Ecasound Interactive Mode: Modify Master Amplification

This article explains the exact syntax and command sequence used to adjust the master output amplification level within Ecasound Interactive Mode (EIAM). It covers the required chain operators for linear and decibel gain control, as well as the interactive parameter commands needed to modify output volume in real time.

In Ecasound, amplification is handled using the amplify chain operators: -ea (linear amplification percentage) or -eadb (amplification in decibels). To modify the output amplification level while running in interactive mode, you must target the specific amplify chain operator attached to your output chain and update its parameter.

1. Adding an Amplification Operator

If your current setup does not already have an amplify operator attached to the output chain, add one using cop-add:

To add a linear gain operator (where 100 is unity gain / 100%):
```
cop-add -ea:100
```
To add a decibel-based gain operator (where 0 is 0 dB / unity gain):
```
cop-add -eadb:0
```

2. Modifying Amplification in Real Time

If the amplify operator is already present in your chain setup, adjust its level using the copp-set parameter syntax:

Select the target chain (if multiple chains exist):
```
c-select <chain-name-or-index>
```
Select the amplify chain operator by its index:
```
cop-select <operator-index>
```
(You can verify operator indices using cop-list.)
Select the gain parameter (parameter 1 corresponds to the gain amount):
```
copp-select 1
```
Set the new amplification level using copp-set:
- For -ea (e.g., setting volume to 150%):
```
copp-set 150
```
- For -eadb (e.g., cutting volume by -6 dB):
```
copp-set -6
```

Once copp-set is executed, Ecasound immediately updates the master amplification level of the audio stream without interrupting playback or processing.