What Is VSF or Video Start Failure? Causes and Solutions Explained

Video Start Failures or VSF defines how many times or how often playback attempts are terminated during video startup before the first video frame is shown. Network issues, incompatible video formats, and technical problems with the players primarily cause Video Start Failures.

The rise of online video streaming has completely revolutionized the way we consume media. People now have access to a vast library of video content through popular OTT streaming platforms (like Netflix, Amazon Prime, and YouTube) that they can access virtually anywhere with an internet connection.

However, this convenience has downsides, as online video streaming is susceptible to many technical problems, including video start failures (VSF).

As defined earlier, Video Start Failures or VSF defines how many times or how often playback attempts are terminated during video startup before the first video frame is shown. It is an important issue to track, and in this article, we’ll explore the causes and solutions for VSF.

VSF or video start failures - causes and solutions for video streaming

Understanding Video Start Failures (VSF)

Video Start Failures or VSF defines how many times or how often playback attempts are terminated during video startup before the first video frame is shown.

In simpler language, if the video does not load after the user has pressed the play button or after playback has been initiated during autoplay, this sort of an unsuccessful playback attempt is called a “Video Start Failure” or VSF.

There are many reasons why VSF may occur.

One of the most common reasons is slow internet speed. When the internet connection is slow, it takes longer for the video to load, and could lead to timeout situations.

Another reason why VSF may occur is due to compatibility issues. Some video formats may not be compatible with specific devices or browsers, leading to playback issues.

We’ll look at common causes of VSF in future sections of this article.

Importance of Addressing VSF

VSF can significantly impact user experience, leading to frustration and sometimes complete disengagement with the video. In some cases, it can even lead to a loss of revenue for businesses that rely on video as part of their marketing strategies.

Therefore, it is crucial to address VSF promptly and efficiently to ensure users have a positive experience with the video content. This can be achieved by optimizing the video for different devices and browsers, ensuring that the internet connection is stable and fast, and using video hosting platforms that are reliable and efficient.

The following are the most common signs and symptoms of VSF:

  • The video takes a long time to start loading.
  • The video fails to play altogether.

It is important to note that VSF can occur on any device, including smartphones, tablets, and desktop computers. Therefore, optimizing the video for different devices is essential to avoid VSF.

In conclusion, VSF is a common issue that can affect the user experience and lead to a loss of revenue for businesses. By addressing VSF promptly and efficiently, it is possible to ensure that users have a positive experience with the video content and that businesses can achieve their marketing goals.

VSF or video start failures - causes and solutions for video streaming

Causes and Solutions for Video Start Failures (VSF)

Poor Internet Connection

Poor internet connection is a common cause of Video Start Failures (VSF). Unstable connectivity can cause interruptions in the video stream, stopping the video altogether. Various factors, including network congestion, signal interference, and distance from the router, can cause this. To avoid this, ensure that you are within range of your router and that there are no obstacles between your device and the router that can interfere with the signal.

Incompatible Video Formats

Another common cause of VSF is having an incompatible video format. Different video players support various video formats, and ensuring your video is compatible with your player is essential. Failure to do so can result in VSF.

To avoid VSF caused by incompatible video formats, ensure that you use a video player that supports the format of your video. As a service provider, it is good to check what devices your end-users use and ensure that your video transcoders and packagers produce the right formats, containers, and codecs.

Related:  Beginner's Guide to Video QoE and QoS

Outdated Video Players and Plugins

Using outdated video players and plugins can also cause VSF. As technology advances, video players and plugins must be updated to support new formats, codecs, and security features. Failure to update these players and plugins can lead to compatibility issues, resulting in VSF.

To avoid VSF caused by outdated video players and plugins, ensure you regularly update your video player and plugins. As a content provider, if you’re providing an end-to-end experience to your users and are building your apps, ensure that the underlying video players (ExoPlayer, AVPlayer, or video.js) are all up-to-date.

Also, ensure that your engineering teams regularly update the players and send app updates to your viewers. This will ensure that bug fixes and improvements from the player vendors are incorporated and reach your users.

Server-Side Issues

Issues on the video server side, such as an overloaded server or technical glitches, can also lead to VSF. These issues can create bottlenecks when streaming video content, leading to delays in loading and buffering problems.

To avoid VSF caused by server-side issues, ensure that you use a reliable video hosting service that can handle high traffic and has a good track record of uptime.

Ad-Blockers and Browser Extensions

Ad-blockers and browser extensions can sometimes interfere with the video player, causing VSF. These extensions may block essential scripts or plugins required for the video player to function correctly.

To avoid VSF caused by ad-blockers and browser extensions, try disabling them temporarily when watching videos. You can also whitelist the website or video player in your ad-blocker or browser extension settings to allow the required scripts and plugins to run.

Technical Problems with the Video’s Manifests or Playlists

Most OTT streaming platforms use either HLS or DASH for video streaming. These protocols use the ABR video streaming technique and depend on the availability of a manifest or a playlist file to initiate video playback. These files indicate where the video segments are located and in what order these video segments are to be played back. If there are problems with these manifest/playlist files, there are great chances of video streaming problems.

Before releasing any content to the public, it is a wise idea to check that there are no problems with the manifest or playlist files. Check that the files point to video segments that are physically present on the server and that there are no syntactical problems with the files.

Go here to learn more about the differences between HLS and MPEG-DASH, which are popular for video streaming.


In conclusion, VSF is a common issue faced by individuals and businesses when using video content for marketing or entertainment purposes. While several causes can lead to VSF, there are also numerous solutions to address the problem depending on the cause.

By understanding these causes and solutions, businesses and individuals can ensure that their video content is watched and enjoyed by users without any issues.

If you are interested in QoE Analytics, then these articles might appeal to you –

  1. What is QoE / QoS Analytics
  2. What is Video Buffering?
  3. What is Video Startup Time?
  4. What is the Exit-Before-Video-Start metric?
  5. Use of Analytics in Sports Streaming
krishna rao vijayanagar
Krishna Rao Vijayanagar

Krishna Rao Vijayanagar, Ph.D., is the Editor-in-Chief of OTTVerse, a news portal covering tech and business news in the OTT industry.

With extensive experience in video encoding, streaming, analytics, monetization, end-to-end streaming, and more, Krishna has held multiple leadership roles in R&D, Engineering, and Product at companies such as Harmonic Inc., MediaMelon, and Airtel Digital. Krishna has published numerous articles and research papers and speaks at industry events to share his insights and perspectives on the fundamentals and the future of OTT streaming.

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