Blockiness...Its driving me crazy

[OrionZodiac]

For the past week and a half I have searched all four corners of the internet for a solution to this problem. Basically there seems to be fluctuating blocks, much like a scrabbled TV signal, in dark regions of the video. Look at the picture, see that thick like line where there appears to be random changes in color from dark gray to light gray. Colors in this part of the video seem to change randomly from dark gray to light gray and vice versa essentially scrambling between the two shades of gray making it an eyesore. So is there a way to have a nice gradient where there is no blocks that turn on or off or maybe stop the blockiness so that it would not fluctuate. As far as the rest of the video is concerned the quality is good, its just on darker regions, such as this gray region that is giving me problems. Any avisynth filters that you might think that will get rid of this problem would be appreciated.

[Dark Shikari]

gradfun2db

[Sharc]

Which encoder did you use? I have observed the same with x264 for natural (non-anime) movies e.g. for dark blue sky scenes. The sky eventually appeared like looking onto the surface of water: fluctuating over time. I am rather new to x264, so I thought there must possibly be better settings. Apart from this the quality of the encode was very good. I am just wondering if the described effect could be a basic "weakness" of x264, and what would be the remedy (filtering, increasing average bitrate, adjusting some bias .........). As I said, I need to gain more experience in using x264 properly, so my observation may not be very relevant.

[Dark Shikari]

Which encoder did you use? I have observed the same with x264 for natural (non-anime) movies e.g. for dark blue sky scenes. The sky eventually appeared like looking onto the surface of water: fluctuating over time. I am rather new to x264, so I thought there must possibly be better settings. Apart from this the quality of the encode was very good. I am just wondering if the described effect could be a basic "weakness" of x264, and what would be the remedy (filtering, increasing average bitrate, adjusting some bias .........). As I said, I need to gain more experience in using x264 properly, so my observation may not be very relevant.No encoder can keep perfect gradients at sane bitrates.

Were you using a version of x264 new enough that it had AQ? AQ tends to help these situations a lot. You could also try FGO.

[Sharc]

Thank you for the hint.
I probably made the experience with an earlier version, not yet supporting AQ.
I encoded the scene again with the current version of x264 supporting AQ, and in fact the result is MUCH better. The quality vs bitrate of x264 is really amazing!
Btw, what is FGO?

[*.mp4 guy]

No encoder can keep perfect gradients at sane bitrates.

... Thats quite a bold statement.

[Dark Shikari]

... Thats quite a bold statement.OK, a less bold statement: no encoder that uses the YV12 colorspace can keep perfect gradients at sane bitrates ;)

A thread with an FGO (film grain optimization) build of x264 and how to use it can be found in the MPEG-4 AVC forum.