---
title: PS1 protocol
url: https://doc.pstreamer.tv/en/manual/ps1.html
lang: en
product: Perfect Streamer
version: 1.13.3.445
---

# PS1 protocol

The PS1 protocol works on the principle of Automatic Repeat reQuest (ARQ). It has low resource consumption and allows to transmit high bitrate streams.

**On transmitter** — configurable in output. Only one copy is available for one stream. It is required to register logins for receivers in **Peer**. UDP listen port is set, must be unique for each stream.

**At the receiver** — configurable in input. The host and port of the transmitter are indicated, as well as the login and password.

Encryption of streams is available (Crypto protection), AES-128 is used. To enable encryption on both sides, enter **Crypt Passphrase** — a shared key.

During operation, the receiver (client) transmits its statistics data to the transmitter (server). This can be viewed in the **Peers** section by selecting a client from the list.

Stream latency and the ability to correct losses depends on the receiver (client) settings:

**Round Trip Time** — RTT, ms, default 300. Estimated delay (ping) in the channel. After starting the stream, the real RTT can be seen in the statistics (PS1 recovery delay).

**Client Latency (RTT multiplexor)** — multiplier to RTT, by default 10, which determines the stream delay on the sender’s buffer. Those. the default buffer delay is 3000 ms.

From the sender’s side there is a delay setting (buffer length) — **Latency (ms)**. It should be greater than the delays specified by clients.

The ability of a protocol to compensate for losses is determined by the number of retransmission requests and depends on **Client Latency (RTT multiplexor)**. Large losses lead to additional network traffic. To reduce latency, you should fine tune these parameters.

See client statistics to check the correct operation of the protocol. Counters **PS1 recovery** — if Not found, increase the sender’s buffer; Duplicates — increase RTT.

When switching the stream input (changing the source) on the transmitter, the send queue may briefly grow. PS1 handles this smoothly: the oldest packets are silently dropped, while the numbering (*seqID*) and timestamps at the receivers remain continuous — the receivers recover the losses through the regular retransmission mechanism (retr), without reinitializing the connection. The number of packets dropped this way is visible in the extended statistics of the PS1 output.

Since the connection is initiated from the side of the receiver, the transmitter requires authentication, the receivers are registered in the peers section. Login and password required.