Sound on the Kobo

fermino · 01-31-2021, 04:50 PM

So, I just saw that as a suggestion in other post and I thought it might be cool. I mean, I don't even have my reader yet and I'm super excited about ripping it apart hahah.

Anyways, I was thinking about a couple of things that could be done in order to have sound in the Kobo.
This is the datasheet for the Clara processor: https://www.nxp.com/docs/en/data-sheet/IMX6SLLCEC.pdf

There are four options I can think of, three of them are absolutely restricted by how exposed are the pins of the IC in the PCB.

1. Using the PWM outputs of the proc to make sound. I'm kind of assuming that the PWM is already used by the backlight controller, I'm not sure about it, but anyways PWM (unless it's really high freq) will not have a decent output quality.

2. Using the Bluetooth interface of the IC: This is doable, but I'm pretty sure that we'll need to add another IC and a custom board. I think this is the hardest option.

3. Using the I2S output and a DAC. There's an I2S interface already available in the proc, and if it's accessible, it shouldn't be *too* hard to be able to hook up a decent digital-analog converter to it, provided we can find the appropriate kernel driver.

4. Stream it through WiFi to another device. This is the most feasible, and it doesn't need to be your phone. With KoboX, we could create a fake output device and stream it over WiFi to another device. That device can be an ESP8266 with an I2S DAC and a 3.5mm jack. It would not involve modding the device (at least in an electronics level), and the receiver wouldn't be expensive or bulky. The cool part is that it's still WiFi, you can leave the reader somewhere else and, provided there's an access point, listen to whatever thing you have there. The quality should be pretty good, and this would open a lot of new possibilities.

Personally I'd love to see option 2 or 3 working, I mean, it would be reeaally cool. But the streaming option doesn't sound (pun intended) too bad either.

Anyways, this couple of weeks I'm going to be pretty busy but I'm willing to put some time on it.
Any suggestions? Anyone willing to dive into this rabbit hole with me?

Elektron · 01-31-2021, 05:00 PM

I think 4 would probably be the best option. The problem is KoBox is still a WIP; still some kernel and touch issues. Moving on, this is an absolutely fantastic idea! I'd be happy to test things out (I have virtually no experience with this kind of stuff).

NiMa · 01-31-2021, 05:07 PM

Quote:

Originally Posted by fermino

So, I just saw that as a suggestion in other post and I thought it might be cool. I mean, I don't even have my reader yet and I'm super excited about ripping it apart hahah.

Anyways, I was thinking about a couple of things that could be done in order to have sound in the Kobo.
This is the datasheet for the Clara processor: https://www.nxp.com/docs/en/data-sheet/IMX6SLLCEC.pdf

There are four options I can think of, three of them are absolutely restricted by how exposed are the pins of the IC in the PCB.

1. Using the PWM outputs of the proc to make sound. I'm kind of assuming that the PWM is already used by the backlight controller, I'm not sure about it, but anyways PWM (unless it's really high freq) will not have a decent output quality.

2. Using the Bluetooth interface of the IC: This is doable, but I'm pretty sure that we'll need to add another IC and a custom board. I think this is the hardest option.

3. Using the I2S output and a DAC. There's an I2S interface already available in the proc, and if it's accessible, it shouldn't be *too* hard to be able to hook up a decent digital-analog converter to it, provided we can find the appropriate kernel driver.

4. Stream it through WiFi to another device. This is the most feasible, and it doesn't need to be your phone. With KoboX, we could create a fake output device and stream it over WiFi to another device. That device can be an ESP8266 with an I2S DAC and a 3.5mm jack. It would not involve modding the device (at least in an electronics level), and the receiver wouldn't be expensive or bulky. The cool part is that it's still WiFi, you can leave the reader somewhere else and, provided there's an access point, listen to whatever thing you have there. The quality should be pretty good, and this would open a lot of new possibilities.

Personally I'd love to see option 2 or 3 working, I mean, it would be reeaally cool. But the streaming option doesn't sound (pun intended) too bad either.

Anyways, this couple of weeks I'm going to be pretty busy but I'm willing to put some time on it.
Any suggestions? Anyone willing to dive into this rabbit hole with me?

I see some headaches coming up...

I'd say that option 4 could be doable. You'd have to use Icecast2 (which gave me more headaches than I ever thought it would) and with some enormous luck you'd have a working audio server on your Kobo.
But the real question is why would you want to do that? If you stream via Wi-Fi, you already have some device nearby which you plug your headphones into. And the likely case is that this device can also play audio...

Elektron · 01-31-2021, 05:52 PM

Hm. Fair. You could (and I'm gonna go out on a limb for a second here) somehow add a 3.5mm jack and audio drivers and then somehow integrate this into nickel.

NiMa · 01-31-2021, 06:04 PM

Quote:

Originally Posted by Elektron

Hm. Fair. You could (and I'm gonna go out on a limb for a second here) somehow add a 3.5mm jack and audio drivers and then somehow integrate this into nickel.

Maybe (if that thing even exists) a wi-fi dongle with a 3.5 mm jack that you'd attach to the Kobo

EDIT: better, you somehow stick that in the case and you drill a hole for the jack

fermino · 01-31-2021, 06:21 PM

So, technically it should be possible to put a 3.5mm jack, but it would require a custom board that talks to the processor in the Kobo (and converts the digital signal to analog), that if and only if the processor pins for the I2S bus are accessible and we find/make a driver for that. Anyways, I see a lot of headaches on that one.

But the 4th is actually quite simple. I mean, for sure it will take some time to have it all working, but once it does making the receiver is actually not that hard.

We'd need to choose an audio compression scheme that is a good tradeoff between quality and speed (I'm pretty sure we should go with UDP here, to start maybe uncompressed audio would be better) and then have that talk to an ESP8266 (it's a programmable chip with an integrated wifi controller). Then that board would talk to a digital to analog converter that goes to the jack.

If there's enough space, we could even jam it inside the Kobo, in the meantime, I found this: https://github.com/chunter1/ESP8266_WLAN_speaker

It still uses PWM so the quality is kind of crappy but it might give us some hints about the streaming part.

We shall see

Btw, we don't need IceCast, if we can make it work with ffmpeg/avconv, which is, if we can make it work in any Linux pc, it shouldn't be too hard to make it work on the Kobo, that should ease things up a little bit.

NiMa · 01-31-2021, 06:23 PM

Quote:

Originally Posted by fermino

So, technically it should be possible to put a 3.5mm jack, but it would require a custom board that talks to the processor in the Kobo (and converts the digital signal to analog), that if and only if the processor pins for the I2S bus are accessible and we find/make a driver for that. Anyways, I see a lot of headaches on that one.

But the 4th is actually quite simple. I mean, for sure it will take some time to have it all working, but once it does making the receiver is actually not that hard.

We'd need to choose an audio compression scheme that is a good tradeoff between quality and speed (I'm pretty sure we should go with UDP here, to start maybe uncompressed audio would be better) and then have that talk to an ESP8266 (it's a programmable chip with an integrated wifi controller). Then that board would talk to a digital to analog converter that goes to the jack.

If there's enough space, we could even jam it inside the Kobo, in the meantime, I found this: https://github.com/chunter1/ESP8266_WLAN_speaker

It still uses PWM so the quality is kind of crappy but it might give us some hints about the streaming part.

We shall see

Btw, we don't need IceCast, if we can make it work with ffmpeg/avconv, which is, if we can make it work in any Linux pc, it shouldn't be too hard to make it work on the Kobo, that should ease things up a little bit.

Yeah, I thought of IceCast2 for streaming the entire audio output of the virtual soundcard. Avconv is good, but playing mp3s is sometimes not enough...

fermino · 01-31-2021, 06:23 PM

Oh, I forgot. Yes, for sure streaming to a phone or another big device is totally pointless, but if we manage to get that thing working and there's not enough space inside the Kobo I can for sure see an iPod mini sized receiver (those 1-inch side x 1-inch side).

fermino · 01-31-2021, 06:25 PM

Quote:

Originally Posted by NiMa

Yeah, I thought of IceCast2 for streaming the entire audio output of the virtual soundcard. Avconv is good, but playing mp3s is sometimes not enough...

You're right, I'll try to stream from my PC to another and if that works I'll slightly start moving towards the electronics part.

NiMa · 01-31-2021, 06:31 PM

Looking forward to your results!

Elektron · 01-31-2021, 10:41 PM

Why not go "to heck with it!!" and make it Bluetooth enabled? (You'd need a dongle though)

NiMa · 01-31-2021, 10:47 PM

Quote:

Originally Posted by Elektron

Why not go "to heck with it!!" and make it Bluetooth enabled? (You'd need a dongle though)

Much more than a dongle, I'd say

sidenote: I've PM'd you for the PEAP thing

fermino · 01-31-2021, 11:09 PM

Quote:

Originally Posted by NiMa

Much more than a dongle, I'd say

Yeap, BT would be hard. TBH I don't have the slightest clue about what module the Freescale proc would use (if we used its internal interface), and even if I knew it would probably take A TON of time to get it working plus the drivers.

Btw, I know the proc has USB OTG. Does the readers actually have it? That would make a ton of things easier. I mean, we could just hook up an USB sound adapter or a BT dongle.

fermino · 01-31-2021, 11:12 PM

BTW have any of you seen this before?
https://www.youtube.com/watch?v=9u4q...ixH%C3%A4dicke

NiMa · 02-01-2021, 08:27 AM

@fernino yes you can have USB OTG, but you have to compile the kernel module

01-31-2021, 04:50 PM	#1
fermino Member Posts: 10 Karma: 20000 Join Date: Jan 2021 Device: Kobo Clara HD	Sound on the Kobo So, I just saw that as a suggestion in other post and I thought it might be cool. I mean, I don't even have my reader yet and I'm super excited about ripping it apart hahah. Anyways, I was thinking about a couple of things that could be done in order to have sound in the Kobo. This is the datasheet for the Clara processor: https://www.nxp.com/docs/en/data-sheet/IMX6SLLCEC.pdf There are four options I can think of, three of them are absolutely restricted by how exposed are the pins of the IC in the PCB. 1. Using the PWM outputs of the proc to make sound. I'm kind of assuming that the PWM is already used by the backlight controller, I'm not sure about it, but anyways PWM (unless it's really high freq) will not have a decent output quality. 2. Using the Bluetooth interface of the IC: This is doable, but I'm pretty sure that we'll need to add another IC and a custom board. I think this is the hardest option. 3. Using the I2S output and a DAC. There's an I2S interface already available in the proc, and if it's accessible, it shouldn't be too hard to be able to hook up a decent digital-analog converter to it, provided we can find the appropriate kernel driver. 4. Stream it through WiFi to another device. This is the most feasible, and it doesn't need to be your phone. With KoboX, we could create a fake output device and stream it over WiFi to another device. That device can be an ESP8266 with an I2S DAC and a 3.5mm jack. It would not involve modding the device (at least in an electronics level), and the receiver wouldn't be expensive or bulky. The cool part is that it's still WiFi, you can leave the reader somewhere else and, provided there's an access point, listen to whatever thing you have there. The quality should be pretty good, and this would open a lot of new possibilities. Personally I'd love to see option 2 or 3 working, I mean, it would be reeaally cool. But the streaming option doesn't sound (pun intended) too bad either. Anyways, this couple of weeks I'm going to be pretty busy but I'm willing to put some time on it. Any suggestions? Anyone willing to dive into this rabbit hole with me?

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01-31-2021, 05:00 PM	#2
Elektron Banned Posts: 2,296 Karma: 5300240 Join Date: Jun 2020 Location: Edmonton, AB Device: Kobo Aura H2O Edition 2 (mark 7), Kobo Mini	I think 4 would probably be the best option. The problem is KoBox is still a WIP; still some kernel and touch issues. Moving on, this is an absolutely fantastic idea! I'd be happy to test things out (I have virtually no experience with this kind of stuff).

01-31-2021, 05:52 PM	#4
Elektron Banned Posts: 2,296 Karma: 5300240 Join Date: Jun 2020 Location: Edmonton, AB Device: Kobo Aura H2O Edition 2 (mark 7), Kobo Mini	Hm. Fair. You could (and I'm gonna go out on a limb for a second here) somehow add a 3.5mm jack and audio drivers and then somehow integrate this into nickel.

01-31-2021, 06:21 PM	#6
fermino Member Posts: 10 Karma: 20000 Join Date: Jan 2021 Device: Kobo Clara HD	So, technically it should be possible to put a 3.5mm jack, but it would require a custom board that talks to the processor in the Kobo (and converts the digital signal to analog), that if and only if the processor pins for the I2S bus are accessible and we find/make a driver for that. Anyways, I see a lot of headaches on that one. But the 4th is actually quite simple. I mean, for sure it will take some time to have it all working, but once it does making the receiver is actually not that hard. We'd need to choose an audio compression scheme that is a good tradeoff between quality and speed (I'm pretty sure we should go with UDP here, to start maybe uncompressed audio would be better) and then have that talk to an ESP8266 (it's a programmable chip with an integrated wifi controller). Then that board would talk to a digital to analog converter that goes to the jack. If there's enough space, we could even jam it inside the Kobo, in the meantime, I found this: https://github.com/chunter1/ESP8266_WLAN_speaker It still uses PWM so the quality is kind of crappy but it might give us some hints about the streaming part. We shall see Btw, we don't need IceCast, if we can make it work with ffmpeg/avconv, which is, if we can make it work in any Linux pc, it shouldn't be too hard to make it work on the Kobo, that should ease things up a little bit.

01-31-2021, 06:23 PM	#8
fermino Member Posts: 10 Karma: 20000 Join Date: Jan 2021 Device: Kobo Clara HD	Oh, I forgot. Yes, for sure streaming to a phone or another big device is totally pointless, but if we manage to get that thing working and there's not enough space inside the Kobo I can for sure see an iPod mini sized receiver (those 1-inch side x 1-inch side).

01-31-2021, 06:31 PM	#10
NiMa Fanatic Posts: 507 Karma: 2390534 Join Date: Jun 2020 Location: Somewhere in the Universe Device: Kobo Libra, Glo HD, Touch C/B, Mini, Glo, Aura SE, Clara HD, KT	Looking forward to your results!

01-31-2021, 10:41 PM	#11
Elektron Banned Posts: 2,296 Karma: 5300240 Join Date: Jun 2020 Location: Edmonton, AB Device: Kobo Aura H2O Edition 2 (mark 7), Kobo Mini	Why not go "to heck with it!!" and make it Bluetooth enabled? (You'd need a dongle though)

01-31-2021, 11:12 PM	#14
fermino Member Posts: 10 Karma: 20000 Join Date: Jan 2021 Device: Kobo Clara HD	BTW have any of you seen this before? https://www.youtube.com/watch?v=9u4q...ixH%C3%A4dicke

02-01-2021, 08:27 AM	#15
NiMa Fanatic Posts: 507 Karma: 2390534 Join Date: Jun 2020 Location: Somewhere in the Universe Device: Kobo Libra, Glo HD, Touch C/B, Mini, Glo, Aura SE, Clara HD, KT	@fernino yes you can have USB OTG, but you have to compile the kernel module

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