k_nenad
Posts: 5
Joined: Wed May 27, 2015 7:32 pm

Pi DAC vs HDMI audio

Wed May 27, 2015 7:55 pm

Hi,
Does anybody have an idea how would audio from a DAC like Wolfson or HiFiBerry RCA output compare to audio from the HDMI taken through a HDMI to AV converter like
http://www.ebay.com/itm/231522682942
or
http://www.ebay.com/itm/HDMI-to-HDMI-Op ... 2c93fed97b
?
Are there any specific pros and cons for using either option?
Thanks,

Tom_A
Posts: 272
Joined: Fri Dec 06, 2013 8:34 am

Re: Pi DAC vs HDMI audio

Sat May 30, 2015 6:40 am

The advantage to the DAC is that you might not be plugging into something that has HDMI. The analog audio is only fair and crackles at low audio when an audio channel is open. The use case for the DAC is to avoid using the analog audio. The HDMI audio is really good.

k_nenad
Posts: 5
Joined: Wed May 27, 2015 7:32 pm

Re: Pi DAC vs HDMI audio

Sat May 30, 2015 9:13 pm

Thanks, but not quite what I was aiming for. The HDMI output goes to HDMI-to-AV converter, which I suppose has the same function as the DAC. So the sound output from the converter should be more or less the same quality as DAC output, if I'm correct?

Tom_A
Posts: 272
Joined: Fri Dec 06, 2013 8:34 am

Re: Pi DAC vs HDMI audio

Sun May 31, 2015 3:08 am

k_nenad wrote:Thanks, but not quite what I was aiming for. The HDMI output goes to HDMI-to-AV converter, which I suppose has the same function as the DAC. So the sound output from the converter should be more or less the same quality as DAC output, if I'm correct?
I would think so. They are both coming from digital sources. There might be some variation between brands of equipment, but I'd expect the results to be go either way. The DACs that are in the form of a HAT, I think, require special drivers. I'm not sure if they have built that in yet. I did see one for sale somewhere that combined the amp in the card so you could wire it directly to speakers. Only think I didn't like about this solution is it doesn't fit inside the cases I've bought.

FM81
Posts: 518
Joined: Wed Apr 17, 2013 4:33 pm

Re: Pi DAC vs HDMI audio

Sun May 31, 2015 5:59 am

k_nenad wrote:So the sound output from the converter should be more or less the same quality as DAC output ...
In theory absolutely YES. But I didn't know, how "solid" these converters are build?

I assume you wish analogue (RCA) output in very good (or high) quality?
Hifiberry is a good choice; about Wolfson-card I didn't know, but it should be good too ...


Greetings, FM_81
A: What does the command 'cat /dev/urandom', can you tell me please?
B: Yeah, that's very simple: It feeds your cat with radioactive material!

User avatar
0xFF
Posts: 202
Joined: Tue Nov 20, 2012 7:52 pm
Location: Poland

Re: Pi DAC vs HDMI audio

Sun May 31, 2015 9:12 am

k_nenad wrote:So the sound output from the converter should be more or less the same quality as DAC output, if I'm correct?
More or less...

HDMI is not designed for audio. It's even worse than S/PDIF.
http://www.avsforum.com/forum/173-2-cha ... st20263655

The one and only purpose for I2S interface is sending audio data with separate clock & data.
http://www.tnt-audio.com/clinica/diginterf1_e.html
In theory, for high quality audio I2S DAC (ie Hifiberry) is better solution.

k_nenad
Posts: 5
Joined: Wed May 27, 2015 7:32 pm

Re: Pi DAC vs HDMI audio

Sun May 31, 2015 12:09 pm

0xFF wrote: More or less...

HDMI is not designed for audio. It's even worse than S/PDIF.
http://www.avsforum.com/forum/173-2-cha ... st20263655

The one and only purpose for I2S interface is sending audio data with separate clock & data.
http://www.tnt-audio.com/clinica/diginterf1_e.html
In theory, for high quality audio I2S DAC (ie Hifiberry) is better solution.


Thanks for the info. My only practical reason for using HDMI audio instead of HAT DAC is to have GPIO available for other things. So if the sound quality is more or less comparable, I would go with HDMI + converter.

k_nenad
Posts: 5
Joined: Wed May 27, 2015 7:32 pm

Re: Pi DAC vs HDMI audio

Sun May 31, 2015 12:14 pm

And I should probably add that the planned use is for a car system, so the sound does not need to be the best there is.

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cyrano
Posts: 714
Joined: Wed Dec 05, 2012 11:48 pm
Location: Belgium

Re: Pi DAC vs HDMI audio

Sun May 31, 2015 1:12 pm

0xFF wrote:HDMI is not designed for audio. It's even worse than S/PDIF.
http://www.avsforum.com/forum/173-2-cha ... st20263655

The one and only purpose for I2S interface is sending audio data with separate clock & data.
http://www.tnt-audio.com/clinica/diginterf1_e.html
In theory, for high quality audio I2S DAC (ie Hifiberry) is better solution.
Both those links are from well respected sources when it comes to hifi-idiots. You know, the kind that buys 1.000 $ power cables, and hears a difference. Or that can tell the difference between an upsampled 192 KHz 24 bit file that has been created from an mp3, coming from different brands of harddisk.

Jitter does matter IF you have a recording setup with multiple sources because it will affect syncing the clocks from these different sources that will have a slightly different conversion latency.

Jitter does not matter much for audio playback on a consumer level (eg output only at 16 bits, 44.1 KHz), if it remains in reasonable limits. And frankly, there is equipment out there that has jitter problems, but it is extremely rare. If a consumer level device sounds bad, it's usually because of lacking filtering, not because of jitter.

HDMI will do very well for playback in a car. It just needs good input. Most mp3's downloaded from the net sound awful because the person who created them has NO knowledge and no speakers that enable him to hear the difference.

If you rip your CD's, experiment a bit and listen to them on good speakers. It won't take more than a day or so to find your own personal best settings.

The new, emerging HD-audio scene is one big fraud. Masters for 99% of the music out there are 44.1 KHz, 24 bit. There's no way they will be re-recorded at higher sample rates, as there is no need to. So if an audio engineer gets a request for higher sample rate masters, he will usually upsample what is available. The other respons to the question: "These don't exist", will not make the customer happy. And engineers usually are friendly people who will do their best to please the customer.

That doesn't mean studio's aren't slowly starting to use higher sample rates. Some even go up to 192 KHz, but that's mostly in film studio's that specialize in surround film productions. For audio, not many will go over 96 KHz, because there is very little use for these higher sample rates. The only use is a couple of rather exotic plugins that can really use them.

k_nenad
Posts: 5
Joined: Wed May 27, 2015 7:32 pm

Re: Pi DAC vs HDMI audio

Mon Jun 01, 2015 7:13 am

Thanks for the extensive info

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