Function UpdatePlayer

Source/Engine/Video/MF/VideoBackendMF.cpp:388–465

    }

    void UpdatePlayer(int32 index)
    {
        PROFILE_CPU();
        PROFILE_MEM(Video);
        auto& player = *Players[index];
        ZoneText(player.DebugUrl, player.DebugUrlLen);
        auto& playerMF = player.GetBackendState<VideoPlayerMF>();

        // Skip paused player
        if (!playerMF.Playing && !playerMF.Seek)
            return;

        // Update playback time
        if (playerMF.FirstFrame)
        {
            playerMF.FirstFrame = 0;
            playerMF.Seek = 1;
        }
        else if (playerMF.Playing)
        {
            playerMF.Time += UpdateDeltaTime;
        }
        if (playerMF.Time > player.Duration && player.Duration.Ticks != 0)
        {
            if (playerMF.Loop)
            {
                // Loop
                playerMF.Time.Ticks %= player.Duration.Ticks;
                playerMF.Seek = 1;
                player.PlayAudio();
            }
            else
            {
                // End
                playerMF.Time = player.Duration;
            }
        }

        // Update current position
        bool canSeek = true;
    SEEK_START:
        if (playerMF.Seek)
        {
            // Reset cached frames timings
            player.VideoFrameDuration = player.AudioBufferDuration = TimeSpan::Zero();

            playerMF.Seek = 0;
            PROPVARIANT var;
            PropVariantInit(&var);
            var.vt = VT_I8;
            var.hVal.QuadPart = playerMF.Time.Ticks;
            PROFILE_CPU_NAMED("SetCurrentPosition");
            playerMF.SourceReader->SetCurrentPosition(GUID_NULL, var);

            // Note:
            // SetCurrentPosition method does not guarantee exact seeking.
            // The accuracy of the seek depends on the media content.
            // If the media content contains a video stream, the SetCurrentPosition method typically seeks to the nearest key frame before the desired position.