freeswitch/src/mod/codecs/mod_lpc10/mod_lpc10.c

/* 
 * FreeSWITCH Modular Media Switching Software Library / Soft-Switch Application
 * Copyright (C) 2005/2006, Anthony Minessale II <anthmct@yahoo.com>
 *
 * Version: MPL 1.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is FreeSWITCH Modular Media Switching Software Library / Soft-Switch Application
 *
 * The Initial Developer of the Original Code is
 * Anthony Minessale II <anthmct@yahoo.com>
 * Portions created by the Initial Developer are Copyright (C)
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 * 
 * Brian K. West <brian.west@mac.com>
 * 
 *
 * mod_lpc10.c -- LPC10 Codec Module
 *
 */  

#include "switch.h"
#include "lpc10/lpc10.h"

enum {
	SamplesPerFrame = 180,
	BitsPerFrame    = 54,
	BytesPerFrame   = (BitsPerFrame+7)/8,
	BitsPerSecond   = 2400
};

#define   SampleValueScale 32768.0
#define   MaxSampleValue   32767.0
#define   MinSampleValue   -32767.0

static const char modname[] = "mod_lpc10";

struct lpc10_context {
	struct lpc10_encoder_state encoder_object;
	struct lpc10_decoder_state decoder_object;
};

static switch_status_t switch_lpc10_init(switch_codec_t *codec, switch_codec_flag_t flags,
									  const switch_codec_settings_t *codec_settings) 
{
	uint32_t encoding, decoding;
	struct lpc10_context *context = NULL;

	encoding = (flags & SWITCH_CODEC_FLAG_ENCODE);
	decoding = (flags & SWITCH_CODEC_FLAG_DECODE);

	if (!(encoding || decoding) || (!(context = switch_core_alloc(codec->memory_pool, sizeof(struct lpc10_context))))) {
		return SWITCH_STATUS_FALSE;
	} else {

		if (encoding) {
			init_lpc10_encoder_state(&context->encoder_object);
		}

		if (decoding) {
			init_lpc10_decoder_state(&context->decoder_object);
		}

		codec->private_info = context;

		return SWITCH_STATUS_SUCCESS;
	}
}

static switch_status_t switch_lpc10_destroy(switch_codec_t *codec) 
{
	codec->private_info = NULL;
	return SWITCH_STATUS_SUCCESS;
}

static switch_status_t switch_lpc10_encode(switch_codec_t *codec, 
										switch_codec_t *other_codec, 
										void *decoded_data,

										uint32_t decoded_data_len, 
										uint32_t decoded_rate, 
										void *encoded_data,

										uint32_t *encoded_data_len, 
										uint32_t *encoded_rate, 
										unsigned int *flag) 
{
	struct lpc10_context *context = codec->private_info;
	uint8_t i;
	int32_t bits[BitsPerFrame];
	real speech[SamplesPerFrame];
	const short *sampleBuffer = (const short *)decoded_data;
	unsigned char *buffer = (unsigned char *)encoded_data;

	if (!context) {
		return SWITCH_STATUS_FALSE;
	}

	for (i = 0; i < SamplesPerFrame; i++)
		speech[i] = (real)(sampleBuffer[i]/SampleValueScale);

	lpc10_encode(speech, bits, &context->encoder_object);

	memset(encoded_data, 0, BytesPerFrame);
	for (i = 0; i < BitsPerFrame; i++) {
		if (bits[i])
			buffer[i>>3] |= 1 << (i&7);
	}

	*encoded_data_len = BytesPerFrame;

	return SWITCH_STATUS_SUCCESS;
}

static switch_status_t switch_lpc10_decode(switch_codec_t *codec, 
										switch_codec_t *other_codec, 
										void *encoded_data,

										uint32_t encoded_data_len, 
										uint32_t encoded_rate, 
										void *decoded_data,

										uint32_t *decoded_data_len, 
										uint32_t *decoded_rate, 
										unsigned int *flag) 
{
	struct lpc10_context *context = codec->private_info;
	int i;
	INT32 bits[BitsPerFrame];
	real speech[SamplesPerFrame];
	short *sampleBuffer = (short *)decoded_data;
	const unsigned char *buffer = (const unsigned char *)encoded_data;

	if (!context) {
		return SWITCH_STATUS_FALSE;
	}

	for (i = 0; i < BitsPerFrame; i++)
		bits[i] = (buffer[i>>3]&(1<<(i&7))) != 0;

	lpc10_decode(bits, speech, &context->decoder_object);

	for (i = 0; i < SamplesPerFrame; i++) {
		real sample = (real)(speech[i]*SampleValueScale);
		if (sample < MinSampleValue)
			sample = MinSampleValue;
		else if (sample > MaxSampleValue)
			sample = MaxSampleValue;
		sampleBuffer[i] = (short)sample;
	}

	*decoded_data_len = SamplesPerFrame*2;

	return SWITCH_STATUS_SUCCESS;
}

/* Registration */ 

static const switch_codec_implementation_t lpc10_implementation = { 
	/*.codec_type */ SWITCH_CODEC_TYPE_AUDIO, 
	/*.ianacode */ 7, 
	/*.iananame */ "LPC", 
	/*.fmtp */ NULL,
	/*.samples_per_second */ 8000,
	/*.bits_per_second */ 240, 
	/*.microseconds_per_frame */ 22500, 
	/*.samples_per_frame */ 180, 
	/*.bytes_per_frame */ 360, 
	/*.encoded_bytes_per_frame */ 7, 
	/*.number_of_channels */ 1, 
	/*.pref_frames_per_packet */ 1, 
	/*.max_frames_per_packet */ 1, 
	/*.init */ switch_lpc10_init, 
	/*.encode */ switch_lpc10_encode, 
	/*.decode */ switch_lpc10_decode, 
	/*.destroy */ switch_lpc10_destroy, 
};

const switch_codec_interface_t lpc10_codec_interface = { 
	/*.interface_name */ "LPC-10 2.4kbps", 
	/*.implementations */ &lpc10_implementation, 
};

static switch_loadable_module_interface_t lpc10_module_interface = { 
	/*.module_name */ modname, 
	/*.endpoint_interface */ NULL, 
	/*.timer_interface */ NULL, 
	/*.dialplan_interface */ NULL, 
	/*.codec_interface */ &lpc10_codec_interface, 
	/*.application_interface */ NULL 
};

SWITCH_MOD_DECLARE(switch_status_t) switch_module_load(const switch_loadable_module_interface_t **module_interface,
													 char *filename)
{
	/* connect my internal structure to the blank pointer passed to me */ 
	*module_interface = &lpc10_module_interface;

	/* indicate that the module should continue to be loaded */ 
	return SWITCH_STATUS_SUCCESS;
}

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