How to improve sound quality and decrease file size?

[ixodid]

I have Audacity 2.0.6 newly installed but my question refers to 2.0.2. Windows 7 x64, .exe installer.

I use Audacity for stitching together segments from my telephone recording software - it records in 15-minute segments. The output is mp3.

One event I regularly record is a conference call. When the conference call host provides the recording (mp3), the sound quality is better and the file size is 30% smaller than my Audacity-processed version.

So I compared the raw telephone recording software mp3 files' sound quality to the conference call provided version and they are similar in sound quality.

Is there a way I can improve the sound quality while decreasing the file size from what I have been achieving with Audacity?

[kozikowski]

They may be using an MP3 editor. Audacity is not an MP3 editor. Audacity converts everything to an internal sound format and then converts to a whole new MP3 on Export adding compression distortion. If all you're doing is cutting and simple editing, an MP3 editor is perfect. They won't do special effects and any work that depends on changing the character of the sound such as equalization.

http://mp3splt.sourceforge.net/mp3splt_page/home.php

Koz

[ixodid]

That's great - thanks for the link and your help, Koz!

[ixodid]

I tried mp3splt-gtk and didn't see how to use it to splice two or more files together.

I played with it and read about it. It appears to be for splitting larger files into smaller files.

The documentation is written above my head.

Is there another choice available for free that you know of?

I tried MP3 Audio Editor from MAESystems but during installation it does everything it can to trick you into installing toolbars and crap a ridiculous number of times. Then I find it's free for 30 days. Then I had trouble uninstalling it.

[Trebor]

...decrease file size...

Use mono rather than stereo if possible.
Reduce sample-rate to 16kHz for telephone conversation (maybe even lower).
Reduce mp3 bit-rate to the lowest you can tolerate, (this will degrade the audio quality).

[a similar question (&answer) here ... http://forum.audacityteam.org/viewtopic.php?p=247565 ]

[Gunnar]

...decrease file size...

Use mono rather than stereo if possible.
Reduce sample-rate to 16kHz for telephone conversation (maybe even lower).
Reduce mp3 bit-rate to the lowest you can tolerate, (this will degrade the audio quality).

In addition to that:
* Be sure you are using the latest version of LAME for MP3 encoding, which is the best MP3 encoder out there
* Be sure you are using ABR (average bitrate) or even better VBR (variable bitrate) mode, do not use CBR (constant bitrate) unless you absolutely have to
* LAME also has an algorithm quality option, which can be used to squish out more quality at the same bitrate - at the cost of slower encoding speed (use -q0 for max. quality)

If the audio format is not necessarily MP3, you could use AAC instead, which beats MP3 at very low bitrates. Or, even better, use a dedicated Speech-Codec like Opus.

[Gale Andrews]

I tried mp3splt-gtk and didn't see how to use it to splice two or more files together.

I played with it and read about it. It appears to be for splitting larger files into smaller files.

The documentation is written above my head.

Is there another choice available for free that you know of?

Yes. This is the link Koz should have given you for multiple tools that let you split and/or join and/or adjust the volume of MP3's losslessly: http://wiki.audacityteam.org/wiki/Lame_ ... tion#lossy .


Gale

[Gale Andrews]

* Be sure you are using the latest version of LAME for MP3 encoding, which is the best MP3 encoder out there

Just to be clear, the lame_enc.dll's on that page will not work with Audacity:

Code: Select all

08:41:31: Error: Couldn't find symbol 'get_lame_version' in a dynamic library (error 127: the specified procedure could not be found.)
08:41:31: Error: Couldn't find symbol 'lame_encode_buffer' in a dynamic library (error 127: the specified procedure could not be found.)
08:41:31: Error: Couldn't find symbol 'lame_set_quality' in a dynamic library (error 127: the specified procedure could not be found.)
08:41:31: Error: Couldn't find symbol 'lame_set_brate' in a dynamic library (error 127: the specified procedure could not be found.)
08:41:31: Error: Couldn't find symbol 'lame_set_VBR' in a dynamic library (error 127: the specified procedure could not be found.)
08:41:31: Error: Couldn't find symbol 'lame_set_VBR_q' in a dynamic library (error 127: the specified procedure could not be found.)
08:41:31: Error: Couldn't find symbol 'lame_set_VBR_min_bitrate_kbps' in a dynamic library (error 127: the specified procedure could not be found.)
08:41:31: Error: Couldn't find symbol 'lame_set_mode' in a dynamic library (error 127: the specified procedure could not be found.)
08:41:31: Error: Couldn't find symbol 'lame_set_preset' in a dynamic library (error 127: the specified procedure could not be found.)
08:41:31: Error: Couldn't find symbol 'lame_set_error_protection' in a dynamic library (error 127: the specified procedure could not be found.)
08:41:31: Error: Couldn't find symbol 'lame_set_disable_reservoir' in a dynamic library (error 127: the specified procedure could not be found.)
08:41:31: Error: Couldn't find symbol 'lame_set_padding_type' in a dynamic library (error 127: the specified procedure could not be found.)
08:41:31: Error: Couldn't find symbol 'lame_set_bWriteVbrTag' in a dynamic library (error 127: the specified procedure could not be found.)
08:41:31: Error: Couldn't find symbol 'lame_get_lametag_frame' in a dynamic library (error 127: the specified procedure could not be found.)
08:41:31: Failed to find a required symbol in the LAME library.

If you must have 3.99.5 for use in Audacity, you need libmp3lame.dll from "libmp3lame 3.99.5" on http://www.rarewares.org/mp3-lame-libraries.php .


Gale