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CDROM: Further improve seek timing

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Fixes background music in World Cup 98, background noise in Idol
Promotion - Yumie Island, probably others.
This commit is contained in:
Stenzek 2024-08-06 21:55:28 +10:00
parent 8ad133dbc0
commit c97516b01d
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1 changed files with 35 additions and 32 deletions
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67
src/core/cdrom.cpp
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@ -1418,7 +1418,7 @@ TickCount CDROM::GetTicksForSeek(CDImage::LBA new_lba, bool ignore_speed_change)
if (g_settings.cdrom_seek_speedup == 0)
return MIN_TICKS;
u32 ticks = static_cast<u32>(MIN_TICKS);
u32 ticks = 0;
// Update start position for seek.
if (IsSeeking())
@ -1426,9 +1426,6 @@ TickCount CDROM::GetTicksForSeek(CDImage::LBA new_lba, bool ignore_speed_change)
else
UpdatePhysicalPosition(false);
const u32 ticks_per_sector =
s_mode.double_speed ? static_cast<u32>(System::MASTER_CLOCK / 150) : static_cast<u32>(System::MASTER_CLOCK / 75);
const u32 ticks_per_second = static_cast<u32>(System::MASTER_CLOCK);
const CDImage::LBA current_lba = IsMotorOn() ? (IsSeeking() ? s_seek_end_lba : s_physical_lba) : 0;
const u32 lba_diff = static_cast<u32>((new_lba > current_lba) ? (new_lba - current_lba) : (current_lba - new_lba));
@ -1441,38 +1438,44 @@ TickCount CDROM::GetTicksForSeek(CDImage::LBA new_lba, bool ignore_speed_change)
ClearDriveState();
}
if (lba_diff < 32)
float seconds;
if (current_lba < new_lba && lba_diff < 10)
{
// Special case: when we land exactly on the right sector, we're already too late.
ticks += ticks_per_sector * std::min<u32>(5u, (lba_diff == 0) ? 4u : lba_diff);
// If we're behind the current sector, and within a small distance, the mech just waits for the sector to come up by
// reading normally (or apparently moves the lens according to some?). This timing is actually needed for
// Transformers - Beast Wars Transmetals, it gets very unstable during loading if seeks are too fast.
const u32 ticks_per_sector =
s_mode.double_speed ? static_cast<u32>(System::MASTER_CLOCK / 150) : static_cast<u32>(System::MASTER_CLOCK / 75);
ticks += ticks_per_sector * std::min<u32>(5u, lba_diff);
seconds = 0.0f;
}
else if (lba_diff < 6200)
{
// Not sled. The point at which we switch from faster to slower seeks varies across the disc. Around ~60 distance
// towards the end, but ~330 at the beginning. Likely based on sectors per track, so we use a logarithmic curve.
const u32 switch_point = static_cast<u32>(
330.0f +
(-63.1333f * std::log(std::clamp(static_cast<float>(current_lba) / static_cast<float>(CDImage::FRAMES_PER_MINUTE),
1.0f, 72.0f))));
seconds = (lba_diff < switch_point) ? 0.05f : 0.1f;
}
else
{
// This is a still not a very accurate model, but it's roughly in line with the behavior of hardware tests.
const float disc_distance = 0.2323384936f * std::log(static_cast<float>((new_lba / 4500) + 1u));
float seconds;
if (lba_diff <= CDImage::FRAMES_PER_SECOND)
{
// 30ms + (diff * 30ms) + (disc distance * 30ms)
seconds = 0.03f + ((static_cast<float>(lba_diff) / static_cast<float>(CDImage::FRAMES_PER_SECOND)) * 0.03f) +
(disc_distance * 0.03f);
}
else if (lba_diff <= CDImage::FRAMES_PER_MINUTE)
{
// 150ms + (diff * 30ms) + (disc distance * 50ms)
seconds = 0.15f + ((static_cast<float>(lba_diff) / static_cast<float>(CDImage::FRAMES_PER_MINUTE)) * 0.03f) +
(disc_distance * 0.05f);
}
else
{
// 200ms + (diff * 500ms)
seconds = 0.2f + ((static_cast<float>(lba_diff) / static_cast<float>(72 * CDImage::FRAMES_PER_MINUTE)) * 0.4f);
}
ticks += static_cast<u32>(seconds * static_cast<float>(ticks_per_second));
// Sled seek. Minimum of approx. 200ms, up to 900ms or so. Mapped to a linear and logarithmic component, because
// there is a fixed cost which ramps up quickly, but the very slow sled seeks are only when doing a full disc sweep.
constexpr float SLED_FIXED_COST = 0.05f;
constexpr float SLED_VARIABLE_COST = 0.9f - SLED_FIXED_COST;
constexpr float LOG_WEIGHT = 0.4f;
constexpr float MAX_SLED_LBA = static_cast<float>(72 * CDImage::FRAMES_PER_MINUTE);
seconds =
SLED_FIXED_COST +
(((SLED_VARIABLE_COST * (std::log(static_cast<float>(lba_diff)) / std::log(MAX_SLED_LBA)))) * LOG_WEIGHT) +
((SLED_VARIABLE_COST * (lba_diff / MAX_SLED_LBA)) * (1.0f - LOG_WEIGHT));
}
constexpr u32 ticks_per_second = static_cast<u32>(System::MASTER_CLOCK);
ticks += static_cast<u32>(seconds * static_cast<float>(ticks_per_second));
if (s_drive_state == DriveState::ChangingSpeedOrTOCRead && !ignore_speed_change)
{
// we're still reading the TOC, so add that time in
@ -1501,8 +1504,8 @@ TickCount CDROM::GetTicksForStop(bool motor_was_on)
TickCount CDROM::GetTicksForSpeedChange()
{
static constexpr u32 ticks_single_to_double = static_cast<u32>(0.8 * static_cast<double>(System::MASTER_CLOCK));
static constexpr u32 ticks_double_to_single = static_cast<u32>(1.0 * static_cast<double>(System::MASTER_CLOCK));
static constexpr u32 ticks_single_to_double = static_cast<u32>(0.7 * static_cast<double>(System::MASTER_CLOCK));
static constexpr u32 ticks_double_to_single = static_cast<u32>(0.8 * static_cast<double>(System::MASTER_CLOCK));
return System::ScaleTicksToOverclock(s_mode.double_speed ? ticks_single_to_double : ticks_double_to_single);
}