Size of SER and ADV file

[Jean-Francois]

Hello,

I'm doing some tests with several cameras and SharpCap.
I check if my EAGLE computer can save 3 films from 3 cameras with 3 instances of SharpCap at the same time ... It works.
I will find the best combination between intern drive and extern drive or both.

But I note now a big difference on the size of the ADV and SER files.

I capture a film with 1 minute with a QHY200M camera.
The file is ~ 2.8 GByte with SER and ~ 0.8 GByte with ADV. What ? ~2 GB difference !

Is that expected ? ... and why ? ... Is the ADV format compressed ?
Or other reason ... SER save the camera pixels on 16 bit, but ADV only with the real bit depth, and with the QHY200 then in 12 bit.

Concerning the compression ... it is very strange, while the camera is in the dark (with cover) mean I take 20 ms in the dark ... = offset.
OK, fast only noise on the images ... it could be better "compress" if the pixels are saved on only the maximum value per image.
I have no idea if the ADV format use this for smaller file size.

Any idea ?

Regards,
Jean-Francois

[admin]

Hi Jean-Francois,

I found a copy of the ADV file format spec (had to go onto the Wayback machine) : http://web.archive.org/web/202010010728 ... Format.pdf . The documentation reveals that ADV does indeed use a QuickLZ compression algorithm to compress data (used to be on http://www.quicklz.com/ , but that web site is gone too, just like the ADV file format).

I'm not sure if ADV takes advantage of the data being 12 bit to pack 2 pixels into 3 bytes (it must be documented somewhere in the file format documentation - finding it is left as an exercise for the reader...). However, I would expect dark frames to compress better than frames with significant image in them and low gain images to compress better than high gain images. Basically, the more variation in pixel values, the less well the compression will do.

cheers,

Robin

[Jean-Francois]

Hello Robin,

OK, if the ADV file uses some compression.
I do not like use it, while no ADV viewer exists (or somebody knows one ?)
Tangra can export an ADV film in AVI format ... but that is not so good.

With SER, it is easier to process a film ... it can be read again in SharpCap, SER Player or PIPP.

Regards,
Jean-Francois

[admin]

Hi,

yes, Tangra is the only application that I know of that handles ADV

cheers,

Robin