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APT-X
slenpree
post Jan 27 2010, 12:16
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see www.aptx.com

this company really annoys me because although they claim APT-X to be so great (near lossless @ 128kbps) there is little evidence to support this claim due to their proprietary nature and hardware focus. Their main codec seems to be common in hardware ISDN codecs due to low delay which suggests low complexity.

All in all I would like to give these folks a chance, they might have some very intelegent (and expensive) sound scientists backing the project. It's come the time where I would like to do some blind listening tests with this codec because with all the focus on MP3 ( and even AAC ) I doubt I will be blown away when comparing it a 128kbps MP3.

However I can't find an APT-X software codec for foobar, or at all. With all the game codec packs for foobar I was quite suprised not to see APT-X as it's been about for quite a while. Perhaps I'm just not looking hard enough and need to use the chinese google. If anyone could save my alot of time and point out the foo_input_aptx component that would be greatly appreciated.

Of course I will share my results on here biggrin.gif

Kind Regards,
Jonathan
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slenpree
post Jan 27 2010, 19:08
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thanks smack, i'll give that a go later and report my results. I've ignored the shanon nyquist theorm before and encoded at 22.05Khz, it sounded absolutely terrible (worse than what i've heard of apt-x but I think that is because apt-X "predicts"?) - though I don't remember which codec it was now.

Welcome to hydrogen audio dtrainor, it's good to speak to someone from apt-X! I work with live audio over satellite a bit, but using UDP/IP based systems and not the usual ISDN based systems, as such AAC seems to be more popular than apt-x with the people I speak to.

Continuing on from you said about low delay and low complexity. Can you refer me to any literature comparing and contrasting the sonic ability of apt-X against the Enhanced Low-Delay AAC at the same bit-rates (assuming very similar delays here). I now understand the two codecs have a different architecture and AAC is probably not so feasable on a hardware based DSP.

But just for fun I would really enjoy some time with a trial version of a apt-X software encoder/decoder wink.gif
UPDATE: converted a FLAC rip of a CD to 16Khz LPCM and it sounds garbage for 512kbps. I should imagine the same test using "Sub-band ADPCM" would be more fair but it sounds like apt-X does add alot of sauce on top.

Regards,
Jonathan

This post has been edited by slenpree: Jan 27 2010, 19:32
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smack
post Jan 28 2010, 09:53
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QUOTE (slenpree @ Jan 27 2010, 19:08) *
UPDATE: converted a FLAC rip of a CD to 16Khz LPCM and it sounds garbage for 512kbps. I should imagine the same test using "Sub-band ADPCM" would be more fair but it sounds like apt-X does add alot of sauce on top.

No, a 128 kbps apt-X file encoded from that 512 kbps PCM file would not sound better. There is no special magic potion that creates the lost bits out of thin air. I know that there are techniques like SBR that appear to do just that, but apt-X does not use it. (or does it and I missed it?)

Btw. apt-X Bluetooth uses a bitrate of 352 kbps and thus preserves the full bandwidth of a 16 bits stereo 44 kHz audio stream. That's a lot more reasonable for "Hi-Fi" applications.
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Posts in this topic
- slenpree   APT-X   Jan 27 2010, 12:16
- - smack   Look at the documents available at the download se...   Jan 27 2010, 16:18
- - slenpree   thanks for pointing me in the right direction smac...   Jan 27 2010, 16:58
|- - smack   QUOTE (slenpree @ Jan 27 2010, 16:58) Doe...   Jan 27 2010, 17:23
- - dtrainor   As someone who works for APTX, hopefully I can she...   Jan 27 2010, 17:17
|- - pdq   QUOTE (dtrainor @ Jan 27 2010, 12:17) For...   Jan 27 2010, 18:45
|- - Woodinville   QUOTE (dtrainor @ Jan 27 2010, 08:17) sma...   Jan 27 2010, 20:32
|- - lbbrhzn   QUOTE (Woodinville @ Jan 27 2010, 20:32) ...   Oct 1 2010, 16:20
|- - saratoga   QUOTE (lbbrhzn @ Oct 1 2010, 11:20) QUOTE...   Oct 1 2010, 16:30
- - slenpree   thanks smack, i'll give that a go later and re...   Jan 27 2010, 19:08
|- - dtrainor   QUOTE (slenpree @ Jan 27 2010, 18:08) Con...   Jan 27 2010, 23:01
||- - smallicoat   QUOTE (dtrainor @ Jan 27 2010, 14:01) QUO...   Sep 9 2010, 22:09
||- - lbbrhzn   QUOTE (dtrainor @ Jan 27 2010, 23:01) QUO...   Oct 1 2010, 16:25
|- - smack   QUOTE (slenpree @ Jan 27 2010, 19:08) UPD...   Jan 28 2010, 09:53
|- - dtrainor   QUOTE (smack @ Jan 28 2010, 08:53) No, a ...   Jan 28 2010, 11:20
- - Garf   Sounds like the area in which CELT is competing, t...   Jan 27 2010, 20:54
|- - dtrainor   QUOTE (Garf @ Jan 27 2010, 19:54) Sounds ...   Jan 27 2010, 23:10
- - skamp   dtrainor: do you know of any Bluetooth emitter + r...   Jan 29 2010, 07:30
|- - dtrainor   QUOTE (skamp @ Jan 29 2010, 06:30) dtrain...   Jan 29 2010, 11:31
|- - skamp   QUOTE (dtrainor @ Jan 29 2010, 11:31) How...   Jan 29 2010, 17:26
||- - dtrainor   QUOTE (skamp @ Jan 29 2010, 16:26) Thanks...   Jan 29 2010, 20:46
|- - atlantic   QUOTE (dtrainor @ Jan 29 2010, 11:31) AFA...   Jun 27 2011, 15:05
|- - dtrainor   QUOTE (atlantic @ Jun 27 2011, 14:05) QUO...   Jul 13 2011, 11:15
- - jmvalin   As far as I understand (but I could be wrong), the...   Feb 23 2010, 00:16
|- - slenpree   QUOTE (jmvalin @ Feb 22 2010, 23:16) As f...   Jul 11 2010, 23:19
- - smartfinder   Hi all, I like the codecs long ago, I would like t...   Jun 19 2010, 21:38
- - Pri3st   This is the only receiver that I have found. It ha...   Jun 27 2011, 15:35
- - Serge Smirnoff   I wonder if there any possibility to save decoded ...   Jul 8 2013, 13:12
- - beng   Hi, Could someone please answer this one: the Sams...   Sep 20 2013, 10:20
|- - beng   QUOTE (beng @ Sep 20 2013, 11:20) Hi, Cou...   Oct 1 2013, 21:18
- - saratoga   If you want to hack ROMs, XDA would be a better pl...   Oct 2 2013, 00:33


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