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Discussion Starter · #1 ·
On my CDR Plus system, my iPod USB playback will occasionally lose sound after I switch from iPod USB to radio or CD and then back to iPod USB. It will connect properly (I can see the track selection and the cover art, and I can even see the playback bar move from left to right and count the seconds), but there is no sound. The only way I have found to get the sound back is to unplug and re-plug the iPod.
:wall:
Has anyone figured out how to fix this?
 

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The only time I've had something like that happen was when I had an alert on my iPhone. The iPhone was connected by bluetooth, the iPod is of course connected via the USB port. It was like the phone sent a message to the head unit which caused it to mute the iPod, then never followed through with anything, so the iPod was still on mute. That only resolved itself when i got a phone call, so the iPhone could mute the head unit, then unmute it once the phone call was over.

That's my theory anyway. Do you have a paired bluetooth device which might have been trying to say something?
 

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Discussion Starter · #3 ·
No just the same iPhone, connected over Bluetooth.

I thought it might be the cable, so I changed the cable, but it didn't help. Moreover, I also discovered that when this problem occurs, I can't listen to my iPhone music through Bluetooth either (although the playback seems otherwise to be working). So it is definitely not a cable problem, but something more fundamental about the car not playing sound coming my iPhone sometimes.

No one else has had this issue?
 

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Have you tried talking to Porsche about this?

There was a time a few years ago when my job involved debugging issues like this, the bugs came in from the car or head unit manufacturers. Of course if you have a very isolated case, and no one else can reproduce the issue there's not a lot that can be done. I could probably tell a lot if I had access to the car and iPod for 5 minutes with my USB analyser.

Which iPod do you have? Does it have the latest available software? The symptoms are reminding me of an authentication failure.
 

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Discussion Starter · #5 ·
Have you tried talking to Porsche about this?

There was a time a few years ago when my job involved debugging issues like this, the bugs came in from the car or head unit manufacturers. Of course if you have a very isolated case, and no one else can reproduce the issue there's not a lot that can be done. I could probably tell a lot if I had access to the car and iPod for 5 minutes with my USB analyser.

Which iPod do you have? Does it have the latest available software? The symptoms are reminding me of an authentication failure.
No, not yet. The problem has annoyed me enough to post here, but not enough for me to spend time to bring the car in to the dealer. It's an iphone 5S. Your suggestion about SW upgrades was good; I'll try that.
:thanks:
 

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I have some odd issues with an iPod touch connected via USB, too. About 20% of the time when I turn on the car it will fail to see the iPod. I always turn the car off with the iPod selected as the playback device, so when this happens it's obvious because the radio comes on instead of the iPod. When this occurs, navigating to the source select screen reveals the iPod is not listed as an available source. I've waited for a number of minutes when this has occurred and it does not appear.

Most times, unlocking the iPod renders it available. Other times, however, this does not work. The first time a simple unlock did not work, I tried reconnecting the USB cord to the iPod. But, I saw something on the iPod about "unsupported device". No matter how many times I reconnected it, it would not appear as a source. I had to power-cycle the iPod for it to become available. Subsequent to that, my "fix" is first to swipe the iPod to unlock it and failing that I power-cycle it. I'd say 90% of the time the power-cycle is not required.

At some point I'll have to trade w/ my wife to see if her older iPod touch has similar issues. Also to see if mine works fine in her Q5.
 

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It's an iphone 5S.
I worked with the other iPods (classic, nano etc) not the iOS ones (iPhone, iPod touch). I never trusted CoreOS to get any of this right. My personal iPod touches including the one in the Porsche are still on iOS 6.1.2, I've heard of various flakiness with the latest OSs.

A reboot is always a good first step when something goes wrong. Rebooting the iPhone is easy, rebooting the head unit may be more tricky. It may reboot if you hold down the volume button until the screen goes off, I'm not sure. It may need to be left unplugged for some indeterminate time.
 

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I was having connection problems with mine as well. I took a small paper clip and gently cleaned out the port where the cable goes into the iPhone. I couldn't believe how much lint I got out of there from carrying the phone in my pocket. Works great now.
 

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I've had it happen a few times with my iPod Classic. I seem to recall it would happen as you said, switching sources, or sometimes when switching tracks.
One time I had a track actually disappear in a playlist I was playing until I did the unplug replug.

Only thing I've found to clear it is to unplug/replug.

The worst is when the PCM seems to bork DVD and iPod playback. I've only had this happen twice, but I expect better. If it happens again, I may actually reach out to PCNA.
http://www.planet-9.com/981-cayman-...pported-seems-kill-ipod-playback-if-used.html
 

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Discussion Starter · #10 ·
I've had it happen a few times with my iPod Classic. I seem to recall it would happen as you said, switching sources, or sometimes when switching tracks.
One time I had a track actually disappear in a playlist I was playing until I did the unplug replug.

Only thing I've found to clear it is to unplug/replug.

The worst is when the PCM seems to bork DVD and iPod playback. I've only had this happen twice, but I expect better. If it happens again, I may actually reach out to PCNA.
http://www.planet-9.com/981-cayman-...pported-seems-kill-ipod-playback-if-used.html
Hm. I haven't run into the disappearing track issue yet. The connection between the iPhone and the car seems ok in every respect except sound. I can select tracks, rewind, fastforward, look at the cover art, even see the playback bar moving from left to right, counting the seconds, just like it's supposed to. I just don't get any sound, in either bluetooth or USB mode. CD and radio sound work fine when this happens ...
:confused:
 

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On a slightly different note -- does anyone know if there's a way to quickly select a different album by the currently playing artist when in iPod source? It seems I have to navigate all the way back through all the artists to the one that's playing, the select an album, then play it. This is cumbersome. I wish I could just click (touch) somewhere on the screen and be brought to the list of albums by the currently playing artists and pick a new one.

Honestly, there are some things about this interface (cover art, touch screen) I like better than my wife's Audi, but most of it sucks in comparison :(.
 

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Does touching the media button get you somewhere useful?
No, touching the media tab button on the touch display does nothing, pressing the hard-button on the radio itself switches sources. I'm not sure it's possible. I really like the Audi's system better, oh well...this is more fun to drive, lol.
 

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Hmm, add me to the list of funky USB port issues.

This morning I had my iPhone connected via the USB port in the glovebox. I pressed Media and selected iPod. When I used PCM to select tracks, no audio would come through the system. I could switch to other artists or tracks, but still no audio. When I manually selected tracks on my iPhone, the audio played without any issues. I should be able to use PCM to control the iPhone music app, I would think.
 

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Interesting...I just experienced this in my Cayenne loaner. My iphone connected to the USB port, info displayed showing that the track was playing but no sound. Skipped to the next track and still no sound. Then, switched over to the Bluetooth connection, voila...music.

I would expect wireless can have issues at times but hard wire???
 

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I would expect wireless can have issues at times but hard wire???
As I mentioned above, I can think of a couple of reasons for this and they're both software glitches, the wire is doing just fine.

The first one happened to me where the iPod was muted because of an event on BlueTooth, then the software forgot to unmute the system. The wire can be happily transmitting the music, but the amplifier is turned off. Bad bug, but easy to write.

The second one sounds like an authentication failure. When Apple implemented digital audio transfer (i.e. via USB) from an iPod to a head unit they required the head unit to authenticate to the iPod to make sure it was an authorized implementation (to ensure a good customer experience, or to collect the appropriate royalties, depending on your point of view). If the authentication fails the iPod looks just like a USB audio device which is streaming sound to the head unit, except the sound is all silence.

I don't know much about the authentication process, someone else handled that, but my code streamed the music. I got a call to say authentication had succeeded at which point I'd start pointing to the buffer which contained the music to stream across USB, rather than a buffer full of zeros. There's a lot of ways that model can screw up.
 

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Discussion Starter · #17 ·
Yeah, it’s not the cable. I swapped the cable with a known good cable, and it didn’t change anything.

The only consistent pattern is that this never happens immediately after I start the car. In other words, when I first start the car, the system is always on radio. When I first switch it from radio to iPod, this problem never happens. It only happens after I have cycled through the radio/iPod sequence at least once already.
 

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It only happens after I have cycled through the radio/iPod sequence at least once already.
If you look at the music player status on the device, what does it show? Another possibility is the head unit paused the playback then forgot to unpause it. As you're using a phone here, you can go look at what the player thinks its doing. If its paused, does pressing play get the music running?
 

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Discussion Starter · #19 ·
I'll have to try it out next time it happens. Thanks for the ideas!
 

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Discussion Starter · #20 ·
If you look at the music player status on the device, what does it show? Another possibility is the head unit paused the playback then forgot to unpause it. As you're using a phone here, you can go look at what the player thinks its doing. If its paused, does pressing play get the music running?
I checked this out yesterday. When this problem happens, my iPhone (just like the car) thinks it is playing music just fine. Pressing Pause on the iPhone and then Play again doesn’t bring the sound back.

Yesterday, though, switching to Bluetooth reactivated the sound. Switching it back to iPod shut the sound off again. In both modes, the car and the phone show music playing in the display ...
:confused:
 
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