software (mp3) question

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GT

I'm compressing a voice recording to mp3 to get the files as tiny as
possible. I have managed to compress 4.5 hours of voice spread over 12 files
down to a total of 80MB (ish), but I need to get it onto 32MB (phone SD
card). I'm using dbPowerAmp Music Converter and have chosen mono, 8000Hz
frequency and 8Kbps bitrate - the lowest settings on offer. The recording is
still more than good enough quality to listen to, so I recon a lower bit
rate or frequency would reduce the filesize further, and still be clear
enough to listen to, but I can't turn things down any lower. Is this the
lowest an MP3 file can be or is this a software limit on the converter?
 
GT said:
I'm compressing a voice recording to mp3 to get the files as tiny as
possible. I have managed to compress 4.5 hours of voice spread over 12
files down to a total of 80MB (ish), but I need to get it onto 32MB (phone
SD card). I'm using dbPowerAmp Music Converter and have chosen mono,
8000Hz frequency and 8Kbps bitrate - the lowest settings on offer. The
recording is still more than good enough quality to listen to, so I recon
a lower bit rate or frequency would reduce the filesize further, and still
be clear enough to listen to, but I can't turn things down any lower. Is
this the lowest an MP3 file can be or is this a software limit on the
converter?
Click to expand...

I can compress the files using WMA down to 24MB. Quality is poor, but enough
to listen to carefully. Or, again using WMA I can compress to around 28MB
and quality is medium and OK to listen to. However, my phone won't play
WMA - needs to be MP3!
 
GT said:
I'm compressing a voice recording to mp3 to get the files as tiny as
possible. I have managed to compress 4.5 hours of voice spread over 12 files
down to a total of 80MB (ish), but I need to get it onto 32MB (phone SD
card). I'm using dbPowerAmp Music Converter and have chosen mono, 8000Hz
frequency and 8Kbps bitrate - the lowest settings on offer. The recording is
still more than good enough quality to listen to, so I recon a lower bit
rate or frequency would reduce the filesize further, and still be clear
enough to listen to, but I can't turn things down any lower. Is this the
lowest an MP3 file can be or is this a software limit on the converter?
Click to expand...
Wouldn't it be easier to just buy a larger SD card? In sizes below 1gB
they are dirt cheap.
 
GT said:
I'm compressing a voice recording to mp3 to get the files as tiny as
possible. I have managed to compress 4.5 hours of voice spread over 12
files down to a total of 80MB (ish), but I need to get it onto 32MB (phone
SD card). I'm using dbPowerAmp Music Converter and have chosen mono,
8000Hz frequency and 8Kbps bitrate - the lowest settings on offer. The
recording is still more than good enough quality to listen to, so I recon
a lower bit rate or frequency would reduce the filesize further, and still
be clear enough to listen to, but I can't turn things down any lower. Is
this the lowest an MP3 file can be or is this a software limit on the
converter?
Click to expand...

Interesting, I tried a couple of other converters and they all had the same
limit as you found.

Jon
 
John McGaw said:
Wouldn't it be easier to just buy a larger SD card? In sizes below 1gB
they are dirt cheap.
Click to expand...

On paper it would be easier, but sourcing a card for the Nokia 6230 confuses
me. It requiers a dual voltage (1.8v/3.0v) MMC card and seems to support up
to 1GB (although I can't find size limits anywhere in a spec). It came with
a 32MB MMC card. The size and contacts looks the same as SD to me, but it
seems to be slightly thinner.

I have been on a few shops websites and searches and found a number of 1GB
MMC cards ranging around £10-£15. Problem is, the MMC cards I have found
either have a different array of contacts, or are a mini version of MMC, or
are advertised as dual voltage, but are the wrong voltage etc. Nothing seems
to be correct, so I haven't bought one!

Besides, I don't have time and will probably never need the space again. I
need this done by tomorrow as I am travelling with work and don't have an
mp3 player (other than this one on my phone). I thought I would compress my
"hitchhikers guide" audio book onto my phone and listen while I sit in a few
airports, bored!

No matter, I'll take some chocolate and crisps instead!
 
I'm compressing a voice recording to mp3 to get the files as tiny as
possible. I have managed to compress 4.5 hours of voice spread over 12 files
down to a total of 80MB (ish), but I need to get it onto 32MB (phone SD
card). I'm using dbPowerAmp Music Converter and have chosen mono, 8000Hz
frequency and 8Kbps bitrate - the lowest settings on offer. The recording is
still more than good enough quality to listen to, so I recon a lower bit
rate or frequency would reduce the filesize further, and still be clear
enough to listen to, but I can't turn things down any lower. Is this the
lowest an MP3 file can be or is this a software limit on the converter?
Click to expand...

It's a software, MP3 codec limitation.

It seems you also have AAC support, so you might want to
find an AAC binary (for windows?) and maybe a front-end
(Google for some if you don't like or can't get desired
result from front-end on this link), and see how small it
can make them choosing a minimal quality and bitrate.

http://softlab.technion.ac.il/project/faac/html/Faac_Executable.htm
 
Jon said:
Interesting, I tried a couple of other converters and they all had the same
limit as you found.

Jon
Click to expand...

The bit rate is declared in the header, and is a four bit field.

http://upload.wikimedia.org/wikipedia/commons/0/01/Mp3filestructure.svg

The encoding for the four bit field, is on pg.23 here. The "free format"
option looks interesting, but I don't know what happens when that is selected.

http://le-hacker.org/hacks/mpeg-drafts/11172-3.pdf

That might be why the bit rate cannot be dropped further. Something to do
with that four bit field.

http://en.wikipedia.org/wiki/MP3

Since AAC is the successor, maybe it can do a bit better.

http://en.wikipedia.org/wiki/Advanced_Audio_Coding

It would be nice if you had the ability to choose whatever compression
scheme that you wanted, as the two above are used for music, and some
clever compression expert probably has something much better for speech.

http://en.wikipedia.org/wiki/Speech_encoding

The ultimate compression, would be storage as text to speech, but then you
lose the original voice characteristics. Imagine 4.5 hours of Stephen Hawking.

Paul
 
GT said:
I'm compressing a voice recording ... but I need to get it onto 32MB
(phone SD card)...
Click to expand...

Software, cellphone... Don't you think you'd have better luck in an
appropriate group?

Do you really think you'll get a better tasting pizza if you order it from a
muffler shop?
 
Software, cellphone... Don't you think you'd have better luck in an
appropriate group?

Do you really think you'll get a better tasting pizza if you order it from a
muffler shop?
Click to expand...

Maybe, some of the pepperoni I've tasted recently was kind
of lame. That's why I grow my own hot peppers.
 
Noozer said:
Software, cellphone... Don't you think you'd have better luck in an
appropriate group?
Click to expand...


Yes, its the wrong group, hence the very clear subject! However, I know
there are several knowledgable members in this group that would be (and have
been) very willing to help.
Do you really think you'll get a better tasting pizza if you order it from
a muffler shop?
Click to expand...

Now who is off-topic! Wouldn't you be better looking on a fast-food or pizza
group?
It would be much more constructive if you suggest another group instead of
just stating the obvious!
 
kony said:
It's a software, MP3 codec limitation.

It seems you also have AAC support, so you might want to
find an AAC binary (for windows?) and maybe a front-end
(Google for some if you don't like or can't get desired
result from front-end on this link), and see how small it
can make them choosing a minimal quality and bitrate.

http://softlab.technion.ac.il/project/faac/html/Faac_Executable.htm
Click to expand...

Thanks Kony - a very useful reply as always! Where do you get it all from -
you must have a head like those guys in the Tefal adverts from the 80s!
 
Thanks Kony - a very useful reply as always! Where do you get it all from -
you must have a head like those guys in the Tefal adverts from the 80s!
Click to expand...

I like music? This time it was just a quick google search
for what your phone supported, I don't actually know what
the lowest bitrate possible is with AAC.
 
kony said:
I like music? This time it was just a quick google search
for what your phone supported, I don't actually know what
the lowest bitrate possible is with AAC.
Click to expand...

It can go down as low as bitrate 1 and 1000Hz, but voice is not clear at
all!
 
It can go down as low as bitrate 1 and 1000Hz, but voice is not clear at
all!
Click to expand...

Maybe that's why MP3 didn't even go this low? I've never
tried to get voice to lowest bitrate possible with lossy AAC
or MP3 codecs and can't say what the practical minimum is.
 
kony said:
Maybe that's why MP3 didn't even go this low? I've never
tried to get voice to lowest bitrate possible with lossy AAC
or MP3 codecs and can't say what the practical minimum is.
Click to expand...

Back from my trip now.
The lowest MP3 setting still leaves voice recording very clear, so using AAC
at a bitrate around 4 and something like 4000Hz was ok to listen to and
fantastic file compression. I gave up with the phone in the end and borrowed
a tiny 1GB MP3 player!
 
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