Merge "AudioTimestamp: advance first timestamp time after start if stale" into qt-dev

    // Prevent retrograde motion in timestamp.

    // This is sometimes caused by erratic reports of the available space in the ALSA drivers.

    if (status == NO_ERROR) {

        // previousTimestampValid is set to false when starting after a stop or flush.

        if (previousTimestampValid) {

            const int64_t previousTimeNanos =

                    audio_utils_ns_from_timespec(&mPreviousTimestamp.mTime);

            int64_t currentTimeNanos = audio_utils_ns_from_timespec(&timestamp.mTime);

        // Fix stale time when checking timestamp right after start().

        // The position is at the last reported location but the time can be stale

        // due to pause or standby or cold start latency.

        //

        // We keep advancing the time (but not the position) to ensure that the

        // stale value does not confuse the application.

        //

        // For offload compatibility, use a default lag value here.

        // Any time discrepancy between this update and the pause timestamp is handled

        // by the retrograde check afterwards.

        int64_t currentTimeNanos = audio_utils_ns_from_timespec(&timestamp.mTime);

        const int64_t lagNs = int64_t(mAfLatency * 1000000LL);

        const int64_t limitNs = mStartNs - lagNs;

        if (currentTimeNanos < limitNs) {

            currentTimeNanos = limitNs;

        }

        // previousTimestampValid is set to false when starting after a stop or flush.

        if (previousTimestampValid) {

            const int64_t previousTimeNanos =

                    audio_utils_ns_from_timespec(&mPreviousTimestamp.mTime);

            // retrograde check

            if (currentTimeNanos < previousTimeNanos) {

                ALOGW("%s(%d): retrograde timestamp time corrected, %lld < %lld",