Video frame encoding and decoding

A method for decoding a predetermined syntax element among syntax elements of a coded bit stream from the coded bit stream, the coded bit stream being an arithmetically encoded version of a pre-coded video signal, the pre-coded video signal being a pre-coded version of a video signal, the video signal representing at least one video frame being composed of picture samples, the picture samples belonging either to a first or a second field being captured at a different time instants, the video frame being spatially divided up into macroblock pair regions, each macroblock pair region being associated with a top and a bottom macroblock, each macroblock pair region being either of a frame coded or a field coded distribution type, wherein, for each macroblock pair region, each of the pixel samples in the respective macroblock pair region is assigned to a respective one of the top and bottom macroblock of the respective macroblock pair region in accordance with the distribution type of the respective macroblock pair region, wherein each of the macroblocks is associated with a respective one of the syntax elements, the predetermined syntax element relating to a predetermined macroblock of the top and bottom macroblocks of a predetermined macroblock pair region of the macroblock pair regions, each syntax element being is a skip indicator specifying, for the respective macroblock, as to whether the respective macroblock is to be skipped when decoding the pre-coded video signal, wherein the method comprises the following steps:

• being performed by a decoder:
• determining, for the predetermined syntax element,
• a neighboring macroblock to the left of the predetermined macroblock at least based upon as to whether the predetermined macroblock pair region is of the frame or the field coded distribution type such that
• if the predetermined macroblock pair region is of the field coded distribution type,
• the neighboring macroblock to the left of the predetermined macroblock is determined to be a bottom macroblock of a macroblock pair region to the left of the predetermined macroblock pair region, if the macroblock pair region to the left is also of the field coded distribution type and the predetermined macroblock is the bottom macroblock of the predetermined macroblock pair region, and
• the neighboring macroblock to the left of the predetermined macroblock is determined to be a top macroblock of the macroblock pair region to the left of the predetermined macroblock pair region, if the macroblock pair region to the left is of the frame coded distribution type, or if the macroblock pair region to the left is of the field coded distribution type with the predetermined macroblock being the top macroblock of the predetermined macroblock pair region, and
• if the predetermined macroblock pair region is of the frame coded distribution type,
• the neighboring macroblock to the left of the predetermined macroblock is determined to be the bottom macroblock of the macroblock pair region to the left of the predetermined macroblock pair region, if the macroblock pair region to the left is also of the frame coded distribution type and the predetermined macroblock is the bottom macroblock of the predetermined macroblock pair region, and
• the neighboring macroblock to the left of the predetermined macroblock is determined to be the top macroblock of the macroblock pair region to the left of the predetermined macroblock pair region, if the macroblock pair region to the left is of the field coded distribution type, or if the macroblock pair region to the left is of the frame coded distribution type with the predetermined macroblock being the top macroblock of the predetermined macroblock pair region;
• and
• a neighboring macroblock to the top of the predetermined macroblock at least based upon as to whether the predetermined macroblock pair region is of a frame or field coded distribution type such that
• if the predetermined macroblock pair region is of the frame coded distribution type the neighboring macroblock to the top of the predetermined macroblock is determined to be
• a top macroblock of the predetermined macroblock pair region if the predetermined macroblock is the bottom macroblock of the predetermined macroblock pair region, and
• a bottom macroblock of the macroblock pair region to the top of the predetermined macroblock pair region if the predetermined macroblock is the top macroblock of the predetermined macroblock pair region,
• if the predetermined macroblock pair region is of the field coded distribution type and the predetermined macroblock is the top macroblock of the predetermined macroblock pair region, the neighboring macroblock to the top of the predetermined macroblock is determined to be
• the bottom macroblock of the macroblock pair region to the top of the predetermined macroblock pair region, if the macroblock pair region to the top of the predetermined macroblock pair region is of the frame coded distribution type,
• the top macroblock of the macroblock pair region to the top of the predetermined macroblock pair region, if the macroblock pair region to the top of the predetermined macroblock pair region is of the field coded distribution
• if the predetermined macroblock pair region is of the field coded distribution type and the predetermined macroblock is the bottom macroblock of the predetermined macroblock pair region, the neighboring macroblock to the top of the predetermined macroblock is determined to be the bottom macroblock of the macroblock pair region to the top of the predetermined macroblock pair region;
• assigning one of at least two context models to the predetermined syntax element of the predetermined macroblock based on a sum of the skip indicators of the neighboring macroblock to the left of the predetermined macroblock and the neighboring macroblock to the top of the predetermined macroblock, wherein each context model is associated with a different probability estimation;
• and
• arithmetically decoding the predetermined syntax element from the coded bit stream based on the probability estimation with which the assigned context model is associated.

An Apparatus for encoding a video signal representing at least one video frame, with the at least one video frame being composed of picture samples, the picture samples belonging either to a first or a second field being captured at different time instants, the video frame being spatially divided up into macroblock pair regions, each macroblock pair region being associated with a top and a bottom macroblock, the apparatus comprising

• means for deciding, for each macroblock pair region, as to whether the respective macroblock pair region is of a frame coded or a field coded distribution type;
• means for assigning, for each macroblock pair region, each of the pixel samples in the respective macroblock pair region to a respective one of the top and bottom macroblocks of the respective macroblock pair region, in accordance with the distribution type of the respective macroblock pair region;
• means for pre-coding the video signal into a pre-coded video signal, to obtain, for each macroblock, a syntax element for the respective macroblock, being a skip indicator specifying as to whether the respective macroblock is to be skipped when decoding the pre-coded video signal;
• means for determining, for the syntax element of a current macroblock associated with a current macroblock pair region of the macroblock pair regions,
• a neighboring macroblock to the left of the current macroblock at least based upon as to whether the current macroblock pair region is of a frame coded or field coded distribution type such that
• if the current macroblock pair region is of the field coded distribution type,
• the neighboring macroblock to the left of the current macroblock is determined to be a bottom macroblock of a macroblock pair region to the left of the current macroblock pair region, if the macroblock pair region to the left is also of the field coded distribution type and the current macroblock is the bottom macroblock of the current macroblock pair region, and
• the neighboring macroblock to the left of the current macroblock is determined to be a top macroblock of the macroblock pair region to the left of the current macroblock pair region, if the macroblock pair region to the left is of the frame coded distribution type, or if the macroblock pair region to the left is of the field coded distribution type with the current macroblock being the top macroblock of the current macroblock pair region, and
• if the current macroblock pair region is of the frame coded distribution type,
• the neighboring macroblock to the left of the current macroblock is determined to be the bottom macroblock of the macroblock pair region to the left of the current macroblock pair region, if the macroblock pair region to the left is also of the frame coded distribution type and the current macroblock is the bottom macroblock of the current macroblock pair region, and
• the neighboring macroblock to the left of the current macroblock is determined to be the top macroblock of the macroblock pair region to the left of the current macroblock pair region, if the macroblock pair region to the left is of the field coded distribution type, or if the macroblock pair region to the left is of the frame coded distribution type with the current macroblock being the top macroblock of the current macroblock pair region and;
• a neighboring macroblock to the top of the current macroblock at least based upon as to whether the current macroblock pair region is of a frame or field coded distribution type such that
• if the current macroblock pair region is of the frame coded distribution type the neighboring macroblock to the top of the current macroblock is determined to be
• a top macroblock of the current macroblock pair region if the current macroblock is the bottom macroblock of the current macroblock pair region, and
• a bottom macroblock of the macroblock pair region to the top of the current macroblock pair region if the current macroblock is the top macroblock of the current macroblock pair region,
• if the current macroblock pair region is of the field coded distribution type and the current macroblock is the top macroblock of the current macroblock pair region, the neighboring macroblock to the top of the current macroblock is determined to be
• the bottom macroblock of the macroblock pair region to the top of the current macroblock pair region, if the macroblock pair region to the top of the current macroblock pair region is of the frame coded distribution type,
• the top macroblock of the macroblock pair region to the top of the current macroblock pair region, if the macroblock pair region to the top of the current macroblock pair region is of the field coded distribution type,
• if the current macroblock pair region is of the field coded distribution type and the current macroblock is the bottom macroblock of the current macroblock pair region, the neighboring macroblock to the top of the current macroblock is determined to be the bottom macroblock of the macroblock pair region to the top of the current macroblock pair region,
• means for assigning one of at least two context models to the current syntax element of the current macroblock based on a sum of the skip indicators of the neighboring macroblock to the left of the current macroblock and the neighboring macroblock to the top of the current macroblock, wherein each context model is associated with a different probability estimation;
• and
• means for arithmetically encoding the syntax element of the current macroblock into a coded bit stream based on the probability estimation with which the assigned context model is associated.

An apparatus for decoding a predetermined syntax element among syntax elements of a coded bit stream from the coded bit stream, the coded bit stream being an arithmetically encoded version of a pre-coded video signal, the pre-coded video signal being a pre-coded version of a video signal, the video signal representing at least one video frame being composed of picture samples, the picture samples belonging either to a first or a second field being captured at a different time instants, the video frame being spatially divided up into macroblock pair regions, each macroblock pair region being associated with a top and a bottom macroblock, each macroblock pair region being either of a frame coded or a field coded distribution type, wherein, for each macroblock pair region, each of the pixel samples in the respective macroblock pair region is assigned to a respective one of the top and bottom macroblock of the respective macroblock pair region in accordance with the distribution type of the respective macroblock pair region, wherein each of the macroblocks is associated with a respective one of the syntax elements, the predetermined syntax element relating to a predetermined macroblock of the top and bottom macroblocks of a predetermined macroblock pair region of the macroblock pair regions, each syntax element being a skip indicator specifying, for the respective macrobloc, as to whether the respective macroblock is to be skipped when decoding the pre-coded video signal, wherein the apparatus comprises

• means for determining, for the predetermined syntax element,
• a neighboring macroblock to the left of the predetermined macroblock at least based upon as to whether the predetermined macroblock pair region is of the frame coded or field coded distribution type such that
• if the predetermined macroblock pair region is of the field coded distribution type,
• the neighboring macroblock to the left of the predetermined macroblock is determined to be a bottom macroblock of a macroblock pair region to the left of the predetermined macroblock pair region, if the macroblock pair region to the left is also of the field coded distribution type and the predetermined macroblock is the bottom macroblock of the predetermined macroblock pair region, and
• the neighboring macroblock to the left of the predetermined macroblock is determined to be a top macroblock of the macroblock pair region to the left of the predetermined macroblock pair region, if the macroblock pair region to the left is of the frame coded distribution type, or if the macroblock pair region to the left is of the field coded distribution type with the predetermined macroblock being the top macroblock of the predetermined macroblock pair region, and
• if the predetermined macroblock pair region is of the frame coded distribution type,
• the neighboring macroblock to the left of the predetermined macroblock is determined to be the bottom macroblock of the macroblock pair region to the left of the predetermined macroblock pair region, if the macroblock pair region to the left is also of the frame coded distribution type and the predetermined macroblock is the bottom macroblock of the predetermined macroblock pair region, and
• the neighboring macroblock to the left of the predetermined macroblock is determined to be the top macroblock of the macroblock pair region to the left of the predetermined macroblock pair region, if the macroblock pair region to the left is of the field coded distribution type, or if the macroblock pair region to the left is of the frame coded distribution type with the predetermined macroblock being the top macroblock of the predetermined macroblock pair region and;
• a neighboring macroblock to the top of the predetermined macroblock at least based upon as to whether the predetermined macroblock pair region is of a frame or field coded distribution type such that
• if the predetermined macroblock pair region is of the frame coded distribution type the neighboring macroblock to the top of the predetermined macroblock is determined to be
• a top macroblock of the predetermined macroblock pair region if the predetermined macroblock is the bottom macroblock of the predetermined macroblock pair region, and
• a bottom macroblock of the macroblock pair region to the top of the predetermined macroblock pair region if the predetermined macroblock is the top macroblock of the predetermined macroblock pair region,
• if the predetermined macroblock pair region is of the field coded distribution type and the predetermined macroblock is the top macroblock of the predetermined macroblock pair region, the neighboring macroblock to the top of the predetermined macroblock is determined to be
• the bottom macroblock of the macroblock pair region to the top of the predetermined macroblock pair region, if the macroblock pair region to the top of the predetermined macroblock pair region is of the frame coded distribution type,
• the top macroblock of the macroblock pair region to the top of the predetermined macroblock pair region, if the macroblock pair region to the top of the predetermined macroblock pair region is of the field coded distribution
• if the predetermined macroblock pair region is of the field coded distribution type and the predetermined macroblock is the bottom macroblock of the predetermined macroblock pair region, the neighboring macroblock to the top of the predetermined macroblock is determined to be the bottom macroblock of the macroblock pair region to the top of the predetermined macroblock pair region
• means for assigning one of at least two context models to the predetermined syntax element of the predetermined macroblock based on a sum of the skip indicators of the neighboring macroblock to the left of the predetermined macroblock and the neighboring macroblock to the top of the predetermined macroblock, wherein each context model is associated with a different probability estimation;
• and
• means for arithmetically decoding the predetermined syntax element from the coded bit stream based on the probability estimation with which the assigned context model is associated.

At least one computer readable storage medium containing a computer program product for encoding a video signal representing at least one video frame, with the at least one video frame being composed of picture samples, the picture samples belonging either to a first or a second field being captured at different time instants, the video frame being spatially divided up into macroblock pair regions, each macroblock pair region being associated with a top and bottom macroblock, the computer program product comprising program code for performing the following steps:

• deciding, for each macroblock pair region, as to whether the respective macroblock pair region is of a first frame coded or a field coded distribution type;
• assigning, for each macroblock pair region, each of the pixel samples in the respective macroblock pair region to a respective one of the top and bottom macroblock of the respective macroblock pair region, in accordance with the distribution type of the respective macroblock pair region;
• pre-coding the video signal into a pre-coded video signal, to obtain, for each macroblock, a syntax element for the respective macroblock, being a skip indicator specifying as to whether the respective macroblock is to be skipped when decoding the pre-coded video signal;
• determining, for the syntax element of a current macroblock associated with a current macroblock pair region of the macroblock pair regions,
• a neighboring macroblock to the left of the current macroblock at least based upon as to whether the current macroblock pair region is of the frame coded or field coded distribution type such that
• if the current macroblock pair region is of the field coded distribution type,
• the neighboring macroblock to the left of the current macroblock is determined to be a bottom macroblock of a macroblock pair region to the left of the current macroblock pair region, if the macroblock pair region to the left is also of the field coded distribution type and the current macroblock is the bottom macroblock of the current macroblock pair region, and
• the neighboring macroblock to the left of the current macroblock is determined to be a top macroblock of the macroblock pair region to the left of the current macroblock pair region, if the macroblock pair region to the left is of the frame coded distribution type, or if the macroblock pair region to the left is of the field coded distribution type with the current macroblock being the top macroblock of the current macroblock pair region, and
• if the current macroblock pair region is of the frame coded distribution type,
• the neighboring macroblock to the left of the current macroblock is determined to be the bottom macroblock of the macroblock pair region to the left of the current macroblock pair region, if the macroblock pair region to the left is also of the frame coded distribution type and the current macroblock is the bottom macroblock of the current macroblock pair region, and
• the neighboring macroblock to the left of the current macroblock is determined to be the top macroblock of the macroblock pair region to the left of the current macroblock pair region, if the macroblock pair region to the left is of the field coded distribution type, or if the macroblock pair region to the left is of the frame coded distribution type with the current macroblock being the top macroblock of the current macroblock pair region and;
• a neighboring macroblock to the top of the current macroblock at least based upon as to whether the current macroblock pair region is of a frame or field coded distribution type such that
• if the current macroblock pair region is of the frame coded distribution type the neighboring macroblock to the top of the current macroblock is determined to be
• a top macroblock of the current macroblock pair region if the current macroblock is the bottom macroblock of the current macroblock pair region, and
• a bottom macroblock of the macroblock pair region to the top of the current macroblock pair region if the current macroblock is the top macroblock of the current macroblock pair region,
• if the current macroblock pair region is of the field coded distribution type and the current macroblock is the top macroblock of the current macroblock pair region, the neighboring macroblock to the top of the current macroblock is determined to be
• the bottom macroblock of the macroblock pair region to the top of the current macroblock pair region, if the macroblock pair region to the top of the current macroblock pair region is of the frame coded distribution type,
• the top macroblock of the macroblock pair region to the top of the current macroblock pair region, if the macroblock pair region to the top of the current macroblock pair region is of the field coded distribution type,
• if the current macroblock pair region is of the field coded distribution type and the current macroblock is the bottom macroblock of the current macroblock pair region, the neighboring macroblock to the top of the current macroblock is determined to be the bottom macroblock of the macroblock pair region to the top of the current macroblock pair region,
• assigning one of at least two context models to the current syntax element of the current macroblock based on a sum of the skip indicators of the neighboring macroblock to the left of the current macroblock and the neighboring macroblock to the top of the current macroblock, wherein each context model is associated with a different probability estimation;
• and
• arithmetically encoding the syntax element of the current macroblock into a coded bit stream based on the probability estimation with which the assigned context model is associated.

At least one computer readable storage medium containing a computer program product for decoding a predetermined syntax element among syntax elements of a coded bit stream from the coded bit stream, the coded bit stream being an arithmetically encoded version of a pre-coded video signal, the pre-coded video signal being a pre-coded version of a video signal, the video signal representing at least one video frame being composed of picture samples, the picture samples belonging either to a first or a second field being captured at a different time instants, the video frame being spatially divided up into macroblock pair regions, each macroblock pair region being associated with a top and a bottom macroblock, each macroblock pair region being either of a frame coded or a field coded distribution type, wherein, for each macroblock pair region, each of the pixel samples in the respective macroblock pair region is assigned to a respective one of the top and bottom macroblock of the respective macroblock pair region in accordance with the distribution type of the respective macroblock pair region, wherein each of the macroblocks is associated with a respective one of the syntax elements, the predetermined syntax element relating to a predetermined macroblock of the top and bottom macroblocks of a predetermined macroblock pair region of the macroblock pair regions, each syntax element being a skip indicator specifying, for the respective macroblock, as to whether the respective macroblock is to be skipped when decoding the pre-coded video signal, the computer program product comprising program code for performing the following steps:

• determining, for the predetermined syntax element,
• a neighboring macroblock to the left of the predetermined macroblock at least based upon as to whether the predetermined macroblock pair region is of a frame coded or field coded distribution type such that
• if the predetermined macroblock pair region is of the field coded distribution type,
• the neighboring macroblock to the left of the predetermined macroblock is determined to be a bottom macroblock of a macroblock pair region to the left of the predetermined macroblock pair region, if the macroblock pair region to the left is also of the field coded distribution type and the predetermined macroblock is the bottom macroblock of the predetermined macroblock pair region, and
• the neighboring macroblock to the left of the predetermined macroblock is determined to be a top macroblock of the macroblock pair region to the left of the predetermined macroblock pair region, if the macroblock pair region to the left is of the frame coded distribution type, or if the macroblock pair region to the left is of the field coded distribution type with the predetermined macroblock being the top macroblock of the predetermined macroblock pair region, and
• if the predetermined macroblock pair region is of the frame coded distribution type,
• the neighboring macroblock to the left of the predetermined macroblock is determined to be the bottom macroblock of the macroblock pair region to the left of the predetermined macroblock pair region, if the macroblock pair region to the left is also of the frame coded distribution type and the predetermined macroblock is the bottom macroblock of the predetermined macroblock pair region, and
• the neighboring macroblock to the left of the predetermined macroblock is determined to be the top macroblock of the macroblock pair region to the left of the predetermined macroblock pair region, if the macroblock pair region to the left is of the field coded distribution type, or if the macroblock pair region to the left is of the frame coded distribution type with the predetermined macroblock being the top macroblock of the predetermined macroblock pair region and;
• a neighboring macroblock to the top of the predetermined macroblock at least based upon as to whether the predetermined macroblock pair region is of a frame or field coded distribution type such that
• if the predetermined macroblock pair region is of the frame coded distribution type the neighboring macroblock to the top of the predetermined macroblock is determined to be
• a top macroblock of the predetermined macroblock pair region if the predetermined macroblock is the bottom macroblock of the predetermined macroblock pair region, and
• a bottom macroblock of the macroblock pair region to the top of the predetermined macroblock pair region if the predetermined macroblock is the top macroblock of the predetermined macroblock pair region,
• if the predetermined macroblock pair region is of the field coded distribution type and the predetermined macroblock is the top macroblock of the predetermined macroblock pair region, the neighboring macroblock to the top of the predetermined macroblock is determined to be
• the bottom macroblock of the macroblock pair region to the top of the predetermined macroblock pair region, if the macroblock pair region to the top of the predetermined macroblock pair region is of the frame coded distribution type,
• the top macroblock of the macroblock pair region to the top of the predetermined macroblock pair region, if the macroblock pair region to the top of the predetermined macroblock pair region is of the field coded distribution
• if the predetermined macroblock pair region is of the field coded distribution type and the predetermined macroblock is the bottom macroblock of the predetermined macroblock pair region, the neighboring macroblock to the top of the predetermined macroblock is determined to be the bottom macroblock of the macroblock pair region to the top of the predetermined macroblock pair region;
• assigning one of at least two context models to the predetermined syntax element of the predetermined macroblock based on a sum of the skip indicators of the neighboring macroblock to the left of the predetermined macroblock and the neighboring macroblock to the top of the predetermined macroblock, wherein each context model is associated with a different probability estimation;
• and
• arithmetically decoding the predetermined syntax element from the coded bit stream based on the probability estimation with which the assigned context model is associated.