I am trying to create a time lapse video from a bunch of jpg files. When I use the files as they came out of my camera everything works fine.
Now I averaged however over multiple images to improve the smoothness. The generated images look exactly the same as before, just a little bit smoother.
When I now try to convert the images to a video via
avconv -start_number 1 -i %d.jpg -b 65536k ~/vid.mp4
the dark areas of the video become almost black. I am aware of this effect, but that doesn't happen here. Because if I use .avi instead:
avconv -start_number 1 -i %d.jpg -b 65536k ~/vid.avi
everything works fine (minus ugly box artefacts).
Tuning up the bitrate didn't help. Neither did using '-pre:0 lossless_ultrafast'
I realized that the averaged images are about 10x smaller than the originals. That made me suspect that maybe avconv thinks the quality of the input is not as good anyway and just decreases the quality automatically.
Might this be the case? and is there a way of preventing this from happening?