What is this thread for?This thread is intended to capture features that would improve jriver's ability to implement an active audio system for both stereo and multichannel use. JRiver has a v rich feature set for DSP that caters to some advanced use cases but also is missing some basic, and not so basic, features that standalone devices using off the shelf DSP chips have implemented. Filling these gaps would round out the offering nicely.
Active in this context is used somewhat loosely to refer to the use of digital filters to implement active crossovers and speaker/room correction.
Why do we need a thread for this?The subject has come up in at least 3 threads and various people (e.g. natehansen66, mwillems) have mentioned similar features before. Collecting them into 1 place makes it more likely that a cohesive design can be constructed and individual features prioritised accordingly. Obviously all this is predicated on jriver deciding to satisfy demand here.
"DSP" is also a particularly tricky string to search for without getting tons of noise in the results
What features do we want?I have put these into broad categories driven by how users would benefit.
PEQ/Crossover Flexibility1) add support for different HP/LP filter types (bessel, linkwitz-riley)what is it?
- let the user select the HP/LP filter type
any workarounds?
- cascade 2 filters to implement an LR
- no workaround for bessel
2) add a new filter type "all pass filter" to PEQwhat is it?
- allow user to select order (1st or 2nd), Fc (in Hertz) and Q of the filter
- the following definitions are used
1st order APF = 180 degree phase rotation
2nd order APF = 360 degree phase rotation
Fc = point at which 1/2 of the total phase rotation has been accomplished
- the reference implementation is the APF filter in
http://www.musicdsp.org/files/Audio-EQ-Cookbook.txtany workarounds?
- no
3) add a new filter type "advanced biquad" to PEQwhat is it?
- allow user to enter biquad parameters as per
https://yabb.jriver.com/interact/index.php?topic=98863.0(NB: this would be sufficient to implement the previous 3 requests)
any workarounds?
- no
4) allow shelf slopes >1what is it?
- the existing PEQ configuration for low/high shelf filters does not allow Q (shelf slope) > 1, this can be useful and is not precisely replicated by stacking shelf filters
any workarounds?
- effect can be approximated by manually stacking peaking filters on top
- the "advanced biquad" would suffice in place of this
NB: also flagged in the too easy thread ->
https://yabb.jriver.com/interact/index.php?topic=98734.msg699035#msg6990355) allow channel count and mixing target to vary independently in Output Formatwhat is it?
- separate dropdowns for channel count (1,2,5,...,n) and mixing target (2.0, 2.1, 5.1, 7.1 etc)
any workarounds?
- apply downmixing manually using PEQ
- NB: this workaround would be much easier to apply if (Ease of Use)/1 were implemented as then we should add something to wiki which provides the set of filters required to downmix correctly
Ease of Use & Interoperability1) provide the ability to export/import PEQ filter banks from/to a defined text formatwhat is it?
- a way to make life easier when you have a lot of filters to enter
- a way to interoperate with auto eq tools like Room EQ Wizard
- implementation could be similar to the convolution implementation or could be more like a DSP load/save
- should also be exposed as a MCWS/MCC command
any workarounds?
- no
2) provide greater granularity in Room Correction for distance settingwhat is it?
- allow choice of units in both distance (ft, mm) and time (ms)
any workarounds?
- use PEQ to specify delay
3) allow user to rename channelswhat is it?
- a way to make it easier to remember which channel is which in an active setup, e.g. replace "channel 10" with "SL-1" or Left with "L-2" (or whatever arbitrary string the user comes up with)
any workarounds?
- no
4) provide a graphical representation of the filters applied to each channelwhat is it?
- a sanity check on what you have configured
any workarounds?
- play a sweep through jriver and measure the electrical result via loopback in your measurement software (e.g. REW)
5) allow user to select which channels are displayed in the analyserwhat is it?
- put checkboxes next to each channel
any workarounds?
- install Voxengo Span which is a free 8 channel VST Plugin
- does not work for higher channel counts
6) change the name of the text field on the HS/LS entry screen from Q to Swhat is it?
- pedantry
- see
http://yabb.jriver.com/interact/index.php?topic=99096.msg686082#msg686082 for details
any workarounds?
- no