[M4IF Technotes] Trouble with Bframe: size goes bigger

[Ramkishor Korada]

Hi,
 There could be some problem with the rate control. You did not mention the PSNR achieved for different cases. 
As the details are not sufficient, difficult to analyze this problem. 
Realizing more compression efficiency by using more number of B frames is dependant on the temporal correlation in the sequence. Increasing the number of B frames does not improve compression efficiency always. 
regards,
ramkishor
Architect - Video
Multimedia Technologies Division
Emuzed India
Bangalore
www.emuzed.com
  ----- Original Message ----- 
  From: Francesco Falconi 
  To: technotes   lists.m4if.org 
  Sent: Tuesday, May 28, 2024 5:43 PM
  Subject: [M4IF Technotes] Trouble with Bframe: size goes bigger
  Hello to everyone,
  I hope someone can find two minutes to answer me. 
  I show you this test: they are only 8 frames to compress, (frame base cosing). My test is about advantage in size compression using more bframe than Pframe. 
  The GOP is 8 frame and i try to change the number of P-B frame (fixing numer of Iframe).
  So i change the value of  Motion.PBetweenICount  and Motion.BBetweenPCount 
  These are the results:
        P=    B=
       GOP 
       Size cmp
       fps
        0    6
       I B B B B B B I
       15944
       0,4097
        1    3
       I B B B P B B I
       14804
       1,3095
        3    1
       I B P B P B P I
       14065
       2,4133
        6    0
       I P P P P P P I
       14023
       2,8229
  I cant't understand why adding Bframe the size goes bigger, it could be the opposite (accordin Mpeg Theory). I try to make other test, the same results.
  Could you explain me the reason?
  Thank you vaery much, this is for my university thesis.
  Francesco Falconi
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