How to: use eAAC+ to put FAR more music on your smartphone

Published by Steve Litchfield at 17:35 BST, May 15th 2008

Guest writer 'Snoyt' takes us expertly through the wonderful world of music compression, to explain how you can get thousands of music tracks on your smartphone, efficiently and in CD quality, using the eAAC+ codec rather than bog standard ol' MP3...

The Art of Cramming Music into your smartphone

 

The world is full of mp3 players and many people own and carry them around next to their mobile phone. You can find anything from 1GB microsized music dice to slimwaisted 160GB iPod-classics. When only parts of my music collection fits on my phone, I find I wanted to play that one number that is missing... But do I really need to lug an 160GB iPod with me for just music? Skip to the How-to to get a quick solution or read the background first for an informed solution.

Mp3 and compression

When mp3-compression became available, it was possible to store  high-sound-quality music rather memory efficiently (read: affordable) onto your PC for random access and playback. Struggling with bitrates and noisy soundcards, it was still largely about: 'because I could'. With increasingly cheaper disk space, better soundcards and compression techniques like AAC, mp3Pro and WMA 9, it became more useful and practical. It became particularly practical for me when convergence hit the mobile phone. My trusty SonyEricsson W800i could not only take 2.1Mpixel pictures, it could play music. As such, it had a cool orange color and sported the Walkman logo...

So several years ago I made the effort of converting all my CD's into 320 kbps mp3 and stored them on my PC. At that time, 320 kbps was needed to preserve the quality. Admittedly mp3-codecs were then sufficiently efficient good that 192 kbps might suffice. But in order to recode them later to lower bitrates without irritating recoding errors, the bitrate of 320 kbps was a much better choice.

Recent developments into compression formats like AAC, HE-AAC, mpc and Ogg show that at 128 kpbs a perfect sound quality can be achieved. A quality where all sound artifacts are beyond the threshold of human perception. See soundexpert.info's 128 kbps testresults. AAC is doing very well, and it's successor HE-AAC v1 is doing even even better in those results. 64 kbps HE-AAC v1 (aka eAAC) performs close to perfect, which is incidently only slightly better than HE-AAC v2 at a lowly 48 kbps, aka eAAC+. All compression formats which the Nokia N95 and many of the NSeries phones support.

Simply explained, AAC +SideBandReplication = HE-AAC v1. AAC + SBR + Parametric Stereo = HE-AAC v2 = eAAC+. SBR (sideband replication) is mostly useful upto 128 kbps and PS (parametric stereo) up to 48 kbps. More about it can be found on the Coding Technologies HE-AAC page. In short, above 48 kbps eAAC+ defaults to eAAC encoding and above 128 kbps eAAC+ defaults to AAC encoding.

Accidently, 48 kbps eAAC+ is the default encoding quality of the Nokia Music Manager. This quality is considered by the progam to be good quality and optimal for mobile application. An additonal bonus of the 48 kbps HE-AAC with SBR and PS encoding is that is designed to be very power efficient to decode/play. Better than mp3 or regular AAC. 64 kbps eAAC is considered by the Nokia Music Manager to be excellent quality.

'How to'

My collection of mostly 320 kbps encoded mp3's (some are 192 kbps) on my home PC requires about 26 GB of diskspace. Converting it into eAAC+ at 48 kbps reduces it into 4.65 gigabyte. Not bad for 'good' not excellent rated compression. We are talking here about 9 days of continuous music. Add about 1.5GB for the maps of USA or the Europe for Nokia Maps and you have about 1.5GB left for recording film, photos on a 8GB memory card. Do you want excellent quality, nearly indistinguishable from the original? Go 64 kbps if you are a classical music-loving audiophile. But otherwise it is not worth it, especially not on your phone.

How to convert? Although Nokia Music Manager can do the encoding for you, it does not cope well with encoding 3000+ music files. It simply crashes at some point. The free version of WinAmp, however, works great and gives a very nice quality. Nero gives even better encoding results. Simply import your mp3's into the WinAmp music libary and 'send to' the 'Format Converter'. Select an output folder choose and the first AAC Plus converter in the list. Next, set 48 kbps and parametric stereo. After 24 hours or so it is finnished converting everything on a 2.4 GHz Pentium 4.

Audio quality, practical aspects and its price tag

An 8 GB microSD card costs about 50 euros and can store about 11 days of music at nearly indistinguishable CD quality in 64 kbps eAAC+, or 15 days of music if you are happy with a pretty good mobile quality of 48 kbps in eAAC+. In comparison, a separate iPod or iTouch with regular AAC at 128 kbps would require at least 21GB of disk space. Neither iPod or iTouch come close to the 50 euros price range. In fact, the iPod classic prices currently start around 230 euros. Of course a 80 Gigabytes mp3-player is very cheap for that price. But it is way too much for just music.

A good argument might be the sound quality. My N95 has a slight hiss at low volumes, the iPod has a better sound. Well this is true. However, a good Bluetooth stereo headset can be bought for a mere 50-60 euros. The Bluetooth headset has its own D/A converter and a good one has no background hiss. The additional advantage is that if you buy a Bluetooth headset like the Nokia BH-500 with a regular 3.5 mm headphone connector, you can connect any headset you like. You can even connect it to your stereo, allowing it to work as a A2DP gateway. Playing music straight from the couch over the stereo. At this point you would still have paid only 110 euros versus 230 euros for the cheapest iPod classic which has no Bluetooth support or a remote controlled headset. Seems to me there is even plenty enough money left to shell out for a spare phone battery of 20 euros ;-)

Currently neither the iPod, the iTouch or the iPhone support any of the better HE-AAC codecs, silly is it not? Particular since it was Apple who put AAC on the consumers map. This year 16GB and 32GB microSD cards are entering the market giving eAAC+ capable phones an even stronger position, particularly against the iTouch/iPhone in musical terms. Even audiophiles with very large music collections (800+ albums) can carry all their music in their 'pocket' at 128 kbps in top notch HE-AAC. No battery draining while streaming, no network load or cost, no ORB or winamp remote required. Just random music access from you on your phone, a properly spelled phone. You see it, don't ya? There is no i in these phones! [enough of the iPhone bashing! - Ed]

P.S. At 3000+ songs, the music player starts becomes a bit sluggish when browsing the songlistings. Minor acceptable delays occur when opening the song/artist/album lists.

Update: A comparison of eAAC+ (48 kbps, SBR+PS) and AAC+ (64 kbps, SBR) can been found at the Hydrogen Audio Forums. Particular this result gives a good representation of the practicality of using parametric stereo. It seems a HE-AAC V3 standard with a variable stereo bitrates would be useful to be developped for classical music.

Snoyt, All About Symbian, 15 May 2008

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Categories: How To
Platforms: Series 60, General, S60 3rd Edition, UIQ 3

Quote:

Originally Posted by basse When searching for _the_ encoder to use, I wouldn't draw to drastic conclusions from the Hydrogen Audio comparison. It's from September 2005, and a lot has changed since then.

@basse: We may surely hope that encoders will improve with time. However HE-AAC v1 and v2 will BOTH profit from improvements in SBR and AAC encoding. However in the hydrogen test the difference between 64 and 48 kbit lies in the usefulness of parametric stereo to reduce bit rates further.

eAAC+ is basically a mono signal, encoded in AAC with SBR, where a limited number of bits is used to assign stereo values for a range or frequency bands (the parametric stereo part). As such more bits remain for encoding the frequency spectrum. Encoding music from large orchestra with a complex stereo image suffers from more quality loss than music from a pop band with a simple stereo image of a few instruments. The point I made in the text and which is nicely supported by the hydrogen testresults.

In simple words HE-AAC v2 at 48bits has nearly the same bitrate for the frequency spectrum as HE-AAC v1 has at 64 bit. There is largely only a quality loss in the stereosound 'image'.

Quote:

Originally Posted by Uridium You forget to mention that any of the apps you suggest will rip out any embedded album art during the conversion process.

Another way to save diskspace ;-) Besides album art supported music browsing does not exist on the N95.

Quote:

Originally Posted by Uridium Additionally transcoding from one lossy format to another is never going to give anything better than dire output.

A mathematical unsound statement. A good lossy compression algorithm stops being lossy when there are suffcient bits. With 48 kbps being the target quality. I really doubt you would here the difference between straight from the CD ripped and recoded from 320 kbps mp3.

Quote:

Originally Posted by Unregistered great stuff! i only have one question though, wouldn't reencoding already compressed music (eg 192kbps mp3) to a different format (eg 64kbps wma or eAAC) cause the audio to loss even more quality.

Don't use WMA at 64 kbps. HE-AACv2, preferably at 48 kbps, is the way to go.

Note that I don't recommend 64 kbps for HE-AAC. The sole reason for this is that there's no PS at speeds larger than 48 kbps any more. This is why I use, in general, 48 kbps to transcode my stuff - and 32 kbps for Internet radio transcoding so that I can listen to them over plain GPRS connections. Vodafone doesn't support EDGE and I have a flat rate Voda subscription. GPRS streaming consumes far less power than 3G (see my Radio Streaming Bible, linked above, to see some real-world N95 figures to see how economical GPRS is, power usage-wise); therefore, it's always preferable.

Quote:

Originally Posted by Unregistered Anyone who believes that compressed music, in whatever format, sounds anything like uncompressed music is dreaming. A website with expert in the name and bar graphs does not prove anything. Compression is perfect for carrying around, the car etc but to say it is perfect is risible. Guy

You're right. However, currently, HE-AACv2 is the best (and most economical) solution for low-speed, low-storage transcoding. Too bad so few mobile devices are (still) able to decode it (no Apples, no Zunes, no Windows Mobile devices w/o using some suboptimal apps with high power consumption and lack of AVRCP etc.)

Quote:

Originally Posted by olevine Excellent review, and thanks particularly for the tip about the Winamp encoder! -Oren (Nokia S60 marketing)

BTW, I heavily recommend my tutorials posted in the N95 forum. You'll like them, I'm pretty sure. See my similar review / tip posted some 5 months ago.

Quote:

Originally Posted by Uridium You forget to mention that any of the apps you suggest will rip out any embedded album art during the conversion process. Additionally transcoding from one lossy format to another is never going to give anything better than dire output. Disk is cheap. rip all your music to FLAC then if you really must carry 100's of tracks around at a time transcode to a medium bitrate aac using omething like DBpoweramp.

Actually, you can easily transfer your album art by, say, simply copying the (hidden) two standalone JPG files from the source (say, MP3) to the target directories. The N95 (or any other HE-AACv2-capable phone) will have no problems reading them.

Quote:

Originally Posted by neilhoskins Will it stream via uPNP?

It will - the audio stream format has nothing to do with the way you access / control it. For example, I've used HE-AACv2 streams / files in my UPnP Bible - see http://www.allaboutsymbian.com/forum...ad.php?t=68115 (I recommend it for anyone still not having read it) - and had absolutely no problems with playing back them over home stereo, using the N95 as the source.

Quote:

Originally Posted by Unregistered Large music collections are easier to organize in folders. MLauncher does this: www.mlauncher.org

So does WinAMP: it does preserve the original structure, assuming you have MP3 ID tags. ID tags, incidentally, get transferred to the target AAC files w/o problems.

Quote:

Originally Posted by ayush3090 well i hav my music cnverted in eAAC+ in my 5700, bt r u sure the bh-500 or other BT headphones/jacks dont use the built in DSP ?

As Snoyt has already explained (and me too in some of my past articles - see the N95 forum for them), most A2DP solutions simply re-encode their input, regardless of their format, to 64 / 128 / 192 / 256 / 320 kbps streams. (Bit speed depending on the encoder and the environment. For example, when there's a wall between the headphones and the source, you'll most likely only have a very low-quality 64 kbps stream, if any.)

However, some (VERY few and, in general, older and no longer mainstream) headphones are also able play to directly play back MP3. With them, no transcoding (further decreasing the audio quality - no matter how little the audio quality loss is) needs to take place.

Quote:

N is better than 5700s DSP (which is crappy tho) ? N wil it sound the same in 5700 as it would in n91 if i use the same BT headphones in both? coz im luking fr sm gud music headphones fr my 5700

In my tests, I've found them exactly the same. Are you sure the 5700 codecs are "crappy"?

Quote:

N which headphone under 100 dollars would u suggest to go along with BH-500 ? Thnx in advance

I recommend -if interested - my A2DP headphones reviews. I'll soon post a big review of three new A2DP headphones to the N95 forum - make sure you follow my articles there. Unfortunately, some headphones have inherent problems when used with a Nokia S60- for example, none of the Plantronics Pulsars are able to use all AVRCP functionalities. Therefore, it's always worth checking out my A2DP headphones tests before shopping for them to avoid having to, later, return the headphones to get a (more) compatible pair of headphones.

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