Picture decoding method

Abstract

The invention relates to method for buffering encoded pictures. The method includes an encoding step for forming encoded pictures in an encoder. The method also includes a transmission step for transmitting said encoded pictures to a decoder as transmission units, a buffering step for buffering transmission units transmitted to the decoder in a buffer, and a decoding step for decoding the encoded pictures for forming decoded pictures. The buffer size is defined so that the total size of at least two transmission units is defined and the maximum buffer size is defined on the basis of the total size.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority under 35 USC §119 to U.S. Provisional Patent Application No. 60 / 544,598 filed on Feb. 13, 2004.FIELD OF THE INVENTION [0002] The present invention relates to a method for buffering encoded pictures, the method including an encoding step for forming encoded pictures in an encoder, a transmission step for transmitting said encoded pictures to a decoder, a decoding step for decoding the encoded pictures for forming decoded pictures, and rearranging step for arranging the decoded pictures in decoding order. The invention also relates to a system, transmitting device, receiving device, an encoder, a decoder, an electronic device, a software program, and a storage medium. BACKGROUND OF THE INVENTION [0003] Published video coding standards include ITU-T H.261, ITU-T H.263, ISO / IEC MPEG-1, ISO / IEC MPEG-2, and ISO / IEC MPEG-4 Part 2. These standards are herein referred to as conventional video coding standards. V...

AI Technical Summary

Benefits of technology

[0067] Another possibility to inform the maximum size of the predecoding buffer is to use transmission units, therein the size of the buffer is informed as maximum amount of transmission units to be buffered. However, the maximum size of the transmission unit is not defined and the size of the transmission unit may vary. If the maximum size were defined and if the size is too small for a certain data unit, the data unit has to be divided into more than one transmission unit, which increases encoding and transmission overhead i.e. decreases the compression efficiency and / or increases system complexity. The maximum size of the transmission unit should be large enough wherein the total size of the buffer may be unnecessarily large.

[0082] Substitutive signalling to any decoding order information in the video bitstream is presented in the following according to an advantageous embodiment of the present invention. A Decoding Order Number (DON) indicates the decoding order of NAL units, in other the delivery order of the NAL units to the decoder. Hereinafter, DON is assumed to be a 16-bit unsigned integer without the loss of generality. Let DON of one NAL unit be D1 and DON of another NAL unit be D2. If D1<D2 and D2−D1<32768, or if D1>D2 and D1−D2>=32768, then the NAL unit having DON equal to D2 precedes the NAL unit having DON equal to D2 in NAL unit delivery order. If D1<D2 and D2−D1>=32768, or if D1>D2 and D1−D2<32768, then the NAL unit having DON equal to D2 precedes the NAL unit having DON equal to D1 in NAL unit delivery order. NAL units associated with different primary coded pictures do not have the same value of DON. NAL units associated with the same primary coded picture may have the same value of DON. If all NAL units of a primary coded picture have the same value of DON, NAL units of a redundant coded picture associated with the primary coded picture should have the same value of DON as the NAL units of the primary coded picture. The NAL unit delivery order of NAL units having the same value of DON is preferably the following:

[0092] The present invention improves the buffering efficiency of the coding systems. By using the present invention it is possible to inform the decoding device how much pre-decoding buffering is required. Therefore, there is no need to allocate more memory for the pre-decoding buffer than necessary in the decoding device. Also, pre-decoding buffer overflow can be avoided.

Problems solved by technology

If the maximum size were defined and if the size is too small for a certain data unit, the data unit has to be divided into more than one transmission unit, which increases encoding and transmission overhead i.e. decreases the compression efficiency and / or increases system complexity.

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