Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Raspberry Pi gets its own sound card

engadget.com

Post reply on HN
Print view View original

21–30 of 33 posts

Re: Raspberry Pi gets its own sound card

#21

Post by asb »

throwawayaway wrote: post #7
bananas wrote: post #2

I love the fact that a whole ecosystem has appeared around patching up the holes in the Pi's architecture[1]. Unfortunately by the time you've purchased them all, you probably could have bought a BeagleBoard instead. [1] The built in codec and filtering is absolutely horrible making it pretty useless for audio applications.

usually when people do [1] or something like that it's to a link. to my ear the audio out of the pi's hdmi port is perfectly fine. i think the DAC used in the RCA jack is probably not very good. I would pay for a HDMI audio to DAC adapter rather than $33 for another soundcard that just works with the pi.

Audio via HDMI is digital so there really are no problems there. The 3.5mm audio jack is just a simple PWM (see plots at http://www.crazy-audio.com/2013/11/quality-of-the-raspberry-...). Sound quality is actually quite improved upon the first release, but it's never going to be great.

Re: Raspberry Pi gets its own sound card

#22

Post by asb »

miahi wrote: post #11
nitrogen wrote: post #9

What bus is used to communicate with the sound card? The obvious candidate is USB, but the Pi's USB bandwidth is limited and I don't recall whether USB is available on the pin headers.

If it uses the P5 header, then it's I2C - so there are no USB issues. I remember reading about (other?) Wolfson DACs on Raspi and they were using I2C.

It's actually I2S primarily. I2C would be used for control (volume etc I suppose)

Re: Raspberry Pi gets its own sound card

#23

Post by lxa2 »

nitrogen wrote: post #9

What bus is used to communicate with the sound card? The obvious candidate is USB, but the Pi's USB bandwidth is limited and I don't recall whether USB is available on the pin headers.

there is no USB on the pin headers, unfortunately (Schematic: http://www.raspberrypi.org/wp-content/uploads/2012/10/Raspbe...)

Re: Raspberry Pi gets its own sound card

#24

Post by yardie »

jablan wrote: post #6
VexXtreme wrote: post #3

Nice. PI's built in audio processing is extremely crappy and the analog 3.5mm output is almost unusable for music.

How can I actually hear this? I am no audiophile, but I can't notice any audio problems with my Pi.

I used my Pi as an Airplay receiver connected to our hifi. It was pretty bad. But I have a v1 Pi a lot of corners were cut to get it out and under budget for early adopters.

Re: Raspberry Pi gets its own sound card

#25

Post by makomk »

the_ancient wrote: post #13
bananas wrote: post #2

I love the fact that a whole ecosystem has appeared around patching up the holes in the Pi's architecture[1]. Unfortunately by the time you've purchased them all, you probably could have bought a BeagleBoard instead. [1] The built in codec and filtering is absolutely horrible making it pretty useless for audio applications.

If you using it for HTPC then beagleboard is useless as it has no hardware based video decoding. That is why the Pi is so popular for HTPC's, built in H264 decoding hardware

The Beagleboard's probably a bad example in this case, but I've got a Cubieboard with hardware video decode and line-in/line-out that cost me less than the Pi + this board. (I believe it also has SPDIF on one of the pin headers. All of this was essentially free - the SoC it uses has built-in audio DAC/ADC, Ethernet controller, SATA, and a bunch of other neat stuff.) Plus a lot of early Pi purchasers won't be able to use this without buying another Pi, since the original version doesn't expose the I2S interface required by this.

Re: Raspberry Pi gets its own sound card

#27

Post by gardarh »

beagle3 wrote: post #5
bananas wrote: post #2

I love the fact that a whole ecosystem has appeared around patching up the holes in the Pi's architecture[1]. Unfortunately by the time you've purchased them all, you probably could have bought a BeagleBoard instead. [1] The built in codec and filtering is absolutely horrible making it pretty useless for audio applications.

I have a beaglebone black, but I can't get it to encode FullHD video in realtime. Am I missing something? or is there actually a justification for both the RasPi and the BeagleBone?

The raspi has a hardware video decoder for some codecs (e.g. H.264) whereas the bbb doesn't. Hence the bbb is not very practical for htpc setup.

Re: Raspberry Pi gets its own sound card

#28

Post by TkTech »

DiabloD3 wrote: post #26

Raspberry Pi has USB right? So why not just get a Schiit Modi? A very high quality DAC that can be entirely USB powered.

The USB on the Pi has some issues. A lot of devices need to use an external, powered USB hub because the board can't supply enough. Your ethernet is also going through the USB hub.

Re: Raspberry Pi gets its own sound card

#29

Post by throwawayaway »

jablan wrote: post #18
throwawayaway wrote: post #8

Earlier quoted context omitted.

apparently the DAC for the RCA out is 11bit - but I can't really find any definitive proof of that.

RCA? Isn't the RCA output for video only? I was referring to 3.5mm green audio output.

right you are - that's what I meant.

Re: Raspberry Pi gets its own sound card

#30

Post by throwawayaway »

jrabone wrote: post #15
throwawayaway wrote: post #8

Earlier quoted context omitted.

apparently the DAC for the RCA out is 11bit - but I can't really find any definitive proof of that.

That should be pretty easy to demonstrate by feeding the output back into a decent 16-bit soundcard - the noise floor should reveal any dithering going on (and if there's no dithering it will be painfully obvious that there's only 2048 discrete output values...) I might have a go tonight.

http://www.raspberrypi.org/phpBB3/viewtopic.php?p=103330 Might be of interest to you.
Post reply on HN