Differences between .ac3, .mpa, .mp2, .m2a etc.

[Creed92]

Hello to everyone!
Yesterday I started trying Projectx.
It's a really good software, so I tried the demux option: the program splits mpeg in two files, an mp2 for audo and m2v for video.
I noticed that other softwares extract audio in other formats like ac3 or mpa, what's the difference between these?
And the other strange factor is that, compared to the DGINDEX's demuxed files or MPG2cut2, these files weigh less than some kb.

[yoda313]

You need to be more specific.

What are the sources?

Mp2 is generally used from older analog capture cards that don't record the audio in ac3 (which is the standard for dvd audio though other formats can be used, mp2 audio being one of them, though in the strictest sense all dvds require at least one ac3 track to be considered "standard" but many to most dvd players can handle mp2 audio alone without ac3, but of course you can always come across an old one that doesn').

I'm not familiar with mpa but ac3 is the basic dvd audio format. Also known as dolby digital. Dts is the other one that is out there for dvd.

Some of these software programs you are using MAY also be converting the audio to another format. You haven't mentioned if you are mainly just demuxing completely or not - yes you do later on but some programs do convert so that might be part of it.

As for the file size issues are you sure they aren't something like avi synth files which are really just text files? They tell programs how to use the video files. In general a two hour video should have a several hundred mb ac3 file depending on of course whether or not its multichannel and how high the bitrate is. Generally speaking commercial movies are encoded at 384kpbs or 448kpbs (fyi 448kpbs is max for standard def dolby digital on dvds).

You can go as low as 192 kpbs I think it is for decent stereo on ac3. Much below that and I believe the sound quality will start to suffer even to non audio snobs. However the lower the bitrate the smaller the audio file will be thus allowing you to increase the video bitrate, to a point of course.

Here is the "what is dvd" link from the left of the website page:

https://www.videohelp.com/dvd

That has all the tech specs for dvds.

If your source isn't a dvd than it can be basically anything.

Please note when you are dealing with video files that aren't from a dvd you can have basically anything in them. Video files are just containers, things like avi, mp4 and mkv. The codecs that make up the audio and video can be virtually anything but there are more common features you'll find in certain formats. Like divx in avi and h264 in mp4 and mkv. However virtually anything can be found in any container.

Use a program like mediainfo to find out more about a given video file.

Sorry if you know this already but I don't know how vast your knowledge is for video related items.

[Case]

The program splits mpeg in two files, an mp2 for audo and m2v for video.
Other softwares extract audio in other formats like ac3 or mpa, what's the difference between these?

https://en.wikipedia.org/wiki/DVD-Video#Audio_data
MP2 and MPA are synonymous, although some programs accept just one of these for suffix , and may not recognize the other. In such cases, simply rename the suffix.

[hech54]

Hello to everyone!
Yesterday I started trying Projectx.
It's a really good software, so I tried the demux option

Why?
Unless you are enhancing the audio or using some off-the-wall DVD authoring software, demuxing (having separate video and audio) is rarely necessary.

[Creed92]

You need to be more specific.

What are the sources?

Mp2 is generally used from older analog capture cards that don't record the audio in ac3 (which is the standard for dvd audio though other formats can be used, mp2 audio being one of them, though in the strictest sense all dvds require at least one ac3 track to be considered "standard" but many to most dvd players can handle mp2 audio alone without ac3, but of course you can always come across an old one that doesn').

I'm not familiar with mpa but ac3 is the basic dvd audio format. Also known as dolby digital. Dts is the other one that is out there for dvd.

Some of these software programs you are using MAY also be converting the audio to another format. You haven't mentioned if you are mainly just demuxing completely or not - yes you do later on but some programs do convert so that might be part of it.

As for the file size issues are you sure they aren't something like avi synth files which are really just text files? They tell programs how to use the video files. In general a two hour video should have a several hundred mb ac3 file depending on of course whether or not its multichannel and how high the bitrate is. Generally speaking commercial movies are encoded at 384kpbs or 448kpbs (fyi 448kpbs is max for standard def dolby digital on dvds).

You can go as low as 192 kpbs I think it is for decent stereo on ac3. Much below that and I believe the sound quality will start to suffer even to non audio snobs. However the lower the bitrate the smaller the audio file will be thus allowing you to increase the video bitrate, to a point of course.

Here is the "what is dvd" link from the left of the website page:

https://www.videohelp.com/dvd

That has all the tech specs for dvds.

If your source isn't a dvd than it can be basically anything.

Please note when you are dealing with video files that aren't from a dvd you can have basically anything in them. Video files are just containers, things like avi, mp4 and mkv. The codecs that make up the audio and video can be virtually anything but there are more common features you'll find in certain formats. Like divx in avi and h264 in mp4 and mkv. However virtually anything can be found in any container.

Use a program like mediainfo to find out more about a given video file.

Sorry if you know this already but I don't know how vast your knowledge is for video related items.

The dvd that I demuxed is an homemade dvd (DVD-5). It's a concert, captured from TV and encoded in mpeg-2. But demuxing doesn't allows any loss of quality or converting, so I don't understand this point of your post:

Some of these software programs you are using MAY also be converting the audio to another format. You haven't mentioned if you are mainly just demuxing completely or not - yes you do later on but some programs do convert so that might be part of it.

Using DGIndex the resulting audio from demux is generally .mpa, with others dvd I get an .ac3 file, so in this case I should not use anymore Projectx? Because gave me a converted .mp2 with loss of many kb

[hech54]

The dvd that I demuxed is an homemade dvd (DVD-5). It's a concert, captured from TV and encoded in mpeg-2. But demuxing doesn't allows any loss of quality or converting, so I don't understand this point of your post:

https://www.videohelp.com/glossary?D#Demultiplex,%20Demultiplexing,%20Demux,%20Demuxing


Whoever told you to use ProjectX, and demux a DVD with ProjectX needs to be slapped.

[Creed92]

I not demux the dvd, I demux the mpeg file taken from that dvd (using dvd decrypter to get a single vob + rename to .MPG)
Speaking of which: what is the best way to demux? From .IFO, from many VOBS, from one single VOB, from mpeg taken with VOB2MPG or from mpeg taken with rename option?

[hech54]

I not demux the dvd, I demux the mpeg file taken from that dvd (using dvd decrypter to get a single vob + rename to .MPG)
Speaking of which: what is the best way to demux? From .IFO, from many VOBS, from one single VOB, from mpeg taken with VOB2MPG or from mpeg taken with rename option?

Do you even know what "demux" means?

[Creed92]

Separate audio and video, right?

[hech54]

Separate audio and video, right?

Taking the video from a DVD with DVDDecrypter, or taking the video from a DVD with DVDDecrypter THEN using something like VOB2MPEG is NOT DEMUXING.
Once you take the video from a DVD with DVDDecrypter, or take the video from a DVD with DVDDecrypter THEN use something like VOB2MPE.....YOU ARE DONE.


99% of the time, "demuxing" (separating the video and audio into two separate streams - m2v video and an audio stream) is not necessary.

[Lowlander]

I not demux the dvd, I demux the mpeg file taken from that dvd (using dvd decrypter to get a single vob + rename to .MPG)

Why don't you let DVDdecrypter do the demuxing in the first place? In IFO mode, the options which streams to demux is found under "stream processing". Choose your video and whatever audio track(s) you'd like to extract, press the Decrypt-button and you're done.

[Cornucopia]

Also, whether using DVDDecrypter or some other software, when you RIP from disc to HDD, if your output is NOT a VOB file (or series of VOB files) but rather MPG, then you have ALREADY demuxed (and remuxed again).

Once and hopefully for all, simply RENAMING a VOB to MPG is a BAD idea!
There are proper ways to do this (VOB2MPEG, etc), but the 2 containers are just in the same family - NOT the same thing!!! Like brother & sister vs. TS (which is a cousin) or MP4 (which is a 2nd cousin). Not identical twins.

Scott

[Creed92]

Maybe I wasn't clear at all. xD (sorry for my bad english, I'm italian)
I must demux because the original mpeg file has errors, and My question is: what is the best method? Decrypt the dvd with DVD Decrypter, get a single vob and then demux it? Or, second method, open the .IFO file? Or ripping the mpeg2 using VOB2MPG in order to demux it?
From Vob, Ifo or mpeg? This is the point.

[El Heggunte]

Copy the VIDEO_TS folder to a HDD with DVDFab HD Decrypter, then demux to M2V and MP2/AC3 files with PgcDemux.

IF necessary, remux to a single MPG file either with TMPGenc Plus or with mplex (freeware, and works well).

[Creed92]

I have Dvd Shrink. It's the same or I should using Dvd Fab?
So the best way is demux by .IFO ??
PS: The dvd in question is already a VIDEO_TS folder, the question is if I should burn on a cd and decrypt in order to get a SINGLE VOB or not

[hech54]

Copy the VIDEO_TS folder to a HDD with DVDFab HD Decrypter, then demux to M2V and MP2/AC3 files with PgcDemux.

IF necessary, remux to a single MPG file either with TMPGenc Plus or with mplex (freeware, and works well).

Hello?

The dvd that I demuxed is an homemade dvd (DVD-5). It's a concert, captured from TV and encoded in mpeg-2.

[El Heggunte]

Copy the VIDEO_TS folder to a HDD with DVDFab HD Decrypter, then demux to M2V and MP2/AC3 files with PgcDemux.

IF necessary, remux to a single MPG file either with TMPGenc Plus or with mplex (freeware, and works well).

Hello?

The dvd that I demuxed is an homemade dvd (DVD-5). It's a concert, captured from TV and encoded in mpeg-2.

And so what? Yes, I'm pushing DVDFab HD Decrypter , what's the problem
I'm still using a very-old version, because new not always means better, and bloated software is evil

[Creed92]

I downloaded this dvd from a bootleg site. It's already a VIDEO_TS folder and ready to burn, so there's really need to decrypt it again?
In the past some users told me that if I use the option to get a single vob and then demux it instead of many vobs, the resulting mpeg2 will be better.

[usually_quiet]

I downloaded this dvd from a bootleg site. It's already a VIDEO_TS folder and ready to burn, so there's really need to decrypt it again?
In the past some users told me that if I use the option to get a single vob and then demux it instead of many vobs, the resulting mpeg2 will be better.

So, this is not a recording you made from TV yourself as implied earlier, it is a bootleg video you downloaded. Read the forum rules. https://forum.videohelp.com/threads/72386-Forum-rules-Acceptable-Use-Policy-(AUP)? We can't help people with their warez problems.

[redwudz]

Creed92, Please read our rules before posting. Thread closed.

Moderator redwudz