RTMP vs RTSP: What's the Difference + Which Protocol is Best for Modern Live Streaming

In the early nineties, home entertainment was ruled by broadcast and cable television, along with Friday night trips to Blockbuster. Just before Y2K, video streaming began to emerge from behind the curtain, slowly gaining momentum through the 2000s and 2010s until it has come to dominate home entertainment today and for the foreseeable future.

In live streaming’s early days, RTMP and RTSP were two of the first streaming protocols to define how video data would travel across a network from source to viewer. Real-Time Messaging Protocol (RTMP) arrived in 1996, followed by Real-Time Streaming Protocol (RTSP) in 1998.

Both are still around in the mid 2020s, but which one truly has stood the test of time? Has one triumphed as the superior protocol for live streaming, or have newer technologies made both of them obsolete? Let’s find out.

Table of Contents

RTMP vs RTSP: The Similarities
RTMP vs RTSP: The Differences
Has Modern Streaming Outgrown RTMP + RTSP?
Final Thoughts

RTMP vs RTSP: The Similarities

It’s worth noting that RTMP and RTSP share quite a bit in common. Both are considered live streaming protocols, meaning they’re designed to deliver video online in near real time. RTMP streams typically have a latency of about three to five seconds, while RTSP is slightly faster at roughly half a second to two seconds in most situations. Neither protocol delivers a truly instantaneous live experience, which isn’t surprising, as true real-time streaming is often complex, costly, and rarely worth the tradeoff.

Since packet loss is common during streaming, both protocols include mechanisms for data retransmission at the transport layer. Although they aim to do the same thing, they handle the recovery process very differently. We’ll dig into that detail in the next section.

Finally, both can work with multiple compression codecs. Historically, however, each has relied most heavily on H.264 rather than H.265. In plain terms, this means they aren’t locked into a single method of compressing video data, which adds flexibility for different streaming setups, depending on the technical capability and preference of the broadcaster.

So, while RTMP and RTSP share some foundational similarities, their differences reveal just how distinct these two protocols truly are.

RTMP vs RTSP: The Differences

While both protocols are used for live streaming, their primary roles have diverged over time. RTMP has become known mainly as an ingest protocol, while RTSP is more often used in closed or private systems. Said in a different way, RTMP is typically used to connect an encoder to a media server, whereas RTSP is commonly used to connect cameras or surveillance systems to a playback source.

That isn’t the only difference between the two. As mentioned earlier, they handle data retransmission in very different ways. RTMP relies exclusively on TCP, which ensures that every data packet arrives in order. If packets are missing, they’re resent until the stream is complete and the viewer receives a clean picture. The tradeoff is that viewers will likely experience buffering until all the data arrives, which can quickly lead to frustration or even lost audiences.

RTSP, on the other hand, can use TCP, but more often relies on UDP by default. This means lost packets are simply left behind, allowing the stream to continue without interruption. Viewers benefit from ongoing playback, but the trade-off is often pixelation and visible video quality degradation when packet loss is persistent or severe. Once again, this can lead to viewer frustration or a lost audience due to poor video quality.

There’s one more similarity to point out, and it’s easiest to describe as If these protocols were people. RTMP would be the last of the Millennials (from 1996) and RTSP the first of Generation Z (from 1998). They’ve both seen a lot of change since the late nineties, and like cars from that era, they’re starting to show their age. A major drawback is that RTMP is no longer supported by HTML5 video players, which means the stream must be transcoded (converted) into a modern format like HLS before it can be delivered to the viewer. This adds extra latency and complexity to the delivery pipeline. While RTSP enjoys slightly broader compatibility, it still isn’t natively supported across all modern browsers. So though they’re still “road legal”, their lack of modern functionality can be a deal breaker for many.

So rather than asking “RTMP vs RTSP: Which is better?” The real question might be whether there are newer live streaming protocols that outperform them both in our day and age.

Has Modern Streaming Outgrown RTMP + RTSP?

Since the nineties, video resolutions have grown bigger and better. Larger files demand stronger compression, especially as streaming quality has climbed far beyond the 480p standard that defined RTMP and RTSP’s early years. While neither protocol is tied to a specific codec, both were built when AVC H.264 compression was the norm. Most broadcasters still rely on this older standard when using these protocols, which was designed for much smaller video files. Today, choosing a newer streaming protocol that supports HEVC H.265 compression by default can help deliver higher quality streams more efficiently, easing the strain on your network.

Network performance is another key limitation of these older protocols. Both RTMP and RTSP operate within fixed, low-latency parameters, which can lead to buffering or degraded quality depending on their retransmission strategies. Modern protocols allow for configurable latency, letting you extend the delay from a few seconds up to ninety seconds. This gives the network extra time for retransmission to keep the stream stable, providing a safety margin that most online viewers won't even notice.

Newer streaming technologies can also use forward error correction to detect and resend data packets before they’re lost. Some even combine UDP and TCP intelligently, creating a hybrid approach that maintains a steady stream without buffering or visual distortion. In addition, some protocols can automatically downscale resolution when network speeds drop, for example shifting from 1080p HD to 720p HD for a portion of the broadcast where packet loss spikes. This is called Link Quality Adjustment, and the result is a smooth picture with only a small dip in quality, which is far better than the frustration of buffering or significant pixelation.

Add up all of these improvements, and modern streaming protocols can reduce upload speed requirements from the 5 to 10 Mbps range of RTMP and RTSP to a far more achievable rate of about 4 Mbps, as well.

Final Thoughts

If you're asked to choose between RTMP and RTSP for your live streaming protocol, our advice is simple: trade in your keys for a newer ride. That ride is BoxCast Flow, our modern streaming protocol engineered to surpass these older standards in nearly every aspect of performance.

Live video streaming is only worth doing if you can do it well. The problem is that older protocols simply weren't designed to handle the size, resolution, and reliability demands of modern video. Your stream needs to be smarter. It should require less upload speed, compress large data files more efficiently, and include features like Forward Error Correction, Link Quality Adjustment, and flexible latency control (which we call Flow Control). Plus, it needs a smarter strategy for handling data retransmission when packets inevitably go missing.

If you'd like to learn more about BoxCast Flow and how it can elevate your live streaming experience, we're ready to show you the difference. Start a free trial of BoxCast today.