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Recording Options

File Name Format

You can select the file name format used by the VRS for audio files. Since recordings are usually displayed in file-name order, if you will usually want to search for a file by line then date select the file name accordingly.

Maximum Record File Length

When VRS is recording long or continuous files, it is good practice to break the recordings into separate files to keep the files to a manageable size.

The default value of 60 minutes being suitable for most logging applications. If you are emailing or uploading files and want a quicker turnaround you can reduce this value. Take care not to use too short a time when recording continuously otherwise the number of files may increase rapidly.

Align recording break times with time of day

If this option is ticked, VRS attempts to align the recording break times to the time of day. For example, if you have a 60 minute maximum record time, VRS will attempt to break each file on the hour (rather than exactly 60 minutes from the start of recording).

Note that when this option is ticked the actual file length might not be exactly the record file length because VRS attempts to align the recordings to the time of day.

If this option is off (unticked), VRS breaks the file at the exact maximum record file length time.

File overlap time

When a long recording 'breaks' to a new file, VRS can use a preset overlap time when the original and the new record file are both recording. This is sometimes used to ensure that the voice at the break time can be easily transcribed. Only a few seconds should be necessary for this.

Prompt for Recording Data on start

When recording is prompted manually, if this option is ticked, VRS will prompt the user for additional text data (eg. a file number). This data is then logged with the recording and can be viewed and searched using Find & Play.

Stop Recording during Playback

When ticked, recording is stopped when you open the Find & Play tool. This option is required if your sound card is not duplex (ie. it cannot play while recording).

Reduce file size using audio compression

If this option is ticked, VRS will compress the recording to reduce storage or upload requirements.

VRS currently supports the file formats ".wav", ".mp3" and ".gsm".

The Wave File Format ".wav" is a broad file type that supports multiple codecs within it. Click on "Set Audio Compression Codec" to see the options. Make sure you select a mono codec if you are recording mono from Channel Properties. See www.nch.com.au/acm for a detailed explanation of codecs. Please not the ".wav" file format can contain MPEG-Layer 3 or GSM6.10 encoded audio, so for example a gsm encoded file can be either ".gsm" or ".wav".

MPEG layer-3 ".mp3" files are very popular for music storage and VRS supports it for logging radio stations. You can select the bitrate using the "Set Audio Compression Codec". 128kbps is high (for stereo music). 8kbs is the low end (for mono voice). It is not very good for low bitrate voice encoding so we do not recommend mp3 for voice recordings.

GSM compression (".gsm" files) is commonly known because it is used for cell phone transmission. It is not the smallest file size but it makes a good compromise between quality and file size so we recommend it for phone and voice logging. Note: It always uses a 8000 sample rate.

Audio Quality Options

Line Hum Reduction Filter

If you have a hum or buzz on recordings, VRS includes signal processing to reduce some of this. Check the Line Hum Reduction box and enter the hum frequency. Usually hums are caused by power supplies which are 60Hz (North America) or 50Hz (rest of the world). You must set the hum frequency exactly for the hum reduction to work.

Hums are usually caused by cheap audio interface devices that have a low impedance microphone output (or do not have sufficient balancing isolation) being used with cheap sound cards that have poor high impedance microphone inputs. The ideal solution is to replace the interface or include an impedance matching or balancing audio transformer. Line hum reduction signal processing should only be used as the last option since it affects overall audio quality. Customers have reported success with the Radio Shack Ground-Loop Isolator (270-054) which can remove hums.

Note: Hum filtering places more demand on the CPU so do not use it if it is not necessary.

Low Frequency Cut Filter

Voice can have a high proportion of its energy in the low frequency bands that do not add much to voice intelligibility but can make the voice sound 'muddy' particularly when using audio compression (see below).

Turning on the low frequency filter with a low cut frequency of between 100 and 600Hz will make the voice sound less muddy (but 'thinner') which can improve the recording.

Note: Low cut filtering places more demand on the CPU so do not use it if it is not necessary.

Use Automatic Gain Control

If the input level is not constant VRS can apply signal processing to regulate the recording volume. For example, if you are recording telephone conversations but find the local and remote volumes are very different.

Note: Automatic gain control places more demand on the CPU so do not use it if it is not necessary.