_add_pad_template (element_class, alawdec_src_template);
gst_element_class_add_pad_template (element_class, alawdec_sink_template);
gst_element_class_set_details (element_class, &alawdec_details);
}
static void
gst_alawdec_class_init (GstALawDecClass * klass)
{
parent_class = g_type_class_ref (GST_TYPE_ELEMENT);
}
static void
gst_alawdec_init (GstALawDec * alawdec)
{
alawdec->sinkpad = gst_pad_new_from_template (alawdec_sink_template, "sink");
gst_pad_set_setcaps_function (alawdec->sinkpad, alawdec_setcaps);
gst_pad_set_getcaps_function (alawdec->sinkpad, alawdec_getcaps);
gst_pad_set_chain_function (alawdec->sinkpad, gst_alawdec_chain);
gst_element_add_pad (GST_ELEMENT (alawdec), alawdec->sinkpad);
alawdec->srcpad = gst_pad_new_from_template (alawdec_src_template, "src");
gst_pad_set_setcaps_function (alawdec->srcpad, alawdec_setcaps);
gst_pad_set_getcaps_function (alawdec->srcpad, alawdec_getcaps);
gst_element_add_pad (GST_ELEMENT (alawdec), alawdec->srcpad);
}
static GstFlowReturn
gst_alawdec_chain (GstPad * pad, GstBuffer * buffer)
{
GstALawDec *alawdec;
gint16 *linear_data;
guint8 *alaw_data;
GstBuffer *outbuf;
gint i;
alawdec = GST_ALAWDEC (GST_OBJECT_PARENT (pad));
alaw_data = (guint8 *) GST_BUFFER_DATA (buffer);
outbuf = gst_buffer_new_and_alloc (GST_BUFFER_SIZE (buffer) * 2);
GST_BUFFER_TIMESTAMP (outbuf) = GST_BUFFER_TIMESTAMP (buffer);
GST_BUFFER_DURATION (outbuf) = GST_BUFFER_DURATION (buffer);
gst_buffer_set_caps (outbuf, GST_PAD_CAPS (alawdec->srcpad));
linear_data = (gint16 *) GST_BUFFER_DATA (outbuf);
for (i = 0; i < GST_BUFFER_SIZE (buffer); i++) {
*linear_data = alaw_to_s16 (*alaw_data);
linear_data++;
alaw_data++;
}
gst_buffer_unref (buffer);
return gst_pad_push (alawdec->srcpad, outbuf);
}