Optimizing video performance for web using analytics

September 13, 2024
15 Min
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With the increasing demand for video content on the web, ensuring optimal video performance is critical for maintaining viewer satisfaction and engagement. Poor video performance can lead to buffering, slow load times, and a degraded user experience, which in turn can result in lost viewers. Leveraging video data analytics is one of the most effective ways to optimize video performance on the web. This article will explore key strategies for enhancing video performance using data analytics.

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Understanding the role of analytics in video performance

Data analytics involves the systematic computational analysis of data. When applied to video performance, it enables content providers to gather, process, and analyze data related to video delivery and viewer behaviour. This data-driven approach helps in identifying performance bottlenecks, optimizing delivery strategies, and ultimately enhancing the user experience.

Key Metrics for Video Performance Optimization:

1. Quality of Experience (QoE)

Quality of Experience (QoE) is a critical factor in optimizing video performance for the web. It represents the overall satisfaction a viewer has with a video service and is influenced by various technical and perceptual factors. By focusing on QoE, content providers can ensure that viewers have a seamless and enjoyable experience, leading to higher engagement and retention. This article will explore how QoE contributes to optimizing video performance and how to calculate it effectively.

Why QoE needs to be measured

Measuring Quality of Experience (QoE) is essential for several reasons, particularly in the context of digital services and video streaming. Here are some key points highlighting the importance of measuring QoE:

  • User-centric perspective: QoE focuses on the user's perception of service quality rather than just technical performance. By measuring QoE, organizations can understand how users feel about their interactions with a service, which is crucial for improving overall satisfaction.
  • Impact on customer retention: A positive QoE directly correlates with customer loyalty and retention. By measuring QoE, businesses can identify factors that contribute to user dissatisfaction and address them proactively, reducing churn rates.
  • Competitive advantage: In an increasingly crowded market, offering a superior QoE can differentiate a service from its competitors. Measuring QoE helps organizations identify strengths and weaknesses in their offerings, allowing them to enhance user satisfaction and attract new customers.
  • Performance optimization: Measuring QoE provides insights into the end-to-end performance of services. By understanding how various factors (e.g., buffering, video quality, and interface usability) affect user experience, organizations can optimize their systems and processes for better performance.
  • Feedback for continuous improvement: Regularly measuring QoE allows businesses to gather user feedback and make informed decisions about product development and service enhancements. This iterative process helps ensure that services evolve to meet changing user expectations.

Metrics that impacts QoE

  1. Video startup time: A longer startup time directly impacts QoE, as viewers are likely to become impatient and may abandon the video if it takes too long to load
  2. Bitrate: Bitrate affects the visual quality of the video. While higher bitrates generally provide better quality, they also require more bandwidth, which could lead to buffering if the network can't support it.
  3. Rebuffering events: Frequent rebuffering events are detrimental to QoE, causing interruptions that disrupt the viewing experience. High buffering ratios are one of the most significant contributors to a poor QoE. Frequent or prolonged buffering disrupts the viewing experience and frustrates users
  4. Video resolution: Higher resolutions provide better image quality, but they also require more data, which can lead to increased buffering or slower startup times if the network can’t handle the higher data rate.
  5. Playback error rate: High error rates significantly lower QoE, as they prevent the video from being viewed as intended.
  6. Viewer engagement: Metrics that reflect how viewers interact with the video content, including playthrough rates, drop-off points, and the time spent watching. Higher engagement typically indicates a better QoE. If viewers watch more of the video, it suggests they are satisfied with the experience.

Calculate QoE score

To calculate the Quality of Experience (QoE) Score for video streaming, each video view is assigned a score between 0 and 100 based on key metrics: Playback success, smoothness, startup time, and quality.

The overall viewer experience score is calculated by averaging these individual scores, but with weighted importance:

  • Playback success is the most critical factor and acts as a multiplier, ensuring that videos that fail to play have a significant negative impact.
  • Smoothness, startup time, and quality are then adjusted for trade-offs, recognizing that improving one aspect might slightly compromise another.

The formula combines these weighted scores, providing a holistic view of the viewer's experience. This approach helps prioritize the most impactful areas for optimization, ultimately enhancing the overall video performance.

Netflix and QoE: A benchmark in streaming optimization

As the leading streaming platform, Netflix faces the challenge of delivering high-quality video content to millions of users across diverse devices and network conditions. Maintaining a superior Quality of Experience (QoE) is crucial for Netflix to keep its users engaged and satisfied, especially in the face of growing competition in the streaming industry.

QoE-driven optimization strategies

  1. Adaptive Bitrate Streaming (ABR)
    • Netflix pioneered the use of adaptive bitrate streaming to optimize QoE.
    • ABR technology dynamically adjusts the video quality based on the user's network conditions and device capabilities.
    • If a user's internet speed drops, Netflix automatically reduces the bitrate to prevent buffering, ensuring smooth playback.
    • This approach balances video quality with playback smoothness, directly enhancing QoE and providing a seamless viewing experience.
  1. Optimized video encoding
    • Netflix invested heavily in optimizing its video encoding techniques, leveraging advanced codecs like AV1 and VP9.
    • By using more efficient codecs, Netflix can deliver high-quality video at lower bitrates, reducing data consumption while maintaining excellent video quality.
    • This optimization benefits users on slower connections by providing a better viewing experience and those with data caps by reducing overall data usage.
    • Netflix's encoding optimizations have led to significant improvements in video quality, with a 3x reduction in bitrate for the same perceived quality compared to their previous encoding methods.
  1. Proactive buffer management
    • To reduce rebuffering events, Netflix implemented a sophisticated buffer management system.
    • By analyzing viewing patterns, device capabilities, and network conditions, Netflix pre-loads enough content to keep playback smooth, even during temporary drops in connection quality.
    • This proactive approach to buffering has significantly improved QoE, reducing interruptions and enhancing user satisfaction.
    • Netflix's buffer management algorithms continuously adapt to user behavior, ensuring that the buffer size is optimized for everyone's viewing experience.
  1. Content Delivery Network (CDN) optimization
    • Netflix's Open Connect program is a key component in delivering high-quality video to its users.
    • By partnering with ISPs and deploying its own CDN servers, Netflix can ensure that content is delivered from the closest possible location, reducing latency and improving QoE.
    • Open Connect servers are optimized for video delivery, with fine-tuned operating systems, network configurations, and even custom hardware to maximize performance.
  1. Continuous experimentation and improvement
    • Netflix relies heavily on A/B testing and data analysis to continuously optimize its QoE.
    • The company uses a proprietary metric called VMAF (Video Multimethod Assessment Fusion) to measure and compare the perceived quality of different video streams.
    • By conducting experiments with different encoding settings, buffer configurations, and delivery optimizations, Netflix can identify the most effective strategies for improving QoE.
    • This data-driven approach allows Netflix to make informed decisions and rapidly iterate on its QoE optimization efforts.

Outcome and impact

Netflix's relentless focus on optimizing QoE has paid off in several ways:

  • Higher user satisfaction and increased user engagement, leading to lower churn rates and stronger brand loyalty.
  • Competitive advantage in the streaming industry, setting a benchmark for other platforms to follow.
  • Ability to deliver high-quality video at lower bitrates, reducing bandwidth costs and environmental impact.
  • Improved accessibility for users with limited internet connectivity or data caps, expanding Netflix's reach and appeal.

By continuously innovating and optimizing its QoE strategies, Netflix has established itself as a leader in the streaming industry, influencing how other platforms approach video performance and user experience. The company's success serves as a testament to the importance of prioritizing QoE in the highly competitive and rapidly evolving world of streaming entertainment.

2. Playback failure

Playback failure is a crucial metric that indicates the proportion of video playback attempts that result in failure. A playback failure can occur due to various reasons, such as network issues, unsupported formats, or player errors.

Importance of monitoring playback failures

  • Playback failures can indicate underlying technical problems, such as server issues, network instability, or content delivery failures.
  • Frequent playback failures can lead to significant frustration for viewers, resulting in increased abandonment rates and lower engagement.
  • High playback failure rates negatively impact QoE, which encompasses user satisfaction and engagement.
  • Tracking playback failures provides valuable data that can inform decision-making processes.

Calculating playback failure percentage

Playback failure percentage = (Number of playback failures / Total playback attempts) * 100

3. Exit before video start

Exit Before Video Start (EBVS) is a critical metric in video analytics that measures the percentage of viewers who leave before the video begins to play, indicating potential issues with the initial user experience. Understanding and monitoring this metric can significantly enhance video performance on the web. Read more about EBVS in detail.

Why EBVS matters?

  • User experience indicator: A high EBVS percentage suggests that viewers are not having a satisfactory experience when they attempt to watch a video. This could be due to slow loading times, poor video quality, or confusing user interfaces. Identifying and addressing these issues can lead to improved viewer satisfaction.
  • Content delivery optimization: EBVS can highlight problems in the content delivery infrastructure. If users frequently exit before the video starts, it may indicate that the video is not loading quickly enough or that there are issues with the server or CDN performance. This insight allows for targeted improvements in content delivery systems.
  • Engagement impact: High EBVS rates can lead to lower engagement metrics overall. If viewers are exiting before they even see the content, they are unlikely to engage with it later. Reducing EBVS can help retain viewers and increase the likelihood of them watching additional content.
  • SEO and discoverability: A high EBVS can negatively affect a video's ranking on search engines and video platforms. If viewers consistently exit before watching, it signals to algorithms that the content may not be engaging, which can impact its visibility and reach.

How to use EBVS for optimization

  • Analyse playback intent: Understanding when viewers drop off is crucial. By capturing playback intent (the moment a viewer clicks to play), you can differentiate between exits caused by slow loading times and those due to other issues. This analysis can help pinpoint specific problems in the playback process.
  • Monitor CDN performance: Regularly check the performance of your Content Delivery Network (CDN). If users are experiencing delays, consider implementing multi-CDN strategies or optimizing your existing CDN setup to ensure faster delivery of video content.
  • Reduce pre-roll ad impact: If you use pre-roll ads, ensure that they do not significantly delay the start of the main video. Long ad load times can frustrate viewers and lead to higher EBVS rates. Consider using shorter ads or optimizing ad delivery.
  • Improve video startup time: One of the most common reasons for high EBVS is slow video startup. Optimizing video startup time involves ensuring that the video player initializes quickly and that the video starts loading immediately upon user interaction.

Calculate Exit Before Video Start (EBVS)

To calculate "Exit Before Video Start" in web using HTML5 playback events, follow these steps:

Track events:

  • Play event: Triggered when the user initiates playback (clicks the play button).
  • Playing event: Triggered when the first frame of the video appears, and playback begins.

Count exits:

  • Exit Before Video Start: Count how many times users exit or quit the video after the play event but before the playing event is emitted. This reflects the number of times users abandon the video during the loading phase, before it starts playing.

Calculate EBVS:

  • EBVS = Number of exits before playing event / Total number of playback initiations

4. Buffer ratio

Buffer Ratio measures the proportion of time spent buffering compared to total playback time. A high buffer ratio indicates that viewers are experiencing significant interruptions during playback, which can lead to frustration and disengagement.

How buffer ratio helps in optimizing videos

  • Identifying performance issues: A high buffer ratio signals potential issues with video delivery, such as inadequate bandwidth or server performance. By monitoring this metric, content providers can identify specific videos or playback scenarios that require optimization.
  • Improving user experience: Reducing the buffer ratio is essential for providing a smooth viewing experience. By optimizing video encoding, using adaptive bitrate streaming, and ensuring efficient content delivery networks (CDNs), providers can minimize buffering and enhance viewer satisfaction.
  • Guiding content delivery strategies: Understanding buffer ratios can inform decisions about content delivery strategies. For instance, if certain geographic regions consistently show high buffer ratios, it may be beneficial to deploy additional CDN nodes in those areas to improve performance.
  • Enhancing video quality: A lower buffer ratio often allows for higher video quality settings, as viewers can stream higher bitrates without interruptions. This can lead to better viewer retention and engagement.

Steps to calculate buffer ratio

Measure buffering time:

Track the total duration during which the video is buffering. This includes all periods when the video is not playing due to buffering.  

Measure total playback time:

Record the total duration for which the video is actively being played. This is the entire time the video is being streamed, including both playback and buffering.

Calculate buffer ratio:

  • Buffer ratio = Buffering time / Total playback time

5. Buffer frequency

Buffer Frequency refers to how often buffering occurs during playback. Frequent buffering can be a major source of viewer frustration, leading to increased exit rates and decreased engagement.

How buffer frequency helps in optimizing videos

  • Understanding viewer frustration points: By tracking buffer frequency, content providers can pinpoint specific moments in videos where buffering occurs. This insight can help identify problematic segments that may need editing or re-encoding for better performance.
  • Optimizing encoding and bitrate: High buffer frequency may indicate that the current encoding settings or bitrate are not suitable for the viewer's network conditions. Implementing adaptive bitrate streaming allows the video quality to adjust dynamically based on the viewer's internet speed, reducing the likelihood of buffering. \
  • Improving network conditions: Frequent buffering can often be traced back to network issues. By analysing buffer frequency in conjunction with viewer location data, providers can make informed decisions about improving network infrastructure or optimizing CDN configurations.
  • Enhancing overall Quality of Experience (QoE): Reducing buffer frequency directly contributes to a better Quality of Experience (QoE). Viewers are more likely to stay engaged with content that plays smoothly without interruptions, leading to higher retention rates and increased likelihood of sharing and recommending the video.

Calculate buffer frequency

  • Buffer frequency = Buffer count / Total watch time
  • Buffer count: Total number of buffering events that occur during the video playback.
  • Total watch time: total time the video is actively being watched which also includes the time video is buffering and seeking.

6. Seek latency

Seek Latency refers to the time it takes for a video to start playing after a viewer seeks to a different point in the video. This metric is crucial in determining the overall viewing experience, as long seek latencies can disrupt the flow of content and lead to viewer frustration.

Why seek latency matters

  • User experience: A long seek latency can significantly degrade the user experience. If viewers frequently encounter delays when trying to jump to different sections of a video, they may become frustrated and abandon the content altogether. This can lead to higher exit rates and lower engagement levels.
  • Engagement and retention: High seek latencies can negatively impact viewer engagement. If users are unable to quickly access the content they want, they are less likely to stay engaged with the video. Reducing seek latency can help retain viewers and encourage them to watch more of your content.
  • Content interactivity: In interactive video scenarios, such as live events or educational content, low seek latency is essential. Viewers may want to jump to specific topics or moments, and any delay can hinder their ability to interact with the content effectively.

Calculating seek latency

In calculating seek latency, HTML5 video playback events are used to track the time it takes for a video to respond when a user transitions from one position in the video to another. Specifically:

  • Seeking event: Triggered when the user initiates a seek, indicating they are jumping to a different point in the video.
  • Seeked event: Triggered when the video has successfully moved to the new position and playback resumes.

To calculate seek latency, the time difference between these two events is measured. By capturing multiple instances of seek events, the total seek duration is accumulated. The average seek latency is then determined by dividing the total seek duration by the total number of seek events:

Seek latency = Total seek duration / Total seek count

7. Average bitrate

Average Bitrate refers to the average amount of data processed per second during video playback, typically measured in kilobits per second (Kbps) or megabits per second (Mbps). This metric is crucial because it directly influences video quality, streaming performance, and viewer experience. Optimizing average bitrate is essential for delivering high-quality video content while ensuring smooth playback across various devices and network conditions.

Why average bitrate matters

  • Video quality: The average bitrate significantly impacts the clarity and detail of the video. Higher bitrates generally provide better quality, as more data is allocated to represent each frame. Conversely, lower bitrates can lead to pixelation and loss of detail, particularly in fast-moving scenes or high-resolution content.
  • Buffering and playback reliability: A well-chosen bitrate can help minimize buffering issues. If the bitrate is too high for the viewer's internet connection, it may lead to frequent buffering, resulting in a frustrating viewing experience. Conversely, if the bitrate is too low, it can compromise video quality. Finding the right balance is crucial for maintaining smooth playback.
  • Adaptability to network conditions: Average bitrate can be adjusted dynamically based on real-time network conditions. This adaptability ensures that viewers receive the best possible quality without interruptions, regardless of their internet speed.

Calculating average bitrate

To calculate the average bitrate for a video, follow these steps:

  1. Measure the total data transferred: This is the amount of data processed during the entire video playback. It can be measured in kilobits (Kb) or megabits (Mb).
  2. Measure the total playback time: This is the duration of the video playback, typically measured in seconds.
         

Average bitrate = Total data transferred / Total playback time

8. Startup time

Startup Time is the duration between when a viewer clicks "play" and when the video begins to play. It’s a critical metric for optimizing video performance on the web because it directly affects the user experience.

Why startup time matters

  • First impressions: A short startup time creates a positive first impression, making viewers more likely to stay engaged with the content. Long delays, on the other hand, can frustrate users and lead to higher abandonment rates.
  • Impact on SEO and discoverability: Search engines and video platforms often consider user engagement metrics, including startup time, when ranking content. A faster startup time can lead to better visibility and higher rankings in search results, driving more traffic to your videos.
  • Performance insights: By monitoring startup time, content providers can identify and address performance bottlenecks, such as server response delays or inefficient video encoding processes.

Calculating startup time

To calculate Startup Time for a video, HTML5 events are used to measure the time difference between two specific events:

  • Play event: This event is triggered when the user initiates video playback by clicking the play button or through automatic playback.
  • Playing Event: This event occurs when the first frame of the video is displayed, indicating that the video has started playing.

Startup time = Time of playing event − Time of play event

This duration reflects how long it takes from the moment the user starts the video to when it begins to play, encompassing initial loading time and any buffering that might occur before playback starts.

Final thoughts

Understanding and measuring these metrics allows content providers to gain valuable insights into user behaviour and pinpoint areas that need improvement. By focusing on these key performance indicators, you can ensure a smoother, more enjoyable viewing experience, which ultimately leads to higher user satisfaction, increased engagement, and better retention rates.  

Whether it's minimizing startup time, reducing buffering, or ensuring high-quality playback, each metric offers actionable data that can be used to fine-tune video delivery strategies. By continuously monitoring and optimizing these metrics, you not only enhance the overall Quality of Experience but also set the foundation for long-term success in delivering superior video content on the web.

For content providers and streaming platforms looking to track video performance metrics and optimize their video delivery, FastPix offers a comprehensive video data solution. By integrating the FastPix web SDK into your video player, you can start capturing detailed metrics on QoE, playback failures, buffering, and more. These insights are surfaced in the FastPix dashboard, allowing you to identify areas for improvement and make data-driven decisions to enhance your video performance.

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