OvejaNegra
8th June 2009, 22:45
Some days ago i made this post: http://forum.doom9.org/showthread.php?t=147410
Ok, it was too much.
But i'm very interested in on this specific topic:
The ratecontrol.
If my info is correct, during 2pass encodes x264 adapts bit rate acording to the complexity of the scene. These changes are limited to avoid sudden bit rate peaks or very low bit rate parts. Usually the buffer controls that, and the buffer size is related to the chosen profile (or maybe to target some hardware device).
Now, what im trying to do (maybe this does not have any sense) is
allow x264 to use as high as possible bit rate for high motion scenes (to avoid blocks) and only the needed bit rate on the rest of the video to produce aceptable quality AND opposite.
No, i just made a mess.
Lower quantizers for high motion scenes (for better quality), producing medium quantizers for low motion scenes (like 18 - 22, but not 14-17). Simply take quality from the low motion scenes for the high motion scenes.
And
The opposite:
As low as possible quantizer for low motion scenes (14 -16) and quickly raise the quantizer on the high motion scenes to allow acceptable perceived quality with low bit rates (yes i know this will produce fluctuating quality but that's what i want). I have seen this behaviour on some real media encodes (nice looking low action scenes ,and suddendly blocky action scenes but the filesize is generally small).
If i'm not wrong, qcomp and cplxblur will help me with that, but i dont know how to use them (lower cplxblur and lower qcomp maybe?). But what about the bit rate? This sudden change on the quantizers will produce many fast bit rate changes and the buffer will avoid that.
Im trying to aim to a speceific size, not to a specific bit rate (like Xvid).
Sorry this is very confusing, for my bad english.
I'm saying something without sense please correct me.
Ok, it was too much.
But i'm very interested in on this specific topic:
The ratecontrol.
If my info is correct, during 2pass encodes x264 adapts bit rate acording to the complexity of the scene. These changes are limited to avoid sudden bit rate peaks or very low bit rate parts. Usually the buffer controls that, and the buffer size is related to the chosen profile (or maybe to target some hardware device).
Now, what im trying to do (maybe this does not have any sense) is
allow x264 to use as high as possible bit rate for high motion scenes (to avoid blocks) and only the needed bit rate on the rest of the video to produce aceptable quality AND opposite.
No, i just made a mess.
Lower quantizers for high motion scenes (for better quality), producing medium quantizers for low motion scenes (like 18 - 22, but not 14-17). Simply take quality from the low motion scenes for the high motion scenes.
And
The opposite:
As low as possible quantizer for low motion scenes (14 -16) and quickly raise the quantizer on the high motion scenes to allow acceptable perceived quality with low bit rates (yes i know this will produce fluctuating quality but that's what i want). I have seen this behaviour on some real media encodes (nice looking low action scenes ,and suddendly blocky action scenes but the filesize is generally small).
If i'm not wrong, qcomp and cplxblur will help me with that, but i dont know how to use them (lower cplxblur and lower qcomp maybe?). But what about the bit rate? This sudden change on the quantizers will produce many fast bit rate changes and the buffer will avoid that.
Im trying to aim to a speceific size, not to a specific bit rate (like Xvid).
Sorry this is very confusing, for my bad english.
I'm saying something without sense please correct me.