[hansheijmans]

Hi all,

I am using an USB DAC (MicroMega MyDAC) in Kodi 15.2 on a Raspberry Pi 2 for playing audio files. When I have to select a device which represents my ALSA USB DAC I can choose from 2 options:

- ALSA: MICROMEGA MYDAC, S/PDIF
- ALSA: MICROMEGA MYDAC, Analog

The further options for either choice differ somewhat. With Analog I selected 2 audio channels with Number of audio channels (option is absent with S/PDIF). With S/PDIF I selected 192 with Limit sample rate (option is absent with Analog).

Which option (Analog or S/PDIF) should I choose to get the best (bitperfect) result and maybe does anyone know any technical differences? I feel like the Analog options sounds slightly better but that also be my imagination.

Thanks!

Hans.

[Ned Scott]

Which connection are you using on the USB DAC? The analog (red/white) jacks or the digital/SPDIF jacks (optical or coax)?

[hansheijmans]

It is an USB DAC so I am using USB...

[Ned Scott]

USB is how the sound gets to the DAC, but then the DAC sends it to something else, yes? An AMP, TV, headphones?

[hansheijmans]

The DAC sends its output to my amplifier using analog connections. But I don't see the relevance to my question which is about how Kodi sends its data to my DAC. DAC stands for Digital to Analog Converter otherwise if I would be using S/PDIF as output on my 'DAC' it would be an USB/SPDIF converter.

Or am I missing something?

[Ned Scott]

You asked if you should use the Analog option or the S/PDIF option for the audio output device as one of your questions. If you are using the analog port on the USB DAC, then that is what you should select in Kodi. Even if both options in Kodi produce sound out of the analog port, selecting the correct option will enable or disable other options that apply to your situation.

[hansheijmans]

@ned,
Thanks for your answer but I still don't think the output on my DAC is relevant to my question.


A more detailed discussion which might bring up the solution when hopefully answered by one of the people who are involved in development of Kodi or OpenElec can be found at the OpenElec forum:

http://openelec.tv/forum/68-audio/74168-...out#154377

[dex1701]

I agree, hansheijmans, outputting SPDIF from a DAC would eliminate the entire purpose of the DAC, unless you want to output from a computer with no sound hardware to a receiver with no analog inputs or something, which seems like an edge-case that nobody would bother supporting, IMO.

I know this is an old-ish thread, but I have the same question. I've tried both the "Analog" and "SPDIF" output devices that correspond to my USB DAC, and the audio appears to be getting run though some kind of mixing or resampling using both output devices. It would appear that a raw bitstream of the audio isn't an option with the last two versions of Kodi (since custom output devices went away along with the old audio engine). I'm basing this on feedback on my DAC's display as well as my ears. I can definitely hear a difference on tracks that I'm really familiar with...particularly classical ones. Heck, even my "the speakers built into the TV sound fine" wife can hear a difference. The instruments and some vocals sound a bit "muffled" or "soft." This is common when audio is being run through a mixer or resampled.

I guess I'm going back to Volumio for now, as the output through my DAC sounds better, but I'm not happy about it. Kodi is perfect for my use case in every way except for this issue, and it's a deal-breaker for me. I'm frustrated with library management, lack of source options, being limited to a web-based front-end, inability to use an IR remote, etc. with Volumio, but audio quality trumps those frustrations. It's disappointing, but I guess we're in the minority with this issue and we're not Kodi's target demo., so it's understandable that it's not a priority for them. I am eagerly awaiting some kind of fix or workaround, however. I'm not familiar with the new audio engine being used, so I have no idea if a fix or workaround is even possible.

[albertstroh77]

I also use a fancy DAC with my kodi. Works like a charm. The one thing I don't see anyone mentioning that you need to get the DAC to work is passthrough enabled. You need to send a digital signal to the DAC and it sends the analog out. I can't tell a difference with either of those two outputs after that is enabled. You should have a clean, crisp sound after that.

[Ned Scott]

@ned,
Thanks for your answer but I still don't think the output on my DAC is relevant to my question.


A more detailed discussion which might bring up the solution when hopefully answered by one of the people who are involved in development of Kodi or OpenElec can be found at the OpenElec forum:

http://openelec.tv/forum/68-audio/74168-...out#154377

You have two options in Kodi because you have two types of output on your DAC. You were asking what the difference was, and I've told you. "USB" is not an audio output type. Kodi and OE is interfacing with your DAC *over* USB, and then controlling things on the DAC itself, so yes, it matters.

I agree, hansheijmans, outputting SPDIF from a DAC would eliminate the entire purpose of the DAC, unless you want to output from a computer with no sound hardware to a receiver with no analog inputs or something, which seems like an edge-case that nobody would bother supporting, IMO.

You're posting in the Raspberry Pi sub-forum. The Raspberry Pi does not have SPDIF, so some people use a USB DAC to get a SPDIF connection. This is not an edge case, but one of many very common configurations.

I know this is an old-ish thread, but I have the same question. I've tried both the "Analog" and "SPDIF" output devices that correspond to my USB DAC, and the audio appears to be getting run though some kind of mixing or resampling using both output devices. It would appear that a raw bitstream of the audio isn't an option with the last two versions of Kodi (since custom output devices went away along with the old audio engine). I'm basing this on feedback on my DAC's display as well as my ears. I can definitely hear a difference on tracks that I'm really familiar with...particularly classical ones. Heck, even my "the speakers built into the TV sound fine" wife can hear a difference. The instruments and some vocals sound a bit "muffled" or "soft." This is common when audio is being run through a mixer or resampled.

The only bitstream options in Kodi were passthrough options, and those are still there. Bitstreaming means you're not using your DAC's analog output, which you just said was an edge case. These options are not controlled through the output device option.

If you are using the analog output then you do not want the bitstream/passthrough options.

I guess I'm going back to Volumio for now, as the output through my DAC sounds better, but I'm not happy about it. Kodi is perfect for my use case in every way except for this issue, and it's a deal-breaker for me. I'm frustrated with library management, lack of source options, being limited to a web-based front-end, inability to use an IR remote, etc. with Volumio, but audio quality trumps those frustrations. It's disappointing, but I guess we're in the minority with this issue and we're not Kodi's target demo., so it's understandable that it's not a priority for them. I am eagerly awaiting some kind of fix or workaround, however. I'm not familiar with the new audio engine being used, so I have no idea if a fix or workaround is even possible.

Please start a new thread about this and give details on your hardware. Tell us what version of Kodi you are using, what your HTPC is (is it a Pi, etc) what exact DAC you are using, and if your final output is analog or not. The more details the better.

I also use a fancy DAC with my kodi. Works like a charm. The one thing I don't see anyone mentioning that you need to get the DAC to work is passthrough enabled. You need to send a digital signal to the DAC and it sends the analog out. I can't tell a difference with either of those two outputs after that is enabled. You should have a clean, crisp sound after that.

No, you do not enable passthrough to use a DAC's analog output. You use passthrough to send a passthrough signal over the DAC's SPDIF connection, and that is all. The passthrough option has no impact on the Pi to DAC part of the connection.

[albertstroh77]

Thanks for your response, Ned. I could very well be mistaken, but it's been my experience that you DO need passthrough enabled to make a DAC work correctly. When I don't, the sound quality suffers and sounds like the guy going back to Volumo is discribing. It sounds like the crappy DAC in the computer is being used. I have half a dozen DAC's and it's like this with all of them. We pay big money for that sound, and when it's not working correctly, I can instantly tell.

They all show the two options talked about earlier, but no matter wich of the two you pick, they all output to the rca. Think about it, if a DAC has a spdif, it is an input, not an output. They only output to rca or xlr. All inputs are a digital signal and the device outputs a analog signal.



Zdac is the dac. Either option selected sends the signal through the usb to the dac. And the sound quality is only there when passthrough is also checked.

Like I said, I wouldn't be surprised if I'm missing some part of the puzzle, but that is definitely how it works on my systems.

[albertstroh77]

Just checked my other type of setup here, signal into hdmi, sound extractor, spdif to dac. Passthrough is required here too, to make the digital sound go through the hdmi to be decoded by the dac.

The digital signal has to be sent to the dac. If you send an analog signal out, it's already been decoded by the pc, thus the crappy sound quality.

Dex1701, does enabling paasthrough give you the sound quality you're looking for?

[Ned Scott]

It's all digital. Passthrough is specifically sending an untouched datastream over HDMI or SPDIF. Your DAC can probably decode a passthrough signal, but it should make zero difference to an analog interface for a USB sound card.

A signal can still be entirely digital without using passthrough.

[albertstroh77]

How is this not the exact purpose that passthrough was created for? You don't want the inferior dac in the pc to do the decoding so we use passthrough to let the dac/processor do the decoding of the untouched signal. The two signals are very different. Both analog signal or a digital one is sent out of the hdmi, depending on weather passthrough is checked or not. Usb signal to the dac seems to follow this same pattern.

[albertstroh77]

Maybe I'm way off base and it's more like pcm vs analog in the usb, the point is it doesn't sound like the dac until I enable passthrough. The whole point of passthrough is to pass the unadulterated signal through and let you dac/ processor handle all decoding. I'm just trying to help the guy stick with kodi. The difference is huge. Not all digital signals are equal.

With no passtrough, my processor has only pcm lights on. When you enable it, dts or whatever kind of audio it is lights come on. There is plenty of difference in digital signals.