FESTIVE stateful bitrate update misunderstanding

[chanh1964]

Dear authors and to whom it may concern,

I have been using this project for my research and I'd like to thank the authors for such a great contribution.

However, I have checked the FESTIVE algorithm and found out that there was a part in your FESTIVE.cc file that might have been misunderstood.

dash/model/festive.cc

Line 39 in 3522e46

m_smooth.push_back (5); // after how many steps switch up is possible

dash/model/festive.cc

Lines 122 to 147 in 3522e46

	if (currentRepIndex < m_highestRepIndex && !decisionMade)
	{
	int count = 0;
	for (unsigned _sd = m_playbackData.playbackIndex.size () - 1; _sd-- > 0; )
	{
	if (currentRepIndex == m_playbackData.playbackIndex.at (_sd))
	{
	count++;
	if (count >= m_smooth.at (0))
	{
	break;
	}
	}
	else
	{
	break;
	}
	}
	if (count >= m_smooth.at (0)
	&& (double) m_videoData.averageBitrate.at (currentRepIndex + 1) <= thrptEstimation)
	{
	refIndex = currentRepIndex + 1;
	answer.decisionCase = 1;
	decisionMade = true;
	}
	}

According to the white paper of FESTIVE, bitrate at level k will remain the same for at least k chunks, before switching up to level k+1. Also in their paper, they've given an example where bitrate at 1130Kbps would switch up after 5 chunks, which I think might have led to this misunderstanding.

Therefore, the comparisons at line #130 and #140 should be if (count >= currentRepIndex), instead of the fixed value of 5.

Hope it helps.

[sjksong]

i think the original code is right ，count represents steps