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USB audio on the Moto G?

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By UnknownAX, Senior Member on 24th November 2013, 01:11 PM
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I already found out, that the Moto G supports USB OTG, but would it support USB DAC's (digital-analog audio converter) ? If any Moto G owner owns a USB Dac or atleast something compareable like a USB headset or USB headphones, I'd be really thankfull if you could try it out.
The dac/headset needs to be plugged into the phone using a USB OTG cable.
Thanks!

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24th November 2013, 06:36 PM |#2  
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Works!! BUT:
I hooked an USB-OTG to Moto G, in there a Creative USB Soundcard with analog/digital output. Analog didn't work (must be the soundcard), but digital. I connected the digital out with a light cable to my RME environment and I could hear the music but with wrong frequency and crackled - but it works
Moto G has enough power to let the soundcard work.

[edit]
Hooked another soundcard in, this time analog works but wrong sample frequency and oversaturated, no option to control the volume.
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24th November 2013, 10:02 PM |#3  
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Wow! This phone seems to be even more incredible value than I ever thought.

The problems that you mention sound pretty weird, though. The first thing that I'd suspect is the lack of special drivers for the soundcards on the Moto g. Maybe a simple DAC that doesn't need any special drivers would work better.

In fact, stock androids rarely work with any USB audio devices. But there's a app that includes special drivers and makes most USB-OTG enabled droids work with USB audio devices. You can the trial version (link in the description of the app) of it if you like:
https://play.google.com/store/apps/d...order+pro+demo

Be aware that the trial only works for 15 minutes and it doesn't play the usual audio formats. ( .flac works) If you try it, you should put a flac on the phone before installing the app.

Oh, and who knows how well this might work when CM and KitKat arrive!

Thanks a lot for your help.

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24th November 2013, 10:37 PM |#4  
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With the app it works, without stuttering and you can control the output volume, although there was an error warning at startup regarding main volume
I tried to record something, but hadn't enough time. First try was unsuccessful unfortunately.
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26th November 2013, 02:53 PM |#5  
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Quote:
Originally Posted by shaftenberg

With the app it works, without stuttering and you can control the output volume, although there was an error warning at startup regarding main volume
I tried to record something, but hadn't enough time. First try was unsuccessful unfortunately.

Well, that's nice to hear. Maybe some Custom ROMs (Cyanogenmod in particular) will have better support for this without the app.
Anyway, I think I'm going to get this phone (Christmas is coming ). Usb audio support (atleast with the app) is crucial for me, so thanks for reporting that it works.

One last thing though, what make and model were the two soundcards that you used for testing?
27th November 2013, 06:14 AM |#6  
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Quote:
Originally Posted by UnknownAX

One last thing though, what make and model were the two soundcards that you used for testing?

First a cheap Creative USB Soundcard, second a DJ-Audio-Player from EKS (www.eks.fi) which has its own soundcard per player.
26th December 2013, 09:19 PM |#7  
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Could you test this on the faux kernel that your running atm, Shaftenberg?

Most people who have tried it on the stock ROM have experienced the same glitches that you mentioned in your first post. On the other hand, there's also one report of it working fine, with the Google music player. The DAC is probably the biggest factor.

Anyway, I'm just waiting for the 16gb version to be available....
27th December 2013, 02:19 PM |#8  
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I tried 2 DACs. One was a CEntrance DACport LX flashed with the iPad firmware, and the other was a cheap off-brand thing (ELE EL-D01 on eBay). Both of them "worked", but I encountered the same issue with each: I tested both by playing a Youtube video, and the audio was not playing back at the proper sampling rate. The audio was slightly slowed down... as a result, pitches were slightly lower, and the audio lagged behind the video pretty significantly. If I had to guess, the audio was 48kHz, and Android was trying to play it back at 44.1kHz without resampling it first.

Why it was doing this, I have no idea: on a Nexus 4 running stock Jellybean with jacknorris' patch (which, AFAIK, doesn't pay attention to sampling rates but just assumes Android will handle that properly elsewhere), this works perfectly. However, it was fascinating/encouraging to see this work at all on the Moto G: it means that with stock firmware, not only does OTG/USB host mode work, and not only does the kernel have the stock Linux USB DAC driver compiled in, but the Android framework itself attempts to use the DAC, which is *definitely* not true with plain-jane AOSP.

One thing I was sad to see (which also seems to be true of a LOT of other Android phones that support OTG out-of-the-box) is that if I injected 5V from an external source into the USB power lines, the phone would NOT charge as long as OTG mode was engaged. Which means that, at least with the stock Moto G firmware, you can't both be in USB host most *and* be charging the battery at the same time. (Interestingly, the very first time you plug the power in, the phone says "charging", but it's quickly obvious it isn't. If you unplug and re-plug the power in after that, it will not show the lightning symbol on the battery any longer until you reboot the phone. Normal USB chargers continue to work without the OTG cable without requiring a reboot.)

-- Nathan
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27th December 2013, 08:26 PM |#9  
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Quote:
Originally Posted by nlra

If I had to guess, the audio was 48kHz, and Android was trying to play it back at 44.1kHz without resampling it first.

That makes sense to me. But what would happen if we played a 44.1kHz track? It wouldn't have to resample then, would it?
Maybe that's why there is a report of it working with google music player...maybe he just happened to try it with a 44.1kHz track?
I'm pretty sure this will/can be fixed with a ROM / Kernel. Like USB OTG charging, it's just a matter of time (I hope). Both things have already been successfully enabled on many different devices.

Thanks for the info, luckily I'm not the only one showing interest in this.
30th December 2013, 02:01 PM |#10  
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It most definitely works with my Moto G and my FiiO E17 (connected via a generic OTG cable)

Trouble is, although it ALMOST worked, I got sporadic but impossible to listen to skipping/stuttering when using Poweramp or the native Google player app.

I finally found an app made by the same people who do the USB Audio Recorder Pro as mentioned by the poster, called USB Audio Player Pro (can't post the link, being a new poster, but a quick search for "USB audio player" gets to it)

...it costs over 5 pounds, and to be frank it is not the world's prettiest or richly featured player, but it certainly works and the output sound is great.

Anyway, just posting to let you know that it works, at least with my Fiio E17.
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31st December 2013, 03:48 PM |#11  
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So here's some good news: after applying the official KitKat 4.4.2 OTA, OTG still works, USB DAC support still exists, and now it even works properly, at least for me! No more strange audio sampling issues: I could attach either one of my DACs and play the same Youtube clip without any difficulty! Audio was perfectly in-sync with the video.

-- Nathan
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