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  #1  
Old 10.08.2017, 19:43
kanink kanink is offline
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Default changing download size after 2nd try

hello.
its a strange.. bug? i dont really know if its a jdownloader bug and firefox bug.. i dont even know if this is the right thread for.. but i dont really know where to ask download-related stuff. and jdownloader is behaving similar to firtefox in this case, so i hope its ok to ask here

its about 8ch.net its an image board and you can see all image sizes in parentheses. so.. when i downoload a image the very first time, its original sized. for example this one:

**External links are only visible to Support Staff****External links are only visible to Support Staff** (its the very first picture with paper mario sticker star)

but then i accidently downloaded the image a second time and i noticed its only 200 KB big now. but before, it was about 800 KB big.
this happened to many different images on 8ch. tested it on jdownloader, on firefox etc.. all same behaviour.

if it helps: the original image with 800 KB said in properties (right click on image and select properties, then details) that the origin of this image is adobe photoshop cs2. but the 200 KB image didnt say that anymore. and some other image with original size said in properties "color representation: uncallibrated" and the smaller versions of these ones didnt say it anymore.

uhm.. can you maybe test this and explain me, why all downloaders (including jdownloader) behave like this on 8ch images and download the riginal size first, but in the second try they download a small sized image? (resolution is the same, and quality looks like kinda same, too. well actually thats what i want to know: do the smaller images have less quality because of less file size?)

Last edited by kanink; 10.08.2017 at 19:47.
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  #2  
Old 10.08.2017, 20:06
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Jiaz Jiaz is offline
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Cloudflare transparently compresses the image
Response Headers:
cf-bgj: imgq:85
cf-cache-status: HIT
cf-polished: origSize=19910

So when image is not in cache you will see the original/uncompressed image. On second /xy hit you will receive the cloudflare compressed image.
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  #3  
Old 10.08.2017, 20:20
kanink kanink is offline
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i see.. i found out another useful information.. maybe. on the second try, the whole exif and xmb data of the image is gone. so.. does that mean cloudflare compressing doesnt lose quality of image, but just deletes the meta data so its compressed? or does the image lose quality when?
EDIT: just read a bit about it. how to find out if the compression was lossless type or lossy type?

which cache do i have to empty to skip cloudflare compression again? (because all downloaders behave the same way and they probably use kinda the same cache. i just dont know where this cahce is. i emptied mozilla cache but still same behaviour.)
thank you

Last edited by kanink; 10.08.2017 at 20:29.
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  #4  
Old 11.08.2017, 02:35
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raztoki raztoki is offline
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its a server side compression/cache in which you have zero control over.

raztoki
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  #5  
Old 11.08.2017, 09:59
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Jiaz Jiaz is offline
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Found a workaround. Wait for next JDownloader update and it will download the original file if possible
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Old 11.08.2017, 10:14
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In my testing it worked fine, wait for next update
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  #7  
Old 11.08.2017, 10:48
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raztoki raztoki is offline
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Nice one

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Old 11.08.2017, 21:06
kanink kanink is offline
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wow really nice! is it possible to explain how you did that and if its possible to use tricks on web browsers, to skip cloudflare compression?
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  #9  
Old 12.08.2017, 05:41
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raztoki raztoki is offline
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request with unique parameter once identified as cached service. Unless you have browser extension experience it wont be a simple fix in browsers.

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