Is audio layer 3 different for MPEG 1 and 2?

Is audio layer 3 different for MPEG 1 and 2?

Post by abuba.. » Fri, 02 Jul 1999 04:00:00



What is the difference between audio layers in MPEG 1 and MPEG2. More
specicically i want to know about mp3. Is it for both MPEG 1 and MPEG 3
or has different versions in each standard.
If one says about an "mp3 decoder", what different
standards/versions/layers should it decode?

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Is audio layer 3 different for MPEG 1 and 2?

Post by Robert Berntse » Fri, 02 Jul 1999 04:00:00



>What is the difference between audio layers in MPEG 1 and MPEG2. More
>specicically i want to know about mp3. Is it for both MPEG 1 and MPEG 3
>or has different versions in each standard.
>If one says about an "mp3 decoder", what different
>standards/versions/layers should it decode?
>Sent via Deja.com http://www.deja.com/
>Share what you know. Learn what you don't.

Look at
http://www.mpeg.org/MPEG/audio.html#audio-overview

Regards R.

 
 
 

Is audio layer 3 different for MPEG 1 and 2?

Post by abuba.. » Sun, 04 Jul 1999 04:00:00


I have seen the FAQ already. But i am still confused. Just tell me does
MPEG1 and MPEG2 have separate mp3 layers or the audio standard is
common. I am working on an mp3 decoder and i want to know what type of
sourced generate mp3.




> >What is the difference between audio layers in MPEG 1 and MPEG2. More
> >specicically i want to know about mp3. Is it for both MPEG 1 and
MPEG 3
> >or has different versions in each standard.
> >If one says about an "mp3 decoder", what different
> >standards/versions/layers should it decode?
> >Sent via Deja.com http://www.deja.com/
> >Share what you know. Learn what you don't.

> Look at
> http://www.mpeg.org/MPEG/audio.html#audio-overview

> Regards R.

Sent via Deja.com http://www.deja.com/
Share what you know. Learn what you don't.
 
 
 

Is audio layer 3 different for MPEG 1 and 2?

Post by Robert Berntse » Tue, 06 Jul 1999 04:00:00



>I have seen the FAQ already. But i am still confused. Just tell me does
>MPEG1 and MPEG2 have separate mp3 layers or the audio standard is
>common. I am working on an mp3 decoder and i want to know what type of
>sourced generate mp3.

Both have the same MPEG audio.
So MPEG audio level-3 (MP3) is common for MPEG1 and MPEG2.
 
 
 

Is audio layer 3 different for MPEG 1 and 2?

Post by Mark Garlange » Wed, 07 Jul 1999 04:00:00




> >I have seen the FAQ already. But i am still confused. Just tell me does
> >MPEG1 and MPEG2 have separate mp3 layers or the audio standard is
> >common. I am working on an mp3 decoder and i want to know what type of
> >sourced generate mp3.

> Both have the same MPEG audio.
> So MPEG audio level-3 (MP3) is common for MPEG1 and MPEG2.

They are not the same... MPEG-1 (layer 3) is only 1 or 2 channel and 32kHz,
44.1kHz, or 48 kHz.  MPEG-2 support 5 channels, (secondary language
changes), 16kHz, 22.05 kHz, and 24 kHz.  I don't have the standards in
front of me, so there may be additional differences between the two.

                    Mark

 
 
 

Is audio layer 3 different for MPEG 1 and 2?

Post by Robert Berntse » Thu, 08 Jul 1999 04:00:00





>> >I have seen the FAQ already. But i am still confused. Just tell me does
>> >MPEG1 and MPEG2 have separate mp3 layers or the audio standard is
>> >common. I am working on an mp3 decoder and i want to know what type of
>> >sourced generate mp3.

>> Both have the same MPEG audio.
>> So MPEG audio level-3 (MP3) is common for MPEG1 and MPEG2.

>They are not the same... MPEG-1 (layer 3) is only 1 or 2 channel and 32kHz,
>44.1kHz, or 48 kHz.  MPEG-2 support 5 channels, (secondary language
>changes), 16kHz, 22.05 kHz, and 24 kHz.  I don't have the standards in
>front of me, so there may be additional differences between the two.

>                    Mark

Still I believe my words are valid. If you look at
http://www.tnt.uni-hannover.de/project/mpeg/audio/faq/#7

you can see a detailed description about this matter like:
"Do I have to use MPEG-1 Audio with MPEG-1 Video and MPEG-2 Audio with
MPEG-2 Video?
No, due to the compatibility, MPEG-2 Audio can be used with MPEG-1 Video as
well. The other way around, MPEG-1 Audio can be used with MPEG-2 Video
without any restrictions. Any combinations of MPEG-1 and MPEG-2 Audio and
Video can be handled by the system as specified by the MPEG-Systems standard
ISO/IEC 11172-1 for MPEG-1 and ISO/IEC 13818-3 for MPEG-2. "

So you are allowed to use all audio profiles with both videostandards. Not
all suppliers have done this. And using the most sofisticated audio with
MPEG1 does not make much sense.

Regards R.

 
 
 

Is audio layer 3 different for MPEG 1 and 2?

Post by Franc » Fri, 09 Jul 1999 04:00:00


MPEG1 and MPEG2 audio are compatible, which implies that an MPEG2 audio
decoder can handle MPEG1 bit streams, and that an MPEG1 decoder can play
back a compatible stereo downmix whenever an MPEG2 multichannel audio stream
is input.

This does not imply that MPEG1 and MPEG2 audio are the same.

MPEG1 audio has three *layers* (NOT *levels*). It describes single or
two-channel coding at sample rates of 32, 44.1 and 48 kHz. Bit rates go from
32kb/s up to 448kb/s.

MPEG2 audio has three layers as well, and it provides two extensions to
MPEG1
1) Low sample rates: it describes single and two-channel coding at sample
rates 16, 22.05 and 24 kHz. Bit rates go from 8kb/s to 160kb/s
2) Multi channel: it describes a system that can handle up to 5.1 channels.
Sample rates are 32, 44.1 and 48 kHz.

If you plan to make a decoder that can handle two-channel signals using the
regular sample rates, you can do with ISO/IEC 11172-3.
If you plan to cover low sample rates and/or multichannel, you need both
11172 and ISO/IEC 13818-3.

Franc Z





>>> >I have seen the FAQ already. But i am still confused. Just tell me does
>>> >MPEG1 and MPEG2 have separate mp3 layers or the audio standard is
>>> >common. I am working on an mp3 decoder and i want to know what type of
>>> >sourced generate mp3.

>>> Both have the same MPEG audio.
>>> So MPEG audio level-3 (MP3) is common for MPEG1 and MPEG2.

>>They are not the same... MPEG-1 (layer 3) is only 1 or 2 channel and
32kHz,
>>44.1kHz, or 48 kHz.  MPEG-2 support 5 channels, (secondary language
>>changes), 16kHz, 22.05 kHz, and 24 kHz.  I don't have the standards in
>>front of me, so there may be additional differences between the two.

>>                    Mark

>Still I believe my words are valid. If you look at
>http://www.tnt.uni-hannover.de/project/mpeg/audio/faq/#7

>you can see a detailed description about this matter like:
>"Do I have to use MPEG-1 Audio with MPEG-1 Video and MPEG-2 Audio with
>MPEG-2 Video?
>No, due to the compatibility, MPEG-2 Audio can be used with MPEG-1 Video as
>well. The other way around, MPEG-1 Audio can be used with MPEG-2 Video
>without any restrictions. Any combinations of MPEG-1 and MPEG-2 Audio and
>Video can be handled by the system as specified by the MPEG-Systems
standard
>ISO/IEC 11172-1 for MPEG-1 and ISO/IEC 13818-3 for MPEG-2. "

>So you are allowed to use all audio profiles with both videostandards. Not
>all suppliers have done this. And using the most sofisticated audio with
>MPEG1 does not make much sense.

>Regards R.

 
 
 

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