Inconsistent Media Resource Count Between resource-summary and network-requests Audits

[LarsFlieger]

FAQ

• [X] Yes, my issue is not about variability or throttling.
• [X] Yes, my issue is not about a specific accessibility audit (file with axe-core instead).
• [X] Yes, my issue is not answered by other FAQs.

URL

http://www.mercedes-benz.com/

What happened?

The resource-summary and network-requests audits do not have the same number of items with resourceType set to Media. In resource-summary, there are 2 items, whereas in network-requests, there are actually 3 items with the media type. I noticed that there is an item with a blob URL in the network requests but couldn't find any documentation stating that this blob should not be counted in the resource-summary.

I have uploaded the report with the information here: https://gist.github.com/LarsFlieger/f6671b59bffdc768a6b4624aefc8f00c

What did you expect?

I expected the number of items with resourceType Media to be consistent between the resource-summary and network-requests audits.

What have you tried?

I have reviewed the audit details and checked the documentation but could not find any information explaining if blob URLs in network requests should not be counted in the resource-summary.

How were you running Lighthouse?

PageSpeed Insights

Lighthouse Version

12.0.0

Chrome Version

125.0.6422.154

Node Version

No response

OS

No response

Relevant log output

No response

[adamraine]

I did some digging. So the blob: scheme is ignored when counting for resource-summary because it represents a non-network request. It is still logged in network-requests because the page made a request for it (but it's transfer size is 0).

The difference is subtle so more docs explaining this would be good, but this is working as intended.