Image upload size negotiation: upload of standard size image fails because too large

[michaelmaguire]

When I try to upload a standard Google Pixel 8a photo of about 4.9M into a post on my mstdn.ca server using the standard Mastodon Android client, the upload fails. If I try to upload e.g. a screenshot of my photo, the upload succeeds.

It seems clear that the mstdn.ca server admins have (quite reasonably) set some kind of image upload size limit. However it's inconvenient that standard sized photos are rejected each time.

Example here showing an image which is a screenshot of the originally failed upload attempt:

https://mstdn.ca/@michaelmaguire/114465342140430763

Surely some kind of pre-negotiation could take place to ensure that a suitably quality-reduced image can be uploaded automatically in place of the over-large image. Or perhaps the client can post-negotiate with a retry of a quality reduced upload automatically based on an initial file-too-big failure message from the server. Hopefully the server failure message contains useful information of allowed limits.

[grishka]

Gotta love Cloudflare...

[grishka]

Anyway, after I got past this alarmingly common part of the Russian Internet Experience™ using a VPN, https://mstdn.ca/api/v2/instance says that

"image_matrix_limit": 33177600,
"image_size_limit": 16777216,

Which means that, the maximum pixel size of uploaded photos is slightly larger than 33 MP, and maximum file size is 16-something MB. Which your photos should fit into...

...unless you're taking them at the full 64 MP. I'm not sure if previous Pixels have a setting for that, but my 9 Pro has one to choose between 12 MP and the full sensor resolution of 50 MP.

Can you please try uploading the same file from the web app? It'll display the error message as returned by the server.

[michaelmaguire]

From the website mstdn.ca it just worked:

https://mstdn.ca/@michaelmaguire/114469317805751323

[michaelmaguire]

Retrying with the Android app, it still fails:

https://mstdn.ca/@michaelmaguire/114469331241807883

Photo details:

https://mstdn.ca/@michaelmaguire/114469331241807883

[grishka]

My current theory is that the app tries to resize the photo (even though it shouldn't because it fits into both limits?) but somehow ends up with a file that the server doesn't like. Can you please upload the original file here so I could try to reproduce this myself? Also, does this only happen with this particular photo, or to all photos taken with the camera?

[michaelmaguire]

Also, does this only happen with this particular photo, or to all photos taken with the camera?

I find it happens with most upload attempts for me from my Pixel 8a.

[michaelmaguire]

[michaelmaguire]

If you want, I can get the app building in the IDE and take a look. Can you point me at a good line in the code to set a breakpoint?

[grishka]

It does upload to mastodon.social just fine ¯\_(ツ)_/¯

If you want, I can get the app building in the IDE and take a look. Can you point me at a good line in the code to set a breakpoint?

No need to do that (at least not yet) — I just checked, API errors are logged to logcat even on release builds. You can filter by MastodonAPIController to see them.