Yes, it is possible to achieve FreeDV output level that follows the input audio amplitude. FreeDV is a digital voice communication mode that uses low-bit-rate codecs to transmit voice over radio frequencies. While FreeDV itself does not provide a built-in feature for automatically adjusting the output level based on the input audio amplitude, you can implement this functionality using external tools or software.
One common approach to achieve level control in digital audio processing is by using a technique called "automatic gain control" (AGC). AGC adjusts the gain or output level based on the input signal's amplitude to maintain a relatively constant output level.
To apply AGC to your FreeDV output, you can use audio processing software or libraries that support AGC functionality. Here's a general outline of how you can implement this:
Capture the input audio signal: Retrieve the audio samples from the input source, such as a microphone or an audio file.
Calculate the input audio amplitude: Measure the amplitude of the input audio signal. This can be done by calculating the RMS (Root Mean Square) value or peak level of the audio samples.
Determine the desired output level: Define the target output level that you want to maintain.
Compute the required gain adjustment: Compare the input audio amplitude with the desired output level and calculate the necessary gain adjustment. This adjustment can be determined by subtracting the input level from the target output level.
Apply the gain adjustment: Multiply the audio samples by the gain adjustment factor to modify the output level.
Transmit the processed audio: Use the modified audio samples as the input to the FreeDV encoder for transmission over the radio.
It's important to note that the specific implementation details will depend on the software or programming language you are using. There are various audio processing libraries available, such as Python's pyaudio or sounddevice, or more specialized libraries like portaudio or libav.
By incorporating AGC or a similar level control mechanism into your FreeDV setup, you can achieve an output level that follows the input audio amplitude, helping to maintain consistent audio levels during transmission.