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Topic: HE-AAC v1 with 24 kbps (Read 5330 times) previous topic - next topic
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HE-AAC v1 with 24 kbps

Hi,
does any one knows the application of HE-AAC v1 with 24 kbps?
or HE-AAC v2 with 24 kbps?
sampling rate is 48 kHz.
thanks

Re: HE-AAC v1 with 24 kbps

Reply #1 –
What? :o

Are you looking for encoders to create 24kbps HE-AAC v1?
There's a bunch of them (i assume you need one on a Windows PC):
- Apple iTunes encoder, you can use the qaac frontend with it
- Fraunhoffer FhG AAC Encoder from Winamp (with fhgaacenc frontend)
- Fraunhoffer FDK AAC encoder from Android (not distributed as binary you have to compile it on your own, Google for "FDK AAC build helper")
- Coding Technologies AAC Encoder from older Winamp versions with enc_aacplus frontend (outdated)
- Nero AAC Encoder (outdated)

Re: HE-AAC v1 with 24 kbps

Reply #2 –
Hi darkbyte ,
thanks for your reply.
I mean some real application using this mode, e.g., the DAB+, streaming audio..
In DAB+ system, the available bit rate if from 8 to 192 kbps, but I don't know which is often used ...

Some paper said the most often used mode of HE-AAC v2 is 24 to 32 kbps for a stereo signal.
But I would like to know whether there are some real application exactly using HE-AAC with 24 kbps, 48 kHz.

Re: HE-AAC v1 with 24 kbps

Reply #3 –
Melbourne, Australia has a DAB+ radio station using 24 kb/s apparently. At least, it shows up in the ensemble list for Melbourne: http://www.wohnort.org/DAB/australia.html#Melbourne on Wohnort. There will probably be more radio stations using that bitrate, likely speech only stations...
Every night with my star friends / We eat caviar and drink champagne
Sniffing in the VIP area / We talk about Frank Sinatra
Do you know Frank Sinatra? / He's dead

Re: HE-AAC v1 with 24 kbps

Reply #4 –
Hi Maurits,
thanks for your information.
If I understand correctly, the bit rate in this website means for HE-AAC, right? since HE-AAC is adopted in the DAB+ system.
It seems they didn't mention the sampling rate, as far as I know, there are four sampling rates can be chosen for DAB+ system.


Quote from: Maurits on
Melbourne, Australia has a DAB+ radio station using 24 kb/s apparently. At least, it shows up in the ensemble list for Melbourne: http://www.wohnort.org/DAB/australia.html#Melbourne on Wohnort. There will probably be more radio stations using that bitrate, likely speech only stations...
Quote from: Maurits on
Melbourne, Australia has a DAB+ radio station using 24 kb/s apparently. At least, it shows up in the ensemble list for Melbourne: http://www.wohnort.org/DAB/australia.html#Melbourne on Wohnort. There will probably be more radio stations using that bitrate, likely speech only stations...

Re: HE-AAC v1 with 24 kbps

Reply #5 –
Hi darkbyte ,
thanks for your reply.
I mean some real application using this mode, e.g., the DAB+, streaming audio..
In DAB+ system, the available bit rate if from 8 to 192 kbps, but I don't know which is often used ...

Some paper said the most often used mode of HE-AAC v2 is 24 to 32 kbps for a stereo signal.
But I would like to know whether there are some real application exactly using HE-AAC with 24 kbps, 48 kHz.

Quote from: darkbyte on
What? :o

Are you looking for encoders to create 24kbps HE-AAC v1?
There's a bunch of them (i assume you need one on a Windows PC):
- Apple iTunes encoder, you can use the qaac frontend with it
- Fraunhoffer FhG AAC Encoder from Winamp (with fhgaacenc frontend)
- Fraunhoffer FDK AAC encoder from Android (not distributed as binary you have to compile it on your own, Google for "FDK AAC build helper")
- Coding Technologies AAC Encoder from older Winamp versions with enc_aacplus frontend (outdated)
- Nero AAC Encoder (outdated)

Re: HE-AAC v1 with 24 kbps

Reply #6 –
Yes, DAB+ can use AAC, HE-AACv1 and HE-AACv2, depending on the bitrate. AAC for higher bitrates, HE-AACv1 for medium bitrates and HE-AACv2 for low bitrates. Essentially, the less bits a radio station has to play with the more they need to use sophisticated tools to make it sound palatable. As such you can’t say that one sounds better than the other. 32 kb/s stereo will sound better using HE-AACv2 than using AAC. Meanwhile 128 kb/s stereo will sound better using AAC than HE-AACv2.

They are configurable by the multiplex operator (where generally the encoding takes place) and often you’ll find that the engineers put the cut-off between v1 and v2 somewhere between 48 and 56 kb/s and the cut-off between v1 and AAC somewhere between 96 and 112 kb/s.

It’s not uncommon to find 32 kb/s for speech, 64 kb/s for pop music and 96 kb/s for classical music all on the same multiplex. It usually depends on the type of content and whether a station is charged per bitrate or not.

As for your sample rate question. As far as I know 48 kHz is the standard with DAB+ radio but smart encoders will automatically use 24 kHz sampling if the bitrate goes under a certain level. If bits are scarce it’s better to allocate them to he important part of the spectrum instead the high frequencies.

Are you aware of the Open Digital Radio project?
Every night with my star friends / We eat caviar and drink champagne
Sniffing in the VIP area / We talk about Frank Sinatra
Do you know Frank Sinatra? / He's dead

Re: HE-AAC v1 with 24 kbps

Reply #7 –
oh, I see, thank you very much.
And normally the stereo signals are used in DAB+, right?
do you happen to know is there any application about mono signals being used? maybe still 24 kbps, 48 kHz?

I didn't know that open digital radio project
Quote from: Maurits on
Yes, DAB+ can use AAC, HE-AACv1 and HE-AACv2, depending on the bitrate. AAC for higher bitrates, HE-AACv1 for medium bitrates and HE-AACv2 for low bitrates. Essentially, the less bits a radio station has to play with the more they need to use sophisticated tools to make it sound palatable. As such you can’t say that one sounds better than the other. 32 kb/s stereo will sound better using HE-AACv2 than using AAC. Meanwhile 128 kb/s stereo will sound better using AAC than HE-AACv2.

They are configurable by the multiplex operator (where generally the encoding takes place) and often you’ll find that the engineers put the cut-off between v1 and v2 somewhere between 48 and 56 kb/s and the cut-off between v1 and AAC somewhere between 96 and 112 kb/s.

It’s not uncommon to find 32 kb/s for speech, 64 kb/s for pop music and 96 kb/s for classical music all on the same multiplex. It usually depends on the type of content and whether a station is charged per bitrate or not.

As for your sample rate question. As far as I know 48 kHz is the standard with DAB+ radio but smart encoders will automatically use 24 kHz sampling if the bitrate goes under a certain level. If bits are scarce it’s better to allocate them to he important part of the spectrum instead the high frequencies.

Are you aware of the Open Digital Radio project?

Re: HE-AAC v1 with 24 kbps

Reply #8 –
I am not aware of any radio stations using 24 kb/s mono but they might exist. For a speech only station (news, sports, traffic announcements etc.) you might as well do it mono, if that saves some money.

I just noticed on Wohnort that Norway has a weather channel (NRK Vær VEST) using only 16 kb/s: http://www.wohnort.org/DAB/norway.html I don't know if it's mono though.
Every night with my star friends / We eat caviar and drink champagne
Sniffing in the VIP area / We talk about Frank Sinatra
Do you know Frank Sinatra? / He's dead

Re: HE-AAC v1 with 24 kbps

Reply #9 –
hmm, interesting, it seems all the stations with DAB+ didn't mention whether it's stereo or mono.
Thanks again.
Quote from: Maurits on
I am not aware of any radio stations using 24 kb/s mono but they might exist. For a speech only station (news, sports, traffic announcements etc.) you might as well do it mono, if that saves some money.

I just noticed on Wohnort that Norway has a weather channel (NRK Vær VEST) using only 16 kb/s: http://www.wohnort.org/DAB/norway.html I don't know if it's mono though.