How to reduce the wav file size in audacity 1.3.13 [SOLVED]

[spartan001]

Hello,

I'm new to this forum, and new to audacity. How can I reduce the wav file size in audacity 1.3.13 so that it has an acceptable size for sending PPT, (powerpoint), over email. I am Belgian, an I use the dutch interface.

Regards,

[kozikowski]

If MP3 file format is acceptable to Power Point, you can install the lame software package to Audacity from here...

http://audacityteam.org/download/

...and Audacity will export compressed MP3 music files. The default compression of 128 is good for most applications and gives a very small file. You can export at smaller sizes with increase in musical damage -- bubbling, honky sound. In extreme, you can mix the music to mono and go as low as 32.

Koz

[spartan001]

Hello Koz,

Thanks for this quick reply. However, Powerpoint, (2007 version), only accepts WAV files. I tried to embed a MP3 file, but it doesn't work, and in the help files of Powerpoint is mentioned that music should be in WAV format.

Regards,

[DVDdoug]

Just for reference:

The size of an uncompressed WAV file is determined by the number of samples per second (i.e. 44,100) and the number of bytes per sample (i.e. 4 bytes per sample with 16-bit stereo).

The size of compressed formats (uncompressed files too) can be calculated from the bitrate (kbps = kilobits per second.) There are 8 bits in a byte, so with a little math and a little rounding we get:
File Size in MB = (Bitrate in kbps x Playing time in minutes)/140

The bitrate for a "CD quality" WAV file (44.1kHz, 16-bit stereo) works-out to about 1411kbps.

[steve]

Thanks for this quick reply. However, Powerpoint, (2007 version), only accepts WAV files. I tried to embed a MP3 file, but it doesn't work, and in the help files of Powerpoint is mentioned that music should be in WAV format.

The file needs to have a WAV header and file extension so that Powerpoint thinks it's a WAV file.
It's possible to cheat.
The (free and open source) program CDex can add a RIFF wav headers to mp3 files. If I recall correctly the option is in the "Convert" menu.

[kozikowski]

You can reduce a WAV file to half by converting from stereo to mono. Past that, WAV files get very messy.

Can you send the show as multiple PPT files? You can stack them for playback, right? Most email programs have a per-email limit of 20 MB -- I think that's Yahoo mail -- although I wouldn't push that.

Koz

[spartan001]

Hello all,

A friend of mine says I need to convert it with MPEG-layer3 and encoder settings 8000 Hr - 18 kBit/s - Stereo - 2kB/sec. I did that with the soundrecorder in Win XP and it works fine. So I managed to reduce a 6 MB WAV into 500 kB WAV. Unfortunatly, the Win 7 soundrecorder has not the options of the soundrecorder Win XP. And I do not have the space to work with two laptops. I cannot find these settings in audacity. Does this ring a bell to guide me to a final sollution?

Regards

[Gale Andrews]

A friend of mine says I need to convert it with MPEG-layer3 and encoder settings 8000 Hr - 18 kBit/s - Stereo - 2kB/sec. I cannot find these settings in audacity.

MPEG layer 3 means export as "MP3 Files" from Audacity (File > Export). Before saving the file, click "Options":
http://manual.audacityteam.org/man/MP3_Export_Options

and choose 16 kbps bit rate (18 kbps is invalid for MP3's).

Sample rate is chosen in "Project Rate" bottom left of the Audacity window. Higher sample rates usually give better quality than lower rates, and higher sample rates do not increase file size in MP3's, so you could use a sample rate up to 24000 Hz with 16 kbps bit rate. However for MP3 exports it is often better to use low sample rates with low bit rates (and vice-versa) because of the way MP3 encoding works. So I would say try 8000 Hz, 12000 Hz and 16000 Hz project rate and see which sounds least bad. Then add RIFF headers to the MP3 using CDex as Steve described, so PowerPoint thinks it is a WAV.

If you want to write a WAV with MP3 inside you can do it with Audacity, choosing "Custom FFmpeg Export" when you export, but you have to add FFmpeg to your computer for Audacity to use.



Gale

[spartan001]

Hello Gale,

I tried this, and it works out fine !!!!
Many, many thanks

Regards,