channel.c

			result = read_frame;
			ast_frfree(write_frame);
		}
	} else {
		if (need_dup) {
			result = ast_frdup(read_frame);
			result->next = ast_frdup(write_frame);
		} else {
			result = read_frame;
			result->next = write_frame;
		}
	}

	return result;
}

static void *silence_generator_alloc(struct ast_channel *chan, void *data)
{
	/* just store the data pointer in the channel structure */
	return data;
}

static void silence_generator_release(struct ast_channel *chan, void *data)
{
	/* nothing to do */
}

static int silence_generator_generate(struct ast_channel *chan, void *data, int len, int samples) 
{
	if (samples == 160) {
		short buf[160] = { 0, };
		struct ast_frame frame = {
			.frametype = AST_FRAME_VOICE,
			.subclass = AST_FORMAT_SLINEAR,
			.data = buf,
			.samples = 160,
			.datalen = sizeof(buf),
		};

		if (ast_write(chan, &frame))
			return -1;
	} else {
		short buf[samples];
		int x;
		struct ast_frame frame = {
			.frametype = AST_FRAME_VOICE,
			.subclass = AST_FORMAT_SLINEAR,
			.data = buf,
			.samples = samples,
			.datalen = sizeof(buf),
		};

		for (x = 0; x < samples; x++)
			buf[x] = 0;

		if (ast_write(chan, &frame))
			return -1;
	}

	return 0;
}

static struct ast_generator silence_generator = {
	.alloc = silence_generator_alloc,
	.release = silence_generator_release,
	.generate = silence_generator_generate, 
};

struct ast_silence_generator {
	int old_write_format;
};

struct ast_silence_generator *ast_channel_start_silence_generator(struct ast_channel *chan)
{
	struct ast_silence_generator *state;

	if (!(state = calloc(1, sizeof(*state)))) {
		ast_log(LOG_WARNING, "Could not allocate state structure\n");
		return NULL;
	}

	state->old_write_format = chan->writeformat;

	if (ast_set_write_format(chan, AST_FORMAT_SLINEAR) < 0) {
		ast_log(LOG_ERROR, "Could not set write format to SLINEAR\n");
		free(state);
		return NULL;
	}

	ast_activate_generator(chan, &silence_generator, state);

	if (option_debug)
		ast_log(LOG_DEBUG, "Started silence generator on '%s'\n", chan->name);

	return state;
}

void ast_channel_stop_silence_generator(struct ast_channel *chan, struct ast_silence_generator *state)
{
	if (!state)
		return;

	ast_deactivate_generator(chan);

	if (option_debug)
		ast_log(LOG_DEBUG, "Stopped silence generator on '%s'\n", chan->name);

	if (ast_set_write_format(chan, state->old_write_format) < 0)
		ast_log(LOG_ERROR, "Could not return write format to its original state\n");

	free(state);
}


/*! \ brief Convert channel reloadreason (ENUM) to text string for manager event */
const char *channelreloadreason2txt(enum channelreloadreason reason) {
	switch (reason) {
	case CHANNEL_MODULE_LOAD:	return "LOAD (Channel module load)";
					break;
	case CHANNEL_MODULE_RELOAD:	return "RELOAD (Channel module reload)";
					break;
	case CHANNEL_CLI_RELOAD:	return "CLIRELOAD (Channel module reload by CLI command)";
					break;
	default:	return "MANAGERRELOAD (Channel module reload by manager)";
					break;
	}
};