[M4IF Technotes] VBV underflow problems

[Ramkishor Korada]

Hi,
 One solution is do not wait till the underflow actually happens. Predict
the buffer underflow ahead and start reacting i.e., start stuffing.
regards,
ramkishor
Architect - Video
Multimedia Technologies Division
Emuzed India
Bangalore
www.emuzed.com
----- Original Message -----
From: <arcangelo.bruna   st.com>
To: <technotes   lists.m4if.org>
Sent: Friday, May 24, 2024 1:47 PM
Subject: [M4IF Technotes] VBV underflow problems
>      Hi.
>      I'm implementing a real time Simple Profile encoder.
>      I have a problem in the VBV implementation.
>      The standard says to use the stuffing bits (bytes) to avoid
underflow,
>      but, in this profile, only the stuffing MB are allowable, because the
>      stuffing_start_code can not be used.
>
>      Unfortunately, for a real time implementation, it is not really a
>      simple thing: in fact, they can not introduced in the next frame
>      because it will be inserted in the VB surely when it is already
empty.
>      So we must insert them only in the already encoded frame, so the
frame
>      size become bigger.
>      But what happen if the frame size become too bigger so that when the
>      decoder requires it the frame it is not transmitted at all?
>
>      Another problem: we can not re-encode the frame (due to the real time
>      encoding constraints), so we will insert the stuffing MB at the end
of
>      the frame. But what happen if, using the Video Packet, the last video
>      packet become bigger than the profile's constraints (2048 bits for
the
>      SP   L1)?
>
>      All these problems could be avoided allowing the stuffing_start_code
>      in each profiles & levels. Is there a reason why it is not so? Is
>      possible to suggest it to the standardization committee?
>
>      Thanks,
>         Arcangelo.
>
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