g711.c

基于sip协议的网络电话源码

    pjmedia_codec *codec = NULL;
    pj_status_t status;

    PJ_ASSERT_RETURN(factory==&g711_factory.base, PJ_EINVAL);

    /* Lock mutex. */
    pj_mutex_lock(g711_factory.mutex);

    /* Allocate new codec if no more is available */
    if (pj_list_empty(&g711_factory.codec_list)) {
	struct g711_private *codec_priv;

	codec = pj_pool_alloc(g711_factory.pool, sizeof(pjmedia_codec));
	codec_priv = pj_pool_zalloc(g711_factory.pool, 
				    sizeof(struct g711_private));
	if (!codec || !codec_priv) {
	    pj_mutex_unlock(g711_factory.mutex);
	    return PJ_ENOMEM;
	}

	/* Set the payload type */
	codec_priv->pt = id->pt;

	/* Create PLC, always with 10ms ptime */
	status = pjmedia_plc_create(g711_factory.pool, 8000, 80,
				    0, &codec_priv->plc);
	if (status != PJ_SUCCESS) {
	    pj_mutex_unlock(g711_factory.mutex);
	    return status;
	}

	/* Create VAD */
	status = pjmedia_silence_det_create(g711_factory.pool,
					    8000, 80,
					    &codec_priv->vad);
	if (status != PJ_SUCCESS) {
	    pj_mutex_unlock(g711_factory.mutex);
	    return status;
	}

	codec->factory = factory;
	codec->op = &g711_op;
	codec->codec_data = codec_priv;
    } else {
	codec = g711_factory.codec_list.next;
	pj_list_erase(codec);
    }

    /* Zero the list, for error detection in g711_dealloc_codec */
    codec->next = codec->prev = NULL;

    *p_codec = codec;

    /* Unlock mutex. */
    pj_mutex_unlock(g711_factory.mutex);

    return PJ_SUCCESS;
}

static pj_status_t g711_dealloc_codec(pjmedia_codec_factory *factory, 
				      pjmedia_codec *codec )
{
    struct g711_private *priv = codec->codec_data;
    pj_int16_t frame[SAMPLES_PER_FRAME];
    int i;

    PJ_ASSERT_RETURN(factory==&g711_factory.base, PJ_EINVAL);

    /* Check that this node has not been deallocated before */
    pj_assert (codec->next==NULL && codec->prev==NULL);
    if (codec->next!=NULL || codec->prev!=NULL) {
	return PJ_EINVALIDOP;
    }

    /* Clear left samples in the PLC, since codec+plc will be reused
     * next time.
     */
    for (i=0; i<2; ++i) {
	pjmedia_zero_samples(frame, PJ_ARRAY_SIZE(frame));
	pjmedia_plc_save(priv->plc, frame);
    }

    /* Lock mutex. */
    pj_mutex_lock(g711_factory.mutex);

    /* Insert at the back of the list */
    pj_list_insert_before(&g711_factory.codec_list, codec);

    /* Unlock mutex. */
    pj_mutex_unlock(g711_factory.mutex);

    return PJ_SUCCESS;
}

static pj_status_t g711_init( pjmedia_codec *codec, pj_pool_t *pool )
{
    /* There's nothing to do here really */
    PJ_UNUSED_ARG(codec);
    PJ_UNUSED_ARG(pool);

    return PJ_SUCCESS;
}

static pj_status_t g711_open(pjmedia_codec *codec, 
			     pjmedia_codec_param *attr )
{
    struct g711_private *priv = codec->codec_data;
    priv->pt = attr->info.pt;
    priv->plc_enabled = (attr->setting.plc != 0);
    priv->vad_enabled = (attr->setting.vad != 0);
    return PJ_SUCCESS;
}

static pj_status_t g711_close( pjmedia_codec *codec )
{
    PJ_UNUSED_ARG(codec);
    /* Nothing to do */
    return PJ_SUCCESS;
}

static pj_status_t  g711_modify(pjmedia_codec *codec, 
			        const pjmedia_codec_param *attr )
{
    struct g711_private *priv = codec->codec_data;

    if (attr->info.pt != priv->pt)
	return PJMEDIA_EINVALIDPT;

    priv->plc_enabled = (attr->setting.plc != 0);
    priv->vad_enabled = (attr->setting.vad != 0);

    return PJ_SUCCESS;
}

static pj_status_t  g711_parse( pjmedia_codec *codec,
				void *pkt,
				pj_size_t pkt_size,
				const pj_timestamp *ts,
				unsigned *frame_cnt,
				pjmedia_frame frames[])
{
    unsigned count = 0;

    PJ_UNUSED_ARG(codec);

    PJ_ASSERT_RETURN(ts && frame_cnt && frames, PJ_EINVAL);

    while (pkt_size >= FRAME_SIZE && count < *frame_cnt) {
	frames[count].type = PJMEDIA_FRAME_TYPE_AUDIO;
	frames[count].buf = pkt;
	frames[count].size = FRAME_SIZE;
	frames[count].timestamp.u64 = ts->u64 + SAMPLES_PER_FRAME * count;

	pkt = ((char*)pkt) + FRAME_SIZE;
	pkt_size -= FRAME_SIZE;

	++count;
    }

    *frame_cnt = count;
    return PJ_SUCCESS;
}

static pj_status_t  g711_encode(pjmedia_codec *codec, 
				const struct pjmedia_frame *input,
				unsigned output_buf_len, 
				struct pjmedia_frame *output)
{
    pj_int16_t *samples = (pj_int16_t*) input->buf;
    struct g711_private *priv = codec->codec_data;

    /* Check output buffer length */
    if (output_buf_len < (input->size >> 1))
	return PJMEDIA_CODEC_EFRMTOOSHORT;

    /* Detect silence if VAD is enabled */
    if (priv->vad_enabled) {
	pj_bool_t is_silence;
	pj_int32_t silence_period;

	silence_period = pj_timestamp_diff32(&priv->last_tx,
					     &input->timestamp);

	is_silence = pjmedia_silence_det_detect(priv->vad, input->buf, 
						(input->size >> 1), NULL);
	if (is_silence && 
	    PJMEDIA_CODEC_MAX_SILENCE_PERIOD != -1 &&
	    silence_period < PJMEDIA_CODEC_MAX_SILENCE_PERIOD) 
	{
	    output->type = PJMEDIA_FRAME_TYPE_NONE;
	    output->buf = NULL;
	    output->size = 0;
	    output->timestamp = input->timestamp;
	    return PJ_SUCCESS;
	} else {
	    priv->last_tx = input->timestamp;
	}
    }

    /* Encode */
    if (priv->pt == PJMEDIA_RTP_PT_PCMA) {
	unsigned i, n;
	pj_uint8_t *dst = output->buf;

	n = (input->size >> 1);
	for (i=0; i!=n; ++i, ++dst) {
	    *dst = pjmedia_linear2alaw(samples[i]);
	}
    } else if (priv->pt == PJMEDIA_RTP_PT_PCMU) {
	unsigned i, n;
	pj_uint8_t *dst = output->buf;

	n = (input->size >> 1);
	for (i=0; i!=n; ++i, ++dst) {
	    *dst = pjmedia_linear2ulaw(samples[i]);
	}

    } else {
	return PJMEDIA_EINVALIDPT;
    }

    output->type = PJMEDIA_FRAME_TYPE_AUDIO;
    output->size = (input->size >> 1);

    return PJ_SUCCESS;
}

static pj_status_t  g711_decode(pjmedia_codec *codec, 
				const struct pjmedia_frame *input,
				unsigned output_buf_len, 
				struct pjmedia_frame *output)
{
    struct g711_private *priv = codec->codec_data;

    /* Check output buffer length */
    PJ_ASSERT_RETURN(output_buf_len >= (input->size << 1),
		     PJMEDIA_CODEC_EPCMTOOSHORT);

    /* Input buffer MUST have exactly 80 bytes long */
    PJ_ASSERT_RETURN(input->size == FRAME_SIZE, 
		     PJMEDIA_CODEC_EFRMINLEN);

    /* Decode */
    if (priv->pt == PJMEDIA_RTP_PT_PCMA) {
	unsigned i;
	pj_uint8_t *src = input->buf;
	pj_uint16_t *dst = output->buf;

	for (i=0; i!=input->size; ++i) {
	    *dst++ = (pj_uint16_t) pjmedia_alaw2linear(*src++);
	}
    } else if (priv->pt == PJMEDIA_RTP_PT_PCMU) {
	unsigned i;
	pj_uint8_t *src = input->buf;
	pj_uint16_t *dst = output->buf;

	for (i=0; i!=input->size; ++i) {
	    *dst++ = (pj_uint16_t) pjmedia_ulaw2linear(*src++);
	}

    } else {
	return PJMEDIA_EINVALIDPT;
    }

    output->type = PJMEDIA_FRAME_TYPE_AUDIO;
    output->size = (input->size << 1);

    if (priv->plc_enabled)
	pjmedia_plc_save( priv->plc, output->buf);

    return PJ_SUCCESS;
}

static pj_status_t  g711_recover( pjmedia_codec *codec,
				  unsigned output_buf_len,
				  struct pjmedia_frame *output)
{
    struct g711_private *priv = codec->codec_data;

    if (!priv->plc_enabled)
	return PJ_EINVALIDOP;

    PJ_ASSERT_RETURN(output_buf_len >= SAMPLES_PER_FRAME * 2, 
		     PJMEDIA_CODEC_EPCMTOOSHORT);

    pjmedia_plc_generate(priv->plc, output->buf);
    output->size = SAMPLES_PER_FRAME * 2;

    return PJ_SUCCESS;
}

#endif	/* PJMEDIA_HAS_G711_CODEC */