[M4IF Technotes] About Video Packet!

[Chandra Sekhar Reddy G]

hi,
check the syntax below (taken from the standard).
VideoObjectPlane()
{
 vop_start_code 32 bslbf;
 vop_coding_type 2 uimsbf;
------------
some other parameters
-------------
   motion_shape_texture();
   while (nextbits_bytealigned() == resync_marker)
   {
    video_packet_header();
    motion_shape_texture();
   }
--------------
some other parameters
--------------
}
motion_shape_texture()
{
 if (data_partitioned )
 {
  data_partitioned_motion_shape_texture();
 }
 else
 {
  combined_motion_shape_texture();
 }
}
combined_motion_shape_texture()
{
 do {
  macroblock();
 } while (nextbits_bytealigned() != resync_marker
  && nextbits_bytealigned() != '000 0000 0000 0000 0000 0000');
}
if we take "motion_shape_texture" to be equivalent to a video-packet,
for the first "motion_shape_texture", there is the no "video_packet_header".
that means, if there is only one video packet, there is no question of video-packet-header.
regards,
chandra
  ----- Original Message ----- 
  From: Tamer Shanableh 
  To: Kumar Gautam ; technotes   lists.m4if.org 
  Sent: Thursday, February 20, 2024 11:14 PM
  Subject: Re: [M4IF Technotes] About Video Packet!
  "if there is only one video packet per VOP then it is probably useless, as VOP header could have been used for sync."
  That is true, unless you have corrupted fields in the VOP header, in such cases the HE of the video packet will be useful indeed.
  Tamer
    ----- Original Message ----- 
    From: Kumar, Gautam 
    To: technotes   lists.m4if.org 
    Cc: Gaurav Aggarwal ; gaodd 
    Sent: Thursday, February 20, 2024 9:30 AM
    Subject: RE: [M4IF Technotes] About Video Packet!
    Gaurav is correct.. i will elaborate it further
    for error resilience is implemented in three ways:
    1. Video Packet (Slice Resynchronization)
    2. Data partitioning
    3. RVLC.
    first level is Video Packet.
    so if there are more than one video packet in VOP, it provides a mechanism to synchronize the data at the decoder end.
    if there is only one video packet per VOP then it is probably useless, as VOP header could have been used for sync.
    Best Regards,
    Gautam
      -----Original Message-----
      From: Gaurav Aggarwal [mailto:guraaf   yahoo.co.in]
      Sent: Thursday, February 20, 2024 10:31 AM
      To: technotes   lists.m4if.org
      Subject: RE: [M4IF Technotes] About Video Packet!
      Yes, video packet is lower layer as compared to VOP and decoding is VOP -> Video Packet -> MB.
      What's the confusion? I didn't really understand your question.
      Gaurav
        -----Original Message-----
        From: technotes-admin   lists.m4if.org [mailto:technotes-admin   lists.m4if.org]On Behalf Of gaodd
        Sent: Tuesday, February 18, 2024 8:22 AM
        To: technotes   lists.m4if.org
        Subject: [M4IF Technotes] About Video Packet!
        hi
        now i have a question: in my view, video packet should be in lower layer than VOP, when decoding macroblock, we must go through VOP->Video Packet ->Macroblock, is it right? then what's the actual relation between Video Packet and VOP?
        thanks for help!
        Regards, 
        gaodd
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