[Mp4-tech] RE: [jvt-experts] rate control code reorganization since JM12.0?

[James (Jianpeng) Dong]

Dear Leontaris,
  Thanks a lot.
  James 
"Leontaris, Athanasios" <aleon dolby.com> wrote:
        Dear James,
  IMG_NUMBER stands for #define IMG_NUMBER (img->number - start_frame_no_in_this_IGOP)
  When the parameter input->NumFrameIn2ndIGOP is set to 0, the IMG_NUMBER returns 0 if the current frame is the first frame in the sequence, and is non-zero otherwise. 
  IMG_NUMBER is primarily useful for differentiating between the first IDR intra-coded picture and Intra-coded pictures inserted within the sequence, as well as for making sure that the rate control works for interlaced coding. This is because the first frame that is composed of two fields may be encoded as I_SLICE (top) and P_SLICE (bottom). The pre-JM 12.0 rate control used a fixed pre-determined QP for all INTRA slices, which is not true anymore, as with RCUpdateMode=1, 2, and 3 one can apply rate control to INTRA slices at arbitrary points in the image sequence.
  Some of these changes were necessary in the original implementation to support these enhancements. However, we then restructured the code and some unnecessary operations may have still remained, which we have not completely cleaned up. This does not impact in any way the operation of the rate control (img->number is zero only for the first frame). Cleanups will be provided in future versions.
  Best regards,
  Thanos
---------------------------------
  From: James (Jianpeng) Dong [mailto:jianpengdong yahoo.com] 
Sent: Tuesday, March 06, 2024 5:10 PM
To: Leontaris, Athanasios; jvt-experts lists.rwth-aachen.de
Cc: mp4-tech lists.mpegif.org
Subject: RE: [jvt-experts] rate control code reorganization since JM12.0?
Dear Thanos and others,
I have a simple question regarding the addition of IMG_NUMBER macro in the rate control algorithm. What is the purpose and what actually IMG_NUMBER stands for? The original G012 does not have this.
Best and thanks,
James
"Leontaris, Athanasios" <aleon dolby.com> wrote:       Dear James,
  You can find more information on the underlying rate control algorithm in documents JVT-G012 and JVT-K049. The algorithm used for all-intra coding is essentially the same as the one used for P-coded pictures. The main difference is that for RCUpdateMode=1 the rate control treats all frames the same regardless of the slice type.
  Best regards,
  Thanos
---------------------------------
  From: James (Jianpeng) Dong [mailto:jianpengdong yahoo.com] 
Sent: Monday, March 05, 2024 11:51 PM
To: Leontaris, Athanasios; jvt-experts lists.rwth-aachen.de
Cc: mp4-tech lists.mpegif.org
Subject: RE: [jvt-experts] rate control code reorganization since JM12.0?
  Thanks a lot.
  May I ask what the basic rate control algorithm is for all intra coding? 
  Thanks again,
  James
"Leontaris, Athanasios" <aleon dolby.com> wrote:
      Dear James,
  We have corrected several bugs and cleaned up the rate control code considerably. Furthermore, the architecture was modified so that it is more "object-oriented", and hence easier to understand and modify. Support was added for MBAFF and PicAFF coding, hierarchical B-pictures structures, RD Picture Decision, and all-Intra coding. 
  The underlying rate control algorithms (the quadratic QP and linear MAD models) remain essentially the same, and we are going to prepare documentation for all the changes in the upcoming JVT meeting.
  Best regards,
  Thanos
---------------------------------
  From: jvt-experts-bounces lists.rwth-aachen.de [mailto:jvt-experts-bounces lists.rwth-aachen.de] On Behalf Of James (Jianpeng) Dong
Sent: Monday, March 05, 2024 9:07 PM
To: jvt-experts lists.rwth-aachen.de
Cc: mp4-tech lists.mpegif.org
Subject: [jvt-experts] rate control code reorganization since JM12.0?
  Dear Experts,
  I noticed that there is a major revision/reorganization of the rate control code since JM 12.0. Just wondering what are the improvements? Is there any JVT documents decribing the new features available?
  Best regards,
  James
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