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What do I do if my CDN reports bitrate errors?

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Some CDNs, including YouTube, AWS MediaConnect, and Techex MWEdge, monitor and report bitrate and Program Clock Reference (PCR) consistency metrics. When using these CDNs, you may encounter errors related to bitrate stability or PCR discrepancies. This guide provides steps to resolve these issues by configuring specific encoding settings on your Videon device.

Related FAQs:

Q1: Why is my CDN reporting bitrate or PCR errors?

CDNs can report errors when there is a mismatch between the expected constant bitrate (CBR) and the actual bitrate being delivered. These errors may be due to minor bitrate fluctuations, which can happen when using standard encoding modes that allow some variability in bitrate. PCR-related errors can also occur when timing inconsistencies are detected in the stream, which are common when streaming over networks with high demands on bitrate precision.

Q2: How can I address CBR or PCR errors on my Videon device?

To mitigate these errors, we recommend configuring your Videon device to use strict constant bitrate modes, which help to maintain consistent bitrate and PCR alignment. Here’s how to adjust these settings:

  1. Set "Strict Constant Bitrate" mode on the device’s video profile/encoder. (Web UI/Cloud UI → Select desired device from “Devices” (Skip this step if you are already on device’s Web UI) → Click desired video profile under “Video Profiles” section → Click “Encoding Mode” → Choose “Strict Constant Bitrate”)
    Screenshot 2024-11-07 at 5.05.56 PM.png
  2. Set "Constant Bitrate" mode on the device’s audio profile/encoder. (Web UI/Cloud UI → Select desired device from “Devices” (Skip this step if you are already on device’s Web UI) → Click desired video profile under “Audio Profiles” section → Click “Encoding Mode” → Choose “Constant Bitrate”)
    Screenshot 2024-11-10 at 10.21.16 PM.png

Using these modes helps create a stable output stream that matches the CDN’s bitrate and PCR requirements.

  • Expected Latency:
    • Switching to strict constant bitrate mode may increase latency. The expected latency based on bitrate settings is as follows:
      • Non-Strict CBR Mode: 300 ms latency
      • Strict CBR on LiveEdge® Node: 700 ms latency
      • Strict CBR on LiveEdge® Max: 1600 ms latency

Q3: What are the recommended settings to avoid bitrate errors on specific CDNs?

Below are sample configurations for specific CDNs to help prevent bitrate or PCR-related errors:

  • YouTube Streaming: When using SRT to YouTube, you may experience errors like bitrate fluctuation or macroblocking. Set the video encoding mode to Strict Constant Bitrate and audio encoding mode to Constant Bitrate to stabilize the stream.
  • AWS MediaConnect + MediaLive: AWS MediaLive may report PCR inconsistency errors if bitrate settings fluctuate. Strict constant bitrate on Videon devices can reduce these inconsistencies and minimize errors during live streaming.

Q4: How do different bitrate modes impact my stream?

Here’s a brief overview of bitrate modes and their impact:

  • Variable Bitrate (VBR): This mode allows bitrate to vary based on content complexity, optimizing quality but leading to unpredictable network usage.
  • Constant Bitrate (CBR): This mode enforces a target bitrate, providing stable network usage but sacrificing flexibility, which can sometimes lead to video quality issues under high motion scenes.
  • Strict Constant Bitrate: This mode provides the most stable output by minimizing bitrate fluctuations and improving PCR accuracy, which is ideal for CDNs that require precise timing but may increase latency.

Strict CBR mode is especially effective for resolving bitrate and PCR errors, as it helps ensure timing precision required by CDNs with strict bitrate requirements.

Q5: Can you provide a configuration example?

Here’s a sample configuration to help you set up your Videon device for strict constant bitrate mode. In this setup, it’s assumed that the output has one video profile/encoder and one or more audio profiles/encoders attached to it:

  • Video Profile/Encoder:
    • Encoding Mode: Strict Constant Bitrate
    • Video Bitrate: Adjust according to your CDN’s requirement (e.g., 20,000 kbps)
    • Keyframe Interval: 2 seconds (recommended for most CDNs)
  • Audio Profile/Encoder:
    • Encoding Mode: Constant Bitrate
    • Audio Bitrate: Adjust as per CDN requirements (e.g., 320 kbps for high-quality audio)

This setup should reduce errors and align with CDN expectations for consistent bitrate and timing.

For more information on encoding bitrate modes, see this article. If you continue experiencing issues, please submit a ticket for additional troubleshooting.

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