Software help archive

Support
VBR Support?
A read-only archive of old serato.com help threads.

VBR Support?

Product
Scratch Live
Version
-
Hardware
Ortofon | Serato S-120
Computer
-
OS
Platform
-
MusicMeister 3:15 PM - 5 April, 2006
Ok, I didn't know where to post this so bear with me. If it should be in another forum please move it appropriately.

IMPORTANCE: LOW: Just so you know, I'm not having problems but only verifying support before I drop some serious coin for my upgrade to a MacBook and SSL (from a PC which died on me and something other than SSL).

REASON FOR QUESTION: In reading about 'other' products used for DJ'ing on the Mac (mostly basic software only mixing) I found that many are built on other products (ie quicktime, iTunes, etc) and have some issues with MP3's encoded using VBR (Variable Bit Rate). Since nearly all of my 50,000+ MP3's are 192kbps VBR using the ABR method I'm a little concerned about playback issues. Re-encoding to another bit rate in CBR (Constant Bit Rate) would kill the sound quality and take a fortnight or more!

UNDERSTANDING OF PROBLEM(S): I'm familiar with the typical issues when using MP3's encoded using VBR like the improper reporting of the bitrate, improper length being reported (unless you fill the 'length' tag in the ID3V2 tags), and the like. These are all very basic and minor issues that are almost expected (and typical on the Windows platform and from my reports, also on Mac OS X).


QUESTION: So, basically, I'm just wanting to verify any issues (or preferably the lack thereof) out there dealing with VBR and the SSL product or Mac OS X in general.



GRATUITOUS SUCKING UP: On a side note, I'm VERY impressed thus far with the support here on the forum and the community surrounding SSL. I'm most impressed with the relatively small number of issues posted here about the product when compared to the other software packages I've been checking out.
Konix 3:30 PM - 5 April, 2006
VBR files work fine in SSL, that is all I use.
nobspangle 4:54 PM - 5 April, 2006
Confirmed,
I my music is mostly VBR and SSL has no issues, both length and bitrate are reported correctly.
The mp3 playback in SSL is not built on top of iTunes or quicktime or any other underlying software library, SSL handles mp3 playing itself.

Just a note for the future, the ABR method is not the best way to make VBR files, try using constant quality.
nik39 5:49 PM - 5 April, 2006
Also using VBR files a lot, no problems encountered.
MusicMeister 9:07 PM - 5 April, 2006
Quote:
<snip>Just a note for the future, the ABR method is not the best way to make VBR files, try using constant quality.


Actually, ABR is one of the best ways to make VBR files. If I used a constant quality it would be a CBR (Constant Bit Rate) and not VBR (Variable Bit Rate).



From the CDex help file dealing with VBR quality:

Variable bit-rate encoding will enable dynamically determined bit-rates that depend on the music content of the current frame. This improves the overall quality of the encoded file without increasing the file size. This option sets the criteria used to determine when to increase the bit-rate for a frame. The lower the number, the lower the criteria will be. Thus VBR_0 will yield the best quality (but the largest file size) while VBR_9 will have less sound quality but the file size will be the smallest. The recommended variable bit-rate option is VBR_4. If you don't want VBR encoding, set this option to None.



And a break down on supported VBR types within CDex (also from within the help file):

VBR-Old: LAME's first functional approach, based on masking, bisection in the bit domain.

VBR-New: LAME's second approach, based on masking and direct noise allocation.

VBR-MTRH: a combination of old and new (VBR) routines

VBR-ABR: The Average Bit Rate (ABR) setting, the encoding principle is similar to what AAC uses as VBR encoding, it is based on perceptual entropy, but more like CBR than VBR. When you select the ABR option in the VBR Settings box, the ABR edit box will be enabled. In this edit box you can specify the target average bit rate. Of course, a larger bit rate will yield generally better-sounding (but larger) MP3 files.
nik39 9:42 PM - 5 April, 2006
Quote:
Actually, ABR is one of the best ways to make VBR files. If I used a constant quality it would be a CBR (Constant Bit Rate) and not VBR (Variable Bit Rate).

I think this is a misunderstanding. Constant bitrate=variable quality in general.
MusicMeister 11:42 AM - 6 April, 2006
I don't understand what you're trying to say.

CBR maintains a constant sampling rate throughout the song regardless of content. During nearly silent parts of the song the sampling rate remains just as constant as during entire orchestral movements. Both pieces of music are handled the same way.

VBR varies the sampling rate based on a variety of algorithms (determined by the type of VBR method used). This means that the quiet parts of the song(s) that have less content, like a solo, are sampled at a lower rate than full orchestral movements. This means that you have a better overall quality of file while keeping the size about the same as a similar CBR file.

Because VBR's inherent increase in quality over similar CBR rates you'll find that most software packages offer VBR up to 256kbps and CBR up to 320kbps.

If this is totally off based let me know but I've yet to find a reputable source that debunks the concept(s) above. Most references have supported the concepts as I posted above.


On a side note, I was aware that SSL wasn't 'built-on' to other apps but I was concerned about VBR support because of what I was seeing in the forums at other products support sites. BTW, if you want to know what the users really feel about the product(s) out there and the overall quality you only need to check out the help forum at most of the sites out there! The excellent support here and lack of any 'real' issues has impressed me far more than any feature list, low price, or celecbrity spokesperson.
nik39 11:55 AM - 6 April, 2006
Quoting Gabriel, who is a developer of LAME from here www.hydrogenaudio.org :
Quote:
The quality obviously fluctuate when using CBR. Only vbr can try to keep constant quality.


Also check this thread here scratchlive.net (warning, its a looong thread).

Wikipedia on CBR ( en.wikipedia.org )
Quote:
Constant bit rate (CBR) is a term used in telecommunications, relating to the quality of service. Compare with variable bit rate.

When referring to codecs, constant bit rate encoding means that the rate at which a codec's output data should be consumed is constant. CBR is useful for streaming multimedia content on limited capacity channels since it is the maximum bit rate that matters, not the average, so CBR would be used to take advantage of all of the capacity. CBR would not be the optimal choice for storage as it would not allocate enough data for complex sections (resulting in degraded quality) while wasting data on simple sections.
MusicMeister 12:46 PM - 6 April, 2006
I read the thread and your posts there only seem to draw me to one conclusion.

You are correct, but we're saying the same thing. The percieved quality of a CBR file will vary based on the amount of musical content. As more content is added the overall quality will degrade because there is more technical content but a potential lack of bandwidth to transfer that additional content.

By using VBR you vary the amount of bandwidth to the content maintaining a constant percieved audion quality within the bandwidth limitations provided.

If I was streaming through ICEcast, Shoutcast, PodCast, etc I'd likely want to use a CBR based encoding scheme since I'm targeting a bandwidth limitation as opposed to achieve maximum sonic quality at an 'average' bandwidth.

VBR will always have a better sonic quality than CBR at the same AVERAGE bitrate because it will achieve higher bitrates than CBR during complex musical movements and drop to lower bitrates when complexity is lacking. If you choose the maximum settings of CBR and a lower VBR rate then they are not being compared 1:1. The comparisons are only valid when dealing with CBR and the AVERAGE bitrate of VBR. That's why the option to encode using VBR is limited to 256kbps average on most software and a maximum bandwidth of 320kbps. But if you're encoding with 320kbps CBR the comparison isn't fair since you're comparing a 256kbps ABR VBR with a 320kbps CBR. It would just as feasible to compare 256kbps CBR with 320kbps CBR.

nik39, I really do think we agree on this we're just saying it in a little different manner.
nik39 12:54 PM - 6 April, 2006
Though I havent understood your point, I trust you when you say that we are saying the same thing :)
MusicMeister 10:46 PM - 6 April, 2006
nobspangle set it off with his post. After that I accidently used the wrong term and forgot to correct it... the quote:
Quote:
Actually, ABR is one of the best ways to make VBR files. If I used a constant quality it would be a CBR (Constant Bit Rate) and not VBR (Variable Bit Rate).

Actually, the term constant quality was incorrect. I should have used the term constant sampling rate instead. It was from there that we went downhill because I didn't realize that I had mispoke.

We both agree that VBR is the better method (over CBR) given the same bit rate since VBR dynamically allocates bandwidth based on complexity. (Assuming the ABR of VBR=CBR bit rate).

We both agree that CBR might be better for some things, like streaming audio/video but sonicly VBR is a better format at simlar bitrates.

We both are picky about people posting stuff that we've reasearched and disagree with. ;-)

Ok, I guessed at the last one... just do a copyright or licensing post to see me go off...
nik39 10:49 PM - 6 April, 2006
Your guess was correct :)

I think its important to be precise and exact. Other people are reading this and may follow your "faults".