Transport-wide Congestion Control (transport-cc, TWCC) is the modern WebRTC scheme for estimating available bandwidth and adapting media rates to avoid congesting the network. Instead of the receiver computing the estimate (as in the older REMB), the receiver simply reports the arrival time of every packet back to the sender, and the sender runs the bandwidth-estimation algorithm itself. Centralizing the logic at the sender gives finer, faster, more consistent reaction to changing conditions and easier iteration. It governs how aggressively the encoders push bits; for audio the practical effect is graceful coexistence with video and adaptation as the link tightens, keeping latency low and avoiding the bufferbloat that wrecks real-time media.
