frame_tracker.cpp

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#include "frame_tracker.h"
 
namespace fl {
 
namespace { // anonymous namespace
long map(long x, long in_min, long in_max, long out_min, long out_max) {
    const long run = in_max - in_min;
    if (run == 0) {
        return 0; // AVR returns -1, SAM returns 0
    }
    const long rise = out_max - out_min;
    const long delta = x - in_min;
    return (delta * rise) / run + out_min;
}
} // anonymous namespace
 
FrameTracker::FrameTracker(float fps) {
    // Convert fps to microseconds per frame interval
    mMicrosSecondsPerInterval = static_cast<uint32_t>(1000000.0f / fps + .5f);
}
 
void FrameTracker::get_interval_frames(uint32_t now, uint32_t *frameNumber,
                                       uint32_t *nextFrameNumber,
                                       uint8_t *amountOfNextFrame) const {
    // Account for any pause time
    uint32_t effectiveTime = now;
 
    // Convert milliseconds to microseconds for precise calculation
    uint64_t microseconds = static_cast<uint64_t>(effectiveTime) * 1000ULL;
 
    // Calculate frame number with proper rounding
    *frameNumber = microseconds / mMicrosSecondsPerInterval;
    *nextFrameNumber = *frameNumber + 1;
 
    // Calculate interpolation amount if requested
    if (amountOfNextFrame != nullptr) {
        uint64_t frame1_start = (*frameNumber * mMicrosSecondsPerInterval);
        uint64_t frame2_start = (*nextFrameNumber * mMicrosSecondsPerInterval);
        uint32_t rel_time = microseconds - frame1_start;
        uint32_t frame_duration = frame2_start - frame1_start;
        uint8_t progress = uint8_t(map(rel_time, 0, frame_duration, 0, 255));
        *amountOfNextFrame = progress;
    }
}
 
uint32_t FrameTracker::get_exact_timestamp_ms(uint32_t frameNumber) const {
    uint64_t microseconds = frameNumber * mMicrosSecondsPerInterval;
    return static_cast<uint32_t>(microseconds / 1000) + mStartTime;
}
 
}  // namespace fl