/* $Id$ */
/* 
 * Copyright (C) 2019 Teluu Inc. (http://www.teluu.com)
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 
 */
#include <pjmedia/vid_conf.h>
#include <pjmedia/clock.h>
#include <pjmedia/converter.h>
#include <pjmedia/errno.h>
#include <pj/array.h>
#include <pj/log.h>
#include <pj/os.h>

#if defined(PJMEDIA_HAS_VIDEO) && (PJMEDIA_HAS_VIDEO != 0)


#define CONF_NAME	"vidconf"
#define CONF_SIGN	PJMEDIA_SIG_VID_CONF

/* If set, conf will stop clock when there is no ports connection. However,
 * this may cause stuck if port remove/disconnect is called from the clock
 * callback. So better disable this for now.
 */
#define AUTO_STOP_CLOCK 0

/* Clockrate for video timestamp unit */
#define TS_CLOCK_RATE	90000

#define THIS_FILE	"vid_conf.c"
#define TRACE_(x)	PJ_LOG(5,x)


/*
 * Conference bridge.
 */
struct pjmedia_vid_conf
{
    pjmedia_vid_conf_setting opt;	/**< Settings.			    */
    unsigned		  port_cnt;	/**< Current number of ports.	    */
    unsigned		  connect_cnt;	/**< Total number of connections    */
    pj_mutex_t		 *mutex;	/**< Conference mutex.		    */
    struct vconf_port	**ports;	/**< Array of ports.		    */
    pjmedia_clock	 *clock;	/**< Clock.			    */
};


/*
 * Rendering state: converter, layout settings, etc.
 */
typedef struct render_state
{
    pjmedia_format_id	src_fmt_id;	/**< Source format ID.		    */
    pjmedia_rect_size	src_frame_size;	/**< Source frame size.		    */
    pjmedia_rect	src_rect;	/**< Source region to be rendered.  */

    pjmedia_format_id	dst_fmt_id;	/**< Destination format ID.	    */
    pjmedia_rect_size	dst_frame_size;	/**< Destination frame size.	    */
    pjmedia_rect	dst_rect;	/**< Destination region.	    */

    pjmedia_converter	*converter;	/**< Converter.			    */

} render_state;


/*
 * Conference bridge port.
 */
typedef struct vconf_port
{
    pj_pool_t		*pool;		/**< Pool.			    */
    unsigned		 idx;		/**< Port index.		    */
    pj_str_t		 name;		/**< Port name.			    */
    pjmedia_port	*port;		/**< Video port.		    */
    pj_uint32_t		 ts_interval;	/**< Port put/get interval.	    */
    pj_timestamp	 ts_next;	/**< Time for next put/get_frame(). */
    void		*get_buf;	/**< Buffer for get_frame().	    */
    pj_size_t		 get_buf_size;	/**< Buffer size for get_frame().   */
    void		*put_buf;	/**< Buffer for put_frame().	    */
    pj_size_t		 put_buf_size;	/**< Buffer size for put_frame().   */

    unsigned		 listener_cnt;	/**< Number of listeners.	    */
    unsigned		*listener_slots;/**< Array of listeners (for info). */

    unsigned		 transmitter_cnt;/**<Number of transmitters.	    */
    unsigned		*transmitter_slots;/**< Array of transmitters.	    */
    pj_pool_t	       **render_pool;	/**< Array of pool for render state */
    render_state       **render_states;	/**< Array of render_state (one for
					     each transmitter).		    */
} vconf_port;


/* Prototypes */
static void on_clock_tick(const pj_timestamp *ts, void *user_data);
static pj_status_t render_src_frame(vconf_port *src, vconf_port *sink,
				    unsigned transmitter_idx);
static void update_render_state(pjmedia_vid_conf *vid_conf, vconf_port *cp);
static void cleanup_render_state(vconf_port *cp,
				 unsigned transmitter_idx);


/*
 * Initialize video conference settings with default values.
 */
PJ_DEF(void) pjmedia_vid_conf_setting_default(pjmedia_vid_conf_setting *opt)
{
    pj_bzero(opt, sizeof(*opt));
    opt->max_slot_cnt = 32;
    opt->frame_rate = 60;
}


/*
 * Create a video conference bridge.
 */
PJ_DEF(pj_status_t) pjmedia_vid_conf_create(
					pj_pool_t *pool,
					const pjmedia_vid_conf_setting *opt,
					pjmedia_vid_conf **p_vid_conf)
{
    pjmedia_vid_conf *vid_conf;
    pjmedia_clock_param clock_param;
    pj_status_t status;

    PJ_ASSERT_RETURN(pool && p_vid_conf, PJ_EINVAL);

    /* Allocate conf structure */
    vid_conf = PJ_POOL_ZALLOC_T(pool, pjmedia_vid_conf);
    PJ_ASSERT_RETURN(vid_conf, PJ_ENOMEM);

    /* Init settings */
    if (opt) {
	vid_conf->opt = *opt;
    } else {
	pjmedia_vid_conf_setting_default(&vid_conf->opt);
    }

    /* Allocate ports */
    vid_conf->ports = (vconf_port**)
		      pj_pool_zalloc(pool, vid_conf->opt.max_slot_cnt *
					   sizeof(vconf_port*));
    PJ_ASSERT_RETURN(vid_conf->ports, PJ_ENOMEM);

    /* Create mutex */
    status = pj_mutex_create_recursive(pool, CONF_NAME, &vid_conf->mutex);
    if (status != PJ_SUCCESS) {
	pjmedia_vid_conf_destroy(vid_conf);
	return status;
    }

    /* Create clock */
    pj_bzero(&clock_param, sizeof(clock_param));
    clock_param.clock_rate = TS_CLOCK_RATE;
    clock_param.usec_interval = 1000000 / vid_conf->opt.frame_rate;
    status = pjmedia_clock_create2(pool, &clock_param, 0, &on_clock_tick,
				   vid_conf, &vid_conf->clock);
    if (status != PJ_SUCCESS) {
	pjmedia_vid_conf_destroy(vid_conf);
	return status;
    }

    /* Done */
    *p_vid_conf = vid_conf;

    PJ_LOG(5,(THIS_FILE, "Created video conference bridge with %d ports",
	      vid_conf->opt.max_slot_cnt));

    return PJ_SUCCESS;
}


/*
 * Destroy video conference bridge.
 */
PJ_DEF(pj_status_t) pjmedia_vid_conf_destroy(pjmedia_vid_conf *vid_conf)
{
    unsigned i;

    PJ_ASSERT_RETURN(vid_conf, PJ_EINVAL);

    /* Destroy clock */
    if (vid_conf->clock) {
	pjmedia_clock_destroy(vid_conf->clock);
	vid_conf->clock = NULL;
    }

    /* Remove any registered ports (at least to cleanup their pool) */
    for (i=0; i < vid_conf->opt.max_slot_cnt; ++i) {
	pjmedia_vid_conf_remove_port(vid_conf, i);
    }

    /* Destroy mutex */
    if (vid_conf->mutex) {
	pj_mutex_destroy(vid_conf->mutex);
	vid_conf->mutex = NULL;
    }

    PJ_LOG(5,(THIS_FILE, "Video conference bridge destroyed"));

    return PJ_SUCCESS;
}


/*
 * Add a media port to the video conference bridge.
 */
PJ_DEF(pj_status_t) pjmedia_vid_conf_add_port( pjmedia_vid_conf *vid_conf,
					       pj_pool_t *parent_pool,
					       pjmedia_port *port,
					       const pj_str_t *name,
					       void *opt,
					       unsigned *p_slot)
{
    pj_pool_t *pool;
    vconf_port *cport;
    unsigned index;

    PJ_ASSERT_RETURN(vid_conf && parent_pool && port, PJ_EINVAL);
    PJ_ASSERT_RETURN(port->info.fmt.type==PJMEDIA_TYPE_VIDEO &&
		     port->info.fmt.detail_type==PJMEDIA_FORMAT_DETAIL_VIDEO,
		     PJ_EINVAL);
    PJ_UNUSED_ARG(opt);

    /* If name is not specified, use the port's name */
    if (!name)
	name = &port->info.name;

    pj_mutex_lock(vid_conf->mutex);

    if (vid_conf->port_cnt >= vid_conf->opt.max_slot_cnt) {
	pj_assert(!"Too many ports");
	pj_mutex_unlock(vid_conf->mutex);
	return PJ_ETOOMANY;
    }

    /* Find empty port in the conference bridge. */
    for (index=0; index < vid_conf->opt.max_slot_cnt; ++index) {
	if (vid_conf->ports[index] == NULL)
	    break;
    }
    pj_assert(index != vid_conf->opt.max_slot_cnt);

    /* Create pool */
    pool = pj_pool_create(parent_pool->factory, name->ptr, 500, 500, NULL);
    PJ_ASSERT_RETURN(pool, PJ_ENOMEM);

    /* Create port. */
    cport = PJ_POOL_ZALLOC_T(pool, vconf_port);
    PJ_ASSERT_RETURN(cport, PJ_ENOMEM);

    /* Set pool, port, index, and name */
    cport->pool = pool;
    cport->port = port;
    cport->idx  = index;
    pj_strdup_with_null(pool, &cport->name, name);

    /* Init put/get_frame() intervals */
    {
	pjmedia_ratio *fps = &port->info.fmt.det.vid.fps;
	pj_uint32_t vconf_interval = (pj_uint32_t)
				     (TS_CLOCK_RATE * 1.0 /
				     vid_conf->opt.frame_rate);
	cport->ts_interval = (pj_uint32_t)(TS_CLOCK_RATE * 1.0 /
					   fps->num * fps->denum);

	/* Normalize the interval */
	if (cport->ts_interval < vconf_interval) {
	    cport->ts_interval = vconf_interval;
	    PJ_LOG(3,(THIS_FILE, "Warning: frame rate of port %s is higher "
				 "than video conference bridge (%d > %d)",
				 name->ptr, (int)(fps->num/fps->denum),
				 vid_conf->opt.frame_rate));
	}
    }

    /* Allocate buffer for put/get_frame() */
    {
	const pjmedia_video_format_info *vfi;
	pjmedia_video_apply_fmt_param vafp;
	pj_status_t status;

	vfi = pjmedia_get_video_format_info(NULL, port->info.fmt.id);
	if (!vfi) {
	    PJ_LOG(4,(THIS_FILE, "pjmedia_vid_conf_add_port(): "
				 "unrecognized format %04X",
				 port->info.fmt.id));
	    return PJMEDIA_EBADFMT;
	}

	pj_bzero(&vafp, sizeof(vafp));
	vafp.size = port->info.fmt.det.vid.size;
	status = (*vfi->apply_fmt)(vfi, &vafp);
	if (status != PJ_SUCCESS) {
	    PJ_LOG(4,(THIS_FILE, "pjmedia_vid_conf_add_port(): "
				 "Failed to apply format %04X",
				 port->info.fmt.id));
	    return status;
	}
	if (port->put_frame) {
	    cport->put_buf_size = vafp.framebytes;
	    cport->put_buf = pj_pool_zalloc(cport->pool, cport->put_buf_size);
	}
	if (port->get_frame) {
	    cport->get_buf_size = vafp.framebytes;
	    cport->get_buf = pj_pool_zalloc(cport->pool, cport->get_buf_size);
	}
    }

    /* Create listener array */
    cport->listener_slots = (unsigned*)
			    pj_pool_zalloc(pool,
					   vid_conf->opt.max_slot_cnt *
					   sizeof(unsigned));
    PJ_ASSERT_RETURN(cport->listener_slots, PJ_ENOMEM);

    /* Create transmitter array */
    cport->transmitter_slots = (unsigned*)
			       pj_pool_zalloc(pool,
					      vid_conf->opt.max_slot_cnt *
					      sizeof(unsigned));
    PJ_ASSERT_RETURN(cport->transmitter_slots, PJ_ENOMEM);

    /* Create pointer-to-render_state array */
    cport->render_states = (render_state**)
			   pj_pool_zalloc(pool,
					  vid_conf->opt.max_slot_cnt *
					  sizeof(render_state*));
    PJ_ASSERT_RETURN(cport->render_states, PJ_ENOMEM);

    /* Create pointer-to-render-pool array */
    cport->render_pool = (pj_pool_t**)
			 pj_pool_zalloc(pool,
					vid_conf->opt.max_slot_cnt *
					sizeof(pj_pool_t*));
    PJ_ASSERT_RETURN(cport->render_pool, PJ_ENOMEM);

    /* Register the conf port. */
    vid_conf->ports[index] = cport;
    vid_conf->port_cnt++;

    PJ_LOG(4,(THIS_FILE,"Added port %d (%.*s)",
	      index, (int)cport->name.slen, cport->name.ptr));

    pj_mutex_unlock(vid_conf->mutex);

    /* Done. */
    if (p_slot) {
	*p_slot = index;
    }

    return PJ_SUCCESS;
}


/*
 * Remove a media port from the video conference bridge.
 */
PJ_DEF(pj_status_t) pjmedia_vid_conf_remove_port( pjmedia_vid_conf *vid_conf,
						  unsigned slot)
{
    vconf_port *cport;

    PJ_ASSERT_RETURN(vid_conf && slot<vid_conf->opt.max_slot_cnt, PJ_EINVAL);

    pj_mutex_lock(vid_conf->mutex);

    /* Port must be valid. */
    cport = vid_conf->ports[slot];
    if (cport == NULL) {
	pj_mutex_unlock(vid_conf->mutex);
	return PJ_EINVAL;
    }

    /* Disconnect slot -> listeners */
    while (cport->listener_cnt) {
	pjmedia_vid_conf_disconnect_port(vid_conf, slot,
					 cport->listener_slots[0]);
    }

    /* Disconnect transmitters -> slot */
    while (cport->transmitter_cnt) {
	pjmedia_vid_conf_disconnect_port(vid_conf,
					 cport->transmitter_slots[0], slot);
    }

    /* Remove the port. */
    vid_conf->ports[slot] = NULL;
    --vid_conf->port_cnt;

    PJ_LOG(4,(THIS_FILE,"Removed port %d (%.*s)",
	      slot, (int)cport->name.slen, cport->name.ptr));

    /* Release pool */
    pj_pool_safe_release(&cport->pool);

    if (AUTO_STOP_CLOCK && vid_conf->connect_cnt == 0) {
	pj_status_t status;

	/* Warning: will stuck if this is called from the clock thread */
	status = pjmedia_clock_stop(vid_conf->clock);
	if (status != PJ_SUCCESS) {
	    PJ_PERROR(4, (THIS_FILE, status, "Failed to stop clock"));
	    return status;
	}
    }

    pj_mutex_unlock(vid_conf->mutex);

    return PJ_SUCCESS;
}


/*
 * Get number of ports currently registered in the video conference bridge.
 */
PJ_DEF(unsigned) pjmedia_vid_conf_get_port_count(pjmedia_vid_conf *vid_conf)
{
    return vid_conf->port_cnt;
}


/*
 * Enumerate occupied slots in the video conference bridge.
 */
PJ_DEF(pj_status_t) pjmedia_vid_conf_enum_ports( pjmedia_vid_conf *vid_conf,
						 unsigned slots[],
						 unsigned *count)
{
    unsigned i, tmp_count=0;

    PJ_ASSERT_RETURN(vid_conf && slots && count, PJ_EINVAL);

    /* Lock mutex */
    pj_mutex_lock(vid_conf->mutex);

    for (i=0; i<vid_conf->opt.max_slot_cnt && tmp_count<*count; ++i) {
	if (!vid_conf->ports[i])
	    continue;

	slots[tmp_count++] = i;
    }

    /* Unlock mutex */
    pj_mutex_unlock(vid_conf->mutex);

    *count = tmp_count;

    return PJ_SUCCESS;
}


/*
 * Get port info.
 */
PJ_DEF(pj_status_t) pjmedia_vid_conf_get_port_info(
					    pjmedia_vid_conf *vid_conf,
					    unsigned slot,
					    pjmedia_vid_conf_port_info *info)
{
    vconf_port *cp;

    /* Check arguments */
    PJ_ASSERT_RETURN(vid_conf && slot<vid_conf->opt.max_slot_cnt, PJ_EINVAL);

    /* Lock mutex */
    pj_mutex_lock(vid_conf->mutex);

    /* Port must be valid. */
    cp = vid_conf->ports[slot];
    if (cp == NULL) {
	pj_mutex_unlock(vid_conf->mutex);
	return PJ_EINVAL;
    }

    info->slot = slot;
    info->name = cp->name;
    pjmedia_format_copy(&info->format, &cp->port->info.fmt);
    info->listener_cnt = cp->listener_cnt;
    info->listener_slots = cp->listener_slots;
    info->transmitter_cnt = cp->transmitter_cnt;
    info->transmitter_slots = cp->transmitter_slots;

    /* Unlock mutex */
    pj_mutex_unlock(vid_conf->mutex);

    return PJ_SUCCESS;
}


/*
 * Enable unidirectional video flow from the specified source slot to
 * the specified sink slot.
 */
PJ_DEF(pj_status_t) pjmedia_vid_conf_connect_port(
					    pjmedia_vid_conf *vid_conf,
					    unsigned src_slot,
					    unsigned sink_slot,
					    void *opt)
{
    vconf_port *src_port, *dst_port;
    unsigned i;

    /* Check arguments */
    PJ_ASSERT_RETURN(vid_conf &&
		     src_slot<vid_conf->opt.max_slot_cnt && 
		     sink_slot<vid_conf->opt.max_slot_cnt, PJ_EINVAL);
    PJ_UNUSED_ARG(opt);

    pj_mutex_lock(vid_conf->mutex);

    /* Ports must be valid. */
    src_port = vid_conf->ports[src_slot];
    dst_port = vid_conf->ports[sink_slot];
    if (!src_port || !src_port->port->get_frame ||
	!dst_port || !dst_port->port->put_frame)
    {
	PJ_LOG(4,(THIS_FILE,"Failed connecting video ports, make sure that "
			    "source has get_frame() & sink has put_frame()"));
	pj_mutex_unlock(vid_conf->mutex);
	return PJ_EINVAL;
    }

    /* Check if connection has been made */
    for (i=0; i<src_port->listener_cnt; ++i) {
	if (src_port->listener_slots[i] == sink_slot)
	    break;
    }

    if (i == src_port->listener_cnt) {
	src_port->listener_slots[src_port->listener_cnt] = sink_slot;
	dst_port->transmitter_slots[dst_port->transmitter_cnt] = src_slot;
	++src_port->listener_cnt;
	++dst_port->transmitter_cnt;

	update_render_state(vid_conf, dst_port);

	++vid_conf->connect_cnt;
	if (vid_conf->connect_cnt == 1) {
	    pj_status_t status;
	    status = pjmedia_clock_start(vid_conf->clock);
	    if (status != PJ_SUCCESS) {
		PJ_PERROR(4, (THIS_FILE, status, "Failed to start clock"));
		return status;
	    }
	}

	PJ_LOG(4,(THIS_FILE,"Port %d (%.*s) transmitting to port %d (%.*s)",
		  src_slot,
		  (int)src_port->name.slen,
		  src_port->name.ptr,
		  sink_slot,
		  (int)dst_port->name.slen,
		  dst_port->name.ptr));
    }

    pj_mutex_unlock(vid_conf->mutex);

    return PJ_SUCCESS;
}


/*
 * Disconnect unidirectional video flow from the specified source to
 * the specified sink slot.
 */
PJ_DEF(pj_status_t) pjmedia_vid_conf_disconnect_port(
					    pjmedia_vid_conf *vid_conf,
					    unsigned src_slot,
					    unsigned sink_slot)
{
    vconf_port *src_port, *dst_port;
    unsigned i, j;

    /* Check arguments */
    PJ_ASSERT_RETURN(vid_conf &&
		     src_slot<vid_conf->opt.max_slot_cnt && 
		     sink_slot<vid_conf->opt.max_slot_cnt, PJ_EINVAL);

    pj_mutex_lock(vid_conf->mutex);

    /* Ports must be valid. */
    src_port = vid_conf->ports[src_slot];
    dst_port = vid_conf->ports[sink_slot];
    if (!src_port || !dst_port) {
	pj_mutex_unlock(vid_conf->mutex);
	return PJ_EINVAL;
    }

    /* Check if connection has been made */
    for (i=0; i<src_port->listener_cnt; ++i) {
	if (src_port->listener_slots[i] == sink_slot)
	    break;
    }
    for (j=0; j<dst_port->transmitter_cnt; ++j) {
	if (dst_port->transmitter_slots[j] == src_slot)
	    break;
    }

    if (i != src_port->listener_cnt) {
	unsigned k;

	pj_assert(j != dst_port->transmitter_cnt);
	pj_assert(src_port->listener_cnt > 0 && 
		  src_port->listener_cnt < vid_conf->opt.max_slot_cnt);
	pj_assert(dst_port->transmitter_cnt > 0 && 
		  dst_port->transmitter_cnt < vid_conf->opt.max_slot_cnt);

	/* Cleanup all render states of the sink */
	for (k=0; k<dst_port->transmitter_cnt; ++k)
	    cleanup_render_state(dst_port, k);

	/* Update listeners array of the source and transmitters array of
	 * the sink.
	 */
	pj_array_erase(src_port->listener_slots, sizeof(unsigned), 
		       src_port->listener_cnt, i);
	pj_array_erase(dst_port->transmitter_slots, sizeof(unsigned), 
		       dst_port->transmitter_cnt, j);
	--src_port->listener_cnt;
	--dst_port->transmitter_cnt;

	/* Update render states of the sink */
	update_render_state(vid_conf, dst_port);

	--vid_conf->connect_cnt;

	if (AUTO_STOP_CLOCK && vid_conf->connect_cnt == 0) {
	    pj_status_t status;
	    /* Warning: will stuck if this is called from the clock thread */
	    status = pjmedia_clock_stop(vid_conf->clock);
	    if (status != PJ_SUCCESS) {
		PJ_PERROR(4, (THIS_FILE, status, "Failed to stop clock"));
		return status;
	    }
	}

	PJ_LOG(4,(THIS_FILE,
		  "Port %d (%.*s) stop transmitting to port %d (%.*s)",
		  src_slot,
		  (int)src_port->name.slen,
		  src_port->name.ptr,
		  sink_slot,
		  (int)dst_port->name.slen,
		  dst_port->name.ptr));
    }

    pj_mutex_unlock(vid_conf->mutex);

    return PJ_SUCCESS;
}


/*
 * Internal functions.
 */

static void on_clock_tick(const pj_timestamp *now, void *user_data)
{
    pjmedia_vid_conf *vid_conf = (pjmedia_vid_conf*)user_data;
    unsigned ci, i;
    pj_int32_t ts_diff;
    pjmedia_frame frame;
    pj_status_t status;

    pj_mutex_lock(vid_conf->mutex);

    /* Iterate all (sink) ports */
    for (i=0, ci=0; i<vid_conf->opt.max_slot_cnt &&
		    ci<vid_conf->port_cnt; ++i)
    {
	unsigned j;
	pj_bool_t got_frame = PJ_FALSE;
	pj_bool_t ts_incremented = PJ_FALSE;
	vconf_port *sink = vid_conf->ports[i];

	/* Skip empty port */
	if (!sink)
	    continue;

	/* Increment occupied port counter */
	++ci;

	/* Skip non-sink port */
	if (!sink->port->put_frame)
	    continue;

	if (sink->ts_next.u64 == 0)
	    sink->ts_next = *now;

	/* Skip if too early for put_frame(), note:
	 * early = (now < ts_next)
	 * But careful for timestamp wrapped around.
	 */
	ts_diff = pj_timestamp_diff32(&sink->ts_next, now);
	if (ts_diff < 0 || ts_diff > TS_CLOCK_RATE)
	    continue;

	/* Clean up sink put buffer (should we draw black instead?) */
	//pj_bzero(sink->put_buf, sink->put_buf_size);

	/* Iterate transmitters of this sink port */
	for (j=0; j < sink->transmitter_cnt; ++j) {
	    vconf_port *src = vid_conf->ports[sink->transmitter_slots[j]];
	    pj_int32_t src_ts_diff;

	    if (src->ts_next.u64 == 0)
		src->ts_next = *now;

	    /* Is it time for src->get_frame()? yes, if (now >= ts_next) */
	    src_ts_diff = pj_timestamp_diff32(&src->ts_next, now);
	    if (src_ts_diff >= 0) {

		/* Call src->get_frame().
		 * Possible optimization: if this src only has one listener,
		 * perhaps we can skip this src buffer and directly render it
		 * to sink buffer (but still need buffer if conversion any).
		 */
		pj_bzero(&frame, sizeof(frame));
		frame.type = PJMEDIA_FRAME_TYPE_VIDEO;
		frame.timestamp = *now;
		frame.buf = src->get_buf;
		frame.size = src->get_buf_size;
		status = pjmedia_port_get_frame(src->port, &frame);
		if (status != PJ_SUCCESS) {
		    PJ_PERROR(5, (THIS_FILE, status,
				  "Failed to get frame from port [%s]!",
				  src->port->info.name.ptr));
		}

		/* Update next src put/get */
		pj_add_timestamp32(&src->ts_next, src->ts_interval);
		ts_incremented = src==sink;
	    }

	    /* Render src get buffer to sink put buffer (based on sink layout
	     * settings, if any)
	     */
	    status = render_src_frame(src, sink, j);
	    if (status != PJ_SUCCESS) {
		PJ_PERROR(5, (THIS_FILE, status,
			      "Failed to render frame from port [%s] to [%s]",
			      src->port->info.name.ptr,
			      sink->port->info.name.ptr));
	    }

	    got_frame = PJ_TRUE;
	}

	/* Call sink->put_frame()
	 * Note that if transmitter_cnt==0, we should still call put_frame()
	 * with zero frame size, as sink may need to send keep-alive packets
	 * and get timestamp update.
	 */
	pj_bzero(&frame, sizeof(frame));
	frame.type = PJMEDIA_FRAME_TYPE_VIDEO;
	frame.timestamp = *now;
	if (got_frame) {
	    frame.buf = sink->put_buf;
	    frame.size = sink->put_buf_size;
	}
	status = pjmedia_port_put_frame(sink->port, &frame);
	if (status != PJ_SUCCESS) {
	    PJ_PERROR(5, (THIS_FILE, status,
			  "Failed to put frame to port [%s]!",
			  sink->port->info.name.ptr));
	}

	/* Update next put/get, careful that it may have been updated
	 * if this port transmits to itself!
	 */
	if (!ts_incremented) {
	    pj_add_timestamp32(&sink->ts_next, sink->ts_interval);
	}
    }

    pj_mutex_unlock(vid_conf->mutex);
}

static pj_bool_t is_landscape(const pjmedia_rect_size *size) {
    return (size->w >= size->h);
}

/* Adjust a frame size to match ratio specified in the ref_size.
 * Either dimension of the frame may be cropped (but will never be
 * expanded).
 */
static void match_ratio_crop(pjmedia_rect_size *size,
			     const pjmedia_rect_size *ref_size)
{
    pjmedia_rect_size res;

    /* Try match width first */
    res.w = size->w;
    res.h = ref_size->h * size->w / ref_size->w;
    
    /* If original height turns out to be shorther, match height */
    if (size->h < res.h) {
	res.w = ref_size->w * size->h / ref_size->h;
	res.h = size->h;
    }

    *size = res;
    return;
}

/* Cleanup rendering states, called when a transmitter is disconnected
 * from a listener, or before reinit-ing rendering state of a listener
 * when new connection has just been made.
 */
static void cleanup_render_state(vconf_port *cp,
				 unsigned transmitter_idx)
{
    render_state *rs = cp->render_states[transmitter_idx];
    if (rs && rs->converter)
    {
	pjmedia_converter_destroy(rs->converter);
	rs->converter = NULL;
    }
    cp->render_states[transmitter_idx] = NULL;

    if (cp->render_pool[transmitter_idx]) {
	pj_pool_safe_release(&cp->render_pool[transmitter_idx]);

	TRACE_((THIS_FILE, "Cleaned up render state for connection %d->%d",
		cp->transmitter_slots[transmitter_idx], cp->idx));
    }
}

/* This function will do:
 * - Recalculate layout setting, i.e: get video pos and size
 *   for each transmitter
 * - Check if converter is needed and setup it.
 * - Those above things will be stored in render_state and
 *   will be used by render_src_frame()
 */
static void update_render_state(pjmedia_vid_conf *vid_conf, vconf_port *cp)
{
    pjmedia_format_id fmt_id, tr_fmt_id[4];
    pjmedia_rect_size size, tr_size[4];
    unsigned i;
    pj_status_t status;

    /* Nothing to render, just return */
    if (cp->transmitter_cnt == 0)
	return;

    TRACE_((THIS_FILE, "Updating render state for port id %d (%d sources)..",
	    cp->idx, cp->transmitter_cnt));

    fmt_id = cp->port->info.fmt.id;
    size   = cp->port->info.fmt.det.vid.size;
    for (i = 0; i < cp->transmitter_cnt; ++i) {
	vconf_port *tr = vid_conf->ports[cp->transmitter_slots[i]];

	/* Cleanup render states & pool */
	cleanup_render_state(cp, i);

	/* Gather format ID, size of each transmitter */
	tr_fmt_id[i] = tr->port->info.fmt.id;
	tr_size[i]   = tr->port->info.fmt.det.vid.size;
    }

    /* If only one transmitter and it has matched format & size, just use
     * plain memcpy(). Usually preview window or call stream window will
     * have matched format & size with its source.
     */
    if (cp->transmitter_cnt == 1 && fmt_id == tr_fmt_id[0] &&
	pj_memcmp(&size, &tr_size[0], sizeof(size))==0)
    {
	TRACE_((THIS_FILE, "This port only has single source with "
			   "matched format & size, no conversion needed"));
	return;
    }

    for (i = 0; i < cp->transmitter_cnt && i < 4; ++i) {
	pj_pool_t *pool;
	render_state *rs;
	pjmedia_conversion_param cparam;
	char tmp_buf[32];

	/* Create pool & render state */
	pj_ansi_snprintf(tmp_buf, sizeof(tmp_buf), "vcport_rs_%d->%d",
			 cp->transmitter_slots[i], cp->idx);
	pool = pj_pool_create(cp->pool->factory, tmp_buf, 128, 128, NULL);
	cp->render_pool[i] = pool;
	rs = cp->render_states[i] = PJ_POOL_ZALLOC_T(pool, render_state);

	TRACE_((THIS_FILE, "Created render state for connection %d->%d",
			   cp->transmitter_slots[i], cp->idx));

	/* Setup format & frame */
	rs->src_fmt_id = tr_fmt_id[i];
	rs->dst_fmt_id = fmt_id;
	rs->src_frame_size = tr_size[i];
	rs->dst_frame_size = size;

	/* For now, draw the whole source frame, will adjust ratio later */
	rs->src_rect.coord.x = rs->src_rect.coord.y = 0;
	rs->src_rect.size = tr_size[i];

	/* Setup layout */
	if (cp->transmitter_cnt == 1) {
	    rs->dst_rect.coord.x = rs->dst_rect.coord.y = 0;
	    rs->dst_rect.size = size;
	} else if (cp->transmitter_cnt == 2) {
	    if (is_landscape(&size)) {
		/*
		 *          |
		 * Source 0 | Source 1
		 *          |
		 */
		rs->dst_rect.coord.x = i * (size.w/2);
		rs->dst_rect.coord.y = 0;
		rs->dst_rect.size.w = size.w / 2;
		rs->dst_rect.size.h = size.h;
	    } else {
		/*
		 * Source 0
		 * --------
		 * Source 1
		 */
		rs->dst_rect.coord.x = 0;
		rs->dst_rect.coord.y = i * (size.h/2);
		rs->dst_rect.size.w = size.w;
		rs->dst_rect.size.h = size.h / 2;
	    }
	} else if (cp->transmitter_cnt == 3) {
	    if (is_landscape(&size)) {
		/*
		 *          | Source 1
		 * Source 0 |---------
		 *          | Source 2
		 */
		rs->dst_rect.coord.x = (i==0)? 0 : size.w/2;
		rs->dst_rect.coord.y = (i!=2)? 0 : size.h/2;
		rs->dst_rect.size.w = size.w / 2;
		rs->dst_rect.size.h = (i==0)? size.h : size.h/2;
	    } else {
		/*
		 * Source 0
		 * --------
		 * Source 1
		 * --------
		 * Source 2
		 */
		rs->dst_rect.coord.x = 0;
		rs->dst_rect.coord.y = i * size.h/3;
		rs->dst_rect.size.w = size.w;
		rs->dst_rect.size.h = size.h/3;
	    }
	} else if (cp->transmitter_cnt == 4) {
	    if (is_landscape(&size)) {
		/*
		 * Source 0 | Source 1
		 * ---------|---------
		 * Source 2 | Source 3
		 */
		rs->dst_rect.coord.x = (i%2==0)? 0 : size.w/2;
		rs->dst_rect.coord.y = (i/2==0)? 0 : size.h/2;
		rs->dst_rect.size.w = size.w/2;
		rs->dst_rect.size.h = size.h/2;
	    } else {
		/*
		 * Source 0
		 * --------
		 * Source 1
		 * --------
		 * Source 2
		 * --------
		 * Source 3
		 */
		rs->dst_rect.coord.x = 0;
		rs->dst_rect.coord.y = i * size.h/4;
		rs->dst_rect.size.w = size.w;
		rs->dst_rect.size.h = size.h/4;
	    }
	}

	/* Adjust source size to match aspect ratio of rendering space. */
	match_ratio_crop(&rs->src_rect.size, &rs->dst_rect.size);

	/* Now adjust source position after source size adjustment. */
	if (rs->src_rect.size.w < tr_size[i].w)
	    rs->src_rect.coord.x = (tr_size[i].w - rs->src_rect.size.w)/2;
	if (rs->src_rect.size.h < tr_size[i].h)
	    rs->src_rect.coord.y = (tr_size[i].h - rs->src_rect.size.h)/2;

	TRACE_((THIS_FILE, "src#%d=%s/%dx%d->%dx%d@%d,%d dst=%dx%d@%d,%d",
			   i, pjmedia_fourcc_name(tr_fmt_id[i], tmp_buf),
			   tr_size[i].w, tr_size[i].h,
			   rs->src_rect.size.w, rs->src_rect.size.h,
			   rs->src_rect.coord.x, rs->src_rect.coord.y,
			   rs->dst_rect.size.w, rs->dst_rect.size.h,
			   rs->dst_rect.coord.x, rs->dst_rect.coord.y));

	/* Create converter */
	pjmedia_format_init_video(&cparam.src, rs->src_fmt_id,
				  rs->src_rect.size.w,
				  rs->src_rect.size.h,
				  0, 1);
	pjmedia_format_init_video(&cparam.dst, rs->dst_fmt_id,
				  rs->dst_rect.size.w,
				  rs->dst_rect.size.h,
				  0, 1);
	status = pjmedia_converter_create(NULL, pool, &cparam,
					  &rs->converter);
	if (status != PJ_SUCCESS) {
	    PJ_PERROR(4,(THIS_FILE, status,
			 "Port %d failed creating converter "
			 "for source %d", cp->idx, i));
	}
    }
}

/* Render frame from source to sink buffer based on rendering settings. */
static pj_status_t render_src_frame(vconf_port *src, vconf_port *sink,
				    unsigned transmitter_idx)
{
    pj_status_t status;
    render_state *rs = sink->render_states[transmitter_idx];

    if (sink->transmitter_cnt == 1 && (!rs || !rs->converter)) {
	/* The only transmitter and no conversion needed */
	pj_assert(src->get_buf_size <= sink->put_buf_size);
	pj_memcpy(sink->put_buf, src->get_buf, src->get_buf_size);
    } else if (rs && rs->converter) {
	pjmedia_frame src_frame, dst_frame;
	
	pj_bzero(&src_frame, sizeof(src_frame));
	src_frame.buf = src->get_buf;
	src_frame.size = src->get_buf_size;

	pj_bzero(&dst_frame, sizeof(dst_frame));
	dst_frame.buf = sink->put_buf;
	dst_frame.size = sink->put_buf_size;

	status = pjmedia_converter_convert2(rs->converter,
					    &src_frame,
					    &rs->src_frame_size,
					    &rs->src_rect.coord,
					    &dst_frame,
					    &rs->dst_frame_size,
					    &rs->dst_rect.coord,
					    NULL);
	if (status != PJ_SUCCESS) {
	    PJ_PERROR(4,(THIS_FILE, status,
			 "Port id %d: converter failed in "
			 "rendering frame from port id %d",
			 sink->idx, transmitter_idx));
	    return status;
	}
    }

    return PJ_SUCCESS;
}


#endif /* PJMEDIA_HAS_VIDEO */