/* GStreamer * Copyright (C) 1999 Erik Walthinsen * PCM - A-Law conversion * Copyright (C) 2000 by Abramo Bagnara * * 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 #include "alaw-encode.h" extern GstPadTemplate *alawenc_src_template, *alawenc_sink_template; /* elementfactory information */ static GstElementDetails alawenc_details = { "PCM to A Law conversion", "Codec/Encoder/Audio", "Convert 16bit PCM to 8bit A law", "Zaheer Merali " }; /* Stereo signals and args */ enum { /* FILL ME */ LAST_SIGNAL }; enum { ARG_0 }; static void gst_alawenc_class_init (GstALawEncClass *klass); static void gst_alawenc_base_init (GstALawEncClass *klass); static void gst_alawenc_init (GstALawEnc *alawenc); static void gst_alawenc_set_property (GObject *object, guint prop_id, const GValue *value, GParamSpec *pspec); static void gst_alawenc_get_property (GObject *object, guint prop_id, GValue *value, GParamSpec *pspec); static void gst_alawenc_chain (GstPad *pad, GstData *_data); /* * s16_to_alaw() - Convert a 16-bit linear PCM value to 8-bit A-law * * s16_to_alaw() accepts an 16-bit integer and encodes it as A-law data. * * Linear Input Code Compressed Code * ------------------------ --------------- * 0000000wxyza 000wxyz * 0000001wxyza 001wxyz * 000001wxyzab 010wxyz * 00001wxyzabc 011wxyz * 0001wxyzabcd 100wxyz * 001wxyzabcde 101wxyz * 01wxyzabcdef 110wxyz * 1wxyzabcdefg 111wxyz * * For further information see John C. Bellamy's Digital Telephony, 1982, * John Wiley & Sons, pps 98-111 and 472-476. */ static inline gint val_seg(gint val) { gint r = 1; val >>= 8; if (val & 0xf0) { val >>= 4; r += 4; } if (val & 0x0c) { val >>= 2; r += 2; } if (val & 0x02) r += 1; return r; } static guint8 s16_to_alaw(gint pcm_val) { gint seg; guint8 mask; guint8 aval; if (pcm_val >= 0) { mask = 0xD5; } else { mask = 0x55; pcm_val = -pcm_val; if (pcm_val > 0x7fff) pcm_val = 0x7fff; } if (pcm_val < 256) aval = pcm_val >> 4; else { /* Convert the scaled magnitude to segment number. */ seg = val_seg(pcm_val); aval = (seg << 4) | ((pcm_val >> (seg + 3)) & 0x0f); } return aval ^ mask; } static GstElementClass *parent_class = NULL; /*static guint gst_stereo_signals[LAST_SIGNAL] = { 0 }; */ static GstPadLinkReturn alawenc_link (GstPad *pad, GstCaps *caps) { GstCaps* tempcaps; gint rate, channels; GstALawEnc* alawenc = GST_ALAWENC (GST_OBJECT_PARENT (pad)); if (!GST_CAPS_IS_FIXED (caps)) return GST_PAD_LINK_DELAYED; if (!gst_caps_get (caps, "rate", &rate, "channels", &channels, NULL)) return GST_PAD_LINK_DELAYED; tempcaps = GST_CAPS_NEW ( "alawenc_src_caps", "audio/x-alaw", "depth", GST_PROPS_INT (8), "width", GST_PROPS_INT (8), "signed", GST_PROPS_BOOLEAN (FALSE), "rate", GST_PROPS_INT (rate), "channels", GST_PROPS_INT (channels), NULL); return gst_pad_try_set_caps (alawenc->srcpad, tempcaps); } GType gst_alawenc_get_type(void) { static GType alawenc_type = 0; if (!alawenc_type) { static const GTypeInfo alawenc_info = { sizeof(GstALawEncClass), (GBaseInitFunc)gst_alawenc_base_init, NULL, (GClassInitFunc)gst_alawenc_class_init, NULL, NULL, sizeof(GstALawEnc), 0, (GInstanceInitFunc)gst_alawenc_init, }; alawenc_type = g_type_register_static(GST_TYPE_ELEMENT, "GstALawEnc", &alawenc_info, 0); } return alawenc_type; } static void gst_alawenc_base_init (GstALawEncClass *klass) { GstElementClass *element_class = GST_ELEMENT_CLASS (klass); gst_element_class_add_pad_template (element_class, alawenc_src_template); gst_element_class_add_pad_template (element_class, alawenc_sink_template); gst_element_class_set_details (element_class, &alawenc_details); } static void gst_alawenc_class_init (GstALawEncClass *klass) { GObjectClass *gobject_class; GstElementClass *gstelement_class; gobject_class = (GObjectClass*)klass; gstelement_class = (GstElementClass*)klass; parent_class = g_type_class_ref(GST_TYPE_ELEMENT); gobject_class->set_property = gst_alawenc_set_property; gobject_class->get_property = gst_alawenc_get_property; } static void gst_alawenc_init (GstALawEnc *alawenc) { alawenc->sinkpad = gst_pad_new_from_template(alawenc_sink_template,"sink"); alawenc->srcpad = gst_pad_new_from_template(alawenc_src_template,"src"); gst_pad_set_link_function (alawenc->sinkpad, alawenc_link); gst_element_add_pad(GST_ELEMENT(alawenc),alawenc->sinkpad); gst_pad_set_chain_function(alawenc->sinkpad,gst_alawenc_chain); gst_element_add_pad(GST_ELEMENT(alawenc),alawenc->srcpad); } static void gst_alawenc_chain (GstPad *pad,GstData *_data) { GstBuffer *buf = GST_BUFFER (_data); GstALawEnc *alawenc; gint16 *linear_data; guint8 *alaw_data; GstBuffer* outbuf; gint i; g_return_if_fail(pad != NULL); g_return_if_fail(GST_IS_PAD(pad)); g_return_if_fail(buf != NULL); alawenc = GST_ALAWENC(GST_OBJECT_PARENT (pad)); g_return_if_fail(alawenc != NULL); g_return_if_fail(GST_IS_ALAWENC(alawenc)); linear_data = (gint16 *)GST_BUFFER_DATA(buf); outbuf=gst_buffer_new(); GST_BUFFER_DATA(outbuf) = (gchar*)g_new(guint8,GST_BUFFER_SIZE(buf)/2); GST_BUFFER_SIZE(outbuf) = GST_BUFFER_SIZE(buf)/2; alaw_data = (guint8*)GST_BUFFER_DATA(outbuf); for (i = 0; i < GST_BUFFER_SIZE(outbuf); i++) { *alaw_data = s16_to_alaw (*linear_data); alaw_data++; linear_data++; } gst_buffer_unref(buf); gst_pad_push(alawenc->srcpad,GST_DATA (outbuf)); } static void gst_alawenc_set_property (GObject *object, guint prop_id, const GValue *value, GParamSpec *pspec) { GstALawEnc *alawenc; /* it's not null if we got it, but it might not be ours */ g_return_if_fail(GST_IS_ALAWENC(object)); alawenc = GST_ALAWENC(object); switch (prop_id) { default: break; } } static void gst_alawenc_get_property (GObject *object, guint prop_id, GValue *value, GParamSpec *pspec) { GstALawEnc *alawenc; /* it's not null if we got it, but it might not be ours */ g_return_if_fail(GST_IS_ALAWENC(object)); alawenc = GST_ALAWENC(object); switch (prop_id) { default: G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec); break; } }