Removed downscaling, which made the image quality worse in the video …

[evekeen]

A naive attempt to fix image quality for imported tasks: #4377

[nmanovic]

@Marishka17 , @azhavoro , please look at comment.

[evekeen]

That's actually a nasty bug, which made the whole dataset look incorrect, since the work was done with down-scaled images, while exported dataset is not downscaled. And objects can be in different locations because of the quality loss.
The issue appears if you create tasks through CLI - they're downscaled

[Marishka17]

@evekeen, Hello, thanks for the contribution. I'm not sure this is the correct solution.
I was able to reproduce the error when creating a task with a *.mov video file using the use_zip_chunks=True flag.
In this case, the ZipCompressedChunkWriter class is used to create a compressed chunk on the server.
If we create a backup of this task and import it, the Mpeg4CompressedChunkWriter will be used on the server.
I guess the problem with different quality is in this.

[evekeen]

@Marishka17 how do you suggest to fix that?

[Marishka17]

As far as I remember the solution in PR was implemented without saving use_zip_chunks in task.json. When a task is creating this check defines a chunk type, but in buckup this option is missing.
So I guess we need to save this metadata when creating a task backup.

[Marishka17]

@azhavoro, Do you have other suggestions?

[evekeen]

@Marishka17 I've just tried settings that option in my task.json, and it was ignored on import:
WARNING cvat.server: the following keys are dropped {'use_zip_chunks'}
Moreover, I see in the code we actually set use_zip_chunks programmatically during the import

[evekeen]

I've supported the use_zip_chunks option on import. However, if you export a task again, it will be exported as an imageset with use_zip_chunks=False. I hope you can take it from here.

Also, I suggest keeping the initial change of downscaling, since I don't see a reason why downscale

[Marishka17]

Hi, @evekeen, thanks for the contribution! Are you still going to contribute to us? If so, could you please resolve conflicts in this PR?

[Marishka17]

@azhavoro, Could you please take a look at the PR? I've resolved conflicts and updated it. PR should resolve issue #4377

[nmanovic]

@evekeen , it looks like most parts of your PR has been merged. I see no changes in the PR. Thank you for the contribution.