What is MPEG layer 3 audio, and can I use it?

[ajmoss]

DivX 5 provides an audio mode called MPEG layer 3; this runs at a bit rate no higher than 56kbit/s, much lower than a standard MP3 recording. In contrast, MPEG-1 and MPEG-2 files use MPEG layer 2 audio, which defaults to 224kbit/s.

What sort of quality will I get from MPEG layer 3 audio? Will it be good enough for a standard TV recording? Will it be good enough for something more important, like a recording of a concert?

Also, I'm at a loss as to how to set the video bit rate. I'm familiar with the idea of the minimum and maximum quantisers, which can be left at their default values of 2 and 12 respectively, but it seems I also need to set the video bit rate directly. This defaults to 780 kbit/s; I need to know what range of values is sensible for a reasonable quality recording.

[Zhnujm]

mpeg layer 3 = mpeg 1 layer 3 audio= mp3 audio
the mp3 codec that comes with windows is limited to max 56kbit at encoding, thats why you cannot select a higher bitrate.
install divx3.11, it comes with a full version of this codec.

[Awatef]

the bitrate depends on the size you want to reach!

READ THE GUIDES BEFORE ASKING SUCH PRIMITIVE QUESTIONS!

[Acaila]

@Awatef:

This isn't the first time I've seen you post like this. Please refrain from losing your temper, and try to answer questions with constructing criticism instead of putting everyone down.

[ajmoss]

Originally posted by Zhnujm
mpeg layer 3 = mpeg 1 layer 3 audio= mp3 audio
the mp3 codec that comes with windows is limited to max 56kbit at encoding, thats why you cannot select a higher bitrate.
install divx3.11, it comes with a full version of this codec.

Or, I suppose, I could just as easily use the LAME MP3 codec.

I'm ferreting around, trying to find a single recommended value for my DivX video bit rate. For example, the recommended audio bit rate for MP3 is 192 kbit/s, or at a pinch, 160 kbit/s. Yet the web page to which Awatef referred me, http://www.doom9.org/bitrate_guide.htm doesn't give a single number like that, or even a range of numbers for different applications.

Is there any merit in recoding standard VCD audio (MP2 audio at 224 kbit/s) into MP3 at 192 or 160 kbit/s?

[ajmoss]

Originally posted by Awatef
the bitrate depends on the size you want to reach!

READ THE GUIDES BEFORE ASKING SUCH PRIMITIVE QUESTIONS!

I don't want to reach a particular file size - I want to minimise the sizes of my files as far as possible, without compromising their quality.

The files I have are all MPEG-1 recordings of PAL programmes, at 352x288 pixels, with a video bandwidth of 2.4 Mbit/s. If you want, you can think of them as being of SVCD quality. This bit rate is overkill - it leaves a lot of unused bytes in the MPEG file, but it ensures no pixellation artifacts, even for complicated scenes. All the other MPEG-1 artifacts are there, such as the halo around subtitles, but the DivX preprocessing option should help smooth them out.

I'd like a single recommended DivX bandwidth that I can use for all these files, just like the 2.4 Mbit/s that I was using for the MPEG-1 source files.

[Awatef]

@ Acaila
Please leave me alone! I'm not in a chirch here! if I'm going to make people down, you'll see what language I'll use! I'm aware of what I am saying and I am weighting my words! (brake is already full on!)

@ ajmoss
That question was already asked here and the answer was: such bitrate doesn't exist: that movie will require only 1000kbps, the other will require 5000kbps, depending on level of action, the max bitrate is easy to find: quality based 100%!
And for DivX you have to transcode your MP2 to MP3 anyway

[Acaila]

@Awatef:

I've asked nicely, I won't warn you again. You've just earned one strike.

Behave, leave or get suspended. Your pick.

[Awatef]

@ Acaila
you scared me! :eek:
What do you think it is here?! a kindergarten?! don't make me lough!