acoustic labs audio editor
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This section describes the tool features of the Acoustic Labs Audio Editor in detail. These tools can be applied to a specific section of the audio data or the entire audio file. The features discussed in this section include editing tools such as adjusting volume, fade in or out, stretch or compress, mute, reverse, swap channels, copy channel, and convert the quality of the audio to another format. Much of the information in this section expects that the user is familiar with the waveform navigating techniques of highlighting audio and using markers. These topics are covered in Section 3: The Audio Editor Interface in Detail.

  • General Overview of the Tool Operations
  • Adjust Volume Levels
  • Fade / Pan Audio
  • Mute Audio
  • Insert Silence
  • Stretch / Compress Audio
  • Reverse Audio
  • Swap Channels
  • Copy Channels
  • Invert Audio
  • Change Current Audio Quality




  • General Overview of the Tool Operations Audio Editor Tools Pulldown

    Beyond the typical editing features of cut, copy and paste users will often want to perform various other operations on specific sections of audio. Common operations include having the ability to modify the volume, fade in or fade out, mute, reverse, time-stretch or compress, and change the quality of the audio. The Acoustic Labs Audio Editor fully supports these features and additional operations - all of which can be accessed via the pull down menu system (visual aid item #1) by selecting the "Tools" pull down menu. To the right is a visual aid that shows the "Tools" pull down menu activated and displays the various features available.




    Adjust Volume Levels

    Audio Editor Volume Dialog One of the most common tool operations utilized is "Adjust Volume". This tool can be used to increase or reduce the volume of a highlighted section of audio, a section of audio selected between markers or the entire audio file that is currently being viewed. By selecting the "Adjust Volume Levels" option from the "Tools" pull down menu system the "Adjust Volume Level" dialog box will appear as shown to the left. At the top of the dialog box you'll notice the option to select which section of audio to apply the volume adjustment to: Highlighted Section, Between Markers or All Audio. Notice that if a highlighted or marker section does not exist, the option will be disabled.

    After selecting which section of audio you wish to modify you can then set the left and right audio levels. Notice that the "Audio Units" dropdown select box will allow you to select between decibel units and a percentage. By moving the sliders for either channels you'll notice that the audio level value changes. When altering the volume levels with respect to decibels, a setting of 0.00 decibels is no change in volume. A negative decibel setting will make the audio level quieter and a positive volume setting will make the audio louder. If altering the volume using percentage units, the percentage is in relation to the existing audio. For example, if you change the level to 50% this will cut the volume level in half. If you set the percentage level to 200% this will double the volume level. If the volume level is set to 100%, there will be no change in the audio level.

    One other option available while adjusting volume is the ability to "Lock Left and Right Channels". If this option is selected levels for both channels will be set identically no matter which slider value is adjusted. This makes setting identical volume levels for both channels easier as you will only have to modify the value for one channel. If this option is not selected you will notice that each channel's slider and level value moves independently. This is necessary when you wish to adjust only one channel's value.



    Fade / Pan Audio Audio Editor Fade Dialog

    The Fade In/Out tool works similarly to the Adjust Volume tool except that the user is able to select both a starting and ending volume level. As with the Adjust Volume tool the user is able to select between using decibel audio units or a percentage value when altering audio levels. Slope type is another setting that is available on the Fade In/Out Tool. The slope type describes the type of slope that will be utilized when adjusting audio levels between the starting and ending volume levels. There are two different types of available slopes: linear and logarithmic.

    When applying the fade tool to audio, the beginning audio adjustment will be whatever level is given as the "Starting Volume Level". As the fade tool is applied to the section of audio, there will be a linear transition to the "Ending Volume Level". For example, if you wish to fade out a highlighted section of audio from its normal level to silence, first click the "Highlight Section" radio button. Then adjust the "Starting Volume Level" to 100% for both channels and adjust the "Ending Volume Level" to 0% for both channels and click OK. The result of this will be a steady transition from normal volume level to silence in the highlighted section.

    The Fade In/Out option also has the ability to use preset values. You'll notice a select box labeled "Presets". Simply double click on any on of the preset names to apply the preset values. To add a new preset value fill in the edit box located below the select box and click "Add".

    Note that when applying percentage levels the volume percentage is in relation to the existing audio. For example, if you change the level to 50% this will cut the volume level in half. If you set the percentage level to 200% this will double the volume level. If the volume level is set to 100%, there will be no change in the audio level. When altering the volume levels with respect to decibels, a setting of 0.00 decibels is no change in volume. A negative decibel setting will make the audio level quieter and a positive volume setting will make the audio louder.



    Mute Audio

    Audio Editor Mute Dialog The "Mute" operation is used to silence existing audio. This operation is rather easy to use as there are only two settings - which section of audio you wish to apply the mute operation to, and which channels you wish to apply the operation to. Like most other tools, the Mute operation can be applied to any highlighted section of audio, a section of audio located between markers or the entire audio file. When specifying which channels you want to mute simply check whichever channels you wish. Selecting the "Left Channel" check box will mute the left channel and selecting the "Right Channel" checkbox will mute the right channel.



    Insert Silence Audio Editor Silence Dialog

    The "Insert Silence" operation is used to insert a specific amount of silence into the existing audio file. The user is able to choose the exact position of where to insert this silence by using either the tracker bar or the begin marker. After selecting where you wish to insert the silence the other necessary parameter is the amount of silence you wish to insert. This amount is given in minutes and seconds and is entered in the edit box labeled "Length of Silence".





    Stretch / Compress Audio

    Audio Editor Stretch Dialog The Acoustic Labs Audio Editor is also equipped with a stretch and compress utility. This tool will shorten or lengthen audio without changing the pitch of the audio. To change the pitch of audio please see the Pitch Shift effect covered in Section 6: Effect Operations. The stretch/compress audio tool allows changes to be made with respect to a ratio of the original audio length. Adjusting the audio to a ratio of 0.75 will speed up the original audio by 25%. Adjusting the audio to a ratio of 1.25 will slow down the original audio by 25%.

    The stretch/compress tool also allows for setting an initial and final ratio. Setting different initial and final ratios will result in a change in speed over the course of the effected audio. For example, if an initial audio ratio of 0.75 is given and a final ratio of 1.25 is given the initial speed of the effected region of audio will be 25% faster, the middle region speed will be unchanged and the end of the effected region of audio will be 25% slower than the original speed.

    Like most other tools, the Stretch/Compress tool can be applied to any highlighted section of audio, a section of audio located between markers or the entire track. This tool also has the ability to use preset values. You'll notice a select box labeled "Presets". Simply double click on any of the preset names to apply the preset values. To add a new preset value fill in the edit box located below the select box and click "Add".



    Reverse Audio Audio Editor Reverse Dialog

    The "Reverse" operation is used to reverse existing audio so that on playback the audio will play backwards. This tool is often useful in developing creative audio mixes. The dialog box interface is very similar to that of the "Mute" operation. There are only two settings: Which section of audio you wish to apply the reverse operation to, and which channels you wish to apply the operation to. Like most other tools, the reverse operation can be applied to any highlighted section of audio, a section of audio located between markers or the entire audio file. When specifying which channels you want to reverse simply check whichever channels apply. Selecting the "Left Channel" check box will reverse the left channel and selecting the "Right Channel" check box will reverse the right channel.



    Swap Channels

    Audio Editor Swap Dialog When editing audio, being able to switch what audio data is located on the left channel with what is located on the right channel is a necessary feature at times. This can be done using the "Swap Left and Right Channels" operation. This operation is very easy to use as only one setting is needed - which section of audio you wish to apply the operation to. Like most other tools, the swap channels operation can be applied to any highlighted section of audio, a section of audio located between markers or the entire audio file.



    Copy Channel Audio Editor Copy Dialog

    The "Copy Channels" operation is used to copy data from one channel to the opposite channel - in other words, you can use this operation to copy what is on the right channel to the left channel, or copy what is on the left channel to the right channel. This can be very useful when you have a mono recording which only has audio on one channel and you wish to make the recording stereo. The copy channels tool has two settings: The section of audio you wish to apply the operation to, and which channels you wish to use as the source and destination. Like most other tools, the operation can be applied to any highlighted section of audio, a section of audio located between markers or the entire audio file. There are two options available when selecting the source and destination channels: "Copy Left Channel to Right" or "Copy Right Channel to Left".



    Invert Audio

    Audio Editor Invert Dialog The "Invert Audio" operation is used to invert the position of samples contained within the area you choose to apply the operation to. Audio samples always have either a positive or negative value centered around a midpoint. Inverting a sample's value will change a positive value to a negative and vice versa. This can be very useful when attempting to remove vocals from music. The invert audio tool has two settings: The section of audio you wish to apply the operation to, and which channels you wish to apply the operation to. Like most other tools, the operation can be applied to any highlighted section of audio, a section of audio located between markers or the entire audio file. When specifying which channels you want to invert simply check whichever channels apply. Selecting the "Left Channel" check box will invert the left channel and selecting the "Right Channel" check box will invert the right channel.



    Change Current Audio Quality Multitrack Recorder Quality Dialog

    The "Change Current Audio Quality" tool can be used to change the audio quality of the current audio file being viewed. There are three main parameters involved whenever considering the quality of a digital audio file: The number of channels, the bit resolution of each sample and the sample rate frequency. The number of channels are limited to being either mono (one channel) or stereo (two channels - left and right channels). The bit resolution of an audio file is limited to either 8 bit or 16 bit. When going for a higher quality of audio always select 16 bit as the resolution. The sample rate frequency is the number samples contained per second. A higher sample rate frequency results in a higher quality recording. To change any of these settings simply select a new value within the dialog box shown to the right and then press "OK". When doing so, the current audio file will be automatically converted to the new audio format.