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AAC Plus (SBR+PS) Audio Quality of ISO/IEC Reference Software

Hi All !

Here is My Problem:
==============

I CAN NOT differentiate between the Audio Quality of AAC Encoded Stream Vs AAC Plus (SBR+PS) Encoded Stream. i.e. Upon listening to both of the streams, audio quality looks same to me, to be honest Audio Quality is really bad with lots of noise and audio artifacts in both streams.


Here is What I have Done:
==================

I downloaded the following AAC & AAC Plus Reference Software from ISO Website.

1) ISO_IEC_14496-5_2001_Software_Reference
http://standards.iso.org/ittf/PubliclyAvai...ware_Reference/

2) ISO_IEC_14496-5_2001_Amd_6_Reference_Software
http://standards.iso.org/ittf/PubliclyAvai...rence_Software/

I was able to compile the "mp4mcEnc" code i.e. the reference software for AAC and AAC Plus (SBR+PS). I have made sure that AAC Plus Reference Software is compiled using both SBR and PS enabled. 

I encoded a sample music track using both AAC & AAC Plus (SBR + PS) Reference Software at 64kbps.
I used foobar2000 v0.8.3 for playing both of the encoded streams. After repeatidly listening to the encoded streams I was NOT able to spot any difference between their quality.

My question is whether I am missing something or I am using the wrong player for playing the encoded bitstreams. or What should be the right way to test the two streams for Audio Quality Differences?

Thanks you all for sharing your ideas.

With Regard,

MMH

AAC Plus (SBR+PS) Audio Quality of ISO/IEC Reference Software

Reply #1
Try to lower the bitrate to 32kbps. The difference should be noticeable.
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AAC Plus (SBR+PS) Audio Quality of ISO/IEC Reference Software

Reply #2
Here is My Problem:
==============

I CAN NOT differentiate between the Audio Quality of AAC Encoded Stream Vs AAC Plus (SBR+PS) Encoded Stream. i.e. Upon listening to both of the streams, audio quality looks same to me, to be honest Audio Quality is really bad with lots of noise and audio artifacts in both streams.



You can ask CodingTechnologies for free Demo of the SBR and PS technologies. They have a set of streams and they compare the quality of AAC,AAC+,eAAC+ and mp3. And there is  a difference in the quality one can find, when listned properly.

AAC Plus (SBR+PS) Audio Quality of ISO/IEC Reference Software

Reply #3
If you using mid-high bitrates you will never noticable differents

AAC Plus (SBR+PS) Audio Quality of ISO/IEC Reference Software

Reply #4
Try to lower the bitrate to 32kbps. The difference should be noticeable.


I have used 32kbps for encoding, but still I am NOT able to hear any difference between their quality. I am using foobar2000 for playing both tracks i.e. AAC Track and AAC Plus Track.

Do you think that AAC player can make any difference in this case.
Kindly also suggest any other AAC Plus Player that can play raw AAC Plus files.

AAC Plus (SBR+PS) Audio Quality of ISO/IEC Reference Software

Reply #5
Kindly also suggest any other AAC Plus Player that can play raw AAC Plus files.


Winamp?


AAC Plus (SBR+PS) Audio Quality of ISO/IEC Reference Software

Reply #7
Quote
I CAN NOT differentiate between the Audio Quality of AAC Encoded Stream Vs AAC Plus (SBR+PS) Encoded Stream. i.e. Upon listening to both of the streams, audio quality looks same to me, to be honest Audio Quality is really bad with lots of noise and audio artifacts in both streams.


Of course you could not, as you used the ISO Reference Software - In the documentation of that software package you will find out that it was not at all intended to be used as a quality reference - actually, its quality is far cry from what a fully optimized AAC / HE-AAC encoder could do.

So, if you really want to compare HE and LC AAC modes, you should use quality-optimized software.

Like this one:

http://www.nero.com/nerodigital/eng/Audio.html

Now, you can use something like this:

neroAacEnc -br 48000 -he -if your_file.wav -of your_file_encoded_with_he_aac.mp4
neroAacEnc -br 48000 -hev2 -if your_file.wav -of your_file_encoded_with_he_aac_v2.mp4
neroAacEnc -br 48000 -lc -if your_file.wav -of your_file_encoded_with_lc_aac.mp4

That will be much better

AAC Plus (SBR+PS) Audio Quality of ISO/IEC Reference Software

Reply #8
I have used nero digital's aac encoder to encode tracks at 32kbps & 64kbps. Now I am able to differentiate between the quality levels of AAC and AAC Plus (v1 & v2). Thanks Ivan  .

Now can you explain the USE of ISO Reference Software? Considering it poor quality as-well-as very slow encoding speed.

What Useful Purpose does the ISO Reference Software Serve?

AAC Plus (SBR+PS) Audio Quality of ISO/IEC Reference Software

Reply #9
Now can you explain the USE of ISO Reference Software? Considering it poor quality as-well-as very slow encoding speed.

What Useful Purpose does the ISO Reference Software Serve?

It is a reference for developers, not for users. It tells developers what their software should do and what format it should use...

AAC Plus (SBR+PS) Audio Quality of ISO/IEC Reference Software

Reply #10
It is a reference for developers, not for users. It tells developers what their software should do and what format it should use...


You mean that its only for the developers to know the output-bitstream FORMAT of encoded data.
OR There is any other use of this Reference Software for developer community.

AAC Plus (SBR+PS) Audio Quality of ISO/IEC Reference Software

Reply #11

It is a reference for developers, not for users. It tells developers what their software should do and what format it should use...


You mean that its only for the developers to know the output-bitstream FORMAT of encoded data.
OR There is any other use of this Reference Software for developer community.

Well, if you are a developer and want to develop a AAC encode, start looking at the source of the reference encoder. It is commented. It demonstrates the technology. It produces a stream in the correct format. Is it clear now?

 
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