Mpeg Layer 2 vs Mpeg Layer 3 data

[Quantum]

Hello,

I have been performing a lot of conversions of Divx 5.+ files to MPEG2 for SVCD and XSVCD use. I've searched a few forums and have been unable to find the answer to my question. I'm currently separating the Mpeg Layer 3 audio into a .WAV using the latest VirtualDub. I then use this as the audio input in TMPGEnc Plus using tooLame as the encoder to Mpeg Layer 2. Would there be an improvement if I increase the bitrate of the Mpeg Layer 2 from that of the source Mpeg Layer 3 audio? For example, I have a Divx file I'm converting to XSVCD that has Mpeg Layer 3 audio at a 160 kbps that I convert to a .WAV. Should I use 160 kbps for the encoded Mpeg Layer 2 audio or would there be a benefit of using 192, 224, or even 384?

Thanks!

[Tommyknocker]

Have you tested this theory yourself using a few samples from each option? The reason I am asking is you are the only judge as to whether or not your final product meets your specs.

[tony123]

There would be no benefit from using 192, 224, or 386 because original source is 160. also, converting mp3 to mp2 will degrade the quality of the audio.

[energy80s]

There would be a benefit in upping the bitrate as MP2 audio is poorer quality than MP3, so a 160k MP3 is about the same as a 224k MP2. That's why UK digital radio sounds so shite using bitrates of 128k MP2 and calling itself CD Radio!!

[ZippyP.]

This is similar to people that try to equate divx bitrates and mpeg video bitrates. MP2 and MP3 use different compresson methods and MP3 requires less bitrate for similar quality. How much difference is for the listener to decide.

[ZippyP.]

.. MP2 audio is poorer quality than MP3..

When the bitrates are the same.

[energy80s]

Correct.

MP2 audio compression was developed about 2 years earlier than MP3 so was adopted first as audio compression technology for the digital age. Likewise AAC coding is better than MP3 and roughly twice as good as MP2, but it doesn't have the support of the general audio community.

[tony123]

It will not sound any better than the original Mp3 source either way.

[bode]

There would be a benefit in upping the bitrate as MP2 audio is poorer quality than MP3, so a 160k MP3 is about the same as a 224k MP2. That's why UK digital radio sounds so shite using bitrates of 128k MP2 and calling itself CD Radio!!

DAB radio, the biggest con. I have watched the BBC (no offense :P ) drop their bitrate drop from 192 to a pathetic 128kbps. Mono on some broadcasts, what century is this?

At least I can have more choice now whether it's more inane commercial chart crap, more minority radio which represents 2% of the population.

If I wanted choice rather than quality, I wouldn't have given up my medium wave radio for FM!

[Quantum]

Thank you for all the responses and debate. This was the information I was looking for and hopefully this post pops up if anyone else has a similar question.

I can't tell the difference between the original MP3 or the encoded MP2, but I haven't been converting video files with sound tracks that really allow me to make a good evaluation. I do have space on the disc left over after reaching the maximum video bitrate, so I will encode at a higher audio rate.

Thanks!

[theDruid]

There would be no benefit from using 192, 224, or 386 because original source is 160. also, converting mp3 to mp2 will degrade the quality of the audio.

tony123 - you seem to be suggesting that the original poster should leave the audio as mp3.

You can't really do this if you're making a (S)VCD - as you need mp2 audio for these formats.

I'd use 192kbps mp2 audio, or 224 if space allows. You're right in saying you can't improve on the mp3 source, but a higher mp2 bitrate would be needed just to maintain the quality. This point has already been made.

cheers,
mcdruid.

[Ste]

Na, I don't think that's what he meant. He was just saying that you have to factor in the degration(is this even a word?) of quality when converting from MP3 to MP2.

Also, don't those DivX files on the net usually have VBR MP3 encoding for the audio?

Then what bitrate would YOU use for the equivalent MP2?
(Rhetorical question)

[tony123]

There would be no benefit from using 192, 224, or 386 because original source is 160. also, converting mp3 to mp2 will degrade the quality of the audio.

tony123 - you seem to be suggesting that the original poster should leave the audio as mp3.

You can't really do this if you're making a (S)VCD - as you need mp2 audio for these formats.

I'd use 192kbps mp2 audio, or 224 if space allows. You're right in saying you can't improve on the mp3 source, but a higher mp2 bitrate would be needed just to maintain the quality. This point has already been made.

cheers,
mcdruid.

I wasn't suggesting to leave the audio as mp3. I think Quantum knows the required audio format for SVCD is mp2 44.1/224.

I have converted MP3 44.1/224 to MP2 44.1/224 and there was a noticeable degradation.

[theDruid]

Right - fair play tony123; I was misunderstanding you. Sorry.

(I was only on my 2nd cup of tea of the morning when I looked at this post!).

cheers,
mcdruid.

[tony123]

I kind of misunderstood Quantum's question. I thought he wanted to know if increasing the Mp2 bitrate above 160 would be an improvement over the MP3 source. The best that can be done is to try and match the original.