In today’s rapidly evolving media landscape, reliable audio and video streaming is essential for broadcasters, enterprises, and content providers. However, streaming over unmanaged and unstable networks – such as public internet connections – poses significant challenges. Packet loss, jitter, and latency fluctuations can degrade the quality of real-time streams, calling for robust streaming solutions.
Forward Error Correction (FEC)
Forward Error Correction (FEC) is a proactive strategy where redundant data packets are transmitted alongside the original packets. If data loss occurs, the missing packets can be reconstructed at the receiver without needing retransmission. While FEC effectively mitigates packet loss, it comes with increased bandwidth overhead.
FEC works by using row and column packet calculations to repair the stream at the receiving end. A higher redundancy factor provides better error correction but increases the required bandwidth, making it crucial to find a balance between effectiveness and available network resources. FEC is particularly useful in multicast scenarios where retransmissions are not feasible.
Dual Streaming
Dual streaming enhances robustness by transmitting the same content over two independent network paths. This method can be implemented in different ways:
- Using different networks: Sending duplicate streams over diverse network infrastructures (e.g., one over cellular and another over satellite) reduces the risk of complete transmission failure.
- Time-offset redundancy: When both streams are sent over the same network, introducing a slight delay between the two streams allows the receiver to switch to the backup stream if packets are lost in the primary stream.
Dual streaming requires twice the bandwidth of a single stream, ideally distributed across separate networks for optimal redundancy.
Reliable Transport Protocols: SRT vs. RIST
Secure and reliable transport protocols offer additional mechanisms to address network-induced impairments. Two widely adopted protocols in the industry are Secure Reliable Transport (SRT) and Reliable Internet Stream Transport (RIST). How do SRT and RIST compare? Here‘s an overview:
|
Feature
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SRT
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RIST
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|---|---|---|
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Industry Support
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Widely used in media workflows, especially for video
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Less widely supported for video
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Accessibility / Standardization
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Proprietary solution, SDK available (risk of vendor lock-in)
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Based on open standards
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(Backwards) Compatibility
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Different SDK versions sometimes incompatible
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Complements RTP streaming via RTCP; receivers without RIST support still receive RTP streams
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|
Security
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Built-in AES encryption
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Encryption must be added externally
|
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Latency
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Typically lower latency due to ARQ (Automatic Repeat reQuest) mechanism ~100 ms to 2 s, depending on setup
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More flexible tuning depending on buffering and FEC settings. Can be tuned for either low-latency or high-reliability streaming
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Multicast Support
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Limited, experimental support, not widely used
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Fully supports multicast via RTP/RTCP
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Bandwidth needed
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Increases with retransmissions (ARQ)
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More efficient with selective retransmissions and optional FEC
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Choosing the Right Solution
Selecting the right approach for robust streaming is not a one-size-fits-all decision – it depends on specific needs, infrastructure constraints, and industry requirements. Here’s how different use cases align with the available technologies:
- Broadcasters may prefer SRT due to its widespread industry support and built-in security.
- Organizations favoring open standards may choose RIST to avoid vendor lock-in and maintain backward compatibility with RTP-based streaming.
- Mission-critical applications may implement a combination of dual streaming or FEC and reliable protocols to achieve the highest reliability.
- Users needing multicast support should opt for RIST, as SRT does not natively support multicast.
As the demand for high-quality, uninterrupted streaming continues to grow, leveraging a combination of these strategies ensures robust and reliable content delivery – even over the most challenging network conditions.
Test Our Error Protection at NAB 2025
Do you want to see these error protection mechanisms in action? Visit our booth at NAB 2025! Our IP-4c device will be set up with a music playlist and four different error protection strategies: no protection, FEC, SRT, and RIST. Attendees will have the opportunity to switch between channels to compare audio quality under different protection methods, emulate different packet loss levels on the transmission to directly observe their impact on each stream, and explore the WebUI of our devices to see real-time data and adjustments.
Don’t miss this unique opportunity to experience these error protection methods firsthand!
