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choo-choo sounds

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    choo-choo sounds

    Seeing there is a "Sounds" forum now, I thought I'd re-post an earlier request in hopes that some developers would build a solution for this. There is a 3rd party addon file which attempts to address this, but alas, the synchronization of the sound is not aligned with the rotation of the drive wheels at 90 degree intervals. Maybe this something only MS can patch. Here is the post.

    One of the greatest areas of unrealistic sound when operating the default steam locos is the unsynchronization of the drive wheel rotation to the sound of steam expelling into the boiler cavity to travel to the stack, and hence the "choo" sound. On a recent trip to Steamtown USA, I watched very carefully the rotation of the drive wheels to the actual "choo" sound being produced which is done at 90 degree intervals. I know someone has attempted to fix this with a addon file , but I'm hoping some sound file developer will produce a program to accurately produce the "choo" sound with every 90 degree rotation of the drive wheels. Just a thought.



    RE: choo-choo sounds

    I don't think that the process is suitable for programming. But a helpful spreadsheet is easy to put together once you understand the sequence involved.

    The sync of the wheel rotation and chuff noise is a case of correctly specifying speed at which each of the sequence of wave files is initiated at. There are far to few of the original wave files, so more, faster ones are required. Try here:-

    Getting the sync right is a bit complex. Firstly the animated wheel rotation in the sim has to be right first. This depends on the number of animation frames used in the .s model file, and the correct specification of the wheel radius in the .eng file (this is even wrong for the sims own Fscot).

    Secondly the correct speeds need to be calculated. From each of the .wav files work out the frequency of the chuffs. Thus work out the representative track speed (knowing the wheel radius and number of beats per revolution required, either 4 or 6). Finally, cofigure the sms file to change from one .wav to the next at the speed mid-way between the representative speeds of the .wav files concerned. This is correct when the sms uses the Speed variable, but if it uses Variable1 then these values need to be converted by a constant factor (don't know why, but they do). This factor seems to vary from loco to loco, again I don't know why. So I have done it by trial and error, eyeing it in.



      RE: choo-choo sounds

      >if it uses Variable1 then
      >these values need to be
      >converted by a constant factor
      >(don't know why, but they
      >do). This factor seems to
      >vary from loco to loco,
      >again I don't know why.

      To my knowledge, the value of the Variable1 is the rotational speed of the wheel... in other words, it depends on the radius of the driving wheels. From this the lenght of the perimeter can be calculated (=2*pi*radius). Speed is a distance traveled per a time unit, the speed in MSTS is in meters/second to my knowledge... so, if the perimeter of the driving wheel is, say 3 meters, the wheel rotates 360 degrees during a second at the speed of 3m/s. And, henceworth, the sound sample triggered around Variable1 value of 3, should have 4 chuffs (depending on the number of cylinders) during one second. And the other speeds can be calculated from that.

      I think I tested this once, but I'm not 100% sure.


        RE: choo-choo sounds


        In the real world if track speed (Speed) and wheel rotation (Variable1) are both measurements of linear velocities (as opposed to one being an angular velocity) then by virtue of the fact the wheels turning moves the loco along then Speed and Variable1 must have the same value for the same set of units. Except of course if slip is occuring at the wheel-track interface, when Variable1 will exceed Speed. Whilst this latter effect does occur in the sim the former doesn't. ie Speed and Variable1 seem to have different value. It's easy to test out. Have a cab view .sms set for Speed and an external view .sms set for Variable1, all trigger values being the same. Accelarate, not to fast, in the sim and see if the sounds in the cab and externally sync. I've tried this agian now, and they don't. They should, but in the sim they don't. My belief is that the sim doesn't use one to calculate the other. They are calculated separately, or related to separate parts/functions of the sim. So when you change Speed to Variable1 you need to re-time the triggers.


          RE: choo-choo sounds

          >then by virtue of the
          >fact the wheels turning moves
          >the loco along then Speed
          >and Variable1 must have the
          >same value for the same
          >set of units. Except of

          Yeah, unless the wheel radius value is wrong. But, I guess it doesn't work like that then.

          There must be a some kind of formula for the Variable1... I hope we find out what it is. It would help making realistic sounds, it would be possible to accurately calculate the needed intervals for the chuffs.

          Someone said the Variable1 seems to vary from locomotive to locomotive... I wonder how. It shouldn't, if the wheel radius is correct. Of course I mean steam locomotives, the Variable1 is different in diesels and electrics.


            RE: choo-choo sounds

            About a month ago I downloaded a new steam engine from UKtrainsim which, as usual, used the SCOTSMAN sound and cab views. When I took it for a first run I noticed that the sound raced away, sounding flat out at only 30mph. And when I looked at the wheel rotations they were clearly rotating too slow against the track speed. So I checked the wheel rads given in the .eng file and these were prototypical. Regardless I started to adjust the values till I got correct looking wheel rotation. This, eyed in, happened at a rad of about half what it should have been. I raised this with the modeller. He advised that when animating the wheels he couldn't get a smooth motion with the usual 8 frames so used 16. He apologised for not correcting the rad because he knew that doubling the animation frames mean't having to halve the wheel rad in the .eng file in order to get correct sim time wheel rotation. Moral of this story... the prototypical wheel rad is not always the correct wheel rad! :-(


              RE: choo-choo sounds

              >He advised that when animating
              >the wheels he couldn't get
              >a smooth motion with the
              >usual 8 frames so used
              >16. He apologised for not

              Oh! I didn't know that MSTS would accept any other number of frames than 8. That's good to know.


                RE: choo-choo sounds

                There is a fix for this on the TrainSim.Com file libary. Which? I don't know, I don't DL from TrainSim.Com, because every time I download somthing from the site, BANG! .zip file corrupt...but it's ok from the message board.



                  RE: choo-choo sounds

                  Another item in steam engines, They sound different in the cab than outside. In the cab, the sound comes partly through the firebox, and has a deep, gut whacking chug, at least when working hard. There's also a lot of misc. rattling and other racket, steam hissing, and various clanking.

                  Outside, the exhaust is sharper, with less of a deep chug.

                  I've been changing my cab sounds with Sound Forge's EQ, humping up the bass, and slightly depressing the treble. It gives a nice effect, when you go from in cab to cab out view. The result isn't perfect, but much closer to my experience.



                    RE: choo-choo sounds

                    What I would like to know, is where do you find this
                    "Variable1" everyone keeps talking about? All I can see
                    in the .sms file is (Variable_Trigger)????

                    Thanks for the help


                      RE: choo-choo sounds

                      Look at UTILS\FFEDIT\ladstr.hdr as about 2/3 way thru it lists all the valid sms statements. Trial and error then lead to the discovery of what Variable1 did.


                        RE: choo-choo sounds

                        If I set up both of my "WheelRadius ( X.XXXXm )" lines in my
                        .ENG file to the proper "scale" radius, the chuffs come very
                        close to the "4 chuffs per 360 turn", but then they don't turn
                        fast enough to keep up with the track movment below.....

                        There's something else going on, we should be able to have our
                        .eng files set to the scale wheel radius, but it doesn't work
                        that way......

                        Go figure.....