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Is there a way to differentiate between aptx and aptx hd codec

asked 2018-06-26 17:41:36 +0000

hassan.siddiqi.14 gravatar image

updated 2018-06-26 17:42:53 +0000

I was trying to figure out which codec my lg g5 phone and anker soundbuds slim+ bluetooth earphones were using while transmitting audio. Both of them support aptx hd.

I captured bluetooth hci packets to a log file using my phone and opened the log file in wireshark. The earphones responded to GetCapabilities request with both sbc and aptx and the phone sent a setConfiguration to aptx which the earphone accepted and aptx audio packets started being sent henceforth.

This confirmed that aptx was being used but how would one differentiate between normal aptx and aptx hd using wireshark, even though in my case its most likely aptx hd. Couldnt find any helpul info on the wireshark aptx codec page.

Another question, roughly 60-70 aptx packets were being sent while listening to both "It's All Well Above Wonder Anyway - Grace Cathedral Park" flac(775kbps) and mp3 (233 kbps). Each aptx packet data payload was 672 bytes or 5376 bits. That would roughly equate to 5376 bits x 65 packets/sec = 349kbps. Is that estimate of bitrate correct? but that also makes me wonder why a lower bitrate mp3 was being transmitted at a higher bitrate. Although this is probably not wireshark's domain. Thanks

Screenshots

https://www.mediafire.com/view/vj9nxr...

https://www.mediafire.com/view/rvomgg...

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answered 2019-12-08 13:10:45 +0000

dandreye gravatar image

updated 2019-12-08 13:11:57 +0000

Hi Hassan,

Just wondering if you've ever managed to figure out the right answer? My own research suggests AptX codec is advertised as 0xFF 0x004F 0x01 while AptX-HD codec is advertised as 0xFF 0x00D7 0x24, so it looks like your earphones only support the former one. A table with several codec IDs can be found here (~60% down): https://habr.com/en/post/456182/

HTH.

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Thanks for posting that. Your research looks interesting. Will look into it when I have time.

Anker soundbuds slim+ and soundcore spirit pro only support aptx. This was confirmed by Anker itself. Email is attached.

https://www.mediafire.com/file/ut9v6x...

hassan.siddiqi.14 gravatar imagehassan.siddiqi.14 ( 2019-12-08 13:40:26 +0000 )edit

Thank you. In fact I don't have either of those devices: I'm using Sanwu SW-HF59 Bluetooth receiver connected to car/home audio. It's based on CSR64215 chip, hence AptX only w/o AptX-HD, at least it doesn't announce 0xFF 0x00D7 0x24 support - only 0xFF 0x004F 0x01. Looking for an equally cheap device with AptX-HD now. Actually the article author also shares how to boost SBC audio quality on most devices to AptX-HD equivalent level.

dandreye gravatar imagedandreye ( 2019-12-08 14:11:02 +0000 )edit

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Asked: 2018-06-26 17:41:36 +0000

Seen: 309 times

Last updated: Dec 08 '19