Ballooning Audio Files

[solarblast]

I recorded some audio of almost 2 hours in length that occupy about 27M of mp3 space. I believe the format was at 32K byte. When I bring it in to Sound Forge 8 and simply Save As it balloons to 44M. A similar thing happens in Audacity. If I select the last 40 minutes, and Export Selection as MP3 it ends up as something like a 55M file! What's going on? Apparently, it resets the audio format it some way. Why doesn't it just remain as the original mp3 format?

[mats.hogberg]

Beacuse as you load audio into an audio editor, it is uncompressed to what basically is wav format. If you don't tell the editor otherwise, it wil be saved uncompressed. In audacity, you use the Export as MP3 function. The MP3 bitrate is set under the File format tab under Preferences, Edit menu.

/Mats

[solarblast]

Thanks. I did some experimenting with SF 8.0 and got the results I needed. Reasonable quality and smaller files.

[AlanHK]

I recorded some audio of almost 2 hours in length that occupy about 27M of mp3 space. I believe the format was at 32K byte. When I bring it in to Sound Forge 8 and simply Save As it balloons to 44M. A similar thing happens in Audacity. If I select the last 40 minutes, and Export Selection as MP3 it ends up as something like a 55M file! What's going on? Apparently, it resets the audio format it some way. Why doesn't it just remain as the original mp3 format?

I think it still is MP3. If it were wave, it would be much larger than that.

One possibility is that your original audio was mono, and it was saved out, which would account for a doubling in size. Also, since most sound editors do convert to a uncompressed format while working on it, it will have to be recompressed on saving, which may be at a default compression rate higher than your original.