Why no MP2 in MPEG2?

[Richard Iredale]

These days, a lot of MPEG2 encoders also encode the audio stream into the MP2 format. But in the NTSC world, the only audio formats officially allowed are PCM, AC3, and DTS. Why did the committee that formally created the MPEG2 format reject the MP2 or even the MP3 audio formats?

I suspect the folks at Dolby did some serious arm-twisting, but that's just a guess. Does anyone know the real reasons?

[Tatjahna]

You're telling us that if I encode my captured audio to mp2 it won't work in my DVD right ? Why then TMPGEnc offers 165 Min. of DVD Video at 3000 bitrate with mp2 audio format using ?

I really don't hope so, because I will be in a real shit if I have to decrease my bitrate to be able to put the pcm audio :mad:

Thanx guys for reply!

[Sequoyan]

Richard, you might do a little more research about audio formats...

MP3 - is actually MPEG-1 layer 3
MP2 - in this case you probably mean MPEG-2

MP3 audio is not DVD-Video compatible but MPEG-2 audio is.

Your encoder probably captures audio in MPEG-2 audio.

- The Sequoyan

[goemon]

Originally posted by Richard Iredale
These days, a lot of MPEG2 encoders also encode the audio stream into the MP2 format. But in the NTSC world, the only audio formats officially allowed are PCM, AC3, and DTS. Why did the committee that formally created the MPEG2 format reject the MP2 or even the MP3 audio formats?

I suspect the folks at Dolby did some serious arm-twisting, but that's just a guess. Does anyone know the real reasons?

The reason is that the big media players wanted DVD to support surround sound, and at the time AC3/DTS were already very well established -- mpeg audio didnt have a well established 5.1 at the time.

IIRC fraunhofer screwed themselves out of the NTSC-DVD standard because they were too greedy -- insisting on a per-unit license fee for each DVD which contained mpeg audio material, while Dolby only charged a single license fee for the encoder/decoder hardware.

[auenf]

there is 3 audio formats that all dvd players can decode to the analogue outputs, PCM (no decoding needed there ;) ), AC3 (Dolby Digital) and MP2 (MPEG-2 Layer 2), DTS needs a external decoder on almost all players, and to make a DVD that is 'in spec' you need to include one of the three audio formats, not DTS by itself.

btw, the mp2 extension can mean Mpeg-2 program stream so i avoid using it, try m2a ;)

when the dvd format was introduced, dolby got their nuts crossed up cause the forum seemed to prefer m2a over ac3, so they managed to pressure region 1 into prefering ac3 over m2a, but all the players sold anywhere should be able to play it fine, its only a problem when people only connect their DVD player to their amp thru the digital connection, cause who knows someone with an amp that can decode m2a (mp3 amps don't count)??

these days i would recommened PCM over m2a, cause multichannel m2a encoding is basically non-existant too ;)

Enf...

[dvman]

Originally posted by Sequoyan
Richard, you might do a little more research about audio formats...

MP3 - is actually MPEG-1 layer 3
MP2 - in this case you probably mean MPEG-2

MP3 audio is not DVD-Video compatible but MPEG-2 audio is.

Your encoder probably captures audio in MPEG-2 audio.


Well almost ;) I agree on MP3 with you but MP2 is not MPEG2. MP2 is actually MPEG-1 layer 2 audio. How about doing a little research yourself. ;);)

[auenf]

Originally posted by dvman


Well almost ;) I agree on MP3 with you but MP2 is not MPEG2. MP2 is actually MPEG-1 layer 2 audio. How about doing a little research yourself. ;);)

well, the 'MP2' that is for dvd audio is MPEG-2 Layer 2, not MPEG-1 ;)

Enf...

[dvman]

Originally posted by auenf


well, the 'MP2' that is for dvd audio is MPEG-2 Layer 2, not MPEG-1 ;)

Enf...

Hmmm... We are talking about MPEG-Audio here. Let's see what the FAQ has to say:


MPEG audio is multi-channel digital audio, using lossy compression from original PCM format with sample rate of 48 kHz at 16 or 20 bits. Both MPEG-1 and MPEG-2 formats are supported. The variable bit rate is 32 kbps to 912 kbps, with 384 being the normal average rate. MPEG-1 is limited to 384 kbps. Channel combinations are (front/surround): 1/0, 2/0, 2/1, 2/2, 3/0, 3/1, 3/2, and 5/2. The LFE channel is optional with all combinations. The 7.1 channel format adds left-center and right-center channels, but will probably be rare for home use. MPEG-2 surround channels are in an extension stream matrixed onto the MPEG-1 stereo channels, which makes MPEG-2 audio backwards compatible with MPEG-1 hardware (an MPEG-1 system will only see the two stereo channels.) MPEG Layer 3 (MP3) and MPEG-2 AAC (aka NBC or unmatrix) are not supported by the DVD-Video standard

http://www.dvddemystified.com/dvdfaq.html


What this means is. MP2 can stand for more than one format of DVD audio which is MPEG1 or MPEG2...


NTSC * PAL / SECAM
---------------------------------------------
needed PCM * PCM
Dolby Digital * Dolby Digital
-- * MPEG-1 Layer II
-- * MPEG-2 Layer II
----------------------------------------------
optional PCM * PCM
Dolby Digital * Dolby Digital
-- * MPEG-1 Layer II
-- * MPEG-2 Layer II
DTS * DTS
SDDS * SDDS

[Sequoyan]

DVMAN,

the last post says it precisely

DVDs can have either mpeg-1 (layer 2) or mpeg-2 (layer 2) audio (as well as others)

Now, the nomenclature does get a bit confusing DVMAN but I think we've developed some standards:

m2a is MPEG-2 layer 2 audio
m1a is MPEG-1 layer 2 audio

My response above was to the very apparant misunderstanding of the original poster.

And as for your attitude problem, read my first post in this thread, I said:

"MP2 - in this case you probably mean MPEG-2"

and you said:

"Well almost I agree on MP3 with you but MP2 is not MPEG2. MP2 is actually MPEG-1 layer 2 audio. How about doing a little research yourself."

I didn't say that MP2 is MPEG-2 audio. I said that the poster was probably using MP2 refering to MPEG-2 audio. There is a difference.

[Arky]

"Seconds out, ROUND TWO!!" :p :D

It's been emotional but nevertheless informative...


Arky ;o)

[TRILIGHT]

Originally posted by Arky
"Seconds out, ROUND TWO!!" :p :D

It's been emotional but nevertheless informative...


Arky ;o)

I just felt like quoting you Arky. hehe :D

[rmtaibo]

Someone has tried with 48KHz encoding instead of 44.1KHz mp2 audio file?. Richard, check if this works. Maybe you are using 44.1 KHz.

I used ATI-AIW capture card, and don't need to convert audio to PCM or DOLBY DIGITAL AUDIO. Think MMC-7.6 version uses mpeg-1 layer 2 audio for DVD encoding @ 48 KHz not 44.1 KHz. And I recorded DVD's with my ATI-AIW capture card.

[auenf]

other way around, mmc 7.6 does 44.1 rather than 48k, 7.7 can do 48k

Enf...

[rmtaibo]

Sorry auenf, I forgot that!

I use TMPGEnc after captures using MMC-7.6
Demux-->Re-Encode only mp2 audio to 48KHz-->and finally Remux with MyDVD