[M4IF Technotes] Use of B-frames

[Gregorio Litinsky]

Dear Colleagues:
I am investigating the use and benefits of B-frames for low bit rate 
communication.
As you all probably know, B-frames are commonly used in MPEG-1 and MPEG-2 
compression. They are bi-directionally predicted in the same fashion from 
either preceding or subsequent I- or P-frames. Where a P-frame generally 
requires 1/2 of the data of an I-frame, a B-frame requires only 1/4.
Could you please help me with the following questions:
1. What is the minimum bit and frame rate where B-frames improve the 
quality? A minimum of 10 fps and 144 Kbps has been mentioned.
2. Which profile supports B-frames? MPEG-4 Simple  Scalable Visual Profile 
supports B-frames, but I understand that this profile requires support for 
temporal and spatial scalability? Is it possible from a compliance 
perspective to only support B-frames in the MPEG-4 Simple  Scalable Visual 
Profile?
3. H.263 (Profile 8) does also support B-frames (Annex M). Is this codec 
better than MPEG-4 Simple  Scalable Visual Profile?
4. Does the MPEG-4 Advanced Simple Visual Profile support B-frames?
5. Does the new H.26L codec support B-frames?
6. Which profile/codes do you recommend for supporting B-frames?
7. Where can I find documentation about profiles/codecs supporting B-frames?
Best Regards,
Gregorio Litinsky
Consultant
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