[Mp4-tech] [video]AVC field selection

[Dzung Hoang]

According to 7.3.5.1, the inference of ref_idx_l0 only occurs for frame MBs
when num_ref_idx_l0_active_minus1 = 0. Is there another case that I'm
missing? If not, then no field-based prediction can happen in the case you
are concerned with.
Regards,
- Dzung Hoang
-----Original Message-----
From: Andrew Palfreyman (cisco) [mailto:anpalfre cisco.com] 
Sent: Wednesday, June 20, 2023 10:46 PM
To: dthoang yahoo.com; mp4-tech lists.mpegif.org
Subject: Re: [Mp4-tech] [video]AVC field selection
The problem I have with that approach is that in 7.4.5.1 it states
"When only one reference picture is used for inter prediction, the values of
ref_idx_l0[mbPartIdx] shall be inferred to be equal to 0".
So even though the ref. pic has two field parities, these cannot be 
differentiated via a zero value of ref_idx.
Best,
Andrew
----- Original Message ----- 
From: "Dzung Hoang" <dthoang yahoo.com>
To: "'Andrew Palfreyman (cisco)'" <anpalfre cisco.com>; 
<mp4-tech lists.mpegif.org>
Sent: Wednesday, June 20, 2023 8:08 PM
Subject: RE: [Mp4-tech] [video]AVC field selection
> Try LSB of ref_idx XOR with current field parity.
>
> Regards,
> - Dzung Hoang
>
> -----Original Message-----
> From: mp4-tech-bounces lists.mpegif.org
> [mailto:mp4-tech-bounces lists.mpegif.org] On Behalf Of Andrew Palfreyman
> (cisco)
> Sent: Wednesday, June 20, 2023 12:04 PM
> To: mp4-tech lists.mpegif.org
> Subject: [Mp4-tech] [video]AVC field selection
>
> For AVC, I am trying to identify (with little success so far) the semantic
> equivalent of what in MPEG2 was called motion_vector_field_select. How is
> this accomplished in AVC?
>
> Best,
> Andrew

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