[Mp4-tech] IDR period and intra period

[Satendra]

Simple terminology
IDR picture is a superset of Intra picture.
IDR picture is an Intra picture, but it says that now onwards decoder can
not use any of the previously decoded pictures as reference picture for
inter decoding.
Best Regards
Satendra
On Mon, Mar 17, 2024 at 10:43 PM, Venkat Subbiah <vsubbiah iavior.com>
wrote:
>
>    1. What is the difference between an IDR picture and Intra picture?
>
> *instantaneous decoding refresh (IDR) picture*: A *coded picture *in which
> all *slices *are *I *or *SI slices *that
>
> causes the *decoding process *to mark all *reference pictures *as "unused
> for reference" immediately after
>
> decoding the IDR picture. After the decoding of an IDR picture all
> following *coded pictures *in *decoding order*
>
> can be decoded without *inter prediction *from any *picture *decoded prior
> to the IDR picture. The first *picture *of
>
> each *coded video sequence *is an IDR picture.
>
>
>
> Above is the definition of an IDR picture from the standard. As you can
> see the focus of the definition is on "all picture all following *coded
> pictures *in *decoding order*
>
> can be decoded without *inter prediction *from any *picture *decoded prior
> to the IDR picture". This part might not be necessarily true for just an I
> picture.
>
>
>
> *I slice*: A *slice *that is not an *SI slice *that is decoded using *prediction
> *only from decoded samples within the
>
> same *slice*.
>
> Ø       Above again is a definition from the standard and as it reads the
> only restriction about I slice is the prediction is only from decoded
> samples within the same slice. And it does **not** say anything about
> following picture.
>
>
>
> -Venkat
>
>
>  ------------------------------
>
> *From:* mp4-tech-bounces lists.mpegif.org [mailto:
> mp4-tech-bounces lists.mpegif.org] *On Behalf Of *ashfiqua tahseen
> *Sent:* Friday, March 14, 2024 12:17 PM
> *To:* mp4-tech lists.mpegif.org
> *Subject:* [Mp4-tech] IDR period and intra period
>
>
>
> Hi,
>
>
>
> 1. What is the difference between an IDR picture and Intra picture? And
> what is the difference between IDR period and intra period?
>
>
>
> 2. We can set different QP for I and P slice. I am just curious, in real
> application, do the companies use different QP for tham?
>
>
>
> Any suggestion will be highly appreciated.
>
>
>
> With regards,
>
> Ashfiqua
>
>
>  ------------------------------
>
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>
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