Zarxrax
26th June 2004, 06:43
I have normally been encoding with the minimun quantizers set to 2 instead of 1. Tonight I made an encode with default b-frame settings, and it came out undersized, and with an average quant of about 3.2.
So I set the quantizer offset to 0 (so b-frames will be encoded at quant 3 instead of quant 4). The filesize only got a tiny bit larger, but now the average quantizer is 2.6, which is quite a bit better.
I still wanted to try and squeeze more quality out of it though, as I still hadn't met the target filesize, so I changed the minimum quants to 1, under the impression that this would improve the quality even more. To my surprize, the average quant of this encode was a whopping 3.6! It used quantizers as high as 7! I looked at the frames with DRF analyzer, and saw that it used quite a few quant 1 frames.
Now, it would make sense if everything was encoded exactly the same as before, and the codec only threw quant 1 frames out only to meet the filesize (which I thought was what its supposed to do), but it used so many quant 1 frames that it had a very adverse effect on the quality!
I wonder if this is something that can be looked into, and possibly improved? I think quant 1 is very important, though many people downplay it a lot. I can definately see the difference between quant 1 and 2 sometimes, so I know that it has the ability to improve the quality of the encode if used smartly.
So I set the quantizer offset to 0 (so b-frames will be encoded at quant 3 instead of quant 4). The filesize only got a tiny bit larger, but now the average quantizer is 2.6, which is quite a bit better.
I still wanted to try and squeeze more quality out of it though, as I still hadn't met the target filesize, so I changed the minimum quants to 1, under the impression that this would improve the quality even more. To my surprize, the average quant of this encode was a whopping 3.6! It used quantizers as high as 7! I looked at the frames with DRF analyzer, and saw that it used quite a few quant 1 frames.
Now, it would make sense if everything was encoded exactly the same as before, and the codec only threw quant 1 frames out only to meet the filesize (which I thought was what its supposed to do), but it used so many quant 1 frames that it had a very adverse effect on the quality!
I wonder if this is something that can be looked into, and possibly improved? I think quant 1 is very important, though many people downplay it a lot. I can definately see the difference between quant 1 and 2 sometimes, so I know that it has the ability to improve the quality of the encode if used smartly.