US 6,982,762 B1 | ||
Sequence adaptive bit allocation for pictures encoding | ||
Yau Wai Lucas Hui, Singapore (Singapore) | ||
Assigned to STMicroelectronics Asia Pacific Pte Limited, Singapore (Singapore) | ||
Appl. No. 9/701,089 PCT Filed May 30, 1998, PCT No. PCT/SG98/00038 § 371(c)(1), (2), (4) Date Jan. 26, 2001, PCT Pub. No. WO99/63760, PCT Pub. Date Dec. 09, 1999. |
||
Int. Cl. H04N 7/18 (2006.01) |
U.S. Cl. 348—405 | 21 Claims |
1. A moving pictures encoder for encoding pictures in a moving pictures sequence according to an overall target bit-rate,
each picture having an assigned picture coding type, the moving pictures encoder including:
a quality factor estimator including means for determining a picture complexity for each assigned picture coding type based
on a number of bits used for past coded pictures of that type, and an average quantization step-size for past coded pictures
of that type;
a bit allocation processor for determining a target number of bits for coding a picture according to the overall target bit-rate,
the assigned picture coding type and a quality factor for the assigned picture coding type, the quality factor being defined
as the product of a visual quality and the average quantization step-size for past coded pictures of that type;
a bit-rate controller for determining a reference quantization step-size based on the target number of bits and the number
of bits used for the picture; and
an adaptive quantization processor for determining a coding quantization step-size based on the reference quantization step-size
and picture activities for the picture, and for determining said average quantization step-size for past coded pictures, wherein
the quality factor estimator includes means for determining the quality factor of the assigned picture coding type as a function
of a ratio of the picture complexity of the assigned picture coding type to the picture complexity of at least one other picture
coding type.
|