Digital Audio

Tech 19 Sep 2026 7 min read

Reduce Voice Recording Noise with FFmpeg Without Destroying Speech

A noisy voice recording is not one problem. Low-frequency handling noise, steady microphone hiss, fan noise, electrical hum, room reverberation, clipping, and codec artifacts have different causes, so a single aggressive denoiser rarely fixes all of them cleanly. FFmpeg provides several useful building blocks for offline cleanup. A practical chain often starts by decoding the source, removing frequencies that clearly do not belong to the wanted signal, applying moderate broadband denoising, and writing the result to an uncompressed WAV file for further processing. The important part is restraint: noise reduction that is too strong can replace background noise with metallic, watery, or gated speech artifacts.

Audio FFmpeg

Tech 19 Sep 2026 7 min read

Reading ESP32 I2S Pin Definitions: MCLK, BCLK, WS, DIN, and DOUT

An ESP32 audio configuration can look deceptively similar to ordinary GPIO setup: const uint8_t I2S_MCLK = 0; const uint8_t I2S_SCK = 5; const uint8_t I2S_WS = 25; const uint8_t I2S_SDOUT = 26; const uint8_t I2S_SDIN = 35; These constants do not define five interchangeable audio wires. Each represents a different part of the I2S timing and data path. A speaker amplifier can remain completely silent even when every GPIO is electrically connected if BCLK and WS are missing, the data direction is reversed, or the frame format does not match the receiving device.

ESP32 I2S

Tech 15 Sep 2026 5 min read

Audio Sample Rate and Bit Depth Describe Different Limits

Two audio files can carry labels such as 44.1 kHz/16-bit and 96 kHz/24-bit, yet those numbers describe separate parts of the digital signal. A larger value in one field does not compensate for a smaller value in the other, and neither number by itself states the quality of the recording, mix, codec, speakers, or headphones. Sample rate describes how often an analog waveform is represented by discrete measurements over time. Bit depth describes how many numerical amplitude values are available for each sample in linear PCM audio. Keeping those roles separate makes format specifications much easier to interpret.

Audio Digital Audio

Tech 05 Sep 2026 8 min read

Stereo vs Mono Audio: What the Difference Means When Listening

Put on headphones and play a stereo recording, and one sound may seem to come from the left while another sits toward the right. Switch the same device to mono audio and that left-right separation can disappear. The difference is not simply that stereo sounds better and mono sounds worse. Mono and stereo describe how audio channels are used. A channel is a separate audio signal. Mono uses one channel for the program, while stereo uses two channels, conventionally called left and right.

Audio Headphones