667203 - Load event fires multiple times for Motion JPG files (mjpg)

Status: RESOLVED INVALID

(Core :: Graphics: ImageLib, defect)

Description

[David Humphrey (:humph)]

Attachment: onload test case with live mjpg (traffic cam)

Working with mjpg files, I'm noticing differences across browser implementations.  In Chrome and WebKit (on OS X 10.6) the attached test case will cause a single 'onload' to be printed below the image.  In Firefox, I get them happening at the framerate.

Which way is right?  Are images loaded once, and then streaming frames part of the image, or is each frame a new image?

I also note, with the attached test case, that Firefox seems to stop updating the stream quite often.  Could be the remote server, or my network.

Comment 1

[David Humphrey (:humph)]

Bug 625012 is possibly related.

Comment 2

[Boris Zbarsky [:bzbarsky]]

> Are images loaded once, and then streaming frames part of the image, or is each 
> frame a new image?

In Gecko, it's the latter.

As far as I know there is no spec for this.

Comment 3

[Ali Juma [:ajuma]]

(In reply to Boris Zbarsky (:bz) from comment #2)
> > Are images loaded once, and then streaming frames part of the image, or is each 
> > frame a new image?
> 
> In Gecko, it's the latter.
> 
> As far as I know there is no spec for this.

Closing as it sounds like Gecko's behaviour is by design. Please reopen if this isn't the case, or if you'd like to use this bug to discuss whether Gecko's behaviour should change anyway.

Comment 4

[Alice0775 White]

http://dev.w3.org/html5/spec/the-img-element.html#the-img-element 
said
"if the resource type is multipart/x-mixed-replace, then each task that is queued by the networking task source while the image is being fetched must also update the presentation of the image, but as each new body part comes in, it must replace the previous image. Once one body part has been completely decoded, the user agent must set the img element to the completely available state and queue a task to fire a simple event named load at the img element."