Optimizing over time
Content delivery is the largest cost-optimization area for organizations streaming content to large audiences. You should always be evaluating the perceptual quality of content and striving to lower video data rates while maintaining, or ideally improving quality through encoder optimization.
| SM_COST3: How do you minimize distribution costs while maintaining visual quality? |
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| SM_CBP5 – Use objective and subjective measurement techniques to benchmark and improve video compression efficiency |
To optimize quality while balancing delivery costs, you should focus on media processing and compression. The codec you use will be dependent on your content complexity, encoder capabilities, and client interoperability. Most codecs provide many controls that can be tuned. Use a combination of objective and subjective measurement to understand and improve your compression efficiency over time.
Though not always an accurate representation of human visual perception, objective measurement tools, like Peak Signal-to-Noise-Ratio (PSNR), Structural Similarity (SSIM), and Video Multi-Method Assessment Fusion (VMAF) are readily available tools to help analyze your compression performance. Given a source, varied encoding job settings, and resulting outputs, compare these metrics to tune for your unique content. In general, though there are many options to consider while tuning video compression settings, high motion content will require a higher data rate than low motion to retain the same perceptual quality.
Subjective measurement techniques will uncover practical issues with your video compression that might not be identified by objective scoring. For subjective testing with human eyes and real network conditions outside of a production environment, consider user feedback mechanisms that enable willing users to provide information on their viewing experience. For a simulated environment, Amazon Mechanical Turk can give you access to humans willing to watch your content and provide feedback. For a small fee, Turkers around the world can provide you with valuable insights on their playback experience, which can be used to improve your workload.
Use this combination of subjective, objective, and real-user-metrics to tune encoding settings and ABR protocol configuration. It is recommended that you familiarize yourself with the codec and encoder you use for delivery so that you can identify optimizations that could save you delivery costs. For example, context-aware or quality-based encoding, available as a QVBR setting for AWS Elemental MediaLive and AWS Elemental MediaConvert, can analyze the complexity of the content and optimize processing on your behalf.
