mORMot Open Source

DavidB3

Member

Registered: 2016-03-02

Posts: 1

Animated jpegs

Hi,

I intend to make a small app to create/modify/view animated jpegs. Maybe even a dll to use in other app.
Why ajpgs and not apngs? Because highres highdetail apngs are very big so it loads slow and take a lot of RAM memory.
For example this one: https://drive.google.com/open?id=0ByKxA … mg5OGFjM0E
It was compressed with APNG Assembler so it has maximum compression. But it's still very big.
But most of the times the jpeg quality is enough.

For now I made a small project to test decoders/resizers/viewers: https://drive.google.com/open?id=0ByKxA … jFvYzNhNXc
It uses these frames: https://drive.google.com/open?id=0ByKxA … XZJVVBQcWs
And it builds this ajpeg file: https://drive.google.com/open?id=0ByKxA … nl2NW5oM00

Your decoder is very fast indeed, good job.
In my tests I got a 48.5 fps using on-the-fly decompression on 768x768 70 KB frames.
I intend to implement a decompression buffer and multithreading. Also a fast but good resize algorithm (for preview).
You said your component it's not thread-safe. Could you modify it to be?

I noticed that, when using the JpegDecode function on the same bitmap, I have to free the bitmap before each decoding. Is there a way to not free/create it every time? It may be faster this way...

Regarding resize: I would prefer a resize algorithm implemented BEFORE decompression. Jpegs are scaled much better than bmps, so why don't we use that?
Is it possible?

Thank you for your help.

Regards,
David