Transmission bandwidth was a crucial, though often misunderstood, concept for broadcasters. If broadcasters don’t have enough bandwidth, their live stream could suffer from buffering and interruptions, or in the worst case, not even reach viewers.
In this post, we’ll look at what streaming bandwidth is and how much bandwidth a typical live streaming event consumes. We’ll also cover ways to reduce the required upload speed and ways to stream reliably even with limited internet speed.
Bandwidth
is
the amount of data an internet connection can transfer in a given period of time, which is usually measured in megabits per second (Mbps). It is important to note that bandwidth is not the speed of a connection, but the volume of data that the connection can transfer. The bandwidth of a connection is usually set by Internet Service Providers (ISPs). While download bandwidth is generally higher, upload bandwidth is more important for live streaming.
Two terms closely related to bandwidth are latency and throughput. Latency is the delay in transferring video data from its source to end users. Performance is the amount of data or packets that are actually delivered. Latency and packet loss adversely affect performance, which can also hinder the viewing experience.
Does streaming use
a lot of bandwidth?
Streaming video requires much more bandwidth than most other media formats, but there are a number of factors that affect how much is necessary. These factors include the video’s codec, resolution, frame rate, and bitrate.
Since the file sizes of RAW video content are so large, an uncompressed video would require too much upload bandwidth. That’s why broadcasters use a video compressor or encoder to reduce file size without severely affecting quality. However, when encoding videos, there are a number of codecs or compression algorithms with varying degrees of compatibility and efficiency to choose from.
The resolution of a video is the size of each frame in terms of pixels. For example, standard definition is 640×360 pixels, while full high definition or 1080p is 1920×1080 pixels. Frame rate is also closely related to resolution, referring to the number of frames per second (FPS) for a particular video.
The bitrate of a video is the amount of data stored during a single second of video content, which is measured in kilobits per second (kbps). A lower bitrate usually corresponds with lower video quality and also means that less bandwidth is required to load the video content. While broadcasters can choose the bitrate during encoding, higher resolutions and frame rates will require a higher bitrate.
Calculating Bitrate & Bandwidth Encoding
With video
on demand, you can calculate the bitrate by simply dividing the file size by the length of the video in seconds. However, for live video streaming, you can calculate the bitrate you will need using the following formula: bitrate
= resolution x
frame rate x bits per pixel / 1000
As mentioned above, resolution is the number of horizontal pixels multiplied by the number of vertical pixels. Bits per pixel (BPP) is the average amount of data stored for a single pixel, ranging from .05 to .150, depending on how much movement there is within the video content. Use our handy streaming bandwidth calculator later in the article to get help with this.
Once
you have the bitrate, calculating the minimum bandwidth required for a particular bitrate is straightforward. Live streaming requires an upload speed that exceeds the bitrate, but broadcasters must also include additional bandwidth (we recommend up to 2.5 times your bitrate) to overcome network fluctuations and account for other traffic. When calculating bandwidth, it is also important to remember to include the audio bitrate, and the video bitrate, of the live stream.
For reference, here are a couple of encoding bitrate recommendations for 720p live streaming on social media platforms:
Facebook Live suggests a maximum bitrate of 4,000 kbps YouTube Live suggests a bitrate between 1,500 kbps and 4,000 kbps
- Twitch suggests a bitrate between 3,000 kbps and 6,000
- kbps
Resi Take a slightly different approach. We know that the highest quality streaming is important to you, while balancing the reliability of your stream. That’s why thanks to Resi’s Resilient Transmission Protocol, high-bitrate transmission is possible even on troubled Internet connections. More on that later.
How
to reduce streaming bandwidth
There are two common ways to reduce bandwidth usage: high-efficiency compression and cloud transcoding. Let’s take a closer look at each of these.
As mentioned above, compression is crucial to achieve a higher quality video stream with the lowest possible bitrate. New codecs like H.265/HEVC and AV1 can often achieve much higher quality with a lower bitrate than legacy codecs like H.264. However, in addition to codecs, broadcasters should consider using variable bit rate (VBR) encoding instead of constant bit rate (CBR) encoding. VBR adjusts the bitrate during encoding based on the video content to achieve higher perceived quality with the same average bitrate.
Most broadcasters want to offer their live streams at various bitrates to maximize compatibility for viewers. The problem is that loading multiple video streams that were encoded locally requires additional bandwidth. That’s why many broadcasters choose to ingest a single video stream on an online video platform and use cloud transcoding to create different bitrate representations. This completely eliminates the need for additional load bandwidth for multiple or adaptive bit rate transmission.
Resi Resilient Transmission Protocol Along with reducing the bitrate of video streaming, the protocol used to stream the video to an online video platform like
Resi’s live streaming platform is crucial. Resi’s Reliable Streaming Protocol (RSP) can ensure that a perfect copy of your live stream arrives on your online video platform for delivery using advanced data verification and caching techniques.
Other protocols (such as RTMP) send video data as a single stream, such as a laser beam. This means that any data that doesn’t reach the cloud perfectly due to fluctuating upload and download speeds will result in buffering or glitching, common to live video, Zoom calls, etc.
The Resi RSP saves the data locally in the encoders and sends a short delay (90 seconds by default). This dramatically increases the integrity of your stream and allows you to stream in much higher quality than typical with confidence.
In fact, you can disconnect your encoder from a network completely for about 1 minute with 2.5x bandwidth, and in 15 seconds the cache will be filled. Also, if your connection is turned off for longer than the cache, the encoder will continue to save data locally and relay what was lost when the connection is restored. This means that Resi can help you transmit confidently even on problematic connections, and even transmit in a much higher quality with integrity, no matter what internet you have.
Resi’s RSP also includes one-to-all simultaneous streaming, meaning streaming content to multiple simultaneous destinations, including Facebook, YouTube, and more, is possible and happens directly from the Resi cloud. Only one upload stream to Resi’s cloud is required, which will relay that data to all its destinations with no additional bandwidth required.
All these reasons are the reason why thousands of organizations use Resi for the highest reliability, quality and integrity of their transmissions. In the end, this leads to exponentially higher viewing times, display averages, and no more damping wheels.
Want to learn more about live streaming and bandwidth? Contact Resi to discuss how our technologies can deliver reliable video streams with any network condition.