7.3.11. Internal Vocoder

License Required

DVSI will require a “Num Internal Vocoder Resources” add-on license key. Contact your Eventide Communications Dealer for assistance.

In this section, you will see the number of internal IMBE/AMBE vocoders the recorder is licensed for, as well as the number of simultaneous users that can transcode calls via playback or export in MediaWorks DX.

The number of resources licensed corresponds to how many users can simultaneously transcode calls with a 1:2 relation.

Example:

  • If you are licensed with 1 resource, then 2 users can simultaneously transcode calls.

This means that 2 users can simultaneously transcode calls via playback, or 1 user can transcode via playback and another user can transcode via export at the same time.

Note

If a 3rd user tries to transcode at that time, they’ll receive a warning.

Internal Vocoders

Fig. 7.68 Internal Vocoders

Once licensed, a user can transcode in MWP by playing back the calls

If you are using a JEM server vocoder for EFJohnson calls then you can configure as many as needed, one IP address per line.

Note

For customers using a pre-existing external DVSI Net-2000 Vocoder IP, configure as needed, one IP address per line.

When internal hardware vocoders are present, it will show you how many are detected. To use this option, select the Enable box

Enable Internal Hardware

Fig. 7.69 Enable Internal Hardware

7.3.11.1. Background Batch Decocoding

Note

As of 2022.3, background vocoding is no longer necessary. Customers installed prior to 2022.3 can continue to use this function and will see an additional section in the UI indicating DVSI hardware vocoders.

As with previous releases, when recording P25 Audio from sources that provide audio in their native codec (IMBE or AMBE), the audio is stored on the recorder’s hard drives in the same native format it was received in. When playback or export is selected from MediaWorks DX or the front panel, the configured vocoding resources (External DVSI Net-2000 boxes, EFJohnson JEM II servers, or DVSI Vocoding hardware installed internally to the NexLog DX-Series), are used to decode the audio on demand.

The advantage of this strategy is that AMBE and IMBE are very efficient at compressing audio, so much less disk space is needed to store the data. On the other hand, the disadvantage is that the amount of required vocoding hardware resources scales linearly with the number of users who are doing playback or export at any one time. Exports of large numbers of files will be slow, generally no faster than 4x real time (e.g. an hour of calls will require at least 15 minutes to export.) And finally, during times when those resources are not being used, they are idle.

The Background Vocoding feature, if enabled, will use those idle resources to convert saved IMBE/AMBE calls on disk to a data format that can be played back without using the vocoding resources at playback time (G.726/16, G.726/32, and G.711 are supported). The advantage of having files pre-converted is that playback and export do not require the vocoder resources and will be just as fast as export/playback of other audio formats. The disadvantage of background vocoding, is that the data formats will require more space on disk than the native IMBE/AMBE data would have.

With the feature enabled, whenever a configured vocoding resource is idle, it will be put to work loading files from the disk, transcoding them, and then resaving them. When you go to playback/export a call, if it has already been vocoded, no vocoder resources will be required at playback and playback/export will be much faster.

The Channel Range to Decode option defaults to checking all calls on all channels, but you can configure this to only evaluate and vocode calls coming in on specific physical channel IDs. You can enter ranges with hyphens or delimit with commas; for example, if you want to decode channels 2,3,4,5,6,17,18,19, you could enter 2-6,17-19.