What is claimed is:
1. A dot recording apparatus, comprising:
a recording head, having a head face on which at least one row of dot forming elements which form dots on a recording medium are arranged in a subscanning direction thereof;
a drive feeding roller, extending in a main scanning direction of the recording head;
a plurality of driven feeding rollers, arranged in the main scanning direction with a predetermined interval, such that the recording head is nipped between the drive feeding roller and the driven feeding rollers to be fed to the recording head; and
a plurality of medium regulators, arranged in the main scanning direction with a predetermined interval which is associated with the arrangement of the driven feeding rollers, the medium regulators being opposed to the head face such that top faces define a distance between the recording medium carried thereon and the head face.
2. The dot recording apparatus as set forth in claim 1, wherein each of the medium regulator extends in the subscanning direction such that the top face thereof while being beyond a portion opposed to an upstream end of the dot row of the dot forming elements.
3. The dot recording apparatus as set forth in claim 1, wherein the predetermined interval of the medium regulator is 20 mm or more.
4. The dot recording apparatus as set forth in claim 1, further comprising a subregulator, disposed between the respective adjacent medium regulators at an area opposed to a downstream side of the head face to support the recording medium together with the medium regulators.
5. The dot recording apparatus as set forth in claim 4, wherein a top face of the subregulator is not higher than the top face of the medium regulator.
6. The dot recording apparatus as set forth in claim 1, further comprising a plurality of discharging roller pairs for discharging the recording medium on which dots are recorded by the recording head,
wherein each of the discharging roller pairs and the associated medium regulator are situated on the same line which extends in the subscanning direction.
7. The dot recording apparatus as set forth in claim 1, wherein two adjacent driven feeding rollers are connected with a shaft which extends in the main scanning direction to form a driven feeding roller unit; and
wherein each of the medium regulator and a center portion in the main scanning direction of the shaft in each of the driven feeding roller unit are situated on the same line which extends in the subscanning direction.
8. The dot recording apparatus as set forth in claim 1, wherein each of the medium regulator and a center portion in the main scanning direction of the associated driven feeding roller are situated on the same line which extends in the subscanning direction.
9. The dot recording apparatus as set forth in claim 1, wherein each of the medium regulator and a center portion in the main scanning direction of every other driven feeding roller are situated on the same line which extends in the subscanning direction.
10. The dot recording apparatus as set forth in claim 1, wherein each of the medium regulator and a portion of the associated driven feeding roller, where is shifted from the center portion thereof in the main scanning direction, are situated on the same line which extends in the subscanning direction.
11. The dot recording apparatus as set forth in claim 1, wherein two adjacent driven feeding rollers are connected with a shaft which extends in the main scanning direction to form a driven feeding roller unit; and
wherein each of the medium regulator and an associated portion between the adjacent driven feeding roller units are situated on the same line which extends in the subscanning direction.
12. The dot recording apparatus as set forth in claim 1, wherein the outermost medium regulator is disposed such that a side edge of the recording medium is placed on a substantially center portion in the main scanning direction of the top face thereof.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1-12. (canceled)
13. Method for detecting errors in received packetized video data, wherein the video data contain a base-layer and at least one enhancement-layer and each layer is organized in frames or slices with a respective header and a group-of-picture structure, wherein the GOP structure contains a plurality of complete GOPs and an incomplete GOP, wherein the incomplete GOP has less pictures or frames than a complete GOP, the method comprising the steps of
reading header information relating to a layer;
generating from the header information a scheme, or selecting a predefined scheme according to said header information, the scheme comprising at least display order number, number of reference frames and temporal level for the frames within a GOP of the respective layer;
extracting from received video data frames parameters, the parameters including display order number, number of reference frames and temporal level;
detecting that one or more frames or packets are missing, wherein the received parameters are compared with the parameters of expected frames according to said scheme and a missing packet or frame is determined by a mismatch between received and expected parameters;
determining for a missing frame if it belongs to a complete GOP or to the incomplete GOP; and
in the case of an incomplete GOP, estimating the maximum GOP size of the incomplete GOP, and generating default packets for missing frames of the incomplete GOP with display order numbers unto the estimated GOP size, and not generating default packets for missing frames with display order numbers above the estimated GOP size.
14. Method according to claim 13, further comprising the steps of
generating for each missing packet or frame a default packet, wherein each default packet gets the display order number, number of reference frames and temporal level of the respective expected packet; and
inserting for each missing packet the generated default packet into the data stream before the data stream is parsed.
15. Method according to claim 13, wherein said inserting of default packets is performed also for all missing frames that belong to complete GOPs.
16. Method according to claim 13, wherein the step of estimating the maximum GOP size of an incomplete GOP comprises
selecting a received frame with odd display order number, the frame having a frame_num parameter value of fc,frame\u2014num;
calculating an upper bound for the GOP size according to GopSizeabn,max=((fc,frame\u2014num\u22121) % (GopSize>>1)<<1)+1 wherein the calculated upper bound is used as estimated maximum GOP size.
17. Method according to claim 13, wherein said header information contains an indication (log2_min_poc_increase) of the difference between the POC numbers of successive frames of a defined spatial layer.
18. Method according to claim 13, wherein said defined spatial layer is the spatial base-layer.
19. Method according to claim 17, wherein the indication is the log2 of said difference.
20. Signal containing packetized video data, wherein the video data are organized in frames or slices and have a respective header and a group-of-picture structure containing a plurality of GOPs, with a plurality of complete GOPs and one incomplete GOP having less pictures or frames than a complete GOP, and wherein each video frame or slice comprises at least an indication of its POC number, and wherein said header contains an indication (log2_min_poc_increase) of the difference between the display order numbers of successive frames.
21. Signal according to claim 20, wherein the video signal has two or more spatial layers and the indication of the difference between the display order numbers of successive frames refers to the frames of a defined spatial layer.
22. Apparatus for detecting errors in received packetized video data, wherein the video data contain a base-layer and at least one enhancement-layer and each layer is organized in frames or slices with a respective header and a group-of-picture structure, wherein the GOP structure contains a plurality of complete GOPs and an incomplete GOP, wherein the incomplete GOP has less pictures or frames than a complete GOP, the apparatus comprising
means for reading header information relating to a layer;
means for generating from the header information a scheme, or selecting a predefined scheme according to said header information, the scheme comprising at least display order number, number of reference frames and temporal level for the frames within a GOP of the respective layer;
means for extracting from received video data frames parameters, the parameters including display order number, number of reference frames and temporal level;
means for detecting that one or more frames or packets are missing, wherein the received parameters are compared with the parameters of expected frames according to said scheme and a missing packet or frame is determined by a mismatch between received and expected parameters;
means for determining for a missing frame if it belongs to a complete GOP or to the incomplete GOP;
means for estimating, in the case of an incomplete GOP, the maximum GOP size of the incomplete GOP; and
means for generating default packets for missing frames of the incomplete GOP with display order numbers unto the estimated GOP size, wherein for incomplete GOPs default packets for missing frames with display order numbers above the estimated GOP size are not generated.
23. Apparatus according to claim 22, further being adapted for performing a method according to claim 14.