20 Mbps is good for 720p video streaming

Internet line and quality of live streaming

The resolution is the number of pixels in width and height that make up a video image. In order for a "moving image", i.e. a film / video, to be created from this, the individual image shown must be replaced with a new one, e.g. 25 times per second. The human eye perceives this as movement.

The higher the resolution, the finer, more detailed and sharper the video stream can appear. However, the higher the data consumption of the current stream. The internet connection at your location (to send the video to the streaming server = "upload") as well as for access to the viewer must be able to transfer a corresponding amount of data.

The camera used must also enable the desired resolution in high image quality and the viewer's display must also be able to show this resolution. FullHD (1920x1080 pixels, called "1080p") or HD (1280x720 pixels, called "720p") are the usual standard today.

Depending on the camera you are using 25 or 30 frames per second ("fps" = frames per second). 50 or 60 fps are also possible, but lead to occasional stuttering in approx. 10-20 percent of viewer devices due to the performance of the hardware.

We will give you many helpful tips when setting up your customer account and will also be happy to advise you in order to enable the optimal resolution, data rate and quality for your live transmission (s).

You can also find a lot more information here.

Required and actually available speeds

In order for your live video to be shown to viewers in good quality, the video stream must pass through the Eye of a needle Your own internet connection to the streaming server. The UPLOAD speed of your connection is relevant for this (not the download speed).

Unit of measurement Kbit / s and Mbit / s:

  • Depending on the encoder, the data rate is specified in "Kbit / s" or "kbps" (both kilobits per second), or "Mbit / s" (megabits per second).
  • Typical data rates today are between 1000 and 6000 Kbit / s and thus between 1 and 6 Mbit / s.
  • Would you like to calculate the data consumption: 1 Mbit / s corresponds to approx. 7.5 MB per minute or 0.5 GB per hour.
    6 Mbit / s therefore corresponds to 6 x 7.5 = 45 MB per minute or 6 x 0.5 GB = approx. 3 GB per hour.

A "DSL-16000" connection, for example, has a download rate of 16,000 kbit / s and an upload speed for sending of 2400 kbit / s. At least on paper - less is often achieved in real terms.
A "VDSL 50,000 or 100,000" connection usually has an upload capacity of at least 10 Mbit / s.

Before a live stream transmission, you should definitely test the real upload. See next point below.
A maximum of 80% of the determined upload data rate should be used, as your live encoder will not reach the desired value exactly, but will fluctuate slightly to strongly depending on the image content.

Unfortunately, there are also fluctuations over hours or days on the existing line. An extreme example is LTE. A connection test can show maximum speeds here, but 2 hours later only a fraction of this is available because other users are using the Internet via the same transmitter mast.

You can test your upload speed e.g. via these pages:

https://www.speedtest.net

https://www.speedcheck.org/de

https://www.wieistmeineip.de/speedtest


Practical example: the download is fairly constant, but the upload fluctuates between 6 and 16 Mbit during the measurement.Relevant for live streaming is not the overall average of 9 Mbit / s as a result, but the lowest value of around 6 Mbit / s for the fluctuations.

Another limitation: unfortunately the results of a speed test are sometimes just wrong. If we measure the speed from one of our offices via Unity Media with a real 150 Mbit / s Down and 12 Mbit / s Up, some tests sometimes show an upload of 580 Mbit / s Upload. We can only recommend carrying out several tests with different speed test providers for a new or unknown line.


Technical subtleties:

  • Unfortunately, the packet loss is more difficult to measure: lost data packets. It is "normal" not only in your own network, but also in particular on the Internet, that a data packet does not arrive, is requested again and then has to be sent again. This is not even noticeable when downloading a website via HTTP / HTTPS.

    In the case of shaky LTE connections or not optimally laid SDSL leased lines (or broken cables, plugs that are not properly connected, etc.), this can become a major problem for live streaming. Then you have a miserable line for live streaming despite good speed measurements. (We can partially compensate for this by increasing the input buffer for the live stream data on the streaming server in order to re-request faulty data packets. This helps significantly.)
  • The "IP overhead" is also relevant. In addition to the pure stream data that is encoded and sent in the live encoder, the protocol also consumes data at the same time. In other words, instructions as to which data packets are coming now, the sequence, checksums, feedback that a packet has not arrived correctly and must be retransmitted, etc. In the next protocol layer, the same comes again for the underlying TCP / IP layer: data for packet descriptions, Checksums, feedback about packets to be retransmitted, etc. This is completely normal on the Internet and also applies to HTTP / HTTPS connections.
    Streaming IP overhead: For IP overhead, about 15-20% of the total data rate is subtracted for a stable stream data rate. If the connection can upload an overall average of 9 Mbit / s but temporarily only 6 Mbit / s, then 6 Mbit / s minus 20% = 4.8 Mbit / s is available as the data rate for the video stream (including audio). These 4800 kbit / s are entered as the maximum value in the live encoder.

Also worth knowing:

  • A connection via WLAN should be avoided for streaming if there are many people (and therefore cell phones) in the vicinity during the transmission.
  • Are other devices connected to the same internet connection? It would be unfavorable for your upload data rate if someone in the same network was using the Internet at the same time or if a Windows or virus killer update were being downloaded unnoticed in the background or if the mail server were to transfer large mail attachments.
  • Some lines fluctuate considerably. Then, during a live broadcast, you suddenly have twice or only half the previously measured speed. If this is to be expected, the bit rate of the stream should be set with a high safety buffer as a precaution.
  • The quality of a mobile connection (e.g. 3 to 5 out of 5 bars on the mobile phone screen) describes the connection between the device and the cell tower. It is important that this does not say anything about how fast this mast is connected to the Internet. Example: You are at an exhibition center, in a congress hall or near a stadium. The connection from your cell phone or LTE router to the mast is perfect. I.e. on the mobile phone you will see 5 out of 5 bars for perfect reception. However, since hundreds of people in your area also use this mast, it may be overloaded and, despite a good connection, can transfer very little or no data at all.

Live stream data rates, resolution and video quality

How much data your stream needs depends on two factors: the set resolution and the Image content of your transfer.

  • resolution
    A 1080p "FullHD" resolution uses 1920x1080 pixels. So about 2 million pixels.
    A 720p stream (1280x720px) only has about 1 million pixels.
    A 360p stream (640x360px) has only 0.26 million pixels.
    In order to clearly display these pixels with good image quality and sharpness even when moving, the higher the resolution, the higher the data rate required.
  • Image content
    Less moving content, such as a speaker in front of a calm background, requires significantly less data rate for good image quality than a strongly moving content (football broadcast, a stage show, broadcasts from a moving car, ...).
    Fine details in the image that may even move (water with waves, a tree with moving leaves, ...) are also extremely data-intensive.

Depending on the resolution and image content, a stream for the same visual quality one different Data rate.

Typical values ​​for the data rate:

  • The audio track should be transmitted as "AAC" or "mp3" with 96 to 192 kbit / s. We recommend 128 kbit / s.
  • 360p (640x360px), quiet content: 500 kbit / s, complex content 1000 kbit / s
  • 480p (854x480px), quiet content: 900 kbit / s, complex content 1600 kbit / s
  • 720p (1280x720px), calm content: 1500 kbit / s, complex content 4000 kbit / s
  • 1080p to 4K (from 1920x1080px), quiet content: 2500 kbit / s, complex content 6000 to 8000 kbit / s
  • 8000 kbit / s corresponds to the maximum data rate on our streaming server packages. After the contract has been amended, higher data rates are permitted.


General tip: we generally advise against using data rates higher than 6000 kbit / s and a maximum of 8000 kbit / s for live content. Please bear in mind that the data must reach the viewers very quickly and without long intermediate storage. In the case of mobile access, the monthly data volume may be used up in a few minutes.

To consider for a 4K resolution:

  • Less than 5% of all internet users have a screen that can display 4K. According to the cross-market statistics from Mozilla, it is only under 2%.
  • The computer and the internet line must also be correspondingly fast in order to be able to display this smoothly and without 4K loading times.

DSL connections and the typical data rates

Typically invites DSL-Connection data much faster than he can send them (download faster than upload). In addition, a DSL connection is often not exactly as fast as the contract name suggests.

Typical speeds

DSL-6000
6 Mbit / s download, 500 kbit / s upload

DSL-16000
16 Mbit / s download, 1000 kbit / s upload (new connections: 2400 kbit / s upload)

VDSL-25000
25 Mbit / s download, 2500 kbit / s upload (new connections: 10,000 kbit / s upload)

VDSL-50000
50 Mbit / s download, 10 Mbit / s upload (new connections: 20,000 kbit / s upload)

VDSL-100000
100 MBit / s download, 40 MBit / s upload

Mobile transmission: 3G, LTE, 5G

The data rates per 3G (UMTS),LTE or even 5G are very good today! With good reception at the transmission location, 3G already provides a very good upload rate of over 1000 kbit / s. LTE and 5G again clear more.
In our experience, we recommend Deutsche Telekom and Vodafone as providers.

However, you should note that the connection capacity a) depends on the respective location and b) may be reduced if many users with their smartphones in the immediate vicinity also use the radio cell. For example in a stadium or on a trade fair site. Because in this case not only the transmission speed from the mobile device to the radio mast is decisive, but in locations with a large number of users, the connection of the radio mast is also decisive - at what speed it is connected to the Internet.

You can test the upload speed with apps on your mobile phone. An app would be e.g. "Speedtest" (for iOS, for Android). If you are using a UMTS / LTE router with access via a PC, you can use this website for testing: http://www.speedtest.net/

However, very high data rates on mobile devices consume the typical, monthly 1-5 GB inclusive data rate of most mobile contracts within a few minutes.

Satellite connections have also become affordable. Some providers offer, for example, an upload of over 5,000 kbit / s from almost every point in Europe as a flat rate for around 90 euros per month. All you need is an aligned satellite dish with a satellite modem (300 euros).

Please note:
a) With some providers, a guaranteed line speed can be booked for a fee. With others, all currently active users share the total available capacity (via the satellite).
b) In heavy rain or snowfall, the connection will be impaired or break off completely.
c) If you want to carry the satellite dish with you on the move and set it up at the place of transmission, the view from this location must be clear in a defined direction. Neither buildings nor trees are allowed to stand here.

If a higher budget is available, a rented satellite car is an option. Booked capacities, significantly higher data rates and higher transmission power are used here, thus balancing points a) and b).