Chapter 29: Mixdown

Pro Tools lets you record and bounce tracks to disk. The Bounce to Disk command lets you write a final mix to disk, create a new loop, print effects, or consolidate any submix. You can also submix, route, and record busses and inputs to new audio tracks.

Bounce to Disk This command writes the current session (if no selection), Edit, or Timeline selection as new audio files to disk. Any available output or bus path can be selected as the bounce source. Use Bounce to Disk to write or master any output or bus path directly to disk.

Sample rate, bit depth, and other conversion processes can be applied during or after the bounce. The Bounce to Disk command lets you bounce all available voices to disk without holding any in reserve. Though you can hear the bounce being created in real time, you cannot adjust mixer or other controls during a Bounce to Disk.

Recording to Tracks This is the process of submixing and recording to new audio tracks, as you would any input signals. This method requires available tracks, voices, and bus paths to accommodate the submix and the new tracks.

While recording to tracks, you can adjust mixer or other controls.

Selecting Audio for Loops, Submixes, and Effects

Both Bounce to Disk and recording to tracks operate on the current Timeline or Edit selection, if any. This makes it easy to turn multitrack selections into mono, stereo, or multichannel loops.

Submixes, stems, and other specialized types of mixes can also be printed to disk using either method, or recorded out to a DAT, MDM, or other recording, transfer, or archiving medium.

Printing effects to disk is the technique of permanently adding real-time effects, such as EQ or reverb, to an audio track by bussing and recording it to new tracks with the effects added. The original audio is preserved, so you can return to the source track at any time. This can be useful when you have a limited number of tracks or effects devices.

AudioSuite plug-ins provide another option for printing a plug-in effect to disk. See the

DigiRack Plug-Ins Guide for details.

Use Bounce to Disk if you need to convert the bounce files, or if you do not want or need to interact with mixer controls during the bounce.

Record to new tracks if you want to adjust controls while the files are being written.

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Dither and Bounce to Disk

Dithering can significantly improve audio quality. Generally, dithering is necessary when reducing the bit depth for digital audio.

If you use Bounce to Disk, it is important to understand that the Bounce to Disk process does

not apply dither.

To dither a bounce file, you should insert one of the included Digidesign Dither plug-ins (such as

POW-r Dither), or another dithering plug-in, on a Master Fader assigned to the bounce source path. Master Faders are often preferable to Auxiliary Inputs because Master Fader inserts are post-fader (better for dithering).

If you do not use a dithering plug-in on your bounce source path, and you choose to convert to a lower resolution during or after a Bounce to

Disk, the resultant file will be converted by truncation.

When to Use a Dithering Plug-In

You should use a dithering plug-in in any situation where you are reducing bit depth, for example, when mastering to a 16-bit file with the

Bounce To Disk command, or when mastering to an external device that records at 16-bit.

This is even necessary when using 16-bit sessions. Even though 16-bit sessions use 16-bit files, they are still being processed at a higher bit rate:

• 24-bit audio input and output signal paths with internal 48-bit mixing and processing for

Pro Tools TDM systems

• 24-bit audio input and output signal paths with internal 32-bit floating point processing for Pro Tools LE systems

For this reason, whether you are using a 16-bit session or a 24-bit session, it is recommended that you use a Dither plug-in when mastering to

16-bits.

When mastering to 24-bits, it is not necessary to use a Dither plug-in.

Using Dither on an Output Mix

Pro Tools includes real-time dithering plug-ins that improve 16-, 18-, or 20-bit performance and reduce quantization noise when mixing or fading low-level signals.

The dithering plug-ins have no user-selectable controls other than Bit Resolution and Noise

Shaping controls.

For more information about dither, see

“Dither” on page 430.

To use a dithering plug-in on a submix:

1 Choose File > New Track and select Master

Fader (stereo) from the pop-up menu.

2 Set the output of the Master Fader to the output or bus path you want to bounce.

3 Assign the outputs of all audio tracks in the session to the same path you selected in step 2.

The Master Fader now controls the output levels of all tracks routed to it.

4 On the Master Fader, click an Insert button and choose one of the Digidesign dithering plug-ins (such as POW-r Dither).

5 In the dithering plug-in window, choose an output Bit Resolution and Noise Shaping setting.

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When you Bounce to Disk you can convert the file to the appropriate resolution. Before being converted by the Bounce to Disk command, the signal will have been dithered to the resolution and noise shaping settings in a dithering plugin.

For more information about the Digidesign dithering plug-ins, refer to the

DigiRack

Plug-Ins Guide

.

Recording to Tracks

You can create a submix in your Pro Tools session and record it to available tracks in the same session. This technique lets you add live input to the mix, as well as adjust volume, pan, mute, and other controls during the recording process.

You can also use this technique instead of

Bounce To Disk, to create mixed tracks directly in your Pro Tools session.

Voice Requirements

Recording a submix to new tracks requires an available voice for each track that you want to record. Make sure you have enough voices available to play back all tracks that you want to record and enough voices available to record the destination tracks.

In contrast, the Bounce to Disk command lets you bounce all available voices to disk without holding any in reserve, but you cannot manually change any controls during the bounce. See

“Bounce to Disk” on page 482 for more infor-

mation.

For information about voice management,

see “Track Priority and Voice Assignment” on page 96.

To record a submix:

1 Apply any plug-ins or external processors you want to add to your audio tracks or Auxiliary Inputs before you record.

2 Set the main channel output of the tracks you want to include in the submix to a bus path. If you are using stereo or multichannel tracks, set the panning of each track.

3 Choose File > New Track and create one or more mono, stereo, or multichannel audio tracks.

4 If you are recording in stereo, pan the new stereo track (or two mono tracks) hard left and right.

5 Set the input of each destination track to match the bus path from which you are recording.

6 Set the output of your new tracks to your main output path.

If you are working with 16-bit files, and you are recording submixes, you should apply dither on the Master Fader.

7 Select Operations > Link Edit and Timeline Selection.

8 Select audio to record. The start, end, and length of the recording can be based on cursor location or Edit and Timeline selections.

• Selection-based recording automatically punches in and out of recording at the selection start and end. Be sure to include time at the end of a selection for reverb tails, delays, and other effects.

• If you don’t make a selection, recording will begin from the location of the playback cursor. Recording will continue until you press Stop.

9 Record enable the new tracks and click Record in the Transport window.

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10 Click Play in the Transport window to begin recording the submix.

11 If recording a selection of audio, recording will stop automatically. If performing an openended recording, click Stop, or punch out of recording. Make sure Loop Playback is not enabled.

Bounce to Disk

The Bounce to Disk command lets you mix down with all available voices on your system.

Since it records to separate audio files, you don’t have to reserve any tracks for a bounce.

Pro Tools bounces are done in real time, so you hear audio playback of your mix during the bounce process (though you can’t adjust it).

You can use the Bounce to Disk command to create and automatically import loops, submixes, or any audio into your session. You can use it to create a final mono, stereo, or multichannel master, in any of several audio file formats. Bounce to Disk provides conversion options for sample rate, bit resolution, and format.

When you bounce a track to disk, the bounced mix includes the following:

Audible Tracks All audible tracks that are routed to the output which is selected as the source of the bounce are included in the bounce. Any muted tracks are not included in the bounce. If you solo one or more tracks, only the soloed tracks are included in the bounced mix.

Automation All read-enabled automation is played back and incorporated in the bounced mix.

Inserts and Sends All active inserts, including real-time plug-ins and hardware inserts, are applied to the bounced mix.

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Selection or Track Length If you make a selection in a track, the bounced mix will be the length of the selection. If there is no selection in any track, the bounce will be the length of the longest audible track in the session.

Time Stamp Information Bounced material is automatically time stamped so that you can drag it into a track and place it at the same location as the original material. For more information

about time stamping, see “Time Stamping” on page 570.

Bounced Files Are “Delay-Compensated”

Pro Tools compensates for any bus delays due to a bounce. This means that if a bounce file is imported back into a session, and placed directly in time against the source mix, it is time-aligned with the original source mix.

Record-Enabled Tracks and TrackInput Enabled

Tracks Cannot Be Bounced

Pro Tools does not allow you to bounce tracks that are either record-enabled or in Input Only monitoring mode.

To Bounce to Disk:

1 Choose File > Bounce to Disk.

2 Configure bounce options as needed and per-

form the bounce (see “Bounce Options” on page 483).

Bouncing with Mute Frees Assigned

Voice (TDM Systems Only)

When bouncing sessions that include muted tracks, enabling “Mute Frees Assigned Voice” can, in some instances, increase the number of tracks that can be successfully bounced. See

“Mute Frees Assigned Voice” on page 102.

Bounce Options

When you use the Bounce to Disk command, you can configure several file options.

Bounce to Disk dialog, with conversion and options enabled

Default Settings

Available options and their default settings are listed in the following table.

Options and Default Settings

Bounce

Option

Default

Bounce

Source

File Type

Format current main output path

session default file type

Auto Stereo Interleaved

Resolution session default resolution

Sample Rate session default sample rate

Conversion

Quality

Good

Use Squeezer

(8-bit only) deselected

Convert During Bounce

Convert After

Bounce deselected selected

Import After

Bounce deselected

Bounce Source

Select any mono, stereo, or multichannel output or bus path as the source for the bounce. All currently active paths as defined in the

I/O Setup dialog are available as the Bounce

Source.

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To set the bounce source:

■

Select an output or bus path from the Source

Selector.

Select a bounce source

File Type

Selects the (creator) type for the bounced files.

Selecting a file type

Sound Designer II

This was the native format for older Macintoshbased Pro Tools systems. Select this to use the bounced audio with any Digidesign application for Macintosh.

BWF (Broadcast .WAV Format)

This was the native format for older Windowsbased Pro Tools systems, but is now supported on Windows and Macintosh. To use a BWF

(.WAV) file in Pro Tools, you can drag and drop from the DigiBase Browser, or use the Import

Audio command. Files in this format do not have to be converted to be used in Pro Tools.

AIFF (Audio Interchange File Format)

To use an AIFF file in Pro Tools, you can drag and drop from the DigiBase Browser, or use the

Import Audio command. Files in this format do not have to be converted to be used in

Pro Tools. AIFF waveform overview data is calculated and saved to a cache file, which is accessed each time the session is opened.

SND Resource

(Macintosh Only)

This file type is supported by some Macintosh software applications and also by Macintosh

System Software. Pro Tools does not directly support this type of file in its sessions. To use a

SND file within Pro Tools, use the Import Audio command. The SND format is useful if you plan to use your audio with other Macintosh applications that do not support Sound Designer II or

AIFF formats. To use a bounced file as a System alert sound, save it in this format and then drag it onto the Macintosh System File.

QuickTime

(Macintosh Only)

This is Apple’s audio file format for QuickTimebased multimedia. Pro Tools does not directly support this type of file in its sessions. To use a

QuickTime audio file within Pro Tools, use the

Import Audio from Other Movie command. The

QuickTime format is popular for attaching to emails, to simplify long-distance project review and approval. Many popular multimedia applications also support QuickTime.

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Windows Media

(Windows Only)

Windows Media formatted files can contain audio, video, or script data stored in Windows Media Format. A Windows Media Format file may have an .asf, .wma, or .wmv file name extension.

RealAudio G2

(Windows and Mac OS 9 Only)

RealAudio G2 was created by Real Networks for streaming audio over the Internet. The RealAudio encoder file is stored in a folder named Codecs inside the DAE folder.

RealAudio G2 Output Options

When you select this format, the Resolution and

Sample Rate pop-up menus in the Pro Tools

Output Options dialog are unavailable, because resolution and sample rate are set by the encoder.

The RealAudio G2 format lets multiple streams with different bit rates be encoded into a single file. During playback, the RealAudio G2 server and the RealPlayer G2 client continuously adjust the bit rate to make the best use of available bandwidth. The RealPlayer G2 is available on the Real Networks Web site (www.real.com).

When you export or bounce to RealAudio G2 format, you can set the following options:

Media Clip Information Type the title, author, and copyright information for your RealAudio clip. This information is displayed on the Real-

Player G2 as the clip plays back.

Copy Protection These settings determine how the clip is handled by the RealPlayer client.

• To let RealPlayer Plus users save your clip using the RealPlayer Plus recording feature, select Allow Recording.

• To let RealPlayer users download your clip to their hard drive, select Allow Download.

If you don’t want RealPlayer users to make copies of your clip, deselect both of these options.

Audio Format From the pop-up menu, select the setting that best matches the type of audio you are bouncing. A brief explanation of each format is displayed.

Target Audience Select the connection speed that most users downloading your clip are likely to have. This setting determines the bit rate at which the audio will be encoded. Depending on the file type you choose (see below), you can choose more than one connection speed.

File Type This option determines the compatibility of the output file with different RealAudio servers and clients.

If you select SureStream, you can select more than one connection speed under Target Audience. With this file type, multiple bit rate streams are encoded into a single output file.

Files encoded with the SureStream option are larger than Single Rate files, and can only be played back from G2 servers.

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Select the “Include RealPlayer 5.0 Compatible

Stream” option to include a backward compatible stream that can be played on older version

5.0 RealPlayers. (This backward compatibility is only available for SureStream-encoded files.)

If you select Single Rate, you can only select one connection speed under Target Audience. With this file type, a single stream is encoded into the output file. Files encoded with the Single Rate option can be played back from either a standard web server or a G2 server.

MP3 (MPEG Layer 3)

The MPEG-1 Layer 3 compression format (MP3) is used for streaming and downloading audio over the Internet, and for playback on portable devices. The MP3 option is required to use this file type.

MP3 Output Options

On Windows and Mac OS 9, the MP3 encoder file is stored in a folder named Codecs inside the

DAE folder; on Mac OS X, the MP3 encoder file is stored in Applications/

Pro Tools/Codecs/MP3/. This version of the encoder uses the latest technology from the developer of the MP3 format, the Fraunhofer Institute. It features improved processing speed and quality, and supports both constant and variable bit rate encoding.

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The MP3 encoder provided as an install option with Pro Tools is a fully functional 30-day demo version. To purchase the full version of the MP3 encoder, visit Digidesign’s Web site

(www.digidesign.com).

When you select this format, the Resolution pop-up menu in the Pro Tools Output Options dialog is unavailable. The resolution is set by the encoder.

The sample rate chosen is given to the codec as a “base” sample rate for operations. The actual sample rate of the resulting file is determined in the MP3 Encoder Options dialog. For example, if a base sample rate of 48000 Hz is chosen, the

MP3 Encoder Options dialog will allow output streams in 48, 24, or 12 kHz, depending on encoding quality.

When you export or bounce to MP3 format, you can set the following options:

Encoder Settings

Encoding Quality Determines the audio quality of the bounced file. The higher the quality, the longer it will take to process the audio. The three options, in ascending order of quality, are Fastest Encoding, Medium Encoding, and Highest

Quality.

The Highest Quality setting can take up to five times longer to process audio than the Fastest

Encoding setting, so you should use it only when the highest fidelity is essential and you have a considerable amount of time to devote to the encoding process. You should experiment with the other encoding quality settings, since they can provide acceptable quality with a significantly shorter encoding time.

Encoding Method Two encoding methods are available:

• Constant Bit Rate (CBR) encodes the file at a single bit rate that you choose from the CBR pop-up menu. Because the bit rate is fixed, the quality of the encoded audio will vary depending on the nature of the material being compressed. This option is best for streaming over the Internet, since it has predictable bandwidth requirements.

• Variable Bit Rate (VBR) encodes the file at a varying bit rate to maintain the level of encoding quality that you choose from the VBR pop-up menu. The bit rate varies automatically depending on the nature of the material being compressed. This option is best for personal jukebox applications.

ID3 Tag Info Settings

ID3 Tag Type The ID3 tag stores data about the encoded audio file that is used by MP3 players to display information about the file. Pro Tools supports three versions of this tag, in order to provide backward compatibility with older MP3 players:

• ID3 v1.0: Appears at the end of a streaming

MP3 file, so that tag information is only displayed after software streaming is finished.

• ID3 v1.1: Same as version 1.0, but adds track number information to the tag.

• ID3 v2.3: Appears at the front of a streaming

MP3 file, so that tag information is displayed when streaming begins.

While ID3 v2.3 is becoming the standard

MP3 format, not all MP3 players currently support ID3 v2.3. Contact the developer of your player software for compatibility information.

Title/Artist/Album/Comment Type the title, artist, and other information for the MP3 file. This information is displayed by many MP3 players.

Genre Choose a genre for the file. This information is displayed by many MP3 players, and can appear in searchable catalogs and databases.

Track Number If you select ID3 tag type v1.1 or v2.3, you can enter a CD track number for the file. This information is displayed by many MP3 players.

Year Enter a year for the file. This information is displayed by many MP3 players.

Advanced Settings

The options listed under Advanced Settings, under normal situations, do not need to be changed from their default values.

Pad To Match Bit Rate Exactly This option determines whether MP3 frames are padded to maintain bit rate very precisely. You should only select this option if you need a file with an exact bit rate, for specific applications (such as synchronous transmission over an ISDN line).

Padding of MP3 frames can cause problems with some versions of Internet streaming software. If your files are destined for desktop or Internet delivery, do not select this option.

Allow Intensity Stereo Coding This option determines whether the encoder takes into account the frequency of a signal when encoding its phase characteristics, allowing for more compression at low bit rates. In most cases, you should leave this option selected. However, if you are working with highly phase-dependent material, such as Dolby Surround, you may want to deselect this option.

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Write CRC Checksums This option adds errordetection data to the MP3 file. This data is not necessary for most computer and Internet applications, and also takes away from the space available for audio data. Select this option only if you are sure your delivery mode requires error correction.

Copyrighted This option sets a bit in the MP3 data stream to indicate that the audio is copyrighted. Not all MP3 players use this information. Selecting this option does not guarantee that the audio file will not be copied.

Original This option sets a bit in the MP3 data stream to indicate that the audio is the original media for the track, rather than a copy. This setting is not widely used.

Private This option sets a bit in the MP3 data stream that is interpreted differently by various applications. It is not normally used.

Mac File Settings

Mac File Type and Creator If you expect your file to be used on a Macintosh, you can enter the

Macintosh file type and creator. This will allow users to double-click the file to open their MP3 player.

Default Button

To restore all settings in this dialog to their default values, click Defaults.

Format

This is the format for the bounced result.

Choices are Mono (summed), Multiple mono, and Interleaved.

To set the bounce file format:

■

Select a file format from the Format Selector.

Mono (Summed) Creates a single disk file that is a summed mono mix of the current sources being monitored.

When bouncing to mono (summed) files, the output may clip. Avoid clipping by monitoring the meters of your bounce source Auxiliary Input or Master Fader. When bouncing stereo tracks to mono (summed) files, clipping occurs if left and right signals exceed –3 dB below maximum, or full code (0 dBFS).

Multiple Mono Creates multiple mono files with the same number of channels as the source path.

• If the source output or bus path is stereo, two mono files will be created, and appended with

“.L” and “.R” suffixes on bounce.

• If a multichannel format is used (for example, six-channel, 5.1), individual mono files will be created for each member of the path. Files will be appended with path suffixes according to the path definition in the I/O Setup dialog.

• If the source output or bus path is mono, the pop-up menu will switch from multiple mono to mono, and will create one mono file (no summing of multiple sources).

Stereo Interleaved Creates a single, interleaved file that contains all of the bounced streams from the chosen output path. In an interleaved stereo bounce, tracks assigned to odd-numbered outputs are sent to the left channel, and tracks assigned to even-numbered outputs are sent to the right channel.

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Pro Tools also lets you create multichannel interleaved files of any supported file type. This can simplify file management of mixes and projects for backup and archiving.

Pro Tools does not support interleaved files natively. This means that they must be split into multi-mono files on import (requiring additional disk space).

Resolution

This option lets you select between three different bit resolutions for the bounce conversion.

Bounce to Disk does not apply dither when converting during or after a bounce to a lower resolution (including when bouncing to 16-bit).

When you need to create a lower resolution bounce file, use a Digidesign Dither plug-in, or similar, on a Master Fader assigned to the bounce source path. This dithers the bounce file, before the Bounce to Disk conversion truncates bits into the final file resolution. (See

“Dither and Bounce to Disk” on page 480.)

Resolution choices include the following:

8-bit This resolution is often used in multimedia applications. If the material you are working with is relatively simple, you can use the

Pro Tools “Squeezer” feature for optimal results.

See “Sample Rate Conversion Quality Option” on page 490 for details.

16-bit This is the Compact Disc standard bit resolution.

24-bit If you plan to use the bounced file with a

Pro Tools TDM system, you can take advantage of the greater resolution and headroom afforded by this higher bit rate.

To set the bounce file resolution:

■

Select a bit depth from the Resolution Selector.

Sample Rate

This option lets you save to any of several sample rates. Choices are dependent on your

Pro Tools system and Digidesign audio interfaces.

Sample Rate Conversion Quality

If you choose a sample rate that differs from the original sample rate of the session, the conversion options become available. You can configure the conversion quality, and schedule conversion to occur during, or after, the bounce. See

“Sample Rate Conversion Quality Option” on page 490 for more information.

The following are the more common sample rates, and their application. Higher sampling rates will provide better audio fidelity for recording and playback, and also for processing with dynamics, dither (with noise shaping), and analog emulation plug-ins.

192000 This is a supported sample rate for some audio DVDs, and provides the highest quality audio fidelity with compatible audio interfaces

(such as the 192 I/O).

176400 You may want to work at a sample rate of 176.4 kHz if the final delivery will be at

44.1 kHz (such as compact disc). This will provide a slightly faster sample rate conversion to

44.1 kHz than from 192 kHz.

96000 This is a supported sample rate for DVD audio and provides high-quality audio fidelity with compatible audio interfaces (such as the

192 I/O, 96 I/O, 96i I/O, and Digi 002).

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88200 You may want to work at a sample rate of

88.2 kHz if the final delivery will be at 44.1 kHz

(such as compact disc). This will provide a slightly faster sample rate conversion to

44.1 kHz than from 96 kHz.

48000 This is a standard sample rate for Professional and DVD video, and is supported by DA-

88/98, DAT, and ADAT decks.

44100 This is the standard sample rate for compact discs (CD), and is supported by DA-88/98,

DAT, and ADAT decks.

Custom For a custom sample rate, click in the sample rate window and manually enter in a value.

Pull-up and Pull-down Rates All available sample rates support pull-up and pull-down rates, or other specialized rates.

Use Squeezer

The Use Squeezer option uses a proprietary DSP algorithm specifically designed for performing

8-bit conversion of simple source files such as voice-overs. It optimizes the dynamics of the audio by preprocessing it using compression, limiting, and gating before conversion to 8-bit resolution. This results in greater apparent loudness in the signal, and improved intelligibility. If you are converting a more complex 16bit audio file to 8-bit resolution, test this option before converting all of your material.

Sample Rate Conversion Quality

Option

The Conversion Quality option sets the quality of sample rate conversion used to create the converted file. The higher the quality of sample rate conversion, the longer it takes to convert the file after the bounce has taken place. There are five possible settings, ranging from Low to

Tweak Head. For most applications, the Better setting yields satisfactory results.

Processing Resources and Conversion Quality

Because the Best and Tweak Head settings take longer than the others, you may want to use them only in cases where the highest fidelity is essential and you are not facing strict time limitations.

Bounce to Disk, Use Squeezer enabled

Convert During or After Bounce

The Bounce dialog can perform any conversion options, including sample rate and bit depth conversion, during a bounce or post-bounce.

Convert During Bounce This option may take less time than Convert After Bounce, but does so at the expense of plug-in automation playback accuracy.

Convert After Bounce The Convert After Bounce option, though it takes more time, offers the highest level of plug-in automation accuracy possible.

Import Into Session After Bounce

The Import Into Session After Bounce option automatically imports the newly bounced files into the Audio Regions List so you can place them in tracks. If your newly bounced files are split stereo files, they are listed together in the

Audio Regions List.

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The Import Into Session After Bounce option is only available if the target bit depth for the bounce is the same or less as the bit depth of the current session, and it is supported by the

Digidesign audio interface.

Help

The Help button opens a display-only dialog that describes the Bounce to Disk features.

Recording a Submix (with

Bounce To Disk)

You can create a submix with the Bounce to Disk command by muting tracks or bypassing inserts that are not part of the submix group, and selecting the part of the session you want to bounce. Or, you could solo only the audio you want to bounce.

You can also create a submix by recording to

new tracks. For details, see “Recording to

Tracks” on page 481.

To bounce a submix to disk and bring it into the session:

1 Configure your submix using sends, auxiliary

inputs, and master faders. (See “Submixing for

Signal Routing and Effects Processing” on page 423.)

2 Do one of the following:

• To bounce the entire session, click Return to Zero in the Transport window to go to the beginning of the session.

– or –

• To bounce a portion of the session, enable

Operations > Link Edit and Timeline Selection, and make a selection in the Edit window.

3 Choose File > Bounce to Disk.

4 Configure bounce options and settings.

5 Verify the bit resolution for the bounced file matches the bit resolution of the session.

6 Verify the sample rate for the bounced file is supported by the session and the audio interface.

7 If required, verify the file type and format for the bounced file matches the file type and format of the session.

8 Select the Import After Bounce option.

9 Click Bounce.

10 Select a destination for the new audio file, enter a name, and click Save.

Pro Tools bounces are done in real time, so you hear audio playback of your mix during the bounce process. You cannot adjust controls during a Bounce to Disk.

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To bring bounced files back into tracks:

1 Do one of the following:

• If the newly bounced audio was automatically imported into the session, drag the new files from the Audio Regions List to existing tracks in your session.

If you bounced from a selection point, you can snap the file to the bounce point: While pressing the Start key (Windows) or Control

(Macintosh), drag the region from the Audio

Regions List to the destination track.

• If the bounced files are not available in the

Audio Regions List, import them into the session by choosing File > Import Audio to

Track, or drag and drop the bounced files from your DigiBase browser.

• If you are placing multiple files, keep channels time-aligned with each other by Shiftselecting them in the Regions List, and dragging them simultaneously into existing tracks of the right format.

2 When working with stereo tracks, set the pan controls hard left and hard right.

3 Mute or turn off the voices of original source tracks so that you don’t double monitor your audio material.

4 Click Play in the Transport window to hear the results of the bounce.

Final Mixdown

In final mixdown, you create a mix that includes all your edits, automation, and effects processing.

To bounce a final mix to disk:

1 Adjust track output levels, finalize any mix automation, and choose an Automation mode for each track in the session.

2 Adjust any real-time plug-in and effects settings and automation for each track in the session.

3 Make sure that all of the tracks you want to include in the bounce are audible (not muted or inactive).

4 Assign the output of each of the tracks you want to include in your bounce to the same output path.

5 Do one of the following:

• To bounce the entire session, click Return to Zero in the Transport window to go to the beginning of the session.

– or –

• To bounce a portion of the session, enable

Operations > Link Edit and Timeline Selection, and make a selection in the Edit window.

6

Add dither. See “Dither and Bounce to Disk” on page 480.

7 Choose File > Bounce to Disk.

8 Choose the source path you want to bounce.

9 Configure other Bounce to Disk settings as ap-

propriate. See “Bounce Options” on page 483.

10 Click Bounce.

11 Select a destination for the new audio file, enter a name, and click Save.

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Mastering

In the final mastering process, you might record directly to disk, DAT, DVD, CD, stereo mastering recorder, or a multitrack recorder (for surround mixes).

Once you have created a master of your session, you can transfer it to a portable medium for duplication. You can transfer the master file to CD or DAT to be used as a master for pressing compact discs.

Mastering to a Digital Recorder

Although it is usually best to master sessions directly to hard disk, Pro Tools also lets you master digitally, direct to any AES/EBU-equipped or

S/PDIF-equipped digital recorder such as a DAT deck.

24-Bit Input and Output

Pro Tools TDM systems support full 24-bit audio input and output signal paths, with 48-bit internal mixing and processing, providing an additional 16 bits of headroom at the top of a channel’s dynamic range, and 8 bits at the bottom.

You can exchange files with other 24-bit recording systems without any bit-depth conversion

(as long as they are in a compatible file format).

Pro Tools LE systems support 24-bit input and output, and uses 32-bit floating point mixing and processing internally.

Mastering and Audio Compression

Although audio compression is often an indispensable tool in analog recording, it can present problems in the digital domain. If you compress an input signal at a very high ratio, you create a signal that contains a much higher overall power level compared to its transients. By recording a number of such signals at the highest possible level on multiple tracks, you create a scenario that is more likely to clip the mixed output signal.

High-power compressed signals, when mixed together, create an extremely high-level output.

This output may rise above the full-code level, resulting in clipping.

To avoid this problem, watch the overall level of your program material—use a meter on a Master

Fader, or use an external mastering deck’s meters to help avoid clipping. If you are mastering to hard disk, avoid mixing full-code audio signals together at unity or “0” level, as this invariably causes clipping.

Mastering and Error-Correcting Media

Random access media (such as hard disks, optical cartridges, Bernoulli cartridges or WORM drives) can produce a true digital copy of your data, because every bit value is maintained. Sequential media (such as DAT tapes) use error correction schemes to fix the occasional bad data that is received in a digital transfer. These corrections are deviations from the actual data, and with successive reproductions, represent a subtle form of generation loss.

You can avoid this loss by creating and maintaining masters on random-access digital media

(such as a hard drive) and transferring them to sequential digital media (such as DAT tapes) only as needed.

Chapter 29: Mixdown 493

To configure Pro Tools for direct digital stereo mastering:

1 Connect your digital recorder to your system’s digital outputs. If your system has multiple digital outputs, use channel 1 and 2 of the audio interface.

2 In Pro Tools, set the appropriate digital format and output from the Hardware Setup dialog or

I/O Setup dialog. (See “Configuring Pro Tools

Hardware Settings” on page 41.)

3 On your digital recorder, choose the appropriate digital format for the connections.

4 In Pro Tools, set all audio tracks you want to your master outputs 1–2 path.

5 Click Return to Zero in the Transport window to go to the beginning of the session.

6 Press Record on your digital recorder.

7 Start playback of your session.

8 When your session has finished playing, stop the digital recorder.

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