Can I use my FIR filter to change the audio on my hdmi video input?

mark_gb

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Hi, I have a FIR filter that gives great results with Roon for audio as an input to my Linn Klimax DSM and I would like to apply it to video audio as well.

I am currently using an Oppo 105 blu ray player with an attached Amazon fire stick, which provides hdmi to the Linn streamer. Ideally I would like an hdmi in to hdmi out box that can apply the FIR filter to the hdmi signal before it reaches the streamer. As a second best, I would consider buying an alternative to the Oppo. But whatever the option, I would like to use my existing filter, stay in the digital domain, and output hdmi.

is this possible?

Many thanks, Mark
 

ddude003

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Maybe your looking for something like the MiniDSP nanoAVR HD... https://www.minidsp.com/images/documents/Product Brief-nanoAVR.pdf
PS, I have no experience with this product I am just aware that MiniDSP has many products like this... Maybe someone out there in AVNirvana land has some hands on with this or another suggestion...
 

mark_gb

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Thanks yes, I had found a couple of mentions of this online, but understand this product has been discontinued with no replacement and even if I got hold of one 2nd hand (which looks like a challenge), I'm not sure if I can just load in my existing FIR filter?
 

Kal Rubinson

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Hi, I have a FIR filter that gives great results with Roon for audio as an input to my Linn Klimax DSM and I would like to apply it to video audio as well.

I am currently using an Oppo 105 blu ray player with an attached Amazon fire stick, which provides hdmi to the Linn streamer. Ideally I would like an hdmi in to hdmi out box that can apply the FIR filter to the hdmi signal before it reaches the streamer. As a second best, I would consider buying an alternative to the Oppo. But whatever the option, I would like to use my existing filter, stay in the digital domain, and output hdmi.

is this possible?

Many thanks, Mark
Yes. The miniDSP nanoAVR will do that exactly. Quite easy to use, too.
 

JStewart

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Thanks yes, I had found a couple of mentions of this online, but understand this product has been discontinued with no replacement and even if I got hold of one 2nd hand (which looks like a challenge), I'm not sure if I can just load in my existing FIR filter?
I have one around here somewhere I can part with. If you’re in the US and interested you’re welcome to pm me.
I won’t have the original packaging.
I believe its hdmi 1.4 so no 4K video if that’s a concern.
I would want to check on obtaining the software for you.
It‘s a really busy time for me so I won’t be able to respond quickly.
 

mark_gb

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I have one around here somewhere I can part with. If you’re in the US and interested you’re welcome to pm me.
I won’t have the original packaging.
I believe its hdmi 1.4 so no 4K video if that’s a concern.
I would want to check on obtaining the software for you.
It‘s a really busy time for me so I won’t be able to respond quickly.
Thanks, pm sent
 

mark_gb

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To clarify, can anyone confirm that the miniDSP nanoAVR convolves full linear phase FIR filters, not just parametric EQ / IIR / biquads?
 

JStewart

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To clarify, can anyone confirm that the miniDSP nanoAVR convolves full linear phase FIR filters, not just parametric EQ / IIR / biquads?
Kal said yes and I’m sure he would be correct, but still happy to confirm this weekend for you. Given your location I understand you want to be 100%.
 

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Does the miniDSP nanoAVR really handle FIR filters? It is not clear to me that they have that capability. If they do, then they would also need to be compatible with the sample rate and tap number of the OP's existing FIR filter. Otherwise filter changes would be needed. I don't have any experience with this box so I may not be correct about its capabilities. I only noted that the below comment is offered on the MiniDSP website, and I didn't find FIR filters mentioned in the nanoAVR information.

From the miniDSP website:
"Looking for an Audio processor with FIR or IIR support?
Check out the OpenDRC series (FIR) or miniDSP series (IIR) @ miniDSP.com"
 

mark_gb

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Section 5.3.2 of the HD and HDA manual (I can't include the link as I don't have 10 posts yet - it is on the minidsp website under support - legacy products) talks about importing a file from REW but it isn't clear whether this has to be a particular configuration type or can be any FIR filter.
 

JStewart

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Section 5.3.2 of the HD and HDA manual (I can't include the link as I don't have 10 posts yet - it is on the minidsp website under support - legacy products) talks about importing a file from REW but it isn't clear whether this has to be a particular configuration type or can be any FIR filter.
Manual.
 

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JStewart

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Looks like @jtalden is correct.

For reference here is the UI from my 2x4HD. Note the separate section to import FIR filters vs PEQ filters.

2022-06-22.png



This is the UI for the Nano AVR HD. Note the lack of an FIR filter section.

52618

,

Thinking there may be a different MiniDSP "plug-in", I logged into the user downloads section and the only available is:
52619


The version I'm running is 1.12.

The section in the manual referring to REW EQ section I believe is referring to this. Note that the NanoAVR is a selectable equalizer. When used REW will generate biquads.

52620



Sorry @mark_gb .
 

mark_gb

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Well I know much more than I did a couple of days ago thanks to your help!

So if I can buy a second-hand nanoAVR for the UK I still have the option of generating biquads in REW, which will be better than my current situation of superb music and obviously suboptimal video audio.

My original goal is:
- Take hdmi input
- Use my existing linear phase FIR filter,
- Stay in the digital domain
- Output hdmi

Are there any other ways of achieving it?

Many thanks

Mark
 

JStewart

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Have you already considered using an hdmi audio extractor?
Something like this


connected to minidsp flex digital version to Linn.

One thing that didn’t occur to me until now. FIR/Convolution filters are typically higher latency. Possibly high enough to cause lip sync problems if video is not delayed to match. Perhaps that’s why minidsp did not have fir on the nano avr?
 

mark_gb

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The only digital inputs to the Linn are hdmi and ethernet streaming. For music, I stream using Roon from a QNAP NAS. For video (including video audio), hdmi is the only option. I'm only HD currently, not 4K. The Oppo only supports hdmi 1.4 but I also only have an HD projector.

Yes, you're right, latency could be an issue. I can set delay on both the Oppo and the Firestick but I would need to check that there is a large enough max.

Mark
 

JStewart

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The only digital inputs to the Linn are hdmi and ethernet streaming. For music, I stream using Roon from a QNAP NAS. For video (including video audio), hdmi is the only option. I'm only HD currently, not 4K. The Oppo only supports hdmi 1.4 but I also only have an HD projector.

Yes, you're right, latency could be an issue. I can set delay on both the Oppo and the Firestick but I would need to check that there is a large enough max.

Mark
Im not familiar with those devices, but in case I wasn’t clear, they typically offer audio delay. In the case of high latency audio, it’s the video that needs delayed.
 

ddude003

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The only other thing that comes to mind would be a Hauppauge Colossus HDMI capture card with HDMI in and out (PCI Express) in a HTPC running JRiver Media Server...

And for the Do It Yourselfers... The Raspberry Pi 4 has two HDMI ports...
 
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mark_gb

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Latency is a really good point. The Oppo allows negative audio delay correction but only up to -100 ms, I currently have it set at +30, this gives me 130ms but I think my existing FIR might result in substantially more than that. I was optimistically hoping there might also be an additional video delay option on my JVC DLA-HD750 projector but it doesn't look like there is. The Linn only has +ve audio delay.

The only other thing that comes to mind would be a Hauppauge Colossus HDMI capture card with HDMI in and out (PCI Express) in a HTPC running JRiver Media Server...

And for the Do It Yourselfers... The Raspberry Pi 4 has two HDMI ports...
Presumably JRiver Media Server on an HTPC with hdmi in/out using the suggested card takes care of latency?

I've not looked into HTPCs before - this is another new world! I have a QNAP TS-253 Pro NAS but I guess there's no flexibility to add an hdmi input. Can you recommend a relatively cheap HTPC that will give the performance I need to run the JRiver convolution that takes the recommended card?

Lastly, I did see something about CamillaDSP with a Raspberry Pi but I would be starting from zero knowledge of a Raspberry Pi and have no experience with Linux so this would be a substantial long-term project!

Many thanks

Mark
 
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