The best audio codec for your realtime session depends on whether you plan to transfer the audio to another computer and if so, what method you will use to effect that transfer.

The following chart shows the size of an audio file at four hours and eight hours using each of the available audio compression rates in Case CATalyst Version 16 and higher. Audio quality is much higher with less compression and a higher sampling rate (measured in Hz); however, lower compression rates result in significantly larger audio files. Large files take much longer to transfer over the internet than to back up to local external media.

If you are planning to use the same computer for both recording and playback, then you can use any of the audio codecs. Before selecting a particular codec, it is advisable to test each codec using your hardware (computer, internal or external sound card, microphone, speakers or headphones) to determine which codec sounds best to you on your system.

If you are planning to record audio on one computer and then transfer the audio to another system then the best codec for you will depend not only on the results of testing to hear the quality of each codec on the hardware used for recording and playback, but also on whether the audio file will be transferred via media (such as a flash drive or external hard drive), or the Internet.

If you are planning to transfer audio recorded on one system to another system via media, for example, back up the job and its audio to a flash drive and then restore the backup to another computer, you can use any of the audio codecs.

If you are planning to transfer audio recorded on one system to another system via the Internet, it is very important to consider the available bandwidth of your Internet connection. While wired Internet connections may have sufficient upload speeds to support lower compression levels, wireless (WiFi or cellular – 5G/4G) networks can seldom efficiently transfer a file recorded with less compression than PCM 11025 Hz at 80 MB/hr. The larger the file, the longer it will take to arrive at its destination; plus, with a cellular internet connection, transferring an audio file can very quickly use up the available data on your data plan. As you see in the chart above, a full day of audio recording at the lowest compression level would be nearly 3 GB of data. A file of that size could take 12 hours or longer to transfer from one site to another via a wireless Internet connection.

As with audio recorded and played back on a single system, you should test the codecs on all hardware that will be used for recording and playback. Record a short sample using each codec (one codec at a time) using the hardware that will be used for recording during realtime, and then test playback both on the equipment used for recording and the equipment used for playback. You may experience different levels of quality with the same codec on different hardware.

TIPS:

• The 6 MB/hr and 15 MB/hr codecs are the same that were available in Case CATalyst Versions 15 and earlier. If you were satisfied with the recording quality in those versions, you can continue to use either of those settings.
  
  
• If you would like a good balance of audio quality file size when using the Internet, Stenograph recommends the PCM 8000 Hz at 58 MB/hr codec instead of the PCM 11025 Hz at 80 MB/Hr. The difference between the quality levels at the 58 MB/hr and 80 MB/hr rates are insignificant on most hardware, and a 58 MB/hr file will transfer more quickly than an 80 MB/hr file.
  
  
• Wav files have a file size limit of 2 Gigabytes. When using the 231 MB/hr. or higher audio codecs, a warning message will inform you how many hours of recording time can be used with this codec and prompt if you would like to change the codec. Select Yes to change the codec or No to continue writing realtime knowing the size limitation.