Converting to mp3 trouble

andei · Post by **andei** » Fri Jul 30, 2010 12:40 am

Hello mates.
Today i rendered a new track i was making from my daw (ableton) and when i converted the audio to mp3 in soundforge in order to send it to a friend in soundforge i experienced some trouble.
I rendered the audio from ableton as a 16 bit file with dither (i used the dithering fuction from my limiter used in the Master Channel, Voxengo Elephant, instead of Ableton's dither, as i've read somewhere it's not soo good), and the audio track with sounded good with no imperfections, when converted to mp3 had some little spikes which according to soundforge level meter made it clip.

What may be causing this?
Here is an image comparision of the 2 files, to make myself clear, because my english is not very good.
Thank you!

hydrogen · Post by **hydrogen** » Fri Jul 30, 2010 5:38 am

for starters... when you render render as 32bit and then do bit rate reduction in soundforge.

You can keep the dither feature on for voxengo then you won't need to apply dither when you reduce the bit-rate. After the track has been rendered at 32bit.

The reason you want to do this is so the audio will be processed at the higher quality.

What is the output level set on your limiter? is it at 0.0 or -0.1. set it to 0.1

andei · Post by **andei** » Fri Jul 30, 2010 7:35 pm

i rendered as a 16 bit from ableton, as i always burn the .wav into a cd for playing it myself and i read that for cd burning i should use 16 bit. is that wrong? shoud i rendered as 32 bit?
the output of the limiter is always set up to -0.3, this case included.

edit: i also tried rendering the audio as a 24 bit wav with the exact same setting (limiting output at -0.3, dithering from voxengo).
the wav looked ok just like this one, and when i converted into mp3 had the same weird spikes problem.

s.k. · Post by **s.k.** » Sat Jul 31, 2010 12:08 am

dont worry too much about it, this is just the result of mp3 convertion. that type of convertion changes the waveform and thus deforms it slightly (via interpolation and all types of other sh!t), so if your wav file was normalized to 0dB or very close under that, theres a good chance that deformation will make it go above zero, be it with amounts not worth caring about.

normalizing to -0.3 should suffice... have in mind some limiters would let occasional spikes through too..

i dont see any problem with the waveform you posted

thomasjaldemark · Post by **thomasjaldemark** » Sat Jul 31, 2010 3:16 am

god damn, let your track breath a little..

thomasjaldemark · Post by **thomasjaldemark** » Sat Jul 31, 2010 3:18 am

double

thomasjaldemark · Post by **thomasjaldemark** » Sat Jul 31, 2010 3:24 am

its kinda funny because it seems the mp3 file looks better than the wav

if you have a wav looking like that for an unmastered track then you really need to learn how to mix a track...

s.k. · Post by **s.k.** » Sat Jul 31, 2010 8:25 am

thomasjaldemark wrote:its kinda funny because it seems the mp3 file looks better than the wav

hehe i though exactly the same at first!

about him learning to mix... thats not nessessarily true - yes the waveform looks like a big blue block, but thats how soundforge displays even the most dynamic tracks when the zoom resolution is too low. thats the case here - these are 3 minutes displayed in that small chunk, theres no other way but to look like that.