Sound

Sound settings are on the Video page, under the picture settings. The capture checkboxes choose what is recorded. The codec settings choose how that sound is stored.

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System audio

Records what the computer is playing: a game, a video, music, a browser, and notification sounds. Loopback means NitroWarp takes that sound inside the computer, before it reaches the speakers, so you do not need a cable or a microphone pointed at the speakers.

Leave System audio checked when the viewer should hear what you hear.

Microphone

Records your voice, or any other microphone. Turn it on for narration, a tutorial where you talk, or commentary over a game. Leave it off when you are not speaking, so room noise is not in the file.

Both can be on at once. The system sound and your voice are mixed into the file. If both are off, the video is silent.

Audio codec

The audio codec compresses the sound. It is separate from the video codec, and separate from the System audio and Microphone checkboxes.

AAC is the one to keep. It sounds clean, the files stay a practical size, and it plays in editors, on phones, and on YouTube. It belongs with an MP4 file.

• Opus often sounds better than AAC at the same bitrate, especially for speech. It fits WebM and MKV. Its natural rate is 48000 Hz.
• PCM (raw) stores the sound with no compression. It is the largest and the most faithful. Use it when you will edit and compress later. Everyday recordings do not need it.

Bitrate, channels, and frequency

Bitrate is how much sound data is stored each second, for AAC and Opus. NitroWarp starts at 192 kbps. 192 or 256 is the useful range for a screen recording with music or a game. 128 is enough for a voice alone. 320 is near the top of what AAC uses. Speech stays clear at a lower bitrate than music does.

PCM ignores the bitrate box. That box is gray, because the size is fixed by the frequency and the channel count. 16-bit PCM at 48000 Hz in stereo is 1536 kbps.

Channels is Stereo or Mono. Stereo keeps left and right, which is what headphones play. Mono mixes everything to one channel and is about half the size. Use Stereo unless you are recording one voice and want a smaller file.

Frequency is how many sound snapshots are taken each second.

• 44100 Hz is the CD rate. Use it when another tool still expects 44.1 kHz.
• 48000 Hz is the video standard and NitroWarp's starting value. Use this for almost every recording.
• 96000 Hz stores more than you can hear and makes a much larger file. AAC often cannot encode 96 kHz and will fall back. Prefer PCM if you truly need that rate for an edit.

For most recordings: AAC, 192 kbps, Stereo, 48000 Hz.

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