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?
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.
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.
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 find quality in-ear headphones extremely revealing of poor quality output. Shure e5c, to pick an older set that I own, are especially unforgiving of noisy output stages and cross-coupled interference. The additional acoustic isolation really helps your brain focus on the audio by cutting out the masking effects of environmental noise. This isn't always a good thing.
For example, the Cowon S9 audio player was supposedly designed for high output quality, with a pile of DSP presets for EQ etc. With the e5c's you can really hear the poor quality processing of the EQ, especially on reverb tails. Have to turn the EQ off completely to eliminate them.
By EQ you are referring to equalizer? So if I don't use EQ on RPi (which I don't), I'm good? Is there some particular audio clip which I can sense the crappiness when listening to?
I was talking about a specific hardware player, but in general any additional signal processing has the potential to add artefacts.
To hear these sorts of things, listen for reverb tails on drum hits, high frequency percussion like cymbals, high-hats, solo human voice (we're quite good at hearing unnatural artefacts in voices) - that sort of thing. Beware it has to be good quality source material to start with though!
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.
It looks like the P5 header that it uses was only added in rev2, and "intended to be a suitable attachment point for ... audio codec boards"[1].
It's definitely a shame that things are fragmented, I was considering adding audio to my old Pi. But at least they're cheap enough to justify buying a second one :-)
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.
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.
The issue with usb on rpi is that it's unstable. It can drop messages. For ethernet it doesn't mean much, because packets will be retransmitted, but for audio it means sound will occasionally stop for a moment. It's very annoing.
The Schiit Modi is double the cost of the Wolfson card and has no audio input capabilities. Seems like for uses outside of an HTPC the Wolfson card provides a lot more flexibility.
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[ 3.0 ms ] story [ 86.2 ms ] thread[1] The built in codec and filtering is absolutely horrible making it pretty useless for audio applications.
almost every HDMI decoder chip has 4x I2S outputs and just spits out digital audio
for example ADV7604
Cheap chinese HDMI-2-VGA adapters use chinese made hdmi receivers, those lack proper i2s outputs and provide only 2 channel SPDIF. example: http://www.taker.im/up/138624609420664378890.jpg http://lontiumsemi.com/English/ProductShow.asp?ProductId=4
Offtopic, but footnotes predate the web by quite some time. If only we had a easy way of formatting super/subscript...
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¹ — https://en.wikipedia.org/wiki/Unicode_subscripts_and_supersc...
I might have a go tonight.
For example, the Cowon S9 audio player was supposedly designed for high output quality, with a pile of DSP presets for EQ etc. With the e5c's you can really hear the poor quality processing of the EQ, especially on reverb tails. Have to turn the EQ off completely to eliminate them.
To hear these sorts of things, listen for reverb tails on drum hits, high frequency percussion like cymbals, high-hats, solo human voice (we're quite good at hearing unnatural artefacts in voices) - that sort of thing. Beware it has to be good quality source material to start with though!
It's disappointing that this doesn't support v1.0 boards. I hadn't realised that RPis had been fragmented like that.
It's definitely a shame that things are fragmented, I was considering adding audio to my old Pi. But at least they're cheap enough to justify buying a second one :-)
[1] http://www.raspberrypi.org/archives/1929