Converting sample types

Last updated on Dec 16, 2021

Learn how to convert sample types in Adobe Audition to change bit depth and optimize audio quality for different workflows.

The Interpret Sample Rate command in the Waveform Editor lets you hear how an audio file sounds at a different sample rate. This command helps you identify files with incorrect rates in their file headers. To permanently convert the sample rate, choose Edit > Convert Sample Type.

In the Waveform Editor, choose Edit > Interpret Sample Rate.

Enter a sample rate in the text box, or choose a common sample rate from the list.
Note

Although you can work with sample rates ranging from 6000 to 192,000 Hz in Audition, your sound card may not support all of them properly. To determine the supported sample rates, consult the card's documentation.

Convert the sample rate of a file

The sample rate of a file determines the frequency range of the waveform. When converting the sample rate, keep in mind that most sound cards support only certain sample rates.

In the Waveform Editor, select Edit > Convert Sample Type.

Note

To quickly access the Convert Sample Type dialog box, double-click the Sample Type section of the status bar

Select a rate from the Sample Rate list, or enter a custom rate in the text box.

In the Advanced section, drag the Quality slider to adjust the quality of the sampling conversion.

Higher values retain more high frequencies, but the conversion takes longer. Lower values require less processing time but reduce high frequencies.

Note

Use higher Quality values whenever you downsample a high rate to a low rate. When upsampling, higher values have little effect.

For the best results, select Pre/Post Filter to prevent aliasing noise.

Convert a waveform between surround, stereo, and mono

The Convert Sample Type command is the quickest way to convert a waveform to a different number of channels.

In the Waveform Editor, select Edit > Convert Sample Type.

From the Channels menu, select Mono, Stereo, or 5.1.

In the Advanced section, enter percentages for Left Mix and Right Mix:

  • When you convert from mono to stereo, the Left Mix and Right Mix options specify the relative amplitudes at which the original mono signal is distributed to the left and right channels of the new stereo signal. For example, you can place the mono source on the left channel only, the right channel only, or any point in between.

  • When you convert from stereo to mono, the Left Mix and Right Mix options control the amount of signal from the respective channel that will be mixed into the final mono waveform. The most common mixing method uses 50% of both channels.

Change the bit depth of a file

The bit depth of a file determines the audio dynamic range. Audition supports up to 32‑bit resolution. You can raise the bit depth of a file to gain a greater dynamic range, or you can lower the bit depth to reduce the file size.

Note

Some common applications and media players require 16-bit or lower audio.

In the Waveform Editor, choose Edit > Convert Sample Type.

Select a Bit Depth from the menu, or enter a custom bit depth in the text box.

In the Advanced section, set the following options:

Dithering

Enables or disables dithering when converting to lower bit depths. If dithering is disabled, bit depth is abruptly truncated, producing a crackly effect on low-volume passages caused by quantization distortion.

Although dithering introduces a small amount of noise, the result is far preferable to the increased distortion that you would otherwise hear at low signal levels. Dithering also lets you hear sounds that would be masked by the noise and distortion limits of audio at lower bit depths.

Dither Type

Controls how dithering noise is distributed relative to the original amplitude value. Usually, Triangular provides the best tradeoff among signal‑to‑noise ratio, distortion, and noise modulation.

 

Dither type

Reduces signal-to-noise ratio

Noise modulation

Triangular

4.8 dB

No

Gaussian

6.0 dB

Negligible

Noise Shaping

Determines which frequencies contain dithering noise. By introducing noise shaping, you may be able to use lower dither depths without introducing audible artifacts. The best shaping depends on the source audio, final sample rate, and bit depth. Noise Shaping is disabled for sample rates below 32Khz because all noise would remain in audible frequencies.

High Pass

With a crossover set to 7.3 kHz, drops dithering noise to -180dB at 0 Hz and -162dB at 100 Hz.

Light Slope

With a crossover set to 11 kHz, it drops noise to -3dB at 0 Hz and -10dB at 5 kHz.

Neutral

Light is flat up to 14 kHz, ramps noise up to a maximum at 17kHz, and is again flat at higher frequencies. Background noise sounds the same as it does without noise shaping, but is about 11dB quieter.

Heavy is flat up to 15.5kHz, placing all dithering noise above 16kHz (or wherever you specify the crossover). Sensitive ears may hear a high-pitched ringing if the crossover is too low. If converting 48 or 96 kHz audio, however, the crossover can be placed well above 20 kHz. Choose a Neutral shape to avoid sonically coloring background hiss. Note, however, that hiss will sound louder than with other shapes.

U-Shaped

Shallow is mostly flat from 2 kHz up to 14 kHz, but gets louder as the audio approaches 0 Hz because low frequencies are much less audible. Medium adds a little more noise above 9 kHz, allowing lower noise below that frequency. Deep increases noise above 9 kHz even more, but also lowers it much more in the 2-6 kHz range.

Weighted

Light attempts to match how the ear perceives low-level sounds by reducing noise more in the 2-6 kHz range and raising it in the 10-14 kHz range. At high volumes, hiss may be more noticeable. Heavy more evenly reduces the most sensitive 2-6KHz range at the expense of more noise above 8kHz.

 

Crossover

Specifies the frequency above which noise shaping will occur.

Strength

Specify the maximum amplitude of noise added to any one frequency.

Adaptive Mode

Varies the distribution of noise across frequencies.

Use sample rate conversion presets

If you need to make the same conversion on multiple files, you can save time by using a sample rate conversion preset.

Choose Edit > Convert Sample Type.

Adjust the settings as desired.

Click the New Preset button.

After you create a preset, it appears in the Presets list at the top of the dialog box. If you want to delete a preset, choose it from the list and click the Delete button .