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Topic: Album file sizes at 320kbps? (Read 14923 times) previous topic - next topic
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Album file sizes at 320kbps?

I'm really confused by this. I have two Elliott Smith albums, both at 320kbps (MP3). One I own myself and converted from a FLAC rip I ripped to MP3 with dbPoweramp, the other I downloaded  (because I couldn't find the other album in a shop ).

The album I own myself and ripped myself is Either/Or by Elliott Smith, which is 36.9 minutes long, and ripped at 320kbps, resulting in a file size for the whole album of 181.7MB.

The other album I downloaded is Elliott Smith by Elliott Smith, which 37.2 minutes long and also ripped at 320kbps, yet it has an overall file size of only 87.5MB.

I understand that there might have been different encoding processes involved and different encoders used (Either/Or was encoded using the CBR (Insane) 320kbps preset, whereas Elliott Smith was apparently encoded using the CBR (Free-Format) 320kbps preset. However I wasn't expecting the two file sizes to be so radically different!

For those who don't know, Elliott Smith is an indie rock singer, and on these two albums he plays mostly acoustic music. On Elliott Smith he only uses an acoustic guitar (with occasional harmonica etc.), and the overall sound is very sparse. However on Either/Or, while still mostly acoustic it uses other instruments and is a bit more 'busy'. However, I am still VERY suprised by the two different file sizes, especially because Elliott Smith is slightly longer than Either/Or.

Can anyone shed any light on as to why this is?

All help appreciated.

Album file sizes at 320kbps?

Reply #1 –
on the second one: (37,2 * 60) * 320 / 8 / 1024 = ~87mb

don't know what's with your first one..

ps. not sure, but there might be a violation of TOS in your post cause of 'torrent'.

Album file sizes at 320kbps?

Reply #2 –
87 MB looks about right.

File Size in MB = (Bitrate in kbps x Playing Time in minutes) / 140

You can derive that formula knowing that bitrate (kbps) is kilobits-per-second and there are 8 bits in a byte (and 1 MB = 1,048,576 Bytes).

There is some rounding in the above formula, and there is some extra space needed for headers & tags.  (I wonder if you have some embedded artwork in BMP format in your version???)

Album file sizes at 320kbps?

Reply #3 –
Quote from: fuflo on
on the second one: (37,2 * 60) * 320 / 8 / 1024 = ~87mb

don't know what's with your first one..

ps. not sure, but there might be a violation of TOS in your post cause of 'torrent'.


Ok. I'll try a re-encode and see what happens. By the way...I don't know what you're talking about

Album file sizes at 320kbps?

Reply #4 –
Quote from: DVDdoug on
87 MB looks about right.

File Size in MB = (Bitrate in kbps x Playing Time in minutes) / 140

You can derive that formula knowing that bitrate (kbps) is kilobits-per-second and there are 8 bits in a byte (and 1 MB = 1,048,576 Bytes).

There is some rounding in the above formula, and there is some extra space needed for headers & tags.  (I wonder if you have some embedded artwork in BMP format in your version???)


Not that I know of. No artwork showed up upon conversion. Anyway, I'm doing my re-encode as I post this just to see if it was a glitch or not...

...Turns out it was a glitch. New file size: 84.6. Weird...
Oh well, at least I have confirmation. Thanks.

Album file sizes at 320kbps?

Reply #5 –
Quote
Ok. I'll try a re-encode and see what happens. By the way...I don't know what you're talking about


What an effective edit

Album file sizes at 320kbps?

Reply #6 –
Quote from: Rontox on
...Turns out it was a glitch. New file size: 84.6. Weird...
Oh well, at least I have confirmation. Thanks.


OK, now I'm curious.  What kind of "glitch" can cause this?  You go from 181.7MB to 84.6MB but give no explanation as to what you did wrong.  Please enlighten us.

Album file sizes at 320kbps?

Reply #7 –
In this thread there are a couple methods to calculate file size from bit rate:

(1) (37,2 * 60) * 320 / 8 / 1024 = ~87mb
(2) File Size in MB = (Bitrate in kbps x Playing Time in minutes) / 140

They are similar but (1) when restated like (2) gives 136.53333... instead of 140. I ran a couple test encodes and found (2) gives a better estimate. (1) is the obvious method and how I would calculate it. Where does the difference come from?

Album file sizes at 320kbps?

Reply #8 –
The first equation is a little off. It should actually be:

(37,2 * 60) * 320000 / 8 / 1024 / 1024 = 85.14mb

Album file sizes at 320kbps?

Reply #9 –
Quote from: dv1989 on
Quote
Ok. I'll try a re-encode and see what happens. By the way...I don't know what you're talking about


What an effective edit


Lol. 

Album file sizes at 320kbps?

Reply #10 –
Quote from: Daffy on
Quote from: Rontox on
...Turns out it was a glitch. New file size: 84.6. Weird...
Oh well, at least I have confirmation. Thanks.


OK, now I'm curious.  What kind of "glitch" can cause this?  You go from 181.7MB to 84.6MB but give no explanation as to what you did wrong.  Please enlighten us.


Sorry about that. I seriously have no idea. Upon putting both albums into iTunes and adding tags, album art etc., the final sizes are Either/Or at 85.3MB and Elliott Smith at 87.5MB (I'd already done this before).

My best guess is that the program simply went apesh*t, and started adding random information to the files that wasn't needed, in other words, empty space. And now that after re-encoding, the album is at the 'correct' size, that further proves that it must have been a random event. I'm not much of a techie, so I don't really know the specifics of why it went wrong, but since I have the album how it 'should' be, I guess I'll just leave it at that.