source: roaraudio/libroar/vs.c @ 5073:f9b421aec994

//vs.c:

/*
 *      Copyright (C) Philipp 'ph3-der-loewe' Schafft - 2010-2011
 *
 *  This file is part of libroar a part of RoarAudio,
 *  a cross-platform sound system for both, home and professional use.
 *  See README for details.
 *
 *  This file is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 3
 *  as published by the Free Software Foundation.
 *
 *  libroar 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 software; see the file COPYING.  If not, write to
 *  the Free Software Foundation, 51 Franklin Street, Fifth Floor,
 *  Boston, MA 02110-1301, USA.
 *
 *  NOTE for everyone want's to change something and send patches:
 *  read README and HACKING! There a addition information on
 *  the license of this document you need to read before you send
 *  any patches.
 *
 *  NOTE for uses of non-GPL (LGPL,...) software using libesd, libartsc
 *  or libpulse*:
 *  The libs libroaresd, libroararts and libroarpulse link this lib
 *  and are therefore GPL. Because of this it may be illigal to use
 *  them with any software that uses libesd, libartsc or libpulse*.
 */

#include "libroar.h"

#if defined(ROAR_HAVE_GETSOCKOPT) && defined(ROAR_HAVE_SETSOCKOPT)
#define _HAVE_SOCKOPT
#endif

#define LOCAL_CLOCK    ROAR_CLOCK_DEFAULT
#define ASYNC_QLEN     4

#define FLAG_NONE      0x0000
#define FLAG_STREAM    0x0001
#define FLAG_NONBLOCK  0x0002
#define FLAG_BUFFERED  0x0004
#define FLAG_CLOSEFILE 0x0008
#define FLAG_FREE_VOL  0x0010
#define FLAG_DEF_PAUSE 0x0020
#define FLAG_ASYNC     0x0040
#define FLAG_DIR_IN    0x1000
#define FLAG_DIR_OUT   0x2000

#define _initerr()  roar_err_clear_all()
#define _seterr(x)  do { if ( error != NULL ) *error = (x); roar_err_set((x)); ROAR_DBG("roar_vs_*(*): *error=%s(%i)", roar_vs_strerr((x)), (x)); } while(0)
#define _seterrre() do { _seterr(roar_error); } while(0)
#define _seterrse() do { roar_err_from_errno(); _seterr(roar_error); } while(0)
#define _ckvss(ret) do { if ( vss == NULL ) { _seterr(ROAR_ERROR_INVAL); return (ret); } } while(0)
#define _ckasync(ret) do { if ( _handle_async(vss, error) == -1 ) { return (ret); } } while(0);

struct roar_vs {
 int flags;
 struct roar_connection con_store;
 struct roar_connection * con;
 struct roar_stream       stream;
 struct roar_vio_calls    vio;
 struct roar_audio_info   info;
 size_t                   readc, writec;
 int                      mixerid;
 int                      first_primid;
 struct roar_buffer     * readbuffer, * writebuffer;
 struct roar_vio_calls    file_store;
 struct roar_vio_calls  * file;
 struct roar_buffer     * readring, * writering;
#ifdef _HAVE_SOCKOPT
 struct {
  float target;
  float window;
  float minlag;
  float p;
 } latc;
#endif
 struct {
  ssize_t last_pos;
  ssize_t last_offset;
  struct roar_time last_time;
 } latmes;
 struct {
  size_t lock;
  size_t qlen;
  int qcmd[ASYNC_QLEN];
  int qsubcmd[ASYNC_QLEN];
 } async;
};

static int _roar_vs_find_first_prim(roar_vs_t * vss);

static int _handle_async_req(roar_vs_t * vss, int * error) {
 struct roar_message mes;
 char * data = NULL;
 uint16_t * ud16 = (uint16_t *) mes.data;
 ssize_t offset;
 int cmd, subcmd;
 int i;

 if ( roar_recv_message(vss->con, &mes, &data) == -1 ) {
  _seterrre();
 }

 cmd    = vss->async.qcmd[0];
 subcmd = vss->async.qsubcmd[0];
 vss->async.qlen--;

 for (i = 1; i < ASYNC_QLEN; i++) {
  vss->async.qcmd[i-1]    = vss->async.qcmd[i];
  vss->async.qsubcmd[i-1] = vss->async.qsubcmd[i];
 }

 if ( mes.cmd == ROAR_CMD_OK ) {
  switch (cmd) {
   case ROAR_CMD_GET_STREAM_PARA:
     if ( subcmd == ROAR_STREAM_PARA_INFO ) {
      if ( mes.datalen >= 16 ) {
       for (i = 0; i < mes.datalen/2; i++) {
        ud16[i] = ROAR_HOST2NET16(ud16[i]);
       }
       if ( ud16[0] == 0 || ud16[1] == 1 ) {
        offset  = ud16[7];
        offset *= 1000;
        offset *= vss->info.rate;
        offset /= 1000000;
        vss->latmes.last_offset = offset;
       }
      }
     } else {
      ROAR_WARN("_handle_async_req(vss=%p, error=%p): Got unexpected reply for command GET_STREAM_PARA, subcommand", vss, error, subcmd);
     }
    break;
   case ROAR_CMD_GET_STREAM:
     vss->latmes.last_offset = mes.pos; // ha, this is a easy one ;)
    break;
   default:
     ROAR_WARN("_handle_async_req(vss=%p, error=%p): Got unexpected reply for command %i", vss, error, cmd);
    break;
  }
 }

 if ( data != NULL )
  free(data);

 _seterr(ROAR_ERROR_NOSYS);
 return -1;
}

static inline int _handle_async(roar_vs_t * vss, int * error) {
 while (vss->async.qlen) {
  if ( _handle_async_req(vss, error) == -1 ) {
   return -1;
  }
 }

 return 0;
}

const char * roar_vs_strerr(int error) {
 const char * ret = roar_error2str(error);

 if ( ret == NULL )
  return "(unknown)";

 return ret;
}

static roar_vs_t * roar_vs_init(int * error) {
 roar_vs_t * vss = roar_mm_malloc(sizeof(roar_vs_t));

 if ( vss == NULL ) {
  _seterrse();
  return NULL;
 }

 memset(vss, 0, sizeof(roar_vs_t));

 vss->mixerid      = -1;
 vss->first_primid = -1;

#ifdef _HAVE_SOCKOPT
 vss->latc.target = -2.; // must be less than latc.minlag!
 vss->latc.window = -1.;
 vss->latc.minlag = -1.;
 vss->latc.p      =  0.005;
#endif

 vss->latmes.last_pos = -1;

 return vss;
}

roar_vs_t * roar_vs_new_from_con(struct roar_connection * con, int * error) {
 roar_vs_t * vss = roar_vs_init(error);

 if ( vss == NULL )
  return NULL;

 vss->con = con;

 return vss;
}

roar_vs_t * roar_vs_new(const char * server, const char * name, int * error) {
 roar_vs_t * vss = roar_vs_init(error);
 int ret;

 if ( vss == NULL )
  return NULL;

 vss->con = &(vss->con_store);

 _initerr();

 ret = roar_simple_connect(vss->con, (char*)server, (char*)name);

 if ( ret == -1 ) {
  roar_vs_close(vss, ROAR_VS_TRUE, NULL);
  _seterrre();
  return NULL;
 }

 return vss;
}

int roar_vs_stream(roar_vs_t * vss, const struct roar_audio_info * info, int dir, int * error) {
 struct roar_stream_info sinfo;
 int ret;

 _ckvss(-1);

 if ( vss->flags & FLAG_STREAM ) {
  _seterr(ROAR_ERROR_INVAL);
  return -1;
 }

 if ( dir == ROAR_DIR_FILTER )
  vss->flags |= FLAG_DEF_PAUSE;

 _initerr();

 if ( info != &(vss->info) )
  memcpy(&(vss->info), info, sizeof(struct roar_audio_info));

 ret = roar_vio_simple_new_stream_obj(&(vss->vio), vss->con, &(vss->stream),
                                      info->rate, info->channels, info->bits, info->codec,
                                      dir
                                     );

 if ( ret == -1 ) {
  _seterrre();
  return -1;
 }

 if ( roar_stream_get_info(vss->con, &(vss->stream), &sinfo) != -1 ) {
  // TODO: fix this:
  // as we currently do not support to select mixer we just check if we hit the
  // right one.
  if ( vss->mixerid != -1 && vss->mixerid != sinfo.mixer ) {
   _seterr(ROAR_ERROR_INVAL); // TODO: should we maybe use a diffrent value?
   roar_vio_close(&(vss->vio));
   return -1;
  }

  vss->mixerid = sinfo.mixer;
  _roar_vs_find_first_prim(vss);
 }

 vss->flags |= FLAG_STREAM;

 switch (dir) {
  case ROAR_DIR_PLAY: vss->flags |= FLAG_DIR_OUT; break;
 }

 return 0;
}

roar_vs_t * roar_vs_new_simple(const char * server, const char * name, int rate, int channels, int codec, int bits, int dir, int * error) {
 roar_vs_t * vss = roar_vs_new(server, name, error);
 int ret;

 if (vss == NULL)
  return NULL;

 memset(&(vss->info), 0, sizeof(vss->info));

 vss->info.rate     = rate;
 vss->info.channels = channels;
 vss->info.codec    = codec;
 vss->info.bits     = bits;

 ret = roar_vs_stream(vss, &(vss->info), dir, error);

 if (ret == -1) {
  roar_vs_close(vss, ROAR_VS_TRUE, NULL);
  return NULL;
 }

 return vss;
}

int roar_vs_file(roar_vs_t * vss, struct roar_vio_calls * vio, int closefile, int * error) {
 _ckvss(-1);

 if ( vio == NULL || (closefile != ROAR_VS_TRUE && closefile != ROAR_VS_FALSE)) {
  _seterr(ROAR_ERROR_INVAL);
  return -1;
 }

 if ( vss->file != NULL ) {
  _seterr(ROAR_ERROR_INVAL);
  return -1;
 }

 vss->file = vio;
 if ( closefile == ROAR_VS_TRUE )
  vss->flags |= FLAG_CLOSEFILE;

 return 0;
}

int roar_vs_file_simple(roar_vs_t * vss, char * filename, int * error) {
 struct roar_vio_defaults def;
 struct roar_vio_calls * file;
 char buf[64];
 ssize_t ret;
 int dir = O_RDONLY;
 int codec = -1;
 const char * content_type;

 _ckvss(-1);

 if ( vss->file != NULL ) {
  _seterr(ROAR_ERROR_INVAL);
  return -1;
 }

 if ( vss->flags & FLAG_STREAM ) {
  switch (vss->flags & (FLAG_DIR_IN|FLAG_DIR_OUT)) {
   case FLAG_DIR_IN:  dir = O_WRONLY; break;
   case FLAG_DIR_OUT: dir = O_RDONLY; break;
   case FLAG_DIR_IN|FLAG_DIR_OUT: dir = O_RDWR; break;
   default:
     _seterr(ROAR_ERROR_INVAL);
     return -1;
  }
 }

 file = &(vss->file_store);

 _initerr();

 if ( roar_vio_dstr_init_defaults(&def, ROAR_VIO_DEF_TYPE_NONE, dir, 0644) == -1 ) {
  _seterrre();
  return -1;
 }

 if ( roar_vio_open_dstr(file, filename, &def, 1) == -1 ) {
  _seterrre();
  return -1;
 }

 if ( !(vss->flags & FLAG_STREAM) ) {
  if ( roar_vio_ctl(file, ROAR_VIO_CTL_GET_MIMETYPE, &content_type) != -1 ) {
   codec = roar_mime2codec(content_type);
  }

  if ( codec == -1 ) {
   ret = roar_vio_read(file, buf, sizeof(buf));

   codec = roar_file_codecdetect(buf, ret);

   if ( codec == -1 ) {
    roar_vio_close(file);
    _seterr(ROAR_ERROR_INVAL); // Other value?
    return -1;
   }

   if ( roar_vio_lseek(file, 0, SEEK_SET) != 0 ) {
    roar_vio_close(file);
   _seterrre();
    return -1;
   }
  }

  memset(&(vss->info), 0, sizeof(vss->info));

  vss->info.rate     = ROAR_RATE_DEFAULT;
  vss->info.channels = ROAR_CHANNELS_DEFAULT;
  vss->info.codec    = codec;
  vss->info.bits     = ROAR_BITS_DEFAULT;

  ret = roar_vs_stream(vss, &(vss->info), ROAR_DIR_PLAY, error);

  if ( ret == -1 ) {
   roar_vio_close(file);
   return -1;
  }
 }

 if ( roar_vs_file(vss, file, ROAR_VS_TRUE, error) == -1 ) {
  roar_vio_close(file);
  return -1;
 }

 return 0;
}

roar_vs_t * roar_vs_new_from_file(const char * server, const char * name, char * filename, int * error) {
 roar_vs_t * vss = roar_vs_new(server, name, error);

 if ( vss == NULL )
  return NULL;

 if ( roar_vs_file_simple(vss, filename, error) != 0 ) {
  roar_vs_close(vss, ROAR_VS_TRUE, NULL);
  return NULL;
 }

 return vss;
}

int roar_vs_buffer(roar_vs_t * vss, size_t buffer, int * error) {
 _ckvss(-1);

 if ( vss->flags & FLAG_BUFFERED )
  return -1;

 if ( roar_buffer_ring_new(&(vss->readring), buffer, 0) == -1 ) {
  _seterrre();
  return -1;
 }

 if ( roar_buffer_ring_new(&(vss->writering), buffer, 0) == -1 ) {
  _seterrre();
  roar_buffer_free(vss->readring);
  vss->readring = NULL;
  return -1;
 }

 vss->flags |= FLAG_BUFFERED;

 return 0;
}

int roar_vs_close(roar_vs_t * vss, int killit, int * error) {
 if ( killit != ROAR_VS_TRUE && killit != ROAR_VS_FALSE ) {
  _seterr(ROAR_ERROR_INVAL);
  return -1;
 }

 _ckvss(-1);
 _ckasync(-1);

 if ( vss->readbuffer != NULL )
  roar_buffer_free(vss->readbuffer);
 if ( vss->writebuffer != NULL )
  roar_buffer_free(vss->writebuffer);

 if ( vss->readring != NULL )
  roar_buffer_free(vss->readring);
 if ( vss->writering != NULL )
  roar_buffer_free(vss->writering);

 if ( vss->file != NULL && vss->flags & FLAG_CLOSEFILE )
  roar_vio_close(vss->file);

 if ( vss->flags & FLAG_STREAM ) {
  if ( killit == ROAR_VS_TRUE ) {
   roar_kick(vss->con, ROAR_OT_STREAM, roar_stream_get_id(&(vss->stream)));
  }

  roar_vio_close(&(vss->vio));
 }

 if ( vss->con == &(vss->con_store) ) {
  roar_disconnect(vss->con);
 }

 roar_mm_free(vss);
 return 0;
}

static ssize_t roar_vs_write_direct(roar_vs_t * vss, const void * buf, size_t len, int * error) {
 ssize_t ret = roar_vio_write(&(vss->vio), (void*)buf, len);

 if ( ret == -1 ) {
#ifdef EAGAIN
  if ( roar_error == ROAR_ERROR_AGAIN )
   return 0;
#endif

  _seterrre();
 } else {
  if ( !(vss->flags & FLAG_BUFFERED) ) {
   //printf("A: vss->writec=%zu, ret=%zi\n", vss->writec, ret);
   vss->writec += ret;
  }
 }

 //printf("B: vss->writec=%zu, ret=%zi\n", vss->writec, ret);
 return ret;
}

ssize_t roar_vs_write(roar_vs_t * vss, const void * buf, size_t len, int * error) {
 ssize_t ret;
 size_t writelen;

 _ckvss(-1);

 if ( !(vss->flags & FLAG_STREAM) ) {
  _seterr(ROAR_ERROR_INVAL);
  return -1;
 }

 _initerr();

 if ( vss->flags & FLAG_BUFFERED ) {
  writelen = len;

  if ( roar_buffer_ring_write(vss->writering, (void*)buf, &writelen) == -1 ) {
   _seterrre();
   return -1;
  }

  ret = writelen;
  vss->writec += ret;
 } else {
  ret = roar_vs_write_direct(vss, buf, len, error);
 }

 return ret;
}

ssize_t roar_vs_read (roar_vs_t * vss,       void * buf, size_t len, int * error) {
 ssize_t ret;

 _ckvss(-1);

 if ( !(vss->flags & FLAG_STREAM) ) {
  _seterr(ROAR_ERROR_INVAL);
  return -1;
 }

 _initerr();

 ret = roar_vio_read(&(vss->vio), buf, len);

 if ( ret == -1 ) {
  _seterrre();
 } else {
  vss->readc += ret;
 }

 return ret;
}

int     roar_vs_sync (roar_vs_t * vss, int wait, int * error) {
 struct roar_event waits, triggered;

 _ckvss(-1);

 if ( !(vss->flags & FLAG_STREAM) ) {
  _seterr(ROAR_ERROR_INVAL);
  return -1;
 }

 if ( wait != ROAR_VS_NOWAIT && wait != ROAR_VS_WAIT ) {
  _seterr(ROAR_ERROR_INVAL);
  return -1;
 }

 _initerr();

 if ( roar_vio_sync(&(vss->vio)) == -1 ) {
  _seterrre();
  return -1;
 }

 if ( wait == ROAR_VS_WAIT ) {
  _ckasync(-1);

  memset(&waits, 0, sizeof(waits));
  waits.event       = ROAR_OE_STREAM_XRUN;
  waits.emitter     = -1;
  waits.target      = roar_stream_get_id(&(vss->stream));
  waits.target_type = ROAR_OT_STREAM;

  if ( roar_wait(vss->con, &triggered, &waits, 1) == -1 ) {
   _seterrre();
   return -1;
  }
 }

 return 0;
}

int     roar_vs_blocking (roar_vs_t * vss, int val, int * error) {
 int old = -1;

 _ckvss(-1);

  if ( !(vss->flags & FLAG_STREAM) ) {
  _seterr(ROAR_ERROR_INVAL);
  return -1;
 }

 old = vss->flags & FLAG_NONBLOCK ? ROAR_VS_FALSE : ROAR_VS_TRUE;

 _initerr();

 switch (val) {
  case ROAR_VS_TRUE:
    if ( roar_vio_nonblock(&(vss->vio), ROAR_SOCKET_BLOCK) == -1 ) {
     _seterrre();
     return -1;
    }
    vss->flags |= FLAG_NONBLOCK;
    vss->flags -= FLAG_NONBLOCK;
    return old;
   break;
  case ROAR_VS_FALSE:
    if ( roar_vio_nonblock(&(vss->vio), ROAR_SOCKET_NONBLOCK) == -1 ) {
     _seterrre();
     return -1;
    }
    vss->flags |= FLAG_NONBLOCK;
    return old;
   break;
  case ROAR_VS_TOGGLE:
    if ( old == ROAR_VS_TRUE ) {
     return roar_vs_blocking(vss, ROAR_VS_FALSE, error);
    } else {
     return roar_vs_blocking(vss, ROAR_VS_TRUE, error);
    }
   break;
  case ROAR_VS_ASK:
    return old;
   break;
 }

 _seterr(ROAR_ERROR_INVAL);
 return -1;
}

static int _roar_vs_find_first_prim(roar_vs_t * vss) {
 struct roar_stream stream;
 struct roar_stream_info info;
 int id[ROAR_STREAMS_MAX];
 int num;
 int i;
 int * error = NULL; // needed for _ckasync() macro

 _ckasync(-1);

 if ( vss->first_primid != -1 )
  return vss->first_primid;

 if ( vss->mixerid == -1 )
  return -1;

 if ( (num = roar_list_streams(vss->con, id, ROAR_STREAMS_MAX)) == -1 ) {
  return -1;
 }

 for (i = 0; i < num; i++) {
  if ( roar_get_stream(vss->con, &stream, id[i]) == -1 )
   continue;

  if ( stream.dir != ROAR_DIR_OUTPUT )
   continue;

  if ( roar_stream_get_info(vss->con, &stream, &info) == -1 )
   continue;

  if ( info.mixer == vss->mixerid ) {
   vss->first_primid = id[i];
   return id[i];
  }
 }

 return -1;
}

ssize_t roar_vs_position(roar_vs_t * vss, int backend, int * error) {
 struct roar_stream stream;
 struct roar_stream      out_stream;
 struct roar_stream_info out_info;
 size_t offset = 0;

 _ckvss(-1);
 _ckasync(-1);

 if ( !(vss->flags & FLAG_STREAM) ) {
  _seterr(ROAR_ERROR_INVAL);
  return -1;
 }

 _initerr();

 if ( roar_get_stream(vss->con, &stream, roar_stream_get_id(&(vss->stream))) == -1 ) {
  _seterrre();
  return -1;
 }

 if ( backend == ROAR_VS_BACKEND_DEFAULT ) {
  backend = ROAR_VS_BACKEND_FIRST;
 }

 switch (backend) {
  case ROAR_VS_BACKEND_NONE:
//    return stream.pos;
    // do nothing.
   break;
  case ROAR_VS_BACKEND_FIRST:
    if ( vss->first_primid == -1 ) {
     _seterr(ROAR_ERROR_UNKNOWN);
     return -1;
    }

    backend = vss->first_primid;
   break;
  default:
    if ( backend < 0 ) {
     _seterr(ROAR_ERROR_INVAL);
     return -1;
    }
   break;
 }


 if ( backend >= 0 ) {
  roar_stream_new_by_id(&out_stream, backend);

  if ( roar_stream_get_info(vss->con, &out_stream, &out_info) == -1 ) {
   _seterrre();
   return -1;
  }

  offset  = out_info.delay * vss->info.rate;
  offset /= 1000000;
 }

 if ( roar_clock_gettime(&(vss->latmes.last_time), LOCAL_CLOCK) == -1 ) {
  vss->latmes.last_pos = -1;
 } else {
  vss->latmes.last_pos    = stream.pos;
  vss->latmes.last_offset = offset;
 }

 return stream.pos + offset;
}

#ifdef _HAVE_SOCKOPT
static void roar_vs_latency_managed(roar_vs_t * vss, roar_mus_t lat) {
 struct roar_vio_sysio_sockopt sockopt;
 float tmp = ((float)lat/1000.0) - vss->latc.target;
 int val;

 tmp *= vss->latc.p;

 sockopt.level   = SOL_SOCKET;
 sockopt.optname = SO_SNDBUF;
 sockopt.optval  = &val;
 sockopt.optlen  = sizeof(val);

 roar_vio_ctl(&(vss->vio), ROAR_VIO_CTL_GET_SYSIO_SOCKOPT, &sockopt);

 val /= 2;

 tmp = 1.0 - tmp;

 val = (float)val*tmp;

 sockopt.optlen  = sizeof(val);

 roar_vio_ctl(&(vss->vio), ROAR_VIO_CTL_SET_SYSIO_SOCKOPT, &sockopt);
}
#endif

roar_mus_t roar_vs_latency(roar_vs_t * vss, int backend, int * error) {
 ssize_t pos  = roar_vs_position(vss, backend, error);
 ssize_t bps;  // byte per sample
 size_t  lioc; // local IO (byte) counter
 size_t  lpos; // local possition
 signed long long int lag;

// printf("pos=%zi\n", pos);

 _initerr();

 _ckvss(0);
 _ckasync(-1);

 if (pos == -1) {
  _seterrre();
  return 0;
 }

 if ( !(vss->flags & FLAG_STREAM) ) {
  _seterr(ROAR_ERROR_INVAL);
  return 0;
 }

 if ( vss->writec == 0 ) {
  lioc = vss->readc;
 } else {
  //printf("writec=%zu\n", vss->writec);
  lioc = vss->writec;
 }

 bps = roar_info2samplesize(&(vss->info));

 if ( bps == -1 ) {
  _seterrre();
  return 0;
 }

 lpos = (lioc*8) / bps;

 //printf("pos=%zi, lpos=%zi, bps=%zi, diff[lpos-pos]=%zi\n", pos, lpos, bps, (lpos - pos));

 lag = (signed long long int)lpos - (signed long long int)pos;
 lag /= vss->info.channels;

 // we now have the lag in frames
 // return value are mus
 // so we need to multiply with 1s/mus and
 // multiply by 1/rate

 lag *= 1000000; // 1s/mus
 lag /= vss->info.rate;

 if ( lag == 0 ) {
  _seterr(ROAR_ERROR_NONE);
 }

#ifdef _HAVE_SOCKOPT
 if (vss->latc.target > vss->latc.minlag) {
  roar_vs_latency_managed(vss, lag);
 }
#endif

 return lag;
}

roar_mus_t roar_vs_latency2(roar_vs_t * vss, int backend, int wait, int * error) {
 ssize_t bps;  // byte per sample
 size_t  lioc; // local IO (byte) counter
 size_t  lpos; // local possition
 signed long long int lag;
 struct roar_time rt;

 _initerr();

 _ckvss(0);

 if ( !(vss->flags & FLAG_STREAM) ) {
  _seterr(ROAR_ERROR_INVAL);
  return 0;
 }

 if ( wait == ROAR_VS_WAIT ) {
  return roar_vs_latency(vss, backend, error);
 } else if ( wait == ROAR_VS_NOWAIT ) {
  if ( vss->latmes.last_pos == -1 ) {
   _seterr(ROAR_ERROR_NODATA);
   return 0;
  }

  if ( vss->writec == 0 ) {
   lioc = vss->readc;
  } else {
   //printf("writec=%zu\n", vss->writec);
   lioc = vss->writec;
  }

  bps = roar_info2samplesize(&(vss->info));

  if ( bps == -1 ) {
   _seterrre();
   return 0;
  }

  lpos = (lioc*8) / bps;

  //printf("pos=%zi, lpos=%zi, bps=%zi, diff[lpos-pos]=%zi\n", pos, lpos, bps, (lpos - pos));

  lag = (signed long long int)lpos - (signed long long int)(vss->latmes.last_pos + vss->latmes.last_offset);
  lag /= vss->info.channels;

  // we now have the lag in frames
  // return value are mus
  // so we need to multiply with 1s/mus and
  // multiply by 1/rate

  lag *= 1000000; // 1s/mus
  lag /= vss->info.rate;

  _initerr();
  if ( roar_clock_gettime(&rt, LOCAL_CLOCK) == -1 ) {
   _seterrre();
   return 0;
  }

//  printf("%lli, %lli\n", (rt.t_sec  - vss->latmes.last_time.t_sec ), (rt.t_ssec/2 - vss->latmes.last_time.t_ssec/2)/ 18446744073710LL);
//  printf("%lli, %llu\n", rt.t_sec, rt.t_ssec);
  lag -= (rt.t_sec  - vss->latmes.last_time.t_sec ) * 1000000LL;
  lag -= ((int64_t)(rt.t_ssec/2) - (int64_t)(vss->latmes.last_time.t_ssec/2)) / 9223372036855LL;

  if ( lag == 0 ) {
   _seterr(ROAR_ERROR_NONE);
  }

  return lag;
 }

 _seterr(ROAR_ERROR_INVAL);
 return 0;
}

static int roar_vs_flag(roar_vs_t * vss, int flag, int val, int * error) {
 struct roar_stream_info info;
 int old = -1;

 _ckvss(-1);
 _ckasync(-1);

 if ( !(vss->flags & FLAG_STREAM) ) {
  _seterr(ROAR_ERROR_INVAL);
  return -1;
 }

 if ( val != ROAR_VS_ASK )
  old = roar_vs_flag(vss, flag, ROAR_VS_ASK, error);

 _initerr();

 switch (val) {
  case ROAR_VS_TRUE:
  case ROAR_VS_FALSE:
    if ( roar_stream_set_flags2(vss->con, &(vss->stream), flag,
                                val == ROAR_VS_TRUE ? ROAR_SET_FLAG : ROAR_RESET_FLAG) == -1 ) {
     _seterrre();
     return -1;
    }
    return old;
   break;
  case ROAR_VS_TOGGLE:
    return roar_vs_flag(vss, flag, old == ROAR_VS_TRUE ? ROAR_VS_FALSE : ROAR_VS_TRUE, error);
   break;
  case ROAR_VS_ASK:
    if ( roar_stream_get_info(vss->con, &(vss->stream), &info) == -1 ) {
     _seterrre();
     return -1;
    }
    return info.flags & flag ? ROAR_VS_TRUE : ROAR_VS_FALSE;
   break;
 }

 _seterr(ROAR_ERROR_INVAL);
 return -1;
}

int     roar_vs_pause(roar_vs_t * vss, int val, int * error) {
 return roar_vs_flag(vss, ROAR_FLAG_PAUSE, val, error);
}

int     roar_vs_mute (roar_vs_t * vss, int val, int * error) {
 return roar_vs_flag(vss, ROAR_FLAG_MUTE, val, error);
}

static int roar_vs_volume (roar_vs_t * vss, float * c, size_t channels, int * error) {
 struct roar_mixer_settings mixer;
 size_t i;
 register float s, max_s = -100.0, scale = 65535.0;
 int oldchannels;
 int mode = ROAR_SET_VOL_ALL;

 _ckvss(-1);
 _ckasync(-1);

 if ( !(vss->flags & FLAG_STREAM) ) {
  _seterr(ROAR_ERROR_INVAL);
  return -1;
 }

 if ( channels > ROAR_MAX_CHANNELS ) {
  _seterr(ROAR_ERROR_INVAL);
  return -1;
 }

 _initerr();

 if ( roar_get_vol(vss->con, roar_stream_get_id(&(vss->stream)), &mixer, &oldchannels) == -1 ) {
  _seterrre();
  return -1;
 }

 if ( vss->flags & FLAG_FREE_VOL ) {
  for (i = 0; i < channels; i++) {
   if ( c[i] > max_s ) {
    max_s = c[i];
   } else if ( c[i] < -0.01 ) {
    _seterr(ROAR_ERROR_RANGE);
    return -1;
   }
  }

  if ( max_s > 1.00 ) {
   scale = 65535.0 / max_s;
  }
 }

 for (i = 0; i < channels; i++) {
  if ( vss->flags & FLAG_FREE_VOL ) {
   s = c[i] * scale;
   if ( s < 0.0 )
    s = 0.0;
  } else {
   s = c[i] * 65535.0;
   if ( s > 66190.0 || s < -655.0 ) {
    _seterr(ROAR_ERROR_RANGE);
    return -1;
   } else if ( s > 65535.0 ) {
    s = 65535.0;
   } else if ( s <     0.0 ) {
    s = 0.0;
   }
  }
  mixer.mixer[i] = s;
 }

 if ( vss->flags & FLAG_FREE_VOL ) {
  mixer.scale = scale;
 } else {
  mixer.scale = 65535;
 }

 if ( channels != oldchannels )
  mode = ROAR_SET_VOL_UNMAPPED;

 if ( roar_set_vol2(vss->con, roar_stream_get_id(&(vss->stream)), &mixer, channels, mode) == 0 )
  return 0;

 if ( mode == ROAR_SET_VOL_ALL ) {
  _seterrre();
  return -1;
 }

 if ( roar_conv_volume(&mixer, &mixer, oldchannels, channels) == -1 ) {
  _seterrre();
  return -1;
 }

 channels = oldchannels;
 mode     = ROAR_SET_VOL_ALL;

 if ( roar_set_vol2(vss->con, roar_stream_get_id(&(vss->stream)), &mixer, channels, mode) == -1 ) {
  _seterrre();
  return -1;
 }

 return 0;
}

int     roar_vs_volume_mono   (roar_vs_t * vss, float c, int * error) {
 return roar_vs_volume(vss, &c, 1, error);
}

int     roar_vs_volume_stereo (roar_vs_t * vss, float l, float r, int * error) {
 float c[2] = {l, r};
 return roar_vs_volume(vss, c, 2, error);
}

int     roar_vs_volume_get    (roar_vs_t * vss, float * l, float * r, int * error) {
 struct roar_mixer_settings mixer;
 int channels;

 if ( vss == NULL || l == NULL || r == NULL ) {
  _seterr(ROAR_ERROR_INVAL);
  return -1;
 }

 if ( !(vss->flags & FLAG_STREAM) ) {
  _seterr(ROAR_ERROR_INVAL);
  return -1;
 }

 _ckasync(-1);

 _initerr();

 if ( roar_get_vol(vss->con, roar_stream_get_id(&(vss->stream)), &mixer, &channels) == -1 ) {
  _seterrre();
  return -1;
 }

 if ( channels == 1 )
  mixer.mixer[1] = mixer.mixer[0];

 *l = mixer.mixer[0] / (float)mixer.scale;
 *r = mixer.mixer[1] / (float)mixer.scale;

 return 0;
}

int     roar_vs_meta          (roar_vs_t * vss, struct roar_keyval * kv, size_t len, int * error) {
 struct roar_meta meta;
 size_t i;
 int type;
 int ret = 0;

 _ckvss(-1);
 _ckasync(-1);

 if ( !(vss->flags & FLAG_STREAM) ) {
  _seterr(ROAR_ERROR_INVAL);
  return -1;
 }

 meta.type   = ROAR_META_TYPE_NONE;
 meta.key[0] = 0;
 meta.value  = NULL;

 _initerr();

 if ( roar_stream_meta_set(vss->con, &(vss->stream), ROAR_META_MODE_CLEAR, &meta) == -1 ) {
  _seterrre();
  ret = -1;
 }

 for (i = 0; i < len; i++) {
  type = roar_meta_inttype(kv[i].key);
  meta.type  = type;
  meta.value = kv[i].value;

  if ( roar_stream_meta_set(vss->con, &(vss->stream), ROAR_META_MODE_ADD, &meta) == -1 ) {
   _seterrre();
   ret = -1;
  }
 }

 meta.type   = ROAR_META_TYPE_NONE;
 meta.key[0] = 0;
 meta.value  = NULL;
 if ( roar_stream_meta_set(vss->con, &(vss->stream), ROAR_META_MODE_FINALIZE, &meta) == -1 ) {
  _seterrre();
  ret = -1;
 }

 return ret;
}

int     roar_vs_role          (roar_vs_t * vss, int role, int * error) {
 _ckvss(-1);
 _ckasync(-1);

 if ( !(vss->flags & FLAG_STREAM) ) {
  _seterr(ROAR_ERROR_INVAL);
  return -1;
 }

 _initerr();

 if ( roar_stream_set_role(vss->con, &(vss->stream), role) == -1 ) {
  _seterrre();
  return -1;
 }

 return 0;
}


int     roar_vs_iterate       (roar_vs_t * vss, int wait, int * error) {
 struct roar_vio_select vios[3];
 struct roar_vio_selecttv rtv = {.sec = 0, .nsec = 1};
 size_t len = 0;
 ssize_t i;
 ssize_t ret;
 int can_read = 0, can_write = 0;
 int can_flush_stream = 0, can_flush_file = 0;
 int is_eof = 0;
 void * data;
 size_t tmp;

 // TODO: fix error handling below.

 _ckvss(-1);

 if ( wait != ROAR_VS_WAIT && wait != ROAR_VS_NOWAIT ) {
  _seterr(ROAR_ERROR_INVAL);
  return -1;
 }

 ROAR_VIO_SELECT_SETVIO(&(vios[len]), &(vss->vio), ((vss->flags & FLAG_DIR_IN  ? ROAR_VIO_SELECT_READ  : 0) |
                                                    (vss->flags & FLAG_DIR_OUT ? ROAR_VIO_SELECT_WRITE : 0)));
 vios[len].ud.vp = &(vss->vio);
 len++;

 ROAR_VIO_SELECT_SETVIO(&(vios[len]), roar_get_connection_vio2(vss->con), ROAR_VIO_SELECT_READ);
 vios[len].ud.vp = vss->con;
 len++;


// TODO: FIXME: need to do two select()s so we can sleep more efficently and test for both directions.
// for the moment we disable file direction and hope it will not block anyway...
/*
 if ( vss->file != NULL ) {
  ROAR_VIO_SELECT_SETVIO(&(vios[len]), vss->file, ((vss->flags & FLAG_DIR_IN  ? ROAR_VIO_SELECT_WRITE : 0) |
                                                   (vss->flags & FLAG_DIR_OUT ? ROAR_VIO_SELECT_READ  : 0)));
  vios[len].ud.vp = vss->file;
  len++;
 }
*/

 ret = roar_vio_select(vios, len, (wait == ROAR_VS_NOWAIT ? &rtv : NULL), NULL);

// part 2 of above hack:
// emulate read handle.
  if ( vss->file != NULL ) {
   vios[len].ud.vp   = vss->file;
   vios[len].eventsa = ROAR_VIO_SELECT_WRITE|ROAR_VIO_SELECT_READ;
   len++;
  }

 // no error here nor EOF.
 if ( ret == 0 )
  return 1;

 for (i = 0; i < len; i++) {
  if ( !vios[i].eventsa )
   continue;

  if ( vios[i].ud.vp == &(vss->vio) ) {
   if ( vios[i].eventsa & ROAR_VIO_SELECT_READ )
    can_read++;

   if ( vios[i].eventsa & ROAR_VIO_SELECT_WRITE ) {
    can_write++;
    can_flush_stream = 1;
   }
  } else if ( vios[i].ud.vp == vss->con ) {
   if ( vss->async.qlen ) {
    _handle_async_req(vss, NULL);
   } else {
    roar_sync(vss->con);
   }
  } else if ( vss->file != NULL && vios[i].ud.vp == vss->file ) {
   if ( vios[i].eventsa & ROAR_VIO_SELECT_READ )
    can_write++;

   if ( vios[i].eventsa & ROAR_VIO_SELECT_WRITE ) {
    can_read++;
    can_flush_file = 1;
   }
  }
 }

 if ( vss->flags & FLAG_BUFFERED ) {
  if ( roar_buffer_ring_avail(vss->readring, NULL, &tmp) != -1 )
   if ( tmp > 0 )
    can_read++;

// no check here to just let the read return zero and we do EOF handling.
/*
  if ( roar_buffer_ring_avail(vss->writering, &tmp, NULL) != -1 )
   if ( tmp > 0 )
*/
    can_write++;
 }

 ROAR_DBG("roar_vs_iterate(vss=%p, wait=%i, error=%p): can_read=%i, can_write=%i", vss, wait, error, can_read, can_write);

 // TODO: FIXME: Need to correct error handling here!

 if ( can_flush_stream && vss->writebuffer != NULL ) {
  if ( roar_buffer_get_data(vss->writebuffer, &data) == -1 )
   return -1;

  if ( roar_buffer_get_len(vss->writebuffer, &len) == -1 )
   return -1;

  ret = roar_vs_write_direct(vss, data, len, error);

  if ( ret == -1 ) {
   return -1;
  } else if ( ret == len ) {
   roar_buffer_free(vss->writebuffer);
   vss->writebuffer = NULL;
  } else {
   if ( roar_buffer_set_offset(vss->writebuffer, ret) == -1 )
    return -1;
  }
 }

 if ( can_flush_file && vss->readbuffer != NULL ) {
  if ( roar_buffer_get_data(vss->readbuffer, &data) == -1 )
   return -1;

  if ( roar_buffer_get_len(vss->readbuffer, &len) == -1 )
   return -1;

  ret = roar_vio_write(vss->file, data, len);

  if ( ret == -1 ) {
   return -1;
  } else if ( ret == len ) {
   roar_buffer_free(vss->readbuffer);
   vss->readbuffer = NULL;
  } else {
   if ( roar_buffer_set_offset(vss->readbuffer, ret) == -1 )
    return -1;
  }
 }

#define _READ_SIZE 1024

 if ( can_read == 2 && vss->readbuffer == NULL ) {
  if ( roar_buffer_new_data(&(vss->readbuffer), (len = _READ_SIZE), &data) == -1 ) 
   return -1;

  ret = roar_vs_read(vss, data, len, error);

  if ( ret == -1 ) {
   roar_buffer_free(vss->readbuffer);
   vss->readbuffer = NULL;
   return -1;
  } else if ( ret == 0 ) {
   is_eof = 1;
   roar_buffer_free(vss->readbuffer);
   vss->readbuffer = NULL;
  } else {
   len = ret;
   if ( roar_buffer_set_len(vss->readbuffer, len) == -1 )
    return -1;

   if ( vss->flags & FLAG_BUFFERED ) {
    tmp = len;
    if ( roar_buffer_ring_write(vss->readring, data, &tmp) == -1 ) {
     ret = -1;
    } else {
     ret = tmp;
    }
   } else {
    ret = roar_vio_write(vss->file, data, len);
   }

   if ( ret == -1 ) {
    return -1;
   } else if ( ret == len ) {
    roar_buffer_free(vss->readbuffer);
    vss->readbuffer = NULL;
   } else {
    if ( roar_buffer_set_offset(vss->readbuffer, ret) == -1 )
     return -1;
   }
  }
 }

 if ( can_write == 2 && vss->writebuffer == NULL ) {
  if ( roar_buffer_new_data(&(vss->writebuffer), (len = _READ_SIZE), &data) == -1 )
   return -1;

  if ( vss->flags & FLAG_BUFFERED ) {
   tmp = len;
   if ( roar_buffer_ring_read(vss->writering, data, &tmp) == -1 ) {
    ret = -1;
   } else {
    ret = tmp;
   }
  } else {
   ret = roar_vio_read(vss->file, data, len);
  }

  ROAR_DBG("roar_vs_iterate(vss=%p, wait=%i, error=%p): ret=%lli", vss, wait, error, (long long int)ret);

  if ( ret == -1 ) {
   ROAR_DBG("roar_vs_iterate(vss=%p, wait=%i, error=%p) = ?", vss, wait, error);

   roar_buffer_free(vss->writebuffer);
   vss->writebuffer = NULL;
   return -1;
  } else if ( ret == 0 ) {
   ROAR_DBG("roar_vs_iterate(vss=%p, wait=%i, error=%p) = ?", vss, wait, error);

   is_eof = 1;
   roar_buffer_free(vss->writebuffer);
   vss->writebuffer = NULL;
  } else {
   ROAR_DBG("roar_vs_iterate(vss=%p, wait=%i, error=%p) = ?", vss, wait, error);

   if ( len != ret ) {
    len = ret;
    if ( roar_buffer_set_len(vss->writebuffer, len) == -1 )
     return -1;
   }

   ROAR_DBG("roar_vs_iterate(vss=%p, wait=%i, error=%p) = ?", vss, wait, error);

   ret = roar_vs_write_direct(vss, data, len, error);

   if ( ret == -1 ) {
    return -1;
   } else if ( ret == len ) {
    roar_buffer_free(vss->writebuffer);
    vss->writebuffer = NULL;
   } else {
    if ( roar_buffer_set_offset(vss->writebuffer, ret) == -1 )
     return -1;
   }
  }
 }

 return is_eof ? 0 : 2;
}

int     roar_vs_run           (roar_vs_t * vss, int * error) {
 int ret;

 _ckvss(-1);

 while ((ret = roar_vs_iterate(vss, ROAR_VS_WAIT, error)) > 0);

 ROAR_DBG("roar_vs_run(vss=%p, error=%p): ret=%i", vss, error, ret);

 if ( ret == 0 ) {
  // flush buffers:
  roar_vs_iterate(vss, ROAR_VS_WAIT, error);
 }

 if ( roar_vs_sync(vss, ROAR_VS_WAIT, error) == -1 )
  return -1;

 return ret;
}

ssize_t roar_vs_get_avail_read(roar_vs_t * vss, int * error) {
 size_t len;

 _ckvss(-1);

 if ( !(vss->flags & FLAG_BUFFERED) ) {
  _seterr(ROAR_ERROR_INVAL);
  return -1;
 }

 if ( roar_buffer_ring_avail(vss->readring, &len, NULL) == -1 ) {
  _seterrre();
  return -1;
 }

 return len;
}

ssize_t roar_vs_get_avail_write(roar_vs_t * vss, int * error) {
 size_t len;

 _ckvss(-1);

 if ( !(vss->flags & FLAG_BUFFERED) ) {
  _seterr(ROAR_ERROR_INVAL);
  return -1;
 }

 if ( roar_buffer_ring_avail(vss->writering, NULL, &len) == -1 ) {
  _seterrre();
  return -1;
 }

 return len;
}

int     roar_vs_reset_buffer(roar_vs_t * vss, int writering, int readring, int * error) {
 _ckvss(-1);

 if ( !(vss->flags & FLAG_BUFFERED) ) {
  _seterr(ROAR_ERROR_INVAL);
  return -1;
 }

 if ( writering != ROAR_VS_TRUE || writering != ROAR_VS_FALSE ||
      readring  != ROAR_VS_TRUE || readring  != ROAR_VS_FALSE ) {
  _seterr(ROAR_ERROR_INVAL);
  return -1;
 }

 if ( writering ) {
  if ( roar_buffer_ring_reset(vss->writering) == -1 ) {
   _seterrre();
   return -1;
  }
 }

 if ( readring ) {
  if ( roar_buffer_ring_reset(vss->readring) == -1 ) {
   _seterrre();
   return -1;
  }
 }

 return 0;
}

int     roar_vs_ctl           (roar_vs_t * vss, roar_vs_ctlcmd cmd, void * argp, int * error) {
 _ckvss(-1);

 switch (cmd) {
  case ROAR_VS_CMD_NOOP:
   break;
  case ROAR_VS_CMD_SET_MIXER:
    vss->mixerid = *(int*)argp;
   break;
  case ROAR_VS_CMD_GET_MIXER:
    *(int*)argp = vss->mixerid;
   break;
  case ROAR_VS_CMD_SET_FIRST_PRIM:
    vss->first_primid = *(int*)argp;
   break;
  case ROAR_VS_CMD_GET_FIRST_PRIM:
    *(int*)argp = vss->first_primid;
   break;
#ifdef _HAVE_SOCKOPT
  case ROAR_VS_CMD_SET_LATC_P:
    vss->latc.p = *(float*)argp;
   break;
  case ROAR_VS_CMD_GET_LATC_P:
    *(float*)argp = vss->latc.p;
   break;
  case ROAR_VS_CMD_SET_LATC_TARGET:
    vss->latc.target = *(float*)argp;
   break;
  case ROAR_VS_CMD_GET_LATC_TARGET:
    *(float*)argp = vss->latc.target;
   break;
  case ROAR_VS_CMD_SET_LATC_WINDOW:
    vss->latc.window = *(float*)argp;
   break;
  case ROAR_VS_CMD_GET_LATC_WINDOW:
    *(float*)argp = vss->latc.window;
   break;
  case ROAR_VS_CMD_SET_LATC_MINLAG:
    vss->latc.minlag = *(float*)argp;
   break;
  case ROAR_VS_CMD_GET_LATC_MINLAG:
    *(float*)argp = vss->latc.minlag;
   break;
#endif
  case ROAR_VS_CMD_SET_FREE_VOLUME:
    switch (*(int*)argp) {
     case ROAR_VS_TRUE:
       vss->flags |= FLAG_FREE_VOL;
      break;
     case ROAR_VS_FALSE:
       vss->flags |= FLAG_FREE_VOL;
       vss->flags -= FLAG_FREE_VOL;
      break;
     case ROAR_VS_TOGGLE:
       if ( vss->flags & FLAG_FREE_VOL ) {
        vss->flags -= FLAG_FREE_VOL;
       } else {
        vss->flags |= FLAG_FREE_VOL;
       }
      break;
     default:
       _seterr(ROAR_ERROR_INVAL);
       return -1;
      break;
    }
   break;
  case ROAR_VS_CMD_GET_FREE_VOLUME:
    *(int*)argp = vss->flags & FLAG_FREE_VOL ? ROAR_VS_TRUE : ROAR_VS_FALSE;
   break;
  case ROAR_VS_CMD_SET_DEFAULT_PAUSED:
    switch (*(int*)argp) {
     case ROAR_VS_TRUE:
       vss->flags |= FLAG_DEF_PAUSE;
      break;
     case ROAR_VS_FALSE:
       vss->flags |= FLAG_DEF_PAUSE;
       vss->flags -= FLAG_DEF_PAUSE;
      break;
     case ROAR_VS_TOGGLE:
       if ( vss->flags & FLAG_DEF_PAUSE ) {
        vss->flags -= FLAG_DEF_PAUSE;
       } else {
        vss->flags |= FLAG_DEF_PAUSE;
       }
      break;
     default:
       _seterr(ROAR_ERROR_INVAL);
       return -1;
      break;
    }
   break;
  case ROAR_VS_CMD_GET_DEFAULT_PAUSED:
    *(int*)argp = vss->flags & FLAG_DEF_PAUSE ? ROAR_VS_TRUE : ROAR_VS_FALSE;
   break;
// use ifndef here so warnings of unhandled enum values will be shown in DEBUG mode.
#ifndef DEBUG
  default:
    _seterr(ROAR_ERROR_INVAL);
    return -1;
   break;
#endif
 }

 return 0;
}

struct roar_connection * roar_vs_connection_obj(roar_vs_t * vss, int * error) {
 _ckvss(NULL);

 return vss->con;
}

struct roar_stream     * roar_vs_stream_obj    (roar_vs_t * vss, int * error) {
 _ckvss(NULL);

 if ( !(vss->flags & FLAG_STREAM) ) {
  _seterr(ROAR_ERROR_INVAL);
  return NULL;
 }

 return &(vss->stream);
}

struct roar_vio_calls  * roar_vs_vio_obj       (roar_vs_t * vss, int * error) {
 _ckvss(NULL);

 if ( !(vss->flags & FLAG_STREAM) ) {
  _seterr(ROAR_ERROR_INVAL);
  return NULL;
 }

 return &(vss->vio);
}

//ll