[M4IF Technotes] MPEG-4 video stuffing bits

[Max Griessl]

There exists a possibility after VOP's in some cases (see document N4350, syntax 
description of VideoObjectLayer()):
if ((preceding_vop_coding_type == "B" || preceding_vop_coding_type == "S" ||
      video_object_layer_shape != "rectangular") &&
     next_bits() == stuffing_start_code)
{
    stuffing_start_code
    while (next_bits() !=  0000 0000 0000 0000 0000 0001 )
      stuffing_byte
}
stuffing_byte is '11111111'.
The other possibility is to use stuffing macro blocks, which works for all VOP 
types.
Bye,
Max Griessl
giuseppe.spampinato   st.com wrote:
>      Hi everybody,
>      in the MPEG-4 standard
>      at the end of each frame you have to insert
>      stuffing bits to be byte-aligned.
>      
>      But could you insert also different consecutive
>      bytes in this manner?
>      And which value these bytes must contain?
>      
>      Reading the standard this seems to be possible
>      and the value of the stuffing bytes should be "011111111",
>      but Momusys decoder does not support this feature,
>      while Microsoft decode these bytes correctly.
>      
>      Is it a bug in Momusys decoder (also in the last version
>      contained in the file w4711.zip) or it is not allowed
>      by the standard.
>      
>      If it is not allowed by the standard, where can I
>      insert other bytes to satisfy the Video Buffer Verifier
>      and avoid underflow? 
>      
>      
>      Many thanks!!!
>      Giuseppe Spampinato
> 
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-- 
Max Griessl                                 DynaPel Laboratories GmbH
Software Design                             Fraunhoferstr. 9/2
Tel: +49 (0) 89 96242812                    D-85737 Ismaning, Germany
Fax: +49 (0) 89 96242890                    http://www.dynapel.de