Audio Engineering

Audio Engineering

Opus, jitter buffers, VAD, AEC, LUFS targets, WebRTC pipeline.

53Articles
53Topics covered
Articles in this category

All 21 articles, sorted alphabetically

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ARTICLE · 01

Acoustic echo cancellation architecture

Deep-dive on AEC: loopback reference capture, delay estimation, partitioned-block frequency-domain NLMS, double-talk detection, residual echo suppress…

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ARTICLE · 02

Automatic gain control architecture

Deep-dive on automatic gain control (AGC) for voice: level estimation, the gain-computer control loop, fast-attack/slow-release dynamics, the noise ga…

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ARTICLE · 03

Clock-drift compensation architecture

Deep-dive on clock-drift compensation in real-time audio: why independent sample clocks inevitably diverge, inferring the parts-per-million drift from…

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ARTICLE · 04

Audio dereverberation architecture

Deep-dive on speech dereverberation: why reverberation is convolution not additive noise, STFT analysis, late-reflection estimation with weighted pred…

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ARTICLE · 05

DTX and comfort noise architecture

Deep-dive on discontinuous transmission and comfort noise generation in voice codecs: a VAD forking speech from silence, DTX stopping full-frame trans…

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ARTICLE · 06

Audio forward error correction

Deep-dive on FEC and redundancy for real-time audio: why retransmission fails against the conversational deadline, in-band Opus FEC and RED-style redu…

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ARTICLE · 07

Acoustic howling suppression architecture

Deep-dive on howling/feedback suppression: loop-gain stability and maximum/added stable gain, feedback detection and notch filtering, frequency shifti…

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ARTICLE · 08

Adaptive jitter buffer architecture

Deep-dive on adaptive jitter buffers: RTP reordering, percentile-based delay estimation, accelerate/expand time-stretching, packet-loss concealment, c…

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ARTICLE · 09

Audio Loudness Normalization

LUFS over peak, and why every platform requires it.

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ARTICLE · 10

Multi-party audio mixing architecture

Deep-dive on server-side multi-party audio mixing (the MCU): per-stream jitter buffering and decoding, resampling to a common clock to correct device …

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ARTICLE · 11

Neural audio codecs -- learned compression and audio tokens

Deep-dive on neural audio codecs: learned compression, the encoder-quantizer-decoder architecture, residual vector quantization (RVQ), the bitrate-vs-…

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ARTICLE · 12

Real-time noise suppression architecture

Deep-dive on streaming noise suppression: framing and STFT features, causal GRU/TCN mask estimators (RNNoise, DTLN, DeepFilterNet), post-filter smooth…

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ARTICLE · 13

Opus codec architecture

Deep-dive on the Opus audio codec: SILK speech and CELT music engines, hybrid mode and content-adaptive switching, flexible frame sizes, FEC and PLC p…

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ARTICLE · 14

Packet loss concealment

Deep-dive on packet loss concealment (PLC) for real-time voice: manufacturing replacement frames for lost packets by extrapolating from recent history…

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ARTICLE · 15

Real-Time Audio Architecture in Depth

A 2500-word walkthrough of real-time audio: capture, AEC, noise, VAD, Opus codec, packetize + FEC, transport, jitter buffer, decoder, ASR, barge-in.

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ARTICLE · 16

Sample-rate conversion architecture

Deep-dive on audio sample-rate conversion (resampling): how to move audio between rates like 48 kHz, 44.1 kHz, and 16 kHz without aliasing or imaging.…

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ARTICLE · 17

Spatial audio -- placing sound in 3D space

Deep-dive on spatial audio: the brain's localization cues (ITD, ILD, spectral), the HRTF, binaural rendering, object-based au…

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ARTICLE · 18

Streaming ASR architecture

Deep-dive on streaming speech recognition: VAD, streaming encoder, CTC/transducer, partials, endpointing, rescore, and observability.

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ARTICLE · 19

Audio Streaming Protocols Compared

HLS, DASH, Icecast, WebRTC — pick by use case.

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ARTICLE · 20

Audio super-resolution -- reconstructing the missing high frequencies

Deep-dive on audio super-resolution (bandwidth extension): the narrowband problem, adding missing high frequencies, learned reconstruction (not upsamp…

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ARTICLE · 21

Voice Activity Detection (VAD)

How VAD identifies when someone is speaking versus silence or background noise.

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