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  • Strange Stereo Issue in MIR Pro

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    Hi,

    In the first video you can see that I have the 1st Violins on the left with a close mic array in the centre. However, on the master output meter it can be seen that there is as much if not more signal going to the right channel. In the second video it can be seen that If I wind back the wet signal, the dry signal is in the correct spot, on the left.

    The output matrix can be seen in the picture.






  • The second video is set to "private", so I can't watch it, but judging from your description you're experiencing the expected behaviour.

    The first video shows that you have set the Icon to 100% wet. This means that there is no direct signal included in the output any more, that's why all the important positioning cues are missing. 

    To include at least a bit of direct ("dry") signal is mandatory to create realistic results with MIR Pro. Please keep in mind that MIR's impulse responses have been edited in a way that there are no remnants of the original direct signal any more, to avoid the inevitable, ugly phasing when mixing them from (at least) eight individual IRs.

    In addition, it seems as you're using the same microphone position for Main and Secondary Mic - this will increase the perceived wetness, as MIR won't produce direct signals for the Secondary Mic (to avoid confusion for the aforementioned positioning cues). It can considered best practice to use different positions for Main and Secondary Mics. 

    What's more: The Violins-Icon you point at is already past the imaginary "in-phase"-axis of your Main Mic. Due to the chosen microphone setup it will capture quite a bit of out-of-phase signals from the back due to its capsules being on the edge to a Figure Eight-polar pattern, which increases the impression of signals coming from the opposite direction.

    ... BTW: Your Boesendorfer will sound close to mono, judging from the video. :-)

    Kind regards,


    /Dietz - Vienna Symphonic Library
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    @Another User said:

    What's more: The Violins-Icon you point at is already past the imaginary "in-phase"-axis of your Main Mic. Due to the chosen microphone setup it will capture quite a bit of out-of-phase signals from the back due to its capsules being on the edge to a Figure Eight-polar pattern, which increases the impression of signals coming from the opposite direction.

    The same was happening with the violas. Is this not the whole idea of the mic capsules, to give a simulated stereo image of the source?. It sounds like what you are saying is that if there is no dry signal, we get a signal that in no way represents the actual position of the source.

    Thanks for the help. 😊


  • To rule out all unknown variables, please create a test session with just one mono source, set its Width to zero and feed it with pink noise (or another well-defined test signal, but not a sine wave). In MIR Pro activate only the Main Mic, use a pure cardioid-based stereo setup and keep the Dry/Wet ratio at default. Move the Icon from the left to the right and watch the stereo image. It should be more or less what you seem to expect as "normal".

    Now switch to a Blumlein Mic setup (i.e. two crossed Figure 8 capsules). You will see that the imaging "flips" to to opposite side as soon as the source crosses the 90° in-phase area (i.e. 45° to the left and the right of the Main Mics center axis, shown by the "arrow" of the microphone flower). The MicSetup you've chosen in your example is much like Blumlein biased towards the front, which explains the effect you hear and see.

    As soon as the direct signal component is completely missing (which is what happens when you keep MIR's signal path at 100%) Wet, the effect will be less predictable due to all the reflections and phase cancellations in the room, but similar. This is of course also true for a (always fully wet) Secondary Mic that points towards the back of the hall. 

    HTH,


    /Dietz - Vienna Symphonic Library
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    The pink noise source seems to remain 100% mono no matter where on the stage I place it and wet/dry ratio has zero effect on the left/right image. What is strange is that the MIR Pro pop up indicates that changing the wet/dry ratio is represented in its stereo output meter but Cubase's output meter stays mono. And the audio is completely mono. Not sure what is happening there. See video.

    Then I set up a violin staccato sample in VI Pro. Now the dry signal is very much on the left of the stereo field but the wet signal is again 100% mono if not more on the right. But if I point the source at 0.0° it immediately sounds better. But at -45° the positioning is lost completely. See second video

    Does this mean that I should really be pointing all my sources at 0.0°?. I always pointed my instruments at the conductor position as this is how players traditionally sit. But now I am questioning that approach as 0.0° or close to it seems to get far better results.

    I'm not sure about this behaviour. It does not seem to represent the way a sound source is processed in the real world.

    If I stand on your left side facing you at a -45° angle and speak to you , you are going to hear me more with your left ear. Your right ear will not be hearing the reverberated sound waves of walls as much if not more than my direct voice in your left ear. I understand that the right mic does not have a physical obstruction i.e. a cranium to contend with, but there should still be more signal reaching the left mic than the right. Distance also should play a role here.

    For such an advanced piece of software, I just think that this behaviour is counter intuitive.






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    @Another User said:

    [...]For such an advanced piece of software, I just think that this behaviour is counter intuitive.

    I'm not sure how to answer this reproach. I have the slight suspicion that you're somehow expecting a typical power-panning-like behaviour you would get from a simple algorithmic stereo reverb, but that's not how actual acoustics react (... sorry if I'm stating the obvious).


    /Dietz - Vienna Symphonic Library
  • I think this particular venue exaggerates the behaviour I am finding difficult to get my head around as it is very narrow. Also, when I point a violin (icon) that has upward facing sound holes at the right wall, I don't expect the reverb in the room to behave like I am pointing a megaphone at that wall. 

    Thanks for all the help.


  • Re. "directivity": Did you use the actual Instrument Profile for the violin, or just a General Purpose profile?

    In any case: We put enormous efforts in measuring the actual frequency dispersion patterns of most instruments used for the original Vienna Instruments back then (... we even developed a new measurement system for the task). If you already find MIR's behaviour "counterintuitive", it would be interesting to get your reactions to some of these directivity profiles. :-D

    -> https://www.vsl.info/en/manuals/mir-pro/think-mir#instrument-directivity-profiles

    Kind regards,


    /Dietz - Vienna Symphonic Library
  • Yeah, those flute lines are all over the place. BTW I always have the correct profile selected.

    I think if there was more information coming from the floor or the ceiling?. Especially when in the 'Conductor' position it would help. Then the 100% wet signal would provide more positional information.


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    @Another User said:

    I think if there was more information coming from the floor or the ceiling?. Especially when in the 'Conductor' position it would help.
     
    The weighting of the 8 (or 16) IRs relies completely on the aforementioned Directivity Profiles.
     
    In the upcoming MIR 3D you will be able to direct the players "Nose" towards the ceiling and the floor, too. You'll be able to check your theory then :-) 

    /Dietz - Vienna Symphonic Library
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    If I turn a trumpet or trombone player -45° then yeah, there would be a lot of reflection off the right wall. Same could be said for a cellist. But a harpist or a violinist turned -45° would have very little influence on the amount of signal bouncing off the right wall.

    @Another User said:

    The weighting of the 8 (or 16) IRs relies completely on the aforementioned Directivity Profiles.

    There seems to be issues with the way some of these profiles have been weighted.

    What we need is icons for specific instruments that don't point in any particular direction. Or a profile that offers a more balanced directivity. A tuba points straight up, as does a saxophone. If MIR 3D allows us to point instruments straight up or 45° down, put me down for a copy.


  • You know - MIR Pro is what it is until the overdue upgrade is ready for prime time. If you don't like the Directivity feature or its implementation, then please just use an Omni setting from the General Purpose Profile selection for your sources and on you go. It's ok to do things differently - even an electric guitar wasn't invented to be played fully distorted :-) 

    Regards,


    /Dietz - Vienna Symphonic Library
  • I just went through a few profiles and they all seem to be accurate except the violins and violas. Violins and violas face upwards not horizontally. So I hope this gets fixed in the future and in MIR 3D. 


  • There's nothing to fix. I'm giving away MIR's crown-jewels for free here --- these are the deltas in respect to the 0°-axis like they are implemented in MIR Pro's Directivity Profiles for Solo Violin and Solo Viola: 

    Image

    Image


    /Dietz - Vienna Symphonic Library
  • PS: We all need a break from that Corona-virus, don't we ... ? 8-)

    Image


    /Dietz - Vienna Symphonic Library
  • If you could tell me which of the following you assigned to the orchestral violins profile I would appreciate it.

    99a, 99b, 99c, 99d, 99e, 99f, 99g, 99x

    P.S. I just added MIR as a plugin and that is what the icon looked like. There must be a bug. 


  • If _this_ is what the MIR Icon looks like on your system, then there's indeed something broken. 8-0 ... here you see the Icon's actual shape and the functions of all its elements.

    -> https://www.vsl.info/en/manuals/mir-pro/creating-new-project#mir-icon-overview

    If the problem persists please get in contact with support@vsl.co.at, including as many information about your setup as possible (OS type and version, host type and version, RAM size, CPU, any other kind of potentially influential hard- or software components).

    Re - Instrument Profile: If you're referring to the Orchestral Strings for Vienna Instruments, then there's a dedicated profile available for them (01/21), based on similar directivity measurement like the ones for the Solo Violin  shown in my previous posting (... which means that there is pronounced signal dispersion towards the ceiling). If you want to avoid any kind of directivity then please use the Omni-setting (00/99a) from the General Purpose profiles, or the Wide Cardioid (00/99b) if you want to hear at least a bit of emphasis towards the front.

    HTH,


    /Dietz - Vienna Symphonic Library
  • How do we delete posts on this forum?


  • The ability to delete posts is reserved for moderators, but you can edit the text you have written at any time. The only thing we kindly ask you to do is to briefly explain the reason for your changes in the text bar provided at the end of the post.


    /Dietz - Vienna Symphonic Library