So if one wishes to append compressed images to a video file without recompressing, we need to construct our own AVI file from scratch - possible but tedious I'm a programmer who works a lot with video - so I'm quite familiar with JPEG (and MJPEG) and AVI files - I already have code modules for everything you need and might consider knocking up a front end app for you (though it would be pretty quick n dirty - don't expect a work of art!). Even mjpegtools makes you convert to YUV first So now I can view and do a lossless rotate of the JPEGsįinally, I tried looking for software that can do a simple reassembly of the JPEGs *without* any recompression. I managed to modify the source code of sfw2jpg (look for it.) and put in default tables. Now, using lavtrans, (part of the mjpegtools suite of software) to split the AVI, the disassembled jpegs are missing Huffman tables (to save space?) and most image processing software will not touch them. In theory it should be possible to split the AVI into separate JPEGs, do a lossless rotate and reassemble the JPEGs with no loss of quality. However, a certain amount of recompression is inevitable, with loss of quality. If we are storing in another format, there are a wide range of tools including VDub.

Now for various reasons we may record a video clip in portrait mode and have to rotate the AVI to watch it properly.

Images are compressed *within* frames, presumably by camera hardware. As many of us know, many digital cameras record video in AVI using MJPEG compression - basically a bunch of JPEGs stacked together.

Ffmpeg rotate video lossless 90 degrees