Audio file compression

[djtaverner]

Hello,

Given very low demands on audio quality what is the smallest filesize I can compress speech to? (say per sec)

What is the best technique to use for compression?

MP3 Variable Bit Rate? or other?

Cheers

[Harry]

It depends on what type of sound it is. Is it speech, music, short sound fx?

There's no one universal solution. Be more precise.

[djtaverner]

Spoken sentences. There will be over 100 so I need to keep the kb down

[Harry]

Use the speech option in the publishing settings.

[djtaverner]

Given speech settings as above, what is the lowest kb/sec or kb/min I can hope for?

[py9jmas]

Off the top of my head, GSM mobiles carry speech at a little under 8 kilobit/sec.

Try mp3 at 8kbit/s. Does it sound OK to you? If you can get hold of it, use Fraunhoffer Institute's mp3 encoder, ISTR it's designed for low bitrates where as lame aims at the high quality end. Otherwise, lame has a "phone" quality preset that aims at 16kbit/s.

[djtaverner]

Is there any way of getting speech down to <4kbs?

[Harry]

There are no magical solution. You can probably reduce the size of a speech, but at the cost of quality.

Also, even if you can reduce a sound file's size, ultimately, the controls within Flash have the last say over its export parameters.