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pcm_packetizer_c: fix packet size calculations

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There's no apparent reason that we need our packets to be "second-aligned".
Neither does the heuristic that picks the divisor looks sensible anyway.

25 should be a good divisor for all common sample rates, as the derived packet
size/length will be sensible and consistent (40ms). The packets will keep on
being "second-aligned", regardless of whether that is necessary.

Also making sure that m_min_packet_size is no less than 4ms for the 44.1KHz
family.
This commit is contained in:
Tom Yan 2021-02-14 10:59:52 +08:00
parent b90c3e7a3d
commit 659a83e542
1 changed files with 8 additions and 9 deletions
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17
src/output/p_pcm.cpp
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@ -36,7 +36,7 @@ pcm_packetizer_c::pcm_packetizer_c(generic_reader_c *p_reader,
, m_samples_per_packet{}
, m_samples_per_packet_packaged{}
, m_packet_size(0)
, m_min_packet_size{static_cast<size_t>(samples_to_size(samples_per_sec * 4) / 1000)} // Minimum: 4ms of samples if we should pass it through unmodified
, m_min_packet_size{}
, m_samples_output(0)
, m_num_durations_provided{}
, m_num_packets_with_different_sample_count{}
@ -44,15 +44,14 @@ pcm_packetizer_c::pcm_packetizer_c(generic_reader_c *p_reader,
, m_s2ts(1000000000ll, m_samples_per_sec)
{
int i;
for (i = 32; 2 < i; i >>= 2)
if ((m_samples_per_sec % i) == 0)
break;
// make sure each packet will not be less than 4ms
if ((samples_per_sec % 225) == 0)
m_min_packet_size = samples_to_size(samples_per_sec / 225);
else
m_min_packet_size = samples_to_size(samples_per_sec / 250);
if ((2 == i) && ((m_samples_per_sec % 5) == 0))
i = 5;
m_samples_per_packet = samples_per_sec / i;
// fall back to 40ms; it merely happens to be "second-aligned" for all common rates
m_samples_per_packet = samples_per_sec / 25;
m_packet_size = samples_to_size(m_samples_per_packet);
set_track_type(track_audio);