Audio - Sync and Caching (Advanced)

Figure 501. The Sync and Caching section

The Sync and Caching section lets you specify audio synchronization and hard disk cache settings.

The Sync and Caching section contains the following settings:

Synchronization

SONAR gives you two choices for synchronizing your audio tracks to SMPTE or MIDI Time Code:

Trigger and Freewheel. With this option audio playback starts (or triggers) at the exact timecode, but then the audio plays at its own internal rate. The audio can gradually drift away from SMPTE time due to variations in the timecode signal.

Full Chase Lock. With this option the speed of audio playback is continuously adjusted to stay with the timecode.

Timing Offset (msec). With this option, used for making very fine adjustments to the audio/MIDI synchronization of your project, you can offset the audio in your project by a number of milliseconds. A positive value delays audio by that amount. A negative value delays MIDI by that amount.

When SMPTE/MTC timecode is detected. This option tells SONAR what to do when it detects SMPTE/MTC timecode. Choose from the following:

Ask first, then switch to clock source and start. This option prompts SONAR to alert you when it detects a SMPTE/MTC signal, asks if you want to sync to the incoming signal, and if you respond that you do, switches the clock source and starts to receive the signal.

Always switch the clock source and start. SONAR automatically switches to the clock source of the incoming signal and begins to receive the signal.

Do not switch clock source, but start if in SMPTE/MTC mode. This option automatically syncs to the incoming signal if SONAR is in SMPTE/MTC mode.

Never switch clock source, never start. SONAR does nothing when incoming SMPTE/MTC timecode is detected.

Note: The final option, Never switch clock source, never start, should never be used if you are attempting to sync to an external clock source.

When clock source is set to SMPTE/MTC or MIDI Sync, pressing play in SONAR will. This option tells SONAR what to do when you press play in SMPTE/MTC or MIDI Sync mode:

Switch current clock source and start playback. Switch the clock to Audio (from SMPTE or Sync), and start playback. This cancels SMPTE (or Sync) mode.

Maintain current clock source and wait for timecode. Do not switch the clock (Stay in SMPTE or Sync mode), but wait for SMPTE or Sync. The playback button remains depressed.

File System

Enable Read Caching and Enable Write Caching. Choosing either of these options lets SONAR use the Windows disk cache while reading or writing audio data. SONAR will usually perform best with all caching disabled, which is the default setting. If your computer has an older IDE disk controller, or a disk controller that does not use DMA transfers, enabling caching may improve SONAR’s audio performance.

Note: Changes to these settings only take effect when you restart SONAR.

I/O Buffer Size. This value determines the buffer characteristics for transfers to and from the disk. Changing this value does not affect audio latency, but will affect the disk throughput for audio tracks. The default setting is 128. A higher value causes more audio to be buffered from the disk ahead of the playback cursor. If you are hearing consistent dropouts/clicks in your audio and if your project contains high bit depth (32/64 bit) or high sample rate audio (88.2K or higher), it may be indicative of a too small I/O buffer size. If so, try a higher I/O buffer size like 256 or 512. If audio problems persist, reset to 128 and try a different remedy.

Also, if you are playing a large file, and using maximum latency, a too-small I/O buffer size may cause dropouts or crashes. Try increasing the buffer size by blocks of 128.

Record Latency Adjustment (samples)

If you loop an audio output back into an audio input, and re-record a track this way, the audio doesn’t line up. For some sound cards, it is off quite significantly. This record latency adjustment is a compensation for that delay.

You can do an approximate measurement of the delay by turning on samples as the resolution unit in the Time Ruler, and comparing the original track with the re-recorded track. Then you can enter a value in the Manual Offset field to compensate.

If you use ASIO mode, enter 0 in the Manual Offset field and leave the Reported Input Latency check box checked (this check box only appears in ASIO mode). This will line up audio in most cases. If you think you can tweak it closer, use the Manual Offset field.

In ASIO mode, the current active ASIO device (remember ASIO can only have one active at a time) reports its “Input Latency.” You can't edit this value. This supposedly accounts for buffer size, A/D Conversion latency, etc. The check box allows you to use this reported value. It is checked by default. In any case, the amount entered into the Manual Offset field will be combined (added to) the reported value if you have it checked.

 

For more information, see:

Synchronization overview

 

See also:

Preferences dialog

Audio - Devices

Audio - Driver Settings

Audio - Playback and Recording

Audio - Audio Profiles (Advanced)

Audio - Configuration File (Advanced)