Macintosh: 16-bit to 8-bit Audio Conversion
I'm recording some voice audio files to be played back into MacroMind
Director. I record them in 16-bit audio with digidesign's AudioMedia card.
I convert the files to 8-bit audio with MacroMedia's SoundEdit Pro. The
converted sound is very low quality.
I realize that 8-bit has a smaller dynamic range than 16-bit, but the noise
added isn't just a steady noise. The noise is a hissing sound that seems
to rise and fall with the speakers voice.
Is this sound degradation expected? Are other programs or sound formats
better at converting 16-bit to 8-bit audio? Are there any steps I can take
to reduce this noise?
Director. I record them in 16-bit audio with digidesign's AudioMedia card.
I convert the files to 8-bit audio with MacroMedia's SoundEdit Pro. The
converted sound is very low quality.
I realize that 8-bit has a smaller dynamic range than 16-bit, but the noise
added isn't just a steady noise. The noise is a hissing sound that seems
to rise and fall with the speakers voice.
Is this sound degradation expected? Are other programs or sound formats
better at converting 16-bit to 8-bit audio? Are there any steps I can take
to reduce this noise?
Downsampling (moving from 16-bit to 8-bit and moving from 44.1 KHz╩to 22
KHz) is strictly a software operation. Therefore, it's the method of
changing from one bit-per-sample/sample rate format to another that is
introducing the noise.
Downsampling only the bits (16-bit to 8-bit) is generally not the part of
the sequence that introduces the most noise. Although, any method of
changing the bit-per-sample count will cause a change of character in the
sound. The conversion from 44.1 KHz sampling rate to a 22 KHz rate creates
the most opportunity for major introduction of noise. The downsampling of
sample rates is more an art than a pure science; thus, different programs
could easily produce quite different results.
We discussed the issue of using SoundEdit Pro for this procedure with the
MacroMedia Tech Support group. They suggested that the downsampling take
place within the software package where the sampling originated. For
example, if the original digital recording is in AudioMedia's Sound
Designer, downsample in Sound Designer. Then use the resulting sound file
in SoundEdit Pro and MacroMind Director.
Degradation should be expected during the downsampling. The exact form it
takes will be based on which hardware/software elements are used to perform
the task. Many sound engineers who must work with 8-bit sound record the
original digital recording in 8-bit. This provides far less room for error
than recording in 16-bit sound and then converting to 8-bit.
The introduction of noise isn't related to the file format, unless
compression (that is, MACE) is used when the file is saved. Compression
can easily add noise, and should be expected when compressing.
To locate a vendor's address and phone numbers, use the vendor name as a
search string.
KHz) is strictly a software operation. Therefore, it's the method of
changing from one bit-per-sample/sample rate format to another that is
introducing the noise.
Downsampling only the bits (16-bit to 8-bit) is generally not the part of
the sequence that introduces the most noise. Although, any method of
changing the bit-per-sample count will cause a change of character in the
sound. The conversion from 44.1 KHz sampling rate to a 22 KHz rate creates
the most opportunity for major introduction of noise. The downsampling of
sample rates is more an art than a pure science; thus, different programs
could easily produce quite different results.
We discussed the issue of using SoundEdit Pro for this procedure with the
MacroMedia Tech Support group. They suggested that the downsampling take
place within the software package where the sampling originated. For
example, if the original digital recording is in AudioMedia's Sound
Designer, downsample in Sound Designer. Then use the resulting sound file
in SoundEdit Pro and MacroMind Director.
Degradation should be expected during the downsampling. The exact form it
takes will be based on which hardware/software elements are used to perform
the task. Many sound engineers who must work with 8-bit sound record the
original digital recording in 8-bit. This provides far less room for error
than recording in 16-bit sound and then converting to 8-bit.
The introduction of noise isn't related to the file format, unless
compression (that is, MACE) is used when the file is saved. Compression
can easily add noise, and should be expected when compressing.
To locate a vendor's address and phone numbers, use the vendor name as a
search string.