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MP3 Encoding Question

post #1 of 11
7/1/09 at 10:36am
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Scroll down until you see the info for encoding using iTunes. It reads "For mp3 files follow the menus: /edit/preferences/General (tab). Select “Import Settings.” On the “Import Using” drop-down, select “MP3 Encoder.” Then on the “Setting” drop-down select “Custom.” A new MP3 Encoder dialog box will open. On the “Stereo Bit Rate" drop-down select “320kbps.” Make sure “Variable Bit Rate” is NOT selected. Sample rate should be 44.1 kHz, Channels should be Stereo, Stereo Mode should be Normal, “Smart Encoding Adjustments” and “Filter Frequencies Below 10Hz” should NOT be checked."

Why should VBR not be used and why should filter frequencies and smart encoding not be checked? I thought VBR is higher quality and I have no idea what the last two are. Can anyone fill me in on this?
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post #2 of 11
7/1/09 at 1:08pm
I am guessing this is just a quirk of what headroom does.
Smart encoding and filter frequencies will lead to the truest reproduction, as will not checking VBR (TMK having VBR 320 will result in a KBPS of about 276 or so). It'll give you more kbps per section, and probably not go over 320 for any section (again, to my knowledge).
VBR is a great medium for storage and whatnot, but I think this is a purists approach if you are planning on using mp3.
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post #3 of 11
7/1/09 at 6:41pm
VBR basically leaves bits out if it thinks they are not needed. This reduces filesize but any removed bit will degrade quality. (audibly or not...)
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post #4 of 11
7/1/09 at 7:43pm
As I understand it, VBR (Variable Bitrate) is exactly what it sounds like. The encoder makes two passes, first to analyze the track and then to encode it. After analyzing it, it assigns a higher bitrate to sections that have more detail & dynamic sounds, and less to parts that have less. This leads to a variance of bitrate throughout the track. The goal is to create a higher quality MP3 in say a 192 VBR encoding, than a 192 CBR (constant bitrate) at the cost of time. It's a an excellent space saving way to have a high quality MP3 (especially when using VBR 0). However, but by logic it is easy to see why a 320 CBR will have equal or higher quality than of the highest bitrate VBR.

If you are ripping CDs yourself, and want the best quality MP3's I would just go for 320 CBR as space is abundant & cheap these days. (Better yet, use the LAME codec and not Apple's MP3 encoder) However, when downloading music online, I would take a (for example) 200 VBR average MP3 over a 224 CBR MP3 anyday...
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post #5 of 11
7/3/09 at 10:41pm
Quote:
Originally Posted by paaj View Post
VBR basically leaves bits out if it thinks they are not needed. This reduces filesize but any removed bit will degrade quality. (audibly or not...)

Ummm...ALL MP3 coding leaves out bits that are assumed not needed. That has nothing to do with VBR. VBR generally results in better sound for a given file size. I have no idea what Headroom's beef with it is. Of course, I use only lossless coding, which also happens to be VBR, but not lossy VBR like MP3.
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post #6 of 11
7/4/09 at 4:42am
HeadRoom is likely just being conservative in their recommended settings. They don't want to recommend MP3 encoding settings that the customer may regret later because they were too compressed. So they go with 320 CBR. I'm also not sure how well the MP3 encoder that comes with Windows does with VBR encoding. HeadRoom gives sane recommendations without getting too complex. It certainly is easy to make things more complicated.
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post #7 of 11
7/4/09 at 6:17am
I think headroom is being silly. You should ALWAYS use the newest version of LAME to encode mp3 (I believe it's 3.98 right now) for the best quality. If you feel like you need 320, go for it but I think the quality vs size graph speaks for itself. I personally use v0.

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post #8 of 11
7/4/09 at 7:49am
I forgot a part , but I always thought sometimes the VBR 192 has a bitrate higher than 192, sometimes lower, but at the end of the song, the average bitrate is 192. Basically just a more effective way is distributing the bits. But now I check iTunes and it says: "with VBR enabled, bit rate settings are used for a guaranteed minimum bit rate."
With 320kb/s it wouldn't make sense to use it then, if I'm right, 320kb/s is the highest bitrate in the mp3 standard.
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post #9 of 11
7/4/09 at 9:13am
You're right - in fact, iTunes doesn't allow "320kbps VBR" - 256kbps VBR is the "highest" VBR setting iTunes allows.
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post #10 of 11
7/5/09 at 12:40am
Quote:
Originally Posted by paaj View Post
I forgot a part , but I always thought sometimes the VBR 192 has a bitrate higher than 192, sometimes lower, but at the end of the song, the average bitrate is 192. Basically just a more effective way is distributing the bits. But now I check iTunes and it says: "with VBR enabled, bit rate settings are used for a guaranteed minimum bit rate."
With 320kb/s it wouldn't make sense to use it then, if I'm right, 320kb/s is the highest bitrate in the mp3 standard.
You're right regarding ABR. However, VBR is best of all. VBR aims for a QUALITY LEVEL rather than a bitrate. In general, at equivalent bitrates you'll find VBR>ABR>CBR. You won't be able to use VBR in iTunes though, you'll need to get LAME.
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post #11 of 11
7/5/09 at 9:56am
Quote:
Originally Posted by AtomikPi View Post
You won't be able to use VBR in iTunes though, you'll need to get LAME.
Actually, iTunes does have VBR encoding, both for MP3 and AAC.
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