12-21-2019, 02:58 AM | #1 |
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Harman Kardon + Apple CarPlay + Amazon HD
Guys I have HK in my G20, I also have Apple CarPlay and Enhanced Bluetooth. Using the latest iPhone I'm looking to get the best out of the sound system.
I've signed up and started to use Amazon HD, so my question is - Are the benefits of the HD/Ultra HD tracks being played back at their best via wireless AppleCar play? If not how do I force playback via USB assuming this will be better? Any help would be great. TIA Charlie. |
12-21-2019, 09:36 AM | #2 | |
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As for your specific situation; why not experiment and tell us what you find? Does sound quality change when you connect via usb? Does sound quality change when you connect via Bluetooth and don't use CarPlay?
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12-21-2019, 10:32 AM | #3 | ||
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12-21-2019, 01:44 PM | #4 |
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CarPlay is wireless only. If you plug the phone via USB you can use it as a USB source for audio playback.
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12-21-2019, 03:46 PM | #5 |
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12-21-2019, 09:18 PM | #6 |
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I think a lot of people assume Wireless carplay is using only bluetooth - but Wireless Carplay actually uses Wifi not Bluetooth to communicate. While it does use Bluetooth for the initial connection, the interface and audio streams over Wifi.
Bluetooth A2DP is not high quality (320 Kbps max bitrate or 0.3Mbit/s), but if you have higher quality audio streaming over Wifi to the car, Wifi should be able to handle it just fine. For reference, the max bitrate of FLAC audio (with 8 channels) which is a lossless codec and greater than CD quality is ~37Mbits/s - even Wifi from 2003 (802.11g) can send data at 54Mbit/s - and most likely the Wifi in the G20 is at least 802.11n that has a max transfer speed of 600Mbit/s. Even though you normally wouldn't see the maximum 600Mbit/s on 802.11n, you still should easily get 100Mbit/s which is more than enough. Uncompressed CD quality audio with 2 channels is only about 1.5Mbit/s and even "High Res" audio is only ~9.2Mbit/s -- suffice it to say, you have nothing to worry about with a wireless Carplay setup. With all the background noise from tires, wind noise, etc while you're driving - and considering the HK system sounds good but isn't anywhere close to an audiophile system, I doubt you'd be able to tell the difference between CD quality audio and anything above that like High Res audio. |
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12-22-2019, 01:10 AM | #8 | |
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Will check it out, as you say once in the car actually being able to tell is one thing, but it's supplementary using this in the car I mostly wanted to try it out for my home set up. Cheers Charlie |
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12-22-2019, 02:49 AM | #9 |
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So does that mean that you have to have your hotspot turned on and need good WiFi coverage to listen to Spotify even if it’s music you’ve previously downloaded?
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12-22-2019, 04:47 AM | #10 | |
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The answer to either though is no, for your phone - Wireless carplay essentially turns your phone into a hotspot for the car automatically (although it is Wifi Point to Point between your phone and the car instead of turning your phone into a Wireless Access Point which allows multiple Wifi connections to your phone) On the car side, you don't need to have the Wifi hotspot option to be able to use Wireless carplay. So it isn't required. As far as having good Wifi coverage - I don't know what this means? When you enable Wireless Carplay, you setup a point to point connection between the phone and the car. The phone and the car are talking directly to each other and create the Wifi connection, no coverage is needed. BTW- If you want to test this for yourself, setup Wireless Carplay on your phone/car and then turn Wifi on your phone off and you'll lose the Carplay connection. Or if you turn on the car and your phone has Bluetooth on but Wifi off, the phone will ask you to turn Wifi on to connect to Carplay. |
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12-22-2019, 04:52 AM | #11 | |
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Wireless carplay will obviously work better when you have a Cellular data connection because any apps that require an Internet connection, like say for instance Waze or Google Maps - can route you dynamically based on traffic conditions, but needs an Internet connection to get the traffic data. However, if you downloaded music previously on Spotify, it wouldn't use your Cellular data connection to stream the music, it can simply play the music you've downloaded already on your phone. This is important because if you downloaded the music from Spotify at very high quality, and then are playing it over Wireless carplay, you'd still by playing the high quality downloaded version of the music. |
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12-22-2019, 10:08 AM | #13 | |
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I also typically play Spotify at the "Normal" setting which is only 96Kbit/s so I probably am not even able to tell the difference between Bluetooth and Wireless Carplay. I did do a bit more research and found that while Wired Carplay streams audio in LPCM format (essentially raw uncompressed audio), Wireless Carplay streams audio in AAC-LC format (other choices are OPUS or AAC-ELD but both are intended for voice and not music). This is at least true for the initial spec of Wireless Carplay. AAC-LC is a lossy audio format and if you're playing something like Spotify it is still compressed audio, even if it is on the High Quality setting. So the bad thing is that it probably has to recompress the audio to AAC-LC which can result in even more degraded audio. I say probably because its possible IOS is smart enough if the audio is already in AAC LC format to simply pass it onto the head unit. So - while Wifi should easily be fast enough to stream a 2 channel PCM stream, or they could have used ALAC (Apple's non-lossy audio format similar to FLAC) it seems that Apple decided to use a lossy codec for Wireless Apple Carplay. It is entirely possible that this has changed over time, and newer versions of IOS support something other than AAC LC for media streams, but everything I've read suggests AAC LC is what is being used. This is still a lot better than using Bluetooth a2dp which is limited to 320Kbit/s, but is not as good as using LPCM since it probably re-encodes audio to a different format. So I'd put Wireless Carplay in the middle between Bluetooth audio and Wired Carplay. Again with all that said - I don't actually think most folks would notice the difference when you're driving the car with all of the other noises going on along with the HK system probably not being good enough. |
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