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Topic: How do i convert CBR mp3 to VBR mp3? (Read 21823 times) previous topic - next topic
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How do i convert CBR mp3 to VBR mp3?

I have some mp3 files that are at 192kbps CBR. How do i convert them to VBR mp3? I am using razorlame and this is the lame options:

-b 32 -h -V 0 -B 192

Is this the best settings?
I set the maximum VBR bitrate at 192kbps because the source file is 192kbps CBR. Is this right?
Do i also do the same for mp3 files that are of a different bitrate? (eg. set the maximum VBR bitrate at 320kbps for 320kbps CBR files & set the maximum VBR bitrate at 128kbps for 128kbps CBR files)


(I know that converting a mp3 to another mp3 will result in quality loss. However, I just want to do it this way for some particular reasons.)

How do i convert CBR mp3 to VBR mp3?

Reply #2 –
If you reencode from one lossy format to another lossy format the result will always be worse than the original.

Do not do it unless you want to save a lot of space (e.g. 320Kb CBR MP3 to 64Kb HE AAC+).

How do i convert CBR mp3 to VBR mp3?

Reply #3 –
Quote from: k5263486 on
I have some mp3 files that are at 192kbps CBR. How do i convert them to VBR mp3? I am using razorlame and this is the lame options:

-b 32 -h -V 0 -B 192

Is this the best settings?
No
Best would be
-V 0
Quote from: k5263486 on
I set the maximum VBR bitrate at 192kbps because the source file is 192kbps CBR. Is this right?
No. It sounds reasonable, but it isn't. Let LAME decide if it needs more for some unknown reason.

I would use
-V 3 (target 155-195) or
-V 2 (target 170-210)

How do i convert CBR mp3 to VBR mp3?

Reply #4 –
Quote from: Vietwoojagig on
-V 2 (target 170-210)

If you were to use -V 2 then not only would the files be lower quality, they would often be bigger than the original 192 kbps.

If your objective is to save space then go for a significant savings, such as -V 4 or -V 5.

How do i convert CBR mp3 to VBR mp3?

Reply #6 –
Remember that when you transcode lossy files you'll always end up with worse quality, regardless of the bitrate you transcode to. Generally the few kbps you might save isn't worth the price you pay.

The only case where transcoding down from 192kbps would make any sense at all is for those rare kinds of material where 192kbps is a complete waste of bitrate and fidelity isn't important (e.g. voice and perhaps old monophonic recordings).

How do i convert CBR mp3 to VBR mp3?

Reply #7 –
Quote from: k5263486 on
Do i also do the same for mp3 files that are of a different bitrate? (eg. set the maximum VBR bitrate at 320kbps for 320kbps CBR files & set the maximum VBR bitrate at 128kbps for 128kbps CBR files)
You can if you want, but nothing says that you have to, and there is no objective reason to. The first MP3 is always decoded before being (re)input to LAME, which may decide to allocate more bits to particular sections than they originally utilised; it has no way of determining their original bitrate, and it can only do its best to analyse the audio signal presented to it. It may interpret this to require more bits than the original MP3 for a variety of reasons.

If you have no objective reason (and I imagine there aren’t many) for setting a maximum VBR bitrate, it’s probably better to avoid doing so. Then again, that might apply to the issue of transcoding as a whole, so…

How do i convert CBR mp3 to VBR mp3?

Reply #8 –
What "particular reasons" would be necessary for this change? I know of no hardware or software that would not support CBR but does support VBR. Is this simply a case of file size?

How do i convert CBR mp3 to VBR mp3?

Reply #9 –
Quote from: Zarggg on
What "particular reasons" would be necessary for this change? I know of no hardware or software that would not support CBR but does support VBR. Is this simply a case of file size?

There have in the past been players that only supported up to 256 kbps cbr, but I doubt that is the case here.

How do i convert CBR mp3 to VBR mp3?

Reply #10 –
Don't wish to hijack this post but I was about to ask a similar question:

I have hundreds of files, Lame encoded at 256 and 320 and would wish (after copying the originals) to transcode to AAC.
What would be a reasonable bitrate for the new AAC files? (My ears are bad having sat in front of various drummers over the years so ABX'ing is not really an option.....hence the direct question).

How do i convert CBR mp3 to VBR mp3?

Reply #11 –
Quote from: auldyin on
Don't wish to hijack this post but I was about to ask a similar question:

I have hundreds of files, Lame encoded at 256 and 320 and would wish (after copying the originals) to transcode to AAC.
What would be a reasonable bitrate for the new AAC files? (My ears are bad having sat in front of various drummers over the years so ABX'ing is not really an option.....hence the direct question).

Is this for use in a portable player? If so then I would just use whatever you normally use.

If this were for use from your home computer then I would recommend a vey high quality setting to minimize the degradation. Of course, for you home computer I would recommend against transcoding at all.

How do i convert CBR mp3 to VBR mp3?

Reply #12 –
Quote
Is this for use in a portable player? If so then I would just use whatever you normally use.

It is indeed for use in portable.
Your suggestion makes eminent sense.
Thank you!

How do i convert CBR mp3 to VBR mp3?

Reply #13 –
I really wonder what it should be good for.

The only thing I can think of is lowering average bitrate to save some space. CBR192 isn't a big storage space eater though in terms of today's storage space.
However for this purpose I'd use -V5 or whatever suits my storage space / quality requirements.

If it's not about saving space but only in order to go VBR for whatever reason the only useful way IMO is to use mp3packer as was suggested. It doesn't change quality as it doesn't change internal mp3 contents, just packs it into frames the VBR way. However I can't imagine why this should be useful. When using CBR320 this procedure can save a few percent of storage space, with CBR192 it won't.

Experience of quality loss when reencoding is the only motivation left for me for going VBR. If minimization of quality loss is the side condition -V0 is the way to go (or whatever is considered best encoder and encoding setting). The fact that the source material is lossy has no influence on best quality setting.
lame3995o -Q1.7 --lowpass 17