Using DSP with the Hxxx's Enabled Optical Out

[ReliquaryOle]

Is it verboten to make a feature request and then post on the same topic on a Rockbox forum?  If so, please disregard this thread.  If not, read on.

Having connected a headphone amp to a DAC and then to the H140's enabled optical out, I've discovered said out is true -- that is, it bypasses amp controls and digital signal processing completely (volume, treble, bass, EQ, etc.).

While a true optical line out is preferable to the non-bypassing sort in most circumstances, there are certain cases when digital signal processing would be useful.  Right now, for example, I'm listening to a harsh Venetian Snares track through questionable Audio-Technica clip-ons and would very much appreciate the ability to dial down the higher frequencies.

Does anyone else miss this feature?  If so, how easy would it be to implement?

Another feature on my wishlist:  Decremental controls for treble and bass (treble:  0 to -6, bass:  0 to -24), for quick adjustments under tinnitus-inducing circumstances in transit.  During a train ride, I'd find it useful to have swift access to a single control for turning down treble.  In transit, adjusting the volume can be insufficient protection against hearing loss; often, the damage is done not by painful volume but by attempts to hear inaudible frequencies over transportation's rumble.  Even the most isolating IEMs in the world can't shut it out completely.

[Llorean]

Feature requests are mostly pointless here. As you've noted, the correct place to put one is on the tracker.

[ReliquaryOle]

This isn't a feature request.  Rather, it's an attempt to discuss certain feature ideas with other users.  Subsequent posters would not be people who were expected to implement/reject the suggestion but, rather, who might have something to say about the idea aesthetically.

To rephrase my subject header as a user-oriented question:  "Would Any of You Have Reason to Use DSP with an Optical out?"

On head-fi.org, for example, a number of members bought HXXX players recently to use with external DACs.  I might have posted this thread in Head-fi's Portable Audio Forum; I thought I'd try Rockbox's more specific forums instead.

Edit:  Having just read the specific and diagnostic FAQs in Llorean's sig, I'll apply their criteria and search through all other FAQs thoroughly before posting anything further.

[LinusN]

Does anyone else miss this feature?  If so, how easy would it be to implement?

See my reply in the tracker

Another feature on my wishlist:  Decremental controls for treble and bass (treble:  0 to -6, bass:  0 to -24), for quick adjustments under tinnitus-inducing circumstances in transit.

I'm not sure what you're after here, but the bass/treble settings are dependent on the codec. If it allows negative gain, Rockbox does too.

For example, the UDA1380 in the iriver H100 and H300 doesn't have negative gain, only positive.

[ReliquaryOle]

See my reply in the tracker

Thanks for your swift reply.  I suppose the main reason it isn't useful to discuss such things on a developer's forum is because boolean answers need not be picked apart by users:  if the possibility isn't there, then variables of usage become irrelevant.

I'm not sure what you're after here, but the bass/treble settings are dependent on the codec. If it allows negative gain, Rockbox does too.

What I'm after is the hearing-preserving dampening of higher frequencies through a single control that is easily enabled/defeated in transit.  (Then again, I suppose an EQ setting is easy to enable/defeat as well.)

Thanks for your answer; I'll look into this and create a few drastic EQ settings for that purpose.  (Strange, that treble/bass can be codec-dependent when EQ is not.)

[pabouk]

(Strange, that treble/bass can be codec-dependent when EQ is not.)

Probably you misunerstood Linus. He was talking about the hardware codecs (DA converter and related circuits). You probably meant software codecs.

[Febs]

Just create a .cfg file for each of the various EQ settings that you need, and store those .cfg files in an easily accessible location, like the root directory or a high-level folder.  (I have a folder called /settings.)  This will allow you to make changes easily.

Incidentally, my IEMs (Shure E4) allow me to listen to music a non-tinnitus causing levels on planes and on the subway.