FEAT: cài đặt tính năng cho volume main out

2026-07-30 09:34:36 +07:00
parent 66eef405a7
commit e64070a83e
3 changed files with 96 additions and 22 deletions
@@ -0,0 +1,72 @@
+# IMPACT OF MAIN OUT VOLUME SLIDER IN THE AUDIO PROCESSING PIPELINE
+
+In Web DAW and Mastering Suite audio architectures (powered by the Web Audio API), the MAIN OUT Volume Slider serves as the final amplification control node (**Post-Processing Master Gain Node**).
+
+Below is a detailed breakdown of how the MAIN OUT slider impacts the audio signal processing chain:
+
+---
+
+## 1. Signal Graph Position
+
+The MAIN OUT Volume Slider controls a `GainNode` located at the very end of the processing chain (**Post-FX Stage**), directly preceding hardware output delivery (`AudioContext.destination` / Speakers / Headphones):
+
+```text
+[ Input Analyser ]
+       │
+       ▼
+[ Processing Chain ] (Dynamic EQ ➔ Stereo Imager ➔ Maximizer / Limiter)
+       │
+       ▼
+[ MAIN OUT Volume Slider (Gain Node) ] ◄── (dB Adjustment Slider)
+       │
+       ▼
+[ Output Analyser / Peak Meter ]
+       │
+       ▼
+[ AudioContext.destination ] (Hardware Speakers / DAC)
+
+```
+
+---
+
+## 2. Specific Impacts on the Audio Stream
+
+### 1. Dynamics & Character Unchanged
+
+Because it is placed after the processing modules (Compressor, Dynamic EQ, Maximizer/Limiter), increasing or decreasing the MAIN OUT level **does NOT** alter compression behavior, harmonic saturation, or the ceiling/threshold point of the Brickwall Limiter.
+
+The audio retains $100\%$ of its tonal color, frequency balance, and dynamic range ratio processed by the Master FX chain.
+
+### 2. Linear Amplitude Scaling
+
+The slider converts decibel values ($\text{dB}$) into a linear gain factor $G$ using the standard formula:
+
+$$G = 10^{\frac{\text{dB}}{20}}$$
+
+All PCM Float32 audio samples ($[-1.0, 1.0]$) passing through the node are multiplied directly by this factor $G$:
+
+$$S_{\text{out}}(t) = S_{\text{processed}}(t) \times G$$
+
+### 3. Impact on Hardware Output & Clipping
+
+* **Decreasing the Slider ($< 0\text{ dB}$):** Reduces the waveform amplitude, allowing users to lower the monitoring volume without affecting the underlying Master processing.
+* **Increasing the Slider ($> 0\text{ dB}$):** Increases signal amplitude. If the scaled amplitude exceeds $1.0$ ($0\text{ dBFS}$), the digital-to-analog converter (DAC) will suffer from hardware clipping and distortion—even if the preceding Maximizer successfully capped true peaks.
+
+### 4. Impact on Output Metering (Post-Fader Metering)
+
+When set to Post-Fader mode, output Peak/RMS/LUFS meters accurately reflect signal levels after multiplication by the MAIN OUT Gain factor. This ensures operators monitor the actual signal level going to speakers or export files.
+
+### 5. Impact on WAV Bounce / Export
+
+During final mix export (**Master WAV Export**), the MAIN OUT Slider value scales the entire final PCM Audio Buffer. Consequently, this slider dictates the absolute volume level of the rendered output WAV file.
+
+---
+
+## 3. Comparison Matrix: MAXIMIZER GAIN vs. MAIN OUT SLIDER
+
+| Parameter / Criteria | Maximizer Boost Gain | MAIN OUT Volume Slider |
+| --- | --- | --- |
+| **Signal Chain Location** | Inside FX Chain (Pre-Limiter) | After FX Chain (Post-Limiter) |
+| **Dynamics Impact** | Alters LUFS, drives signal into Ceiling, increases compression density. | Does NOT alter dynamics; purely scales master output volume. |
+| **Clipping Risk** | **No** (Controlled/limited by the Brickwall Ceiling). | **Yes** (Boosting $> 0\text{ dB}$ can exceed $0\text{ dBFS}$ and clip the DAC). |
+| **Primary Purpose** | Increases perceived loudness (LUFS). | Controls monitoring volume for speakers/headphones or final export scaling. |