Use the Audio Effects SDK in Applications

The Audio Effects API is a C API but can also be used with applications that are built using C++.

This page describes the typical workflow for using an effect in applications.

This flow is a simplified version of the sample programs (effects_demo and, for Linux, effects_delayed_streams_demo). The same flow is also used for chained effects, with a few differences in API calls.

1. Create an effect handle for the effect:

   #include <nvAudioEffects.h>
   #include <nvAFXDenoiser.h>  // From features/nvafxdenoiser/include
   
   NvAFX_Handle handle;
   
   // Create single effect
   NvAFX_Status status = NvAFX_CreateEffect(NVAFX_EFFECT_DENOISER, &handle);
   
   // Create chained effect
   NvAFX_CreateChainedEffect(NVAFX_CHAINED_EFFECT_SUPERRES_8k_TO_16k_DENOISER_16k, &handle);
   

2. Set the required parameters:

   Windows

   // Set model name
   
   // Single effect (can also use SetStringList with size 1)
   NvAFX_SetString(handle, NVAFX_PARAM_MODEL_PATH, "denoiser_48k.trtpkg");
   
   // Chained effect
   NvAFX_SetStringList(handle, NVAFX_PARAM_MODEL_PATH, model_files, num_model_files);
   
   // Set input and output sample rates
   NvAFX_SetU32(handle, NVAFX_PARAM_INPUT_SAMPLE_RATE, 48000);
   NvAFX_SetU32(handle, NVAFX_PARAM_OUTPUT_SAMPLE_RATE, 48000);
   

   Linux

   // Set model name
   
   // Single effect (can also use SetStringList with size 1)
   NvAFX_SetString(handle, NVAFX_PARAM_MODEL_PATH, "denoiser_48k.trtpkg");
   
   // Chained effect
   NvAFX_SetStringList(handle, NVAFX_PARAM_MODEL_PATH, model_files, num_model_files);
   
   // Set input sample rate and number of streams
   NvAFX_SetU32(handle, NVAFX_PARAM_INPUT_SAMPLE_RATE, 48000);
   NvAFX_SetU32(handle, NVAFX_PARAM_NUM_STREAMS, 20);
   

3. Set the optional parameters by using the NvAFX_SetU32/NvAFX_SetFloat parameters:

   • Intensity ratio.

   • Use default GPU.

   • VAD enable/disable.

   • CUDA graph enable/disable (Windows only).

   • Delayed streams enable/disable (Linux only).

   • Samples per input frame. A list of supported input sample rates can be queried by using NvAFX_GetU32List. (Refer to Get the Parameters of an Audio Effect.)

   • Effect version (by using NvAFX_SetU32), if using the experimental Denoiser effect.

   • GPU on which the model will be loaded. For more information, refer to Use Multiple GPUs.

4. Load the model:

   NvAFX_Load(handle);
   

5. After a successful load, query the input/output sample rate, channels, and samples per frame for the effect:

   // Sample rate
   NvAFX_GetU32(handle, NVAFX_PARAM_INPUT_SAMPLE_RATE, &input_sample_rate);
   NvAFX_GetU32(handle, NVAFX_PARAM_OUTPUT_SAMPLE_RATE, &output_sample_rate);
   
   // Channels
   NvAFX_GetU32(handle, NVAFX_PARAM_NUM_INPUT_CHANNELS, &num_input_channels);
   NvAFX_GetU32(handle, NVAFX_PARAM_NUM_OUTPUT_CHANNELS, &num_output_channels);
   
   // Samples per frame
   NvAFX_GetU32(handle, NVAFX_PARAM_NUM_SAMPLES_PER_INPUT_FRAME, &num_samples_per_input_frame);
   NvAFX_GetU32(handle, NVAFX_PARAM_NUM_SAMPLES_PER_OUTPUT_FRAME, &num_samples_per_output_frame);
   

6. For each input sample, process the audio by using NvAFX_Run:

   const float* input_buffers[] = { input_samples };
   float* output_buffers[] = { output_samples };
   NvAFX_Run(handle, input_buffers, output_buffers,
             num_samples_per_input_frame, num_input_channels);
   

7. If a disconnection occurs in audio processing (for example, a batch that was reused for a different audio source), reset the internal effect states by calling NvAFX_Reset:

   Windows

   NvAFX_Reset(handle);
   

   Linux

   NvAFX_Reset(handle, states_array, input_wav_list.size());
   

8. On Linux only: During batching, to temporarily pause streams (for example, if data is not ready for that stream but is available for processing for other streams) use NVAFX_PARAM_ACTIVE_STREAMS as required.

After audio processing is complete, to free resources, use NvAFX_DestroyEffect. For more information, see Run an Audio Effect on Delayed Audio Streams on Linux.