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I am decoding video frames from a stream and sws_scale gives me a buffer of decoded RGB image data (PIX_FMT_RGB24). I have an existing front-end application that requires the input be DIB. So I need to know how to convert this buffer to DIB?

From what I understand DIB on windows is BGR and bottom to top and requires a header. Rather than do that manually, I'm hoping this problem has already been solved. I'm also wondering maybe sws_scale can do it natively.

kevincw01
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  • If you do decide on doing it yourself there's tons of information on the DIB headers of the bitmap format here: http://en.wikipedia.org/wiki/BMP_file_format#DIB_Header_.28Bitmap_Information_Header.29 – Andrew Rasmussen Nov 18 '11 at 22:33

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This isn't the answer you're looking for. But, this is about all I've got.

DIB stands for Device Independent Bitmap which is just a bitmap with an extra (DIB) header in it specifying some information about the image data so that it can be understood by more than one device/platform. You can easily link to a free external library such as DevIL to generate the bitmap, but I don't know of any libraries which will create the DIB header for you. However, there's a lot of information about the DIB header on the wiki page and it doesn't look that hard to do yourself and let some other library (I suggest DevIL) do the image conversion.

I hope somebody else comes up with a nice third party library that does exactly what you're asking. Good luck!

Andrew Rasmussen
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  • ok so I've changed the destination format for sws_scale to "PIX_FMT_BGR24" to get the pixel colors correct. Then I wrote a loop to reverse the order of the lines (bottom up). I confirmed that works with a hex editor. Now I need to figure out that 40 byte DIB header. I remember the last time I looked at that wiki page, it didnt seem simple. – kevincw01 Nov 19 '11 at 18:33
  • ok, got it working. Not sure how efficient this is going to be at 30fps...but it is what it is. – kevincw01 Nov 19 '11 at 20:24
  • You figured out how to generate the header on your own? And it works? Cool stuff. 33 milliseconds should be plenty of time to do all that. – Andrew Rasmussen Nov 20 '11 at 05:59
  • To test it out I manually inserted the bitmap header (on top of 40byte DIB header) to see if it was viewable in a typical image viewer and it worked. As far as the 33ms, I'm not sure yet. I'm doing video decoding and yuv to rgb conversion in the same interval. If I'm over I might need to modify the sws_scale source to go straight from yuv to DIB. – kevincw01 Nov 20 '11 at 19:06