My source is a hardware mpeg2 tv card encoded mpeg1 layer 2 audio. Should I...

1.) MP2 (384kbps) -> ACC (64kbps) -> ACCGain, or
2.) MP2 (384kbps) -> PCM -> WAVEGain -> ACC (64kbps)?


choice 1 is easier, but will it results in worse quality than choice 2?


for MP2 -> ACC or MP2 -> PCM, I'll be using ffmpeg's faac.

Thank you...

FAAC is a pretty poor encoder. At that bitrate, the performance of FAAC is going to be more noticable then anything else.

Otherwise it doesn't really matter. If 1 is easier I would just do that.

I see...

I'm planning to encode to HE-ACC, which encoder should I use at that bitrate?

some said iTune AAC encoder is good, but does it support Command Line?

How about Nero? Why is it not free, but comes with many freeware like BeLight or foobar?


Thank you.

Several popular HE-AAC were tested recently at 48 kbps:

http://www.mp3-tech.org/tests/aac_48/results.html


They're all statistically tied but it can be said with a certain confidence (not 90% though) that 3GPP reference encoder is slightly inferior to Nero Digital and Coding Tech/Winamp. The tested Nero encoder isn't the official one, but is available separately (follow the link) and should be officially released next week according to Ivan Dimkovic.
Apart quality, Winamp encoder is free (Nero is free for 30 days only) and is faster (to be verified but on my old computer it's the case). And is working with foobar2000 and BeLight as well (both program don't include Nero encoder).

what is HE_v1 and HE_v2 ?

I thought there's only one HE_AAC format?

and HE_v2 performs worse, generally?? hum......

at what bitrate is AAC-HE better than AAC-LC? below 64? what if @ ~96?

HE-AACv2 should correspond to a HE-AAC encoding using the Parametric Stereo mode. As this stereo coding mode introduce strong loss, it's only designed for very low bitrate. The recent test showed that for 48 kbps (thus higher bitrate) it's likely (but not certain) that HE-AAC without Parametric stereo (HE-AACv1) would offer a better choice (in most situation at least).

For HE-AAC vs LC-AAC: the frontier is somewhere inside the 75-95 kbps range; it depends a lot of the encoders but also from the listeners preference. At 96 kbps, LC-AAC should theoretically offer a better choice. Simply avoid faac, which is clearly decent (if not more) at higher bitrate, but definitely lost below 100 kbps.

Thank you...

video+audio mp4 file, where bitrate ~48-64kps, should use AAC-HE
for audio only file, where bitrate ~128kbs, should use ACC-LC?

Is this correct? or should i stay with mp3 @ 192kps for audio only?

Which free command-line / scriptable encoder can I use for AAC-HE and AAC-LC, since you guys said FAAC sucks?

There are no rules. For some users it's likely that 64 kbps encodings with HE-AAC is good enough even for music. For some others, 192 kbps LC is still not transparent (it's at least what they would claim). In my case, I still have troubles to accept HE-AAC encodings even for movies (probably because I'm used to listen them with headphones which reveal some specific issues). But for music, I consider 128 kbps LC-AAC as excellent for three years (see here) with iTunes AAC encoder (Nero is constantly reducing the gap), at least for non-critical purpose.
LAME MP3 at ~192 kbps (VBR) is better than AAC at 128 kbps, and even LAME MP3 at ~130 kbps (VBR again) is fully competitive with LC-AAC as it was revealed during the last multiformat test.

So you should test by yourself. Several people choose to stay with MP3 and some others decided to get back to MP3 after a small Vorbis/AAC/MPC escape (it's my case, but I consider AAC as better without one hesitation - see again my tests). The need for an alternative format is not obvious unless you're interested by low bitrate; in this case, HE-AAC is probably the best choice.


For scripting a modern AAC encoder: Dimzon has published two small applications which makes the use of Nero AAC and Winamp AAC possible and easy through different software (like foobar2000). Take also a look on kurtnoise BeLight

thank you guruboolez for your wonderful advices, yea, I'm looking at both low and mid-bitrate solution.
For mp4 video and audio for my SonyEricsson walkman phone~

test myself? I would just be safe and stay with FLAC if for local playback.
I do not have great audio setup nor good sensitive ears.

You don't need golden ears and high-end audiophile equipment to perform a test. If your purpose is to get the most efficient setting for yourself and on your small phone/earbuds, then test it on real conditions. On one sense, it's even better to test encoders on real life conditions instead of ABX situation, at home and with HD headphones. You may discover that 80 kbps encodings are perfectly transparent for a street usage, who knows...
I'm very happy with 130 kbps encodings with LAME with my portable player, and several people are considering guruboolez's ears as exceptionally good . Most artefact I can hear during ABC/HR tests are simply not audible anymore on a nomad situation. But I still have everything in lossless on HDD/DVD, because I also listen music on better conditions and because it makes re-encoding more convinient (no need to extract again, to tag again, etc...)

oh mine... I can't believe this.


My result for 32bps - 64bps on my SE W800i.

iTune 6.0.4.2 LC > FAAC LC > NERO 3.2.0.24 HE/LC.

NERO has a weird ECHO on the voice. Is it possible to get latest NERO's encoder for 30days trail? What to download?

Was that a blind test?

no, but it is too obvious.

but no worry, this is only a test on SE W800i (a phone... with its original earphones)

Does your phone support AAC with HE profile? If it sounds very dull (no high frequency content at all), then your phone doesn't support it and play your HE files like LC ones at 22050Hz instead of 44100. It may explain why faac sounds better than Nero HE-AAC at such low bitrate.

I am not sure actually, maybe it doesn't. However, I also tried NERO LC-AAC, but still sound a bit weird compare to FAAC.

Maybe 'cause Nero doesn't support Mono? Even though I have the downmix to Mono on, it is still a stereo MP4. Is there a flag I can force Nero to output Mono?

Also, the source is 48khz. If I tried to set it to 44kHz or 32kHz, the file size is twice as large and play at half the rate. Weird.

Where can I get the latest Nero AAC Encoder??

On Nero website (bundled with Nero 7).

Thank you.

once I got Nero 7 Trial, is there a command line interface available for the encoder?

Dimzon has coded one:
http://www.gotdotnet.com/workspaces/worksp...54-b0999e8e223e

There are other tools for it, but I'm not sure they're still working with latest nero. They should be hosted on rarewares IIRC (otherwise search for naac).

foobar2000 0.9 is also bundled with a neroaac wrapper, and it's maybe working outside foobar2000 (see here). I'm not too familiar with these tools (I'm using GUI like foobar2000 or BeLight), perhaps other people could give you better information on that question