1929528 - ImageDecoder.decode from WebCodecs API doesn't support progressive JPEG

Status: ASSIGNED

(Core :: Audio/Video: Web Codecs, defect)

Description

[Adrien CLERC]

Attachment: -1.jpeg

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:132.0) Gecko/20100101 Firefox/132.0

Steps to reproduce:

I used the example from https://developer.mozilla.org/en-US/docs/Web/API/ImageDecoder/decode#partial_decoding_of_a_progressive_image_frame

I added a console.log() between result declaration and complete assignation, to show in console how much decode there is.

I call this code using a progressive JPEG with a fetch call

Actual results:

Within Firefox 133.0b4, I got only one call to decode(). In MS Edge, I got as much call as progressive scan lie in the file.

Expected results:

Firefox should returns from decode() whenever the first StartOfScan is complete, not the complete file.

I didn't read https://w3c.github.io/webcodecs/#imagedecoder-decode-progressive-frame in detail, but seems that there's nothing more to add from the call to have intermediate progressive frames.

Comment 1

[Andrew Osmond [:aosmond] (he/him)]

The decoder abstractions under the hood do progressive images correctly, I think we reuse the surface though, so I need to make it copy on each pass so it actually yields the frames.