[Mp4-tech] Re: Mp4-tech Digest, Vol 49, Issue 16

[Sugeeth]

Reply to Ashfiqua:
I have some questions regarding the H.264 encoding (I am using JM12.2):
  1. Is there any way to find out the number of encoded bits before performing the encoding? I mean how can I know that the encoded I frame will contain x bits, P frame will contain y bits etc.?
    As far as i know , it may not be practically possible to predict the exact number of bits , more over , the bits will not match between 2 encoders, because in all probability, the MotionEstimation algorithm will differ and hence accordingly, skip decisions, motion vectors will vary. Hence, the Encoded bits wont match. I even dont think it is possible to predict the exact number of bits in your own encoder. Anyway, wat is the reason for you to know this? Can may be suggest you an alternative solution, if i know.
  2. And if I want that each I and P frame will contain exactly 2 slices, how to do that?
     H.264 supports slices of any nature. Baseline profile in h.264 supports upto 8 slices and the slices can be of any order and of any size. You can configure your slices to be exactly same for a resolution  CIF - 22 MB's (352*288) , but it is not possible to do so for a resolution like D1 as it has 45 MB's in its width. you cannot have 2 exact slices for D1 resolution. A 23 MB/22MB width slice split would be ideal for D1.( incase you want to use 2 slices only).
  3. After encoding, how can I know that this packet belongs to I, P or B frame?
     There is information coded within a NAL unit that tells information like Frame type, Deblocking filter, MBtype, MV difference, Modes for I frames.. Refer to the Decoder parser functions to get the relevant information in detail.
  I'll highly appreciate any information regarding this.
  Thanking you,
  Ashfiqua
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> Today's Topics:
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>    1. Number of bits encoded (ashfiqua tahseen)
>    2. FGS Specification Document (Erik van Zijst)
>    3. Re: FGS Specification Document (Herbert Thoma)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 21 Aug 2023 17:30:25 -0700 (PDT)
> From: ashfiqua tahseen <ashfiqua03 yahoo.com>
> Subject: [Mp4-tech] Number of bits encoded
> To: mp4-tech lists.mpegif.org
> Message-ID: <476622.78212.qm web53409.mail.re2.yahoo.com>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Hi,
>    
>   I have some questions regarding the H.264 encoding (I am using JM12.2):
>    
>   1. Is there any way to find out the number of encoded bits before performing the encoding? I mean how can I know that the encoded I frame will contain x bits, P frame will contain y bits etc.?
>    
>   2. And if I want that each I and P frame will contain exactly 2 slices, how to do that?
>    
>   3. After encoding, how can I know that this packet belongs to I, P or B frame?
>    
>   I'll highly appreciate any information regarding this.
>    
>   Thanking you,
>   Ashfiqua
>
>        
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> Message: 2
> Date: Wed, 22 Aug 2023 12:30:38 +0200
> From: Erik van Zijst <mp4-tech erik.prutser.cx>
> Subject: [Mp4-tech] FGS Specification Document
> To: mp4-tech lists.mpegif.org
> Message-ID: <46CC104E.4060206 erik.prutser.cx>
> Content-Type: text/plain; charset=windows-1252; format=flowed
>
> Hi folks,
>
> I'd like to know where I can find the specification of the MPEG-4 FGS 
> technology (Fine Grained Scalability). I’ve got the MPEG-4 ISO document 
> of 2001, but it is not listed there. Is it in the 2004 version?
>
> I've browsed the ISO website and it looks like FGS could be found in 
> ISO/IEC 14496-2:2004, but before continue to purchase this rather 
> expensive document, I'd like to be sure that is indeed in there. Anyone 
> out there who can confirm or deny this?
>
> cheers,
> Erik van Zijst
>