Limit the max sample rate to 48kHz? - Xiaomi Mi 9 Questions & Answers

Hi, is there a way of limiting the sample rate to 48kHz in Android 10 (AOSP Rom)?
I'm using a USB-C to headphone dongle and according to the developer, Viper4Android doesn't support a sample rate greater than 48kHz, so my current driver status is abnormal. Note that my bluetooth headphones work fine.
In system/etc, I have a audio_policy.conf, but not an audio_policy_configuration.xml ( https://source.android.com/devices/audio/implement-policy )
Any alternative ways of limiting the sample rate would be much appreciated.

The mixer in Android downsamples everything to 44100Hz anyway, so that is probably not the issue.
It won't ever go past the above value other than the case where you use an application that creates a pass-through between the DAC (whether that is the internal one by Qualcomm or an external dongle one) and the output, thus offering bitperfect quality

Dariusdd said:
The mixer in Android downsamples everything to 44100Hz anyway, so that is probably not the issue.
It won't ever go past the above value other than the case where you use an application that creates a pass-through between the DAC (whether that is the internal one by Qualcomm or an external dongle one) and the output, thus offering bitperfect quality
Click to expand...
Click to collapse
Thanks for your response - do you have any other ideas why viper doesn't work?

Absolutely none, it's old and unmaintained as far as I remember. I am unsure of the compatibility of the newer fork of it as well. Good luck getting it to work

I mean you can try jdsp

Yeah James DSP does work actually, but it's missing a few features. It seems the only way of fixing this issue is using a passive headphone adapter, which aren't that common on amazon at least.

Related

[MOD] Increase A2DP Bluetooth bitpool settings

I've recently acquired a new car which has a built in stereo system (Renault Megane Estate 2012 Bose edition) which is able to receive CBR encoded A2DP streams. It works well, connects, music plays, even controls work.
Awesome!
Using catlog I can see that the bitpool that is negotiated is 51. While the sound isn't horrible, I believe the handsets (Samsung Galaxy SIII Int. and Nexus 7, both running CM10 nightly) are able to encode and transmit at a higher bitrate/bitpool then currently is set.
I've tried my best effort in changing this settings. I've built my own Ubuntu kitchen, followed all the guides and have from the looks of it compiled a successful ROM image. Sadly enough when I flash it, my tablet dies (black screen) and even CWM is destroyed. Using fastbood and USB I've been able to recover the tablet, so no problem there, but still, no working ROM. Even without changing something. But that is not what this thread is for, I'll figure that out eventually.
I am trying to recreate the results that are in the following topic : http://forum.xda-developers.com/showthread.php?t=1880298
Sadly, the files provided are not compatible with my CM10 devices and changing the source and then compiling it and replacing the files yields no result. Whatever I try, it stays at 51 (The bitpool it SENDS to the radio as max). There are several files which are connected to the settings, such as cbr.c , audio.a2dp.default.so, etc. but I don't really know what to change to get the desired results.
If anyone is able to help, that would be greatly appreciated. Point me to the right file where I can find the values to change, either in a compiled ROM or in the source so that I can compile it and change the files in
my running ROM using rootexplorer. Whatever works.
I would like to try settings as high as 125. But ideally, I would like to experiment what my headunit accepts, what it can be forced to, and thus finding the highest quality possible using my combination of equipment.
In this the Nexus 7 is the most important because that will be permanently located in the car.
update--
I have found a thread on bluez surrounding this topic.
http://www.spinics.net/lists/linux-bluetooth/msg23091.html
Could someone more knowledgeable then me please take a look at this for me and maybe change the file? Sadly that goes way beyond my programming knowledge, but I would really love to give it a try!
update--
Some extra information and a good explanation as to why I am looking for this (and maybe more people with me).
Bitpool values as high as 128 are possible on Windows Mobile devices (including mine), which means they are possible in A2DP. Such a high value is necessary for some genres of current music, which are highly
compressed (the problem was once discussed in one of Xiph Foundation's articles). SBC is unable to encode such material properly if it doesn't have enough bandwidth.
Click to expand...
Click to collapse
I've done some more tests editing and replacing files and I think I've actually gotten it to sync higher but it still displays it's at 51. The sound just sounds a lot better, but of course, that can always be a placebo effect. :silly:
So, anyone have any insight, or who can point me into the right direction of what needs to be changed and where? As said, I think I have reached the quality increase (bitpool 100) but the logs still display 51.... not quite there yet. And in light of people using the Nexus 7 in a cars a lot (which I also intend) and the borked headphones output I read everywhere, CD quality streaming over A2DP (It's possible) would be awesome!
Kitchen fixed
So I got my kitchen working and am cooking working ROM's.
Just getting the right files changed is giving me some problems.
I think I fixed most of it, but for some reason when I check the logs it still states that it's sending a max bitpool of 51. I believe in the background it's using the 128 as I stated in the source files, but still. I would like the logs to show the same, just to acknowledge I'm a not having a placebo effect.
The files I have changed are the following:
/android/system/external/bluetooth/bluez
a2dp.c
gsta2dpsink.c
gstscenc.c
liba2dp.c
pcm_bluetooth.c
I used the patch listed above on the pcm_bluetooth.c. And I do believe it overrides the settings and it's not set to 51 anymore but the 128 I put in all the files manually. Music sounds great, but it's hard to subjectively test.
Hopefully we can find some people who have a greater understanding of bluez.
Little kick
Little kick to see if someone wants to assist me on this or not. I think it could potentially benefit a lot of people making Bluetooth audio/A2DP go from barely adequate to High Fidelity!
I'd love to help you test this - I also find the A2DP quality to be lacking in a lot of more "active" or compressed music. Acoustic and softer music sounds great, but rock/metal tends to sound like a 128kbps mp3. It actually seems to sound better from my Galaxy Nexus than the 7 as well. I'm running a Bugless Beast ROM now but was running CM10.
Also, not sure if you've seen this but I found an article (soundexpert.org/news/-/blogs/bluetooth-audio-quality-a2dp, sorry can't post links yet) that shows the bitrate per bitpool value. At a bitpool value of 53, the bitrate is around 320kbps. A2DP itself supports a bitrate of up to 512kbps for stereo, but through other optionally-supported codecs. SBC however, in this profile, only seems to go to ~320. It might be worth checking out if your car stereo supports mp3 over A2DP - there is an option in /etc/bluetooth/audio.conf to set MPEG12Sources from 0 to 1 and SBCSources from 1 to 0.
ROM up for download
Hi there, thnx's for joining the cause.
I compiled a new daily today with settings set to bitpool 128. But I don't really hear much change, maybe the setting is too high, maybe something else is going wrong. As stated above, in the logs I can only see it sending 51 as max pool to the device and setteling with it. But since I'm using an edit pcm_bluetooth.c it should override that setting, say it's going to do 51 and then stream and the values I defined in the files.
.....in theory at least...... the only subjective evidence I have for this are my own ears.
So, I will provide you with access to the 128 version and am going to compile a 64 version while I'm at it.
Use an FTP client to connect to:
host: oss.quindorian.org
user: XDA
pass: ROMROM
Anyone is welcome to give it a try. I have put limits on the FTP site, so please beware of that. But I'll put ROM's there you can try and report back on. Tell me if you think it does nothing or if you think it makes it sound like a singing angel. Any feedback is appreciated.
As source I use the CM10 repository so I am basically building modded nightly builds. Today it allready has the 4.1.2 flavor with the newest drivers and everything included. Don't forget to flash gapps if you need them.
Understand
ChrisK15 said:
Also, not sure if you've seen this but I found an article (soundexpert.org/news/-/blogs/bluetooth-audio-quality-a2dp, sorry can't post links yet) that shows the bitrate per bitpool value. At a bitpool value of 53, the bitrate is around 320kbps. A2DP itself supports a bitrate of up to 512kbps for stereo, but through other optionally-supported codecs. SBC however, in this profile, only seems to go to ~320. It might be worth checking out if your car stereo supports mp3 over A2DP - there is an option in /etc/bluetooth/audio.conf to set MPEG12Sources from 0 to 1 and SBCSources from 1 to 0.
Click to expand...
Click to collapse
Yeah, I understand what that article says. But for me, the quality just isn't up to par to listening to a 320Kbit stream. Also, there is what A2DP officialy supports and there is what works. I'm shooting for the last type. If I can get a 1000Kbit stream between my device and my headunit, I will, even if it doens't add much above say 786Kbit, more is always better in this case. If it works that is, ofcourse.
Because I wish to use spotify, I believe my only choice is to use the SBC encoder. Spotify will never let you transfer it's source file to anywhere because of DRM. Alternativly, if we could enable an AAC stream or something (also supported I believe) we'd need less bitrate/bitpool for better quality! And from what I have read, the SBC encoder standard used it just quite crappy. So while a 320Kbit LAME encoded MP3 might sound great/perfect, using a sub-standard encoder can still give it artifacts and low quality. Thus the hunt for insane amounts of bitrate!
Awesome, I'll definitely give it a shot. If it's possible to exceed the Bluetooth standard spec then that'd be awesome. I'm more worried about our receivers not being able to support the higher bandwidth - my head unit is new but only supports SBC unfortunately.
Cool
ChrisK15 said:
Awesome, I'll definitely give it a shot. If it's possible to exceed the Bluetooth standard spec then that'd be awesome. I'm more worried about our receivers not being able to support the higher bandwidth - my head unit is new but only supports SBC unfortunately.
Click to expand...
Click to collapse
Cool, I just put the bitpool64 version there too. Tested it and I notice no real difference. Sadly the quality is still not great, it's not horrible.... but certainly not great so I still feel like my settings are maybe not having any effect whatsoever. As reflected by the logs using catlog. It sen bitpool 51 max and settles for that. For all the values I have changed in the files and that stay the same, I really do not understand. Wish I could fix that, but with my knowledge I have just run out of places where to look.
Let me know if in your case it makes any difference!
I just tried it out and to me it seems like there's an improvement. I normally stream Pandora One in my car, and that definitely seemed like it had more clarity. However Google Music streaming sounded the same, although it was already good to begin with. I would think that compressing more highly-compressed music from the start (Pandora) would have a worse effect on quality than less-compressed music, which seems to be the case. Or maybe I'm just hearing things
Thanks for looking into this, I've been trying to find a way to do this for a while!
Quindor said:
Hi there, thnx's for joining the cause.
I compiled a new daily today with settings set to bitpool 128. But I don't really hear much change, maybe the setting is too high, maybe something else is going wrong. As stated above, in the logs I can only see it sending 51 as max pool to the device and setteling with it. But since I'm using an edit pcm_bluetooth.c it should override that setting, say it's going to do 51 and then stream and the values I defined in the files.
.....in theory at least...... the only subjective evidence I have for this are my own ears.
(...) .
Click to expand...
Click to collapse
perhaps you can test if the patch does anything - by setting bitpool to some very LOW value ?
ChrisK15 said:
It might be worth checking out if your car stereo supports mp3 over A2DP - there is an option in /etc/bluetooth/audio.conf to set MPEG12Sources from 0 to 1 and SBCSources from 1 to 0.
Click to expand...
Click to collapse
On my CM12.1 official nightly ROM (2015/12/03) for my Samsung i9505, there is no file audio.conf
Does that mean I can simply create it with the two lines
MPEG12Sources=1
SBCSources=0
in order to test wether a bluetooth SNK device such as a car stereo or a headset supports mp3 over A2DP?
So does anyone have some actual logs or HCI captures showing bitpool above 53?
..

Audio Extractor for $ OR Is it possible ROOT for simultaneous cast?

My friend from South Korea sent me an early birthday gift and low and behold it was a cool Chromecast key :victory::laugh: WOW THANKS but... I have a unique setup a 180" screen and Projector. This AMAZING projector (W7000) has no audio out and no way to utilize audio from Chromecast :crying: How sad... Well I discovered these audio extractors to get audio out but frankly I would love to retain max color, 3d, and 7.1 on DD+ this is not going to be easy. Then I got to thinking how come no one has developed an app which can sync the 2 outputs (multicast) from DDWRT or other at the router / gateway. Or in another way perhaps.
Two questions remain
1) Audio extractor where can I get a cheap but good one ? (seen them exceeding 200 dollars common)
THE BIG QUESTION IS
anyone know how to do this yet or perhaps if I should sell the thing and get a different setup for these projectors I have 3. (kinda committed to the output device already hehe.):cyclops:
This is what I used because the Chromecast wasn't compatible with my TV. (I had video but no audio)
www,ebay,com/itm/291119088532 $29 - has optical audio out.
Impossible to sync audio to two separate sources that are networked...
What you really want to do is get yourself a good AV Amplifier (with HDMI Inputs), not an Audio Breakout.
You will get full Surround support and would plug the CCast into the Amp and send the video from the amp to the Projector.
To answer the second question in your subject, root won't help you here. As @Asphyx said, it's near-impossible to accurately maintain A/V sync between separate networked devices. It requires sub-second synchronization and without some other constant reference not subject to network transmission delay it's very prone to failure.
funkypc said:
This is what I used because the Chromecast wasn't compatible with my TV. (I had video but no audio)
www,ebay,com/itm/291119088532 $29 - has optical audio out.
Click to expand...
Click to collapse
Don't want to loose the 3d though and according to Wiki (not their ad on ebay) there is no 3d until 1.4 : so how come they are advertising 1.3 with 3d ?
Ohh btw does this device work 1:1 for lag or is there a few ms' wait ?
Thanks guys this really helps
futiless said:
Don't want to loose the 3d though and according to Wiki (not their ad on ebay) there is no 3d until 1.4 : so how come they are advertising 1.3 with 3d ?
Ohh btw does this device work 1:1 for lag or is there a few ms' wait ?
Thanks guys this really helps
Click to expand...
Click to collapse
AFAIK Chromecast doesn't support 120 Hz output (so no full-res 3D), though side-by-side 3D should work on pre-HDMI 1.4 as it's not doubling the rate to get L/R.
There shouldn't be any noticeable lag introduced as it's simply a de-embed at the endpoint.

Should I go with raspberry Pi 2 as Media center

I have already got MK808 android stick, which is 1.2 GHz dual core with Mali 400 GPU.
After using it long as general purpose device, decided to convert it as media centric device, with 2.1 speaker setup
I am facing following limitations,
1. Not able to play HD/1080 videos smoothly
2. Tried USB sound card to connect it to 2.1 speaker, but quality is not good
So I started to look for alternate devices. I liked RPI 2 especially due to it's support, but before buy, I have some questions unanswered
1. Since I have 1.2 GHz device, I am just wondering with RPI 2 being 900 MHz, is it powerful enough device as media PC. Especially can we consider it for future proof (may be 3 years)? I am thinking because, I don't want to fall in situation to buy another device only after next 1 year due to RPI2 limitation.
2. When I add case, WiFi dongle, power cable, HDMI cable etc, it's going to about 75 USD. At this price, there are many choices like,
# Android stick MXIII, which seems more powerful with android support
# Dedicated media player like,
http://www.amazon.in/s/ref=nb_sb_noss_1?url=search-alias=aps&field-keywords=media+player
But I don't know, how to compare those with RPI 2 and conclude which one will be more powerful and future proof
Any suggestion?
RmatriX1218 said:
I have already got MK808 android stick, which is 1.2 GHz dual core with Mali 400 GPU.
After using it long as general purpose device, decided to convert it as media centric device, with 2.1 speaker setup
I am facing following limitations,
1. Not able to play HD/1080 videos smoothly
2. Tried USB sound card to connect it to 2.1 speaker, but quality is not good
So I started to look for alternate devices. I liked RPI 2 especially due to it's support, but before buy, I have some questions unanswered
1. Since I have 1.2 GHz device, I am just wondering with RPI 2 being 900 MHz, is it powerful enough device as media PC. Especially can we consider it for future proof (may be 3 years)? I am thinking because, I don't want to fall in situation to buy another device only after next 1 year due to RPI2 limitation.
2. When I add case, WiFi dongle, power cable, HDMI cable etc, it's going to about 75 USD. At this price, there are many choices like,
# Android stick MXIII, which seems more powerful with android support
# Dedicated media player like,
http://www.amazon.in/s/ref=nb_sb_noss_1?url=search-alias=aps&field-keywords=media+player
But I don't know, how to compare those with RPI 2 and conclude which one will be more powerful and future proof
Any suggestion?
Click to expand...
Click to collapse
I have been using Raspberry Pi 2 B+ for a month as media center with the Rasplex OS. I have tried 1080p, 720p and a few different formats like mp4 mkv, avi etc and they all work fine, even while seeking. The main reason for this could be that the processing/trans-coding of the video is done on the server(the files are not stored on Pi, and no HDD is connected to it.) This all works on a WiFi adapter.
If You can use Plex app on Your Android Stick and use a plex server somewhere, You won't need to buy a Pi. Although You would need to buy Plex pass to come over restriction in Android app I think.
Rpi 1 can run almost limitless video bitrate via smb share. But it has issues with very heavy audio since 1 pi's processing power is not great basically. But mines 1 still run movies with 10mbps video and 5mbps audio well. Above that it starts to buffer maybe its network bottlenecking. Audio quality via hdmi is great. I got a pi 2 just a while ago looking forward to test it with openelec. I have chromecast stick too i think that i wouldn't need rpi if i didn't had media at local share. Chromecast is far more better if u use only netflix, viaplay, youtube, popcorn, etc and can use it with android device phone/tablet.
Thanks for replies.
Has anyone connected it to 2.1 speaker system?
Because, that is my one of the aim.
Can anyone tell quality if connected to AV cable/stereo jack?
And, is it possible to get video through HDMI cable and audio through AV cable to 2.1 speaker?
Can someone, who already have similar configuration, help me out to build similar one.
RmatriX1218 said:
Thanks for replies.
Has anyone connected it to 2.1 speaker system?
Because, that is my one of the aim.
Can anyone tell quality if connected to AV cable/stereo jack?
And, is it possible to get video through HDMI cable and audio through AV cable to 2.1 speaker?
Can someone, who already have similar configuration, help me out to build similar one.
Click to expand...
Click to collapse
Yes, it can output both video through HDMI cable and audio through AV cable at the same time.
Nypan sr said:
Yes, it can output both video through HDMI cable and audio through AV cable at the same time.
Click to expand...
Click to collapse
How do you rate quality through AV cable out?
I believe, AV out doesn't give good quality as HDMI.
Through USB sound card on my MK808, I am loosing bass. Woofer doesn't give any sound.
I am worried, same should not be with RPI as I'll loose all fun of watching movies.
Anybody with 2.1 speaker setup hear?
RmatriX1218 said:
How do you rate quality through AV cable out?
I believe, AV out doesn't give good quality as HDMI.
Through USB sound card on my MK808, I am loosing bass. Woofer doesn't give any sound.
I am worried, same should not be with RPI as I'll loose all fun of watching movies.
Anybody with 2.1 speaker setup hear?
Click to expand...
Click to collapse
HDMI is better. My 2.1 system is connected to my LG-tv, so i dont know what quality the 3,5 mm output is.
Nypan sr said:
HDMI is better. My 2.1 system is connected to my LG-tv, so i dont know what quality the 3,5 mm output is.
Click to expand...
Click to collapse
Unfortunately, my LED TC has onlu audio jack. So, if I connect 2.1 system with it, I get very low volume.
So, only option to get sound from RPI AV jack.
Can you check in your system with AV jack and report the difference in output?
Any though on
RPI2 vs MXIII vs MXQ?
RmatriX1218 said:
How do you rate quality through AV cable out?
I believe, AV out doesn't give good quality as HDMI.
Through USB sound card on my MK808, I am loosing bass. Woofer doesn't give any sound.
I am worried, same should not be with RPI as I'll loose all fun of watching movies.
Anybody with 2.1 speaker setup hear?
Click to expand...
Click to collapse
Composite video out quality is pretty good. On OpenELEC, playing 720p live stream Russia Today. Output is classic PAL resolution. Image quality is better than 576p SD DVB-S thru SCART with good quality sat reciever. I have big old widescreen CRT Panasonic Quintrix TV.
If you play any 720p movie, quality will be comparable to DVD player with SCART.
I dont know how is your audio input for these 2.1 speakers. Just single 3 pole 3.5mm or also separate one for subwoofer? If it need 2 connectors then you need 5.1 sound card with (usually orange) center/subwoofer connector.
I think you should turn up your headphone volume on your tv
Sent from my thl T6S using XDA Free mobile app
Ideal for local media or media on a NAS but not being able to access Netflix, Hulu etc (like you can on Android) might be a bit of a put off. Shame really coz the Pi2 is more than powerful enough to support these streaming services

Head units with android USB Audio!

TL;DR Auxillary and bluetooth have much lesser quality than USB. Video links below show stereo head units that support Android USB audio with app control for the best quality connection (Spotify, Pandora, Google Play Music via USB in your car!) These are single DIN head units without AA.
For audiophiles such as myself, auxiliary cables or Bluetooth is unacceptable when connecting to my car audio system. With these methods, the phone acts as the digital to audio converter instead of the head unit thus greatly reducing sound quality on a high end system. With a USB connection, the phone only acts as storage and a music player while the head unit acts as the DCA.
Finding head units that have a compatible USB connection to android devices has been very difficult in the past. I resorted to storing all my music on an old iPod touch to get Spotify working with my car through USB. The new Android Open Accessory 2.0 is changing that.
I have found a few of youtube videos demonstrating Android USB plug and play connection with two different modes:
App control: Spotify, Pandora, iHeartRadio, Google Play Music ect. (Yes SPOTIFY!!!)
MTP: browse local music files.
- supports basic functions such as play/pause/next/prev
- should work with android version 4.1+
- beware: some head unit models require a software update which can be installed through usb.
- warning: these videos only show connection to nexus phones, meaning if your phone isn't running google edition AOSP, it could cause problems.
- note: AOA 2.0 is different than the android audio update with lollipop, which was meant to allow connection to a separate external DCA via USB OTG.
- more info about the 3 types of android USB connection found in this thread: http://forums.androidcentral.com/an...3-will-android-l-allow-usb-audio-out-car.html
Videos with demonstration:
Pioneer DEH-X2800UI
https://youtu.be/gssbmXJ2pzw
Pioneer DEH-X3800UI
https://youtu.be/dztgOvrUnSE
Pioneer DEH-X5800HD
https://youtu.be/kReFemy4UmU
JVC KW-R910BT
https://youtu.be/h1n6WVefhKc
There are undoubtedly many other head units that support AOA 2.0, but these have video proof!
I have a Nexus 5x, I just ordered the Pioneer DEH-X3800UI for $75 on Amazon.
Ill have the head unit installed within the next week, and will give an update.
Hello Android USB Audio! Goodbye and good riddance iPod touch!
I'm hoping somebody has bought one of these headunits & can confirm how well it works.
Does it essentially work like a USB DAC would & all audio including waze, Poweramp youtube all play through the headunit and speakers?
edit: I found the answer, yes ALL audio goes through the headunit. See here:
go to 5:15
https://www.youtube.com/watch?v=ZyOh32a-cY8
TL;DR probably All head units with AOA 2.0 support that on the market right now have a clicking/micro pausing problem.
Sorry for a late response, I had to do some research, as explained below.
Now its time for the good, the bad, and the ugly!
The Good: The head unit preformed as promised, it was simple plug and play to rout all audio from the phone to the car speakers, matching Ipod via USB quality. Spotify, Youtube, Soundcloud, and even Maps navigation all worked.
The Bad: Every 5-30 seconds there is a quick high pitch clicking sound accompanied by a micro pause of the audio of about a quarter of a second. This clicking only happens with a constant audio stream such as a song, not with something brief such as a Maps navigation direction, nor when the phone is plugged in without any audio being streamed. Sometimes I would get lucky and the audio would be perfect for a couple minutes, once even for a couple songs. But when it does happen, the clicking is quite loud and high pitch and with micro pause it is easily noticeable during a normal song. I had 3 friends come listen to my "new setup" to ask them how it sounds, and all 3 of them noticed it. Unacceptable for an audiophile such as myself, so i did some research and conducted some experiments.
The Ugly: I devised a way to easily notice and keep track of the clicks. I played a low constant tone of a 40hz sine wave at high volume which made the abrupt high pitch clicks very loud (and annoying) in contrast to the low constant tone, and it made the micro pauses very obvious due to the interruption of the bass. With my phone I would hear random clicks every 5-30 seconds. I then tested 5 different android phones with various ROMs and about 10 different usb cords and many combinations of them. Clicking was reliably random. I changed kernel settings on some of the phones to see if the cpu performance was effecting it. I tried various apps such as sound about and the pioneer music app. Nothing changed.
I then went to an electronics store that had 8 head units available in store that supported Android Open Accessory 2.0. all hooked up for listening and ready for testing. There were 3 Pioneers, 2 JVC's, and 3 Kenwoods. ALL of them had the clicking problem. The Pioneers were the worst: the most frequent and loud clicks, followed closely behind by the JVC's. The Kenwoods, had clicks every 30 seconds to 2 minutes, and were about 40% less loud. I suspect that with the Kenwood head unit the average person might not be able to detect the clicking and micro pauses during a normal song, but I know i could in my high end system, especially after all this nonsense i would be passively listening for it.
Conclusion: I suspect that there is either a fundamental problem with Android Open Accessory 2.0 that causes the clicking, or the stereo manufacturers are cutting corners somewhere, or maybe some incompatibility issue with the software. I just don't know. I tried to do more research but I have found nothing online about this specific issue.
ibCurlyFry said:
TL;DR probably All head units with AOA 2.0 support that on the market right now have a clicking/micro pausing problem.
Sorry for a late response, I had to do some research, as explained below.
Now its time for the good, the bad, and the ugly!
The Good: The head unit preformed as promised, it was simple plug and play to rout all audio from the phone to the car speakers, matching Ipod via USB quality. Spotify, Youtube, Soundcloud, and even Maps navigation all worked.
The Bad: Every 5-30 seconds there is a quick high pitch clicking sound accompanied by a micro pause of the audio of about a quarter of a second. This clicking only happens with a constant audio stream such as a song, not with something brief such as a Maps navigation direction, nor when the phone is plugged in without any audio being streamed. Sometimes I would get lucky and the audio would be perfect for a couple minutes, once even for a couple songs. But when it does happen, the clicking is quite loud and high pitch and with micro pause it is easily noticeable during a normal song. I had 3 friends come listen to my "new setup" to ask them how it sounds, and all 3 of them noticed it. Unacceptable for an audiophile such as myself, so i did some research and conducted some experiments.
The Ugly: I devised a way to easily notice and keep track of the clicks. I played a low constant tone of a 40hz sine wave at high volume which made the abrupt high pitch clicks very loud (and annoying) in contrast to the low constant tone, and it made the micro pauses very obvious due to the interruption of the bass. With my phone I would hear random clicks every 5-30 seconds. I then tested 5 different android phones with various ROMs and about 10 different usb cords and many combinations of them. Clicking was reliably random. I changed kernel settings on some of the phones to see if the cpu performance was effecting it. I tried various apps such as sound about and the pioneer music app. Nothing changed.
I then went to an electronics store that had 8 head units available in store that supported Android Open Accessory 2.0. all hooked up for listening and ready for testing. There were 3 Pioneers, 2 JVC's, and 3 Kenwoods. ALL of them had the clicking problem. The Pioneers were the worst: the most frequent and loud clicks, followed closely behind by the JVC's. The Kenwoods, had clicks every 30 seconds to 2 minutes, and were about 40% less loud. I suspect that with the Kenwood head unit the average person might not be able to detect the clicking and micro pauses during a normal song, but I know i could in my high end system, especially after all this nonsense i would be passively listening for it.
Conclusion: I suspect that there is either a fundamental problem with Android Open Accessory 2.0 that causes the clicking, or the stereo manufacturers are cutting corners somewhere, or maybe some incompatibility issue with the software. I just don't know. I tried to do more research but I have found nothing online about this specific issue.
Click to expand...
Click to collapse
ok wow, I'll try to get to a shop soon& test my tablet.
I'm really hoping I can use an OTG cable + hub & then go into one of these headunits. I need the hub in my car for rear camera & SSD media drive.
s2g-unit said:
ok wow, I'll try to get to a shop soon& test my tablet.
I'm really hoping I can use an OTG cable + hub & then go into one of these headunits. I need the hub in my car for rear camera & SSD media drive.
Click to expand...
Click to collapse
Yeah OTG >> USB DAC is what im going to have to do too, unless i find a fix for the clicks.
This post could help: http://www.head-fi.org/t/595071/android-phones-and-usb-dacs/5430#post_10929191
ibCurlyFry said:
Yeah OTG >> USB DAC is what im going to have to do too, unless i find a fix for the clicks.
This post could help: http://www.head-fi.org/t/595071/android-phones-and-usb-dacs/5430#post_10929191
Click to expand...
Click to collapse
I do actually have a Hifimediy u2 USB DAC.
I'm hoping to go from nexus 7>otg>hub>straight into the AOA 2.0 receiver.
If not my backup will be the USB DAC into a Pioneer 80prs.
Anybody have input?
What would be better in terms of sound quality?
-The aoa 2.0 allows me USB streaming digital into HU
vs
-USB DAC (by passing internal DAC) into Pioneer 80PRS (Amazing Sound quality HU for 250$) but this will have to be done via AUX.
Does the fact I have to use AUX even matter? will it degrade the quality?
s2g-unit said:
I do actually have a Hifimediy u2 USB DAC.
I'm hoping to go from nexus 7>otg>hub>straight into the AOA 2.0 receiver.
If not my backup will be the USB DAC into a Pioneer 80prs.
Anybody have input?
What would be better in terms of sound quality?
-The aoa 2.0 allows me USB streaming digital into HU
vs
-USB DAC (by passing internal DAC) into Pioneer 80PRS (Amazing Sound quality HU for 250$) but this will have to be done via AUX.
Does the fact I have to use AUX even matter? will it degrade the quality?
Click to expand...
Click to collapse
I know using straight AUX from the device tremendously reduces sound quality due to the device acting as a crappy DAC, then sending the audio signal through the AUX to the unit.
But if it goes to a separate DAC then through AUX, i dont know. I would like to find out also
ibCurlyFry said:
I know using straight AUX from the device tremendously reduces sound quality due to the device acting as a crappy DAC, then sending the audio signal through the AUX to the unit.
But if it goes to a separate DAC then through AUX, i dont know. I would like to find out also
Click to expand...
Click to collapse
I've posted on a few car audio boards. Nobody seems to ask this in the past becasue everybody in the past used ipod via usb. Bluetooth if they dont care about quality.
I think in most cases like you said, the response was negative to using AUX but thats because of the headphone jack / internal DAC as you know.
I'm just curious like you to know how much we would loose by using AUX. Maybe some will say it's because of another D/A conversion but can anybody really tell? I'll wait for some answers.
In regards to the OP, if you have a high end car system, why not shell out for an Android Auto head unit? The data for music is sent via USB I'm pretty sure as I can tell a clear difference between my Kenwood's BT vs AA.
(I suppose flac files are an issue but you mentioned spotify, which does have AA support)
Soul0Reaper said:
In regards to the OP, if you have a high end car system, why not shell out for an Android Auto head unit? The data for music is sent via USB I'm pretty sure as I can tell a clear difference between my Kenwood's BT vs AA.
(I suppose flac files are an issue but you mentioned spotify, which does have AA support)
Click to expand...
Click to collapse
I don't get why you think he needs an Android Auto Setup?
Double DIN radio are more for toys. They don't have the EQ or processing power of single DIN's.
s2g-unit said:
I don't get why you think he needs an Android Auto Setup?
Double DIN radio are more for toys. They don't have the EQ or processing power of single DIN's.
Click to expand...
Click to collapse
Uh... I never said that he "needed" AA. I am certainly not an expert on head units and am not a claimed audiophile but based on what the requirements were, I don't see a reason why AA can't work. It is simpler to setup, includes spotify support, as well as a more cohesive and unified interface. Based on the issues getting audio over USB to work I think AA is a good alternative.
I'm not sure how DDs have less processing power but if you need such a thing, just add a DSP. I personally am fine with just an amp. Seems very extreme to claim them as toys. I wouldn't be so prejudiced...
Soul0Reaper said:
In regards to the OP, if you have a high end car system, why not shell out for an Android Auto head unit? The data for music is sent via USB I'm pretty sure as I can tell a clear difference between my Kenwood's BT vs AA.
(I suppose flac files are an issue but you mentioned spotify, which does have AA support)
Click to expand...
Click to collapse
Main reasons:
-Touch screens are difficult to operate while driving
-My car would need modifications to install a double din
-And of course the price. I do have a quite high end system, but It is extremely cost efficient.
I believe AA is a waste of money if all you care about is sound quality because the cheapest solution for usb quality app radio is still just a $70 head unit and a used ipod touch for $50.
This is what I had before I heard about these new head units that still cost $70 but allow usb connection to android with aoa so I could potentially get rid of the ipod and just use my phone, but it hasn't worked out so far lol.
ibCurlyFry said:
Conclusion: I suspect that there is either a fundamental problem with Android Open Accessory 2.0 that causes the clicking, or the stereo manufacturers are cutting corners somewhere, or maybe some incompatibility issue with the software. I just don't know. I tried to do more research but I have found nothing online about this specific issue.
Click to expand...
Click to collapse
AOA only supports 44.1 KHz sampling rate. Maybe a re-sampling issue.
To test I'd try 44.1 source material on a device that is native 44.1.
Note also that Google considers AOA deprecated and discourages it's further use. Very few people used it so Google may not bother fixing bugs, and it may not be a part of their Compatibility Test Suite..
mikereidis said:
AOA only supports 44.1 KHz sampling rate. Maybe a re-sampling issue.
To test I'd try 44.1 source material on a device that is native 44.1.
Note also that Google considers AOA deprecated and discourages it's further use. Very few people used it so Google may not bother fixing bugs, and it may not be a part of their Compatibility Test Suite..
Click to expand...
Click to collapse
Thanks for the info, ill test the sampling rate theory
And its crazy that these head units that support aoa didnt come out until mid-late last year... The stereo companies need to get on track with google and take a break from suckling the teet of Apple
ibCurlyFry said:
Thanks for the info, ill test the sampling rate theory
And its crazy that these head units that support aoa didn't come out until mid-late last year... The stereo companies need to get on track with google and take a break from suckling the teet of Apple
Click to expand...
Click to collapse
None of the shops near me have any of these HU's setup. I'll wait a 1-2 weeks for other peoples developments. If its still the same , I'll just buy a Pioneer 80PRS.
s2g-unit said:
None of the shops near me have any of these HU's setup. I'll wait a 1-2 weeks for other peoples developments. If its still the same , I'll just buy a Pioneer 80PRS.
Click to expand...
Click to collapse
Theres actually alot more than i thought, heres a more complete list:
JVC models: http://www.jvc.net/cs/car/firmware/2014/aoa/
Kenwood models: http://www.kenwood.com/cs/ce/aoa2/
Pioneer models: DEH X2800UI, X32800UI, X3800S, X4800BT, X5800HD, X6800BT, MVH X380BT
ibCurlyFry said:
Main reasons:
-Touch screens are difficult to operate while driving
-My car would need modifications to install a double din
-And of course the price. I do have a quite high end system, but It is extremely cost efficient.
I believe AA is a waste of money if all you care about is sound quality because the cheapest solution for usb quality app radio is still just a $70 head unit and a used ipod touch for $50.
This is what I had before I heard about these new head units that still cost $70 but allow usb connection to android with aoa so I could potentially get rid of the ipod and just use my phone, but it hasn't worked out so far lol.
Click to expand...
Click to collapse
Indeed that is a good point. My unit basically cost the same as what I paid for my speakers and amp. I wish you luck on finding a solution!
With more research i concluded that in the following connection:
Device > USB OTG > DAC > AUX > Head Unit
The aux will not effect the sound quality, but this connection will only be on par with USB if the external DAC is capable of grater or equal sound quality of the Head Unit DAC, AND if the AUX cable is of good quality as well.
That being said, i also concluded that depending on the bit rate of the audio, and the quality of your hardware, bluetooth quality might be indistinguishable from USB, especially in the sound environment of a car. But you would have to test that yourself.
I will be going for the external DAC
ibCurlyFry said:
With more research i concluded that in the following connection:
Device > USB OTG > DAC > AUX > Head Unit
The aux will not effect the sound quality, but this connection will only be on par with USB if the external DAC is capable of grater or equal sound quality of the Head Unit DAC, AND if the AUX cable is of good quality as well.
That being said, i also concluded that depending on the bit rate of the audio, and the quality of your hardware, bluetooth quality might be indistinguishable from USB, especially in the sound environment of a car. But you would have to test that yourself.
I will be going for the external DAC
Click to expand...
Click to collapse
I have one more shop to check out this week hopefully. I want to test these AOA 2.0 headunits myself with otg cable + usb hub to see if I can still control the tabelt via headunit + test for the problems you had.
s2g-unit said:
I have one more shop to check out this week hopefully. I want to test these AOA 2.0 headunits myself with otg cable + usb hub to see if I can still control the tabelt via headunit + test for the problems you had.
Click to expand...
Click to collapse
sounds good
Just note the problems i had were occurring when i connected to a AOA 2.0 compatible head unit only via USB (USB A to micro USB).
Not with USB OTG or a USB hub. Idk if it works that way, but let me know

Mate 10 Pro LDAC Playback Quality

Hi, got a Huawei Mate 10 Pro BLA-L29 8.0.0.136(C185) and a Shanling M0 as a Bluetooth receiver. When I get them connected using LDAC, there are two menu sections where I can set the audio quality to be fed to the M0. One is the Developer Options where, apart from selecting the BT codec itself, I can set sample rate at 44.1 to 96 kHz, bit depth of 16 to 32 bits per sample, and stream bitrate at 330 to 990 kbps. These settings behave in a weird manner, always reverting to default every time I disconnect the BT or even while it's connected. The other instance is the properties of an individual BT device where I can set the LDAC playback quality to either "Optimized for audio quality" or "Balanced audio and connection quality".
Problem: if the BT device is "Optimized for audio quality", I only get decent transmission if stream bitrate is set to 660 kbps or lower in the Developer Options. Inversely, if the latter is set to 990 kbps, it only works decently if the device-specific setting is "Balanced audio and connection quality". If both are set to maximum audio quality, the playback starts gagging violently, interruptions happening up to twice a second if the phone is active and like once every five to ten seconds if the screen is off (the two devices 5 inches away from each other with nothing but air between them).
I brought the Shanling M0 to the nearest Sony store and paired it with a demo phone with LDAC audio quality set to 32/96 at 990 kbps and it worked like a charm without a single hiccup.
Anyone else has this issue and/or aware of a fix?
I have been to a number of stores since the original post and was able to pair my Shanling M0 to various devices:
1. Huawei P20, Android 8.1, Bluetooth 4.2 - same problem.
2. Samsung Galaxy S9+, Android 8.0, Bluetooth 5.0 - no problem.
3. Samsung Galaxy A6, Android 8.0, Bluetooth 4.2 - no problem.
Apparently, Android version is not responsible for the malfunction, neither is Bluetooth version. It's the manufacturer.
Crap, crossing fingers about having this issue fixed. Have you reported it to Huawei customer service and Shanling's one ?
Thank you for the feedback. I'm interested in this small DAP (nostalgic for my beloved Sansa Clip), even if I'm quite sure I probably won't use the Shanling M0 as BT receiver.
Scalpos said:
I'm interested in this small DAP (nostalgic for my beloved Sansa Clip), even if I'm quite sure I probably won't use the Shanling M0 as BT receiver.
Click to expand...
Click to collapse
If you ask me, you should just grab your money and go get it, because it works fine with other phones than Huawei. Even with mine, if I set it to "Balanced audio and connection quality", it's doing great. Actually, the LDAC standard bitrate of 660 kbps is amply sufficient to deliver music from major streaming services like Google Play Music. Whatever the problem is, I don't believe it's Shanling's fault, because the intensity of gagging depends heavily on whether the phone screen is on or off, which has nothing to do with connection quality.
As to the DAP itself, I find its sound signature and stage presentation nothing short of amazing, at least on par with my favorite Hidizs AP100 and far better than vivo Xplay6 or anything else I tried. Sansa Clip+ is nowhere near. The way I feel right now, I'm far more likely to ditch the Huawei phone than the Shanling DAP, because there are reasonable alternatives to the former, but not the latter.
anton79ru said:
If you ask me, you should just grab your money and go get it, because it works fine with other phones than Huawei. Even with mine, if I set it to "Balanced audio and connection quality", it's doing great. Actually, the LDAC standard bitrate of 660 kbps is amply sufficient to deliver music from major streaming services like Google Play Music. Whatever the problem is, I don't believe it's Shanling's fault, because the intensity of gagging depends heavily on whether the phone screen is on or off, which has nothing to do with connection quality.
As to the DAP itself, I find its sound signature and stage presentation nothing short of amazing, at least on par with my favorite Hidizs AP100 and far better than vivo Xplay6 or anything else I tried. Sansa Clip+ is nowhere near. The way I feel right now, I'm far more likely to ditch the Huawei phone than the Shanling DAP, because there are reasonable alternatives to the former, but not the latter.
Click to expand...
Click to collapse
Indeed, I started following Head-fi.org's thread few weeks ago, this device looks great.
I currently own a Cowon Plenue D for more than 2 years, I'm quite happy with it: relatively small, great battery life and sound. But I'd like to have a smaller good DAP I can bring with me when I run, or simply don't want to suck smartphone's battery. I bought a Sansa Sport Clip+ (BT DAP) one year ago, crappiest DAP I ever met...
What's your battery life experience using BT head/earphones wiht this DAP ?
Hello there,
Just to share the using LDAC experience with a mate 10 pro (BLA-L29 145 (C432))
I have a Sony headsets (WH-1000XM2) and it works just fine, I'm able to use LDAC perfectly, sound is very good but you need to be close to the phone, 5m apart and it starts to break.
I know its not the same situation, but this is my experience.
Best regards.
And the volume?
Mine with my sennheiser 4.50 BT NC is very low..
Scalpos said:
What's your battery life experience using BT head/earphones wiht this DAP ?
Click to expand...
Click to collapse
I have no such experience, I only use M0 as a BT receiver with wired IEM connected to it. I never even bothered to measure battery life, since it's more than two days of my regular use, i connect it to a USB port earlier than I need to charge.
sartan said:
And the volume? Mine with my sennheiser 4.50 BT NC is very low.
Click to expand...
Click to collapse
If you want to control volume on your headphones, you need to set it to maximum on the DAP. The rest of it will be the responsibility of your headphones' integrated amp - if the volume's too low, then it's just not powerful enough, there is no way a bluetooth source can fix that, as it does not transmit loudness.
sadmam said:
Hello there,
Just to share the using LDAC experience with a mate 10 pro (BLA-L29 145 (C432))
I have a Sony headsets (WH-1000XM2) and it works just fine, I'm able to use LDAC perfectly, sound is very good but you need to be close to the phone, 5m apart and it starts to break.
I know its not the same situation, but this is my experience.
Best regards.
Click to expand...
Click to collapse
Thank you very much indeed, because that's exactly the diagnostic step that I missed. Need to try that to locate the problem more precisely. Are you sure that the LDAC playback quality setting in your bluetooth device options was at "Optimized for audio quality"?
anton79ru said:
I have no such experience, I only use M0 as a BT receiver with wired IEM connected to it. I never even bothered to measure battery life, since it's more than two days of my regular use, i connect it to a USB port earlier than I need to charge.
If you want to control volume on your headphones, you need to set it to maximum on the DAP. The rest of it will be the responsibility of your headphones' integrated amp - if the volume's too low, then it's just not powerful enough, there is no way a bluetooth source can fix that, as it does not transmit loudness.
Click to expand...
Click to collapse
With other smartphone is working perfectly and with strong volume.
Where is possible to maximize the volume on the DAP? Simply with volume buttons?
Thanks.
sartan said:
With other smartphone is working perfectly and with strong volume.
Where is possible to maximize the volume on the DAP? Simply with volume buttons?
Click to expand...
Click to collapse
I would suggest that you go to the Shanling M0 thread on head-fi, there's a company representative on that forum who's very cooperative, you should describe your issue to him. I wish I could give you a hand, but my experience is limited to operating the volume wheel on the DAP.
anton79ru said:
Thank you very much indeed, because that's exactly the diagnostic step that I missed. Need to try that to locate the problem more precisely. Are you sure that the LDAC playback quality setting in your bluetooth device options was at "Optimized for audio quality"?
Click to expand...
Click to collapse
Yes... it has to be... or it wont use LDAC at all... it will use APTX or something else... LDAC is only used on the setting "Optimised for audio quality".

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