BaseRepresentation *
NearOptimalAdaptationLogic::getNextQualityIndex( BaseAdaptationSet *adaptSet, RepresentationSelector &selector,
float gammaP, mtime_t VD, mtime_t Q )
{
BaseRepresentation *ret = NULL;
BaseRepresentation *prev = NULL;
float argmax;
for(BaseRepresentation *rep = selector.lowest(adaptSet);
rep && rep != prev; rep = selector.higher(adaptSet, rep))
{
float arg = ( VD * (getUtility(rep) + gammaP) - Q ) / rep->getBandwidth();
if(ret == NULL || argmax <= arg)
{
ret = rep;
argmax = arg;
}
prev = rep;
}
return ret;
}
BaseRepresentation *PredictiveAdaptationLogic::getNextRepresentation(BaseAdaptationSet *adaptSet, BaseRepresentation *prevRep)
{
RepresentationSelector selector(maxwidth, maxheight);
BaseRepresentation *rep;
vlc_mutex_lock(&lock);
std::map<ID, PredictiveStats>::iterator it = streams.find(adaptSet->getID());
if(it == streams.end())
{
rep = selector.highest(adaptSet);
}
else
{
PredictiveStats &stats = (*it).second;
double f_buffering_level = (double)stats.buffering_level / stats.buffering_target;
double f_min_buffering_level = f_buffering_level;
unsigned i_max_bitrate = 0;
if(streams.size() > 1)
{
std::map<ID, PredictiveStats>::const_iterator it2 = streams.begin();
for(; it2 != streams.end(); ++it2)
{
if(it2 == it)
continue;
const PredictiveStats &other = (*it2).second;
f_min_buffering_level = std::min((double)other.buffering_level / other.buffering_target,
f_min_buffering_level);
i_max_bitrate = std::max(i_max_bitrate, other.last_download_rate);
}
}
if(stats.starting())
{
rep = selector.highest(adaptSet);
}
else
{
const unsigned i_available_bw = getAvailableBw(i_max_bitrate, prevRep);
if(!prevRep)
{
rep = selector.select(adaptSet, i_available_bw);
}
else if(f_buffering_level > 0.8)
{
rep = selector.select(adaptSet, std::max((uint64_t) i_available_bw,
(uint64_t) prevRep->getBandwidth()));
}
else if(f_buffering_level > 0.5)
{
rep = prevRep;
}
else
{
if(f_buffering_level > 2 * stats.last_duration)
{
rep = selector.lower(adaptSet, prevRep);
}
else
{
rep = selector.select(adaptSet, i_available_bw * f_buffering_level);
}
}
}
BwDebug( for(it=streams.begin(); it != streams.end(); ++it)
{
const PredictiveStats &s = (*it).second;
msg_Info(p_obj, "Stream %s buffering level %.2f%",
(*it).first.str().c_str(), (double) s.buffering_level / s.buffering_target);
} );
BwDebug( if( rep != prevRep )
msg_Info(p_obj, "Stream %s new bandwidth usage %zu KiB/s",
adaptSet->getID().str().c_str(), rep->getBandwidth() / 8000); );