Mp3 AC3 Mp2 Compressions

[aamir12345678]

Assuming there are no other factors to be considered, what are the differences in compression between [.mp3], [.mp2], & [.ac3]?

If I have a 128 kb/s [.mp3] file, what audio bitrate should I use to maintain audio quality if I am to convert to:

[.ac3]:


[.mp2]:

[yoda313]

Hello,
It's not that simple. AC3 and MP2 are SPECIFICALLY for video. MP3 is music. Go with ac3 for the best compatibility, regardless of compression rates.

Kevin

[aamir12345678]

If I go to [.ac3] (for DVD), what bitrate would you suggest if the original [.mp3] is 128 kb/s?

[yoda313]

Hello,
Well for ac3 most REAL movies use 384kbps (that's for dolby digital - Star Wars and others use 448). I've had some dvds made by a friend from a home dvd recorder (settop model). It uses 256. I guess 256kbps would be ideal.
Kevin

P.S. Sorry if I have the kilobits per second abbreviation wrong, you get my point though.

[aamir12345678]

Thanks.

[mats.hogberg]

AC3 and MP2 are SPECIFICALLY for video.

?? Mostly used in Video DVD, yes, but that's all.

If I have a 128 kb/s [.mp3] file, what audio bitrate should I use to maintain audio quality if I am to convert to:

[.ac3]:


[.mp2]:

There exist no such bit rate, as every reencode reduces the quality (when using lossy codecs like AC3 or MP2). The higher the bit rate, the more like the original, but never 100%

/Mats

[aamir12345678]

I think whenever people ask this type of question, they are mainly asking at what point will it be overkill. Yes, with both video & audio, there is going to be some subjectivity based on your personal satisfaction standards. If you really like a particular show, anime, movie, etc., you'll want to know what's the absolute best quality you can achieve; i.e. you'll be picky. But if you don't care as much about something else, you'll (very naturally) regard less quality as acceptable even if you are trying to achieve - let's say, dvd quality both times.

However, there have to be general rules. For example, encoding from clean Mpeg4 sources, it has been determined that it can be from about 3-6 times the original bitrate when encoding to Mpeg2. This helps set some guidelines. There must then be a way to determine how to maintain quality from [.mp3] sources when encoding to the [.ac3] & [.mp2] formats.

There is a way to determine overkill for video using the Constant Quantize method of encoding. Is there some similar encoding method with [.mp2] & [.ac3] encoders?