SRT Probe - Detailed Guide
This document provides detailed feature descriptions and usage instructions for SRT Probe.
📖 What is the SRT Protocol?
SRT (Secure Reliable Transport) is an open-source protocol developed for real-time delivery of high-quality video and audio over the Internet.
Key Features of SRT
- Low Latency: Lower latency compared to traditional delivery protocols
- Packet Loss Recovery: Accurate data delivery even when the network is unstable
- Encryption Support: Secure communication with AES encryption
- Firewall Traversal: Works in NAT and firewall environments
Use Cases
- SRT tool connection testing
- Live streaming (sports broadcasts, event streaming, etc.)
- Video transmission between broadcasting stations
- Remote production (REMI: Remote Integration Model)
- Cloud-based video production
✨ Complete Feature List
🌍 5 Language Support
- Supports English, 日本語, 中文, 한국어, Español
📊 Real-time Statistics
SRT Probe displays the following network quality metrics in real-time during connection:
RTT (Round Trip Time)
Round trip time. The time it takes for data to reach the destination and return.
Throughput
Data transfer rate displayed in Mbps (megabits per second).
Packet Loss
The percentage (%) of packets lost out of all transmitted packets.
Dynamic graphs using Chart.js display the following information over time:
- RTT Chart: Visualizes delay transitions
- Throughput Chart: Displays transfer speed variations
- Packet Loss Chart: Monitors network quality changes
🔄 3 Connection Modes
SRT Probe supports three SRT protocol connection modes:
1. CALLER (Client) Mode
- Role: The side that initiates the connection (client)
- Usage: When connecting from source to destination
- Settings: Specify destination IP address and port number
Example:
Sender (caller) → Receiver (listener)
Source connects to server and sends data
2. LISTENER (Server) Mode
- Role: The side that waits for connection (server)
- Usage: When waiting as a destination
- Settings: Specify listening port number (IP is usually 0.0.0.0)
Example:
Sender (listener) ← Receiver (caller)
Source waits as server and receives connection from receiver
3. RENDEZVOUS Mode
- Role: Both sides attempt to connect simultaneously (P2P)
- Usage: When firewall or NAT traversal is needed
- Settings: Use the same port number on both sides
Example:
Sender (rendezvous) ⇄ Receiver (rendezvous)
Both sides initiate connection simultaneously (peer relationship)
💾 Preset Feature
Save frequently used settings and easily recall them next time.
Saving Presets
- Enter connection settings (IP, port, mode, etc.)
- Click the Save button
- Enter preset name (e.g., “Head Office Server”, “Tokyo Site”)
- Click Save
Loading Presets
- Select a saved preset from the dropdown
- Click the Load button
- Settings are automatically filled in
Deleting Presets
- Select the preset to delete from the dropdown
- Click the Delete button
🎨 3-Panel UI Layout
The SRT Probe UI consists of three panels:
- Test Mode: Select sending/receiving mode
- Connection Settings: Configure IP and port number
- Advanced Settings: Detailed settings (described below)
- Preset Management: Save and load presets
Right Top Panel: Real-time Statistics
- Connection Status: Connected / Disconnected
- RTT: Real-time delay display
- Throughput: Throughput display
- Packet Loss: Packet loss rate display
- Performance Chart: Time-series graph
Right Bottom Panel: Log Output
- Real-time Logs: Connection status and error messages
- Log Filters: Filter by Debug / Info / Warn / Error
- Clear Logs: Clear log display
⚙️ Advanced Settings
When you expand Advanced Settings, you can adjust the following settings:
Interval (Data Transmission Interval)
- Description: Interval for sending data packets (milliseconds)
- Default: 100ms
- Recommended Values:
- High frequency test: 50-100ms
- Normal test: 100-500ms
- Low frequency test: 500-1000ms
Data Size (Transmission Data Size)
- Description: Data size per transmission (bytes)
- Default: 1316 bytes (SRT recommended value)
- Recommended Values:
- Standard: 1316 bytes (optimized for MTU 1500)
- Small size: 512-1024 bytes
- Large size: 2048-4096 bytes
Log Level
- Description: Level of detail for displayed logs
- Levels:
- Debug: Display all logs (for development/debugging)
- Info: Display normal operation logs (recommended)
- Warn: Display warnings and errors only
- Error: Display errors only (minimum)
Verbose Output
- Description: Output more detailed log information
- Usage: Enable during troubleshooting
- Note: Increases log volume, so usually disabled is OK
Duration (Test Duration)
- Description: Automatic stop time for test (seconds)
- Default: 0 (unlimited)
- Recommended Values:
- Short-term test: 10-60 seconds
- Long-term test: 300-3600 seconds (5 minutes to 1 hour)
🎯 Usage Scenario Guide
Scenario 1: LAN Network Testing
Purpose: Verify SRT connection on internal LAN
Settings:
- Receiver side:
- Mode: Receiver (listener)
- IP: 0.0.0.0
- Port: 9000
- Sender side:
- Mode: Sender (caller)
- IP: 192.168.1.100 (Receiver IP address)
- Port: 9000
Expected Results:
- RTT: 1-10ms
- Packet Loss: 0-0.1%
- Throughput: Depends on network speed (typically 100Mbps to 1Gbps)
Scenario 2: Internet Distribution Test (Reverse Connection Pattern)
Purpose: Verify SRT distribution quality between locations (using source as server)
Settings:
- Source (Sender):
- Mode: Sender (listener)
- IP: 0.0.0.0
- Port: 9000
- Open port 9000 in firewall
- Destination (Receiver):
- Mode: Receiver (caller)
- IP: [Source global IP]
- Port: 9000
Use Case:
Effective when the source side has firewall configuration authority or when operating the source as a fixed server.
Expected Results:
- RTT: 20-150ms (depends on distance)
- Packet Loss: 0.1-1%
- Throughput: Depends on line speed
Scenario 3: P2P Test Through Firewall
Purpose: Testing when both sides are inside firewalls
Settings:
- Same settings on both sides:
- Mode: Rendezvous
- IP: Other side’s global IP
- Port: 9000
- Click “Start Test” simultaneously on both sides
Notes:
- Recommended in environments with UPnP enabled
- Or manual port forwarding configuration is required
🔍 Reading Statistics and Troubleshooting
Example of Normal Connection
Status: Connected
RTT: 25ms
Throughput: 8.5 Mbps
Packet Loss: 0.05%
→ No problem. High-quality connection.
Example of High Latency
Status: Connected
RTT: 450ms
Throughput: 2.1 Mbps
Packet Loss: 0.2%
→ High RTT. Possible long-distance connection or routing issues.
Solutions:
- Check network route
- Investigate relay routers with traceroute
- Contact ISP
Example of High Packet Loss
Status: Connected
RTT: 35ms
Throughput: 4.2 Mbps
Packet Loss: 8.5%
→ High packet loss. Network is unstable.
Solutions:
- Switch to wired LAN if using Wi-Fi
- Possible bandwidth shortage (stop other communications)
- Restart network equipment (router, switch)
Example of Low Throughput
Status: Connected
RTT: 18ms
Throughput: 0.3 Mbps
Packet Loss: 0.1%
→ Low throughput. Possible bandwidth limitation.
Solutions:
- Reduce Interval (send data more frequently)
- Increase Data Size
- Check network bandwidth
📞 Support and Feedback
Support Channels
If you have questions or issues with SRT Probe, please contact us through the following methods:
GitHub Issues
For technical issues and bug reports, please report at GitHub Issues.
Including the following information enables faster response:
- Windows version
- SRT Probe version
- Error messages (if any)
- Reproduction steps
- Log files
Email Support
General inquiries: videosp.info@gmail.com
Frequently Asked Questions (FAQ)
For frequently asked questions, please refer to the FAQ section in the Troubleshooting Guide.