I have a bunch of html5 video elements, with their preload attribute set to "auto". They start loading just fine, but I think there might be a problem with their caching, because each time I reload the page (without clearing the cache), they start all over again.
When I checked the Network panel in firebug, I noticed everything else (images and files) was giving me a "304 not modified" message as espected, while the videos (and audio) files were giving me a "206 partial content" message, in duplicated entries.
The "206 partial content" response also appears in duplicated entries when the page is loaded with the cache cleared, instead of a "200 OK" response, as it would be expected.
Is this a normal behavior for video and audio elements? If not, how could it be corrected?
This Partial Content code (206) may be sent from the server when the client has asked for a range (e.g. "give me the first 2MB of video data").
It is vital for downloading data in chunks which avoids fetching unused resources. (I seldom watch a full video online.) Look at the outgoing request for a Range header.
See Status Codes (RFC2616 - HTTP/1.1) (note that any 2xx code means "Success"):
10.2.7 206 Partial Content:
The server has fulfilled the partial GET request for the resource. The request MUST have included a Range header field (section 14.35) indicating the desired range, and MAY have included an If-Range header field (section 14.27) to make the request conditional.
And from the Range header section:
If the server supports the Range header and the specified range or ranges are appropriate for the entity
- The presence of a Range header in an unconditional GET modifies what is returned if the GET is otherwise successful. In other words, the response carries a status code of 206 (Partial Content) instead of 200 (OK).
I do not understand the intricicies of caching and/or ETags or what to expect in FireFox, however.
In firefox on my local development machine I couldn't get .webm videos to play unless the server was configured to use them. Firebug would show 206 but nothing would show. This can be as resolved by adding
AddType video/webm .webm
to your .htaccess.
According to https://httpstatuses.com/206
"A server MUST NOT generate a multipart response to a request for a single range, since a client that does not request multiple parts might not support multipart responses. However, a server MAY generate a multipart/byteranges payload with only a single body part if multiple ranges were requested and only one range was found to be satisfiable or only one range remained after coalescing. A client that cannot process a multipart/byteranges response MUST NOT generate a request that asks for multiple ranges.
When a multipart response payload is generated, the server SHOULD send the parts in the same order that the corresponding byte-range-spec appeared in the received Range header field, excluding those ranges that were deemed unsatisfiable or that were coalesced into other ranges. A client that receives a multipart response MUST inspect the Content-Range header field present in each body part in order to determine which range is contained in that body part; a client cannot rely on receiving the same ranges that it requested, nor the same order that it requested."
来源：https://stackoverflow.com/questions/9755168/why-does-firebug-show-a-206-partial-content-response-on-a-video-loading-reques