Images, frames, slices, and Nalu are some of the concepts that are often confusing to people who have studied H. m, and I am here to elaborate on my own understanding, and welcome you to discuss:
The innovation of the concept of H.
no concept of I-frames, p-frames, B-frames, or IDR frames at all。 For some of the concepts appearing in H. S, from large to small, the following sequence is:
sequence, image, slice Group, slice, NALU, macro block, Yahong block, block, Pixel。 Here are a few points worth explaining:
(1) in the agreement of H.
An image is a collection conceptTop
fields, bottom fields, and frames can all be called images(The concept of this image is a collection concept). So we can see what we are familiar with in terms of the term "H.", for example:
I-frames, P-frames, B-frames, and so on, we actually have the concept of the image to be specific and small。 We
The "frame" mentioned in the "H" is usually the image that does not divide the field;
(2), if
do not use FMO (flexible macro block sorting)Mechanism, then
An image has only one slice set；
(3), if
without the use of multiple slices, only one slice of a slice；
(4), if
Do not useDP (
Data Segmentation) Mechanism, the
A piece is a Nalu，
a Nalu is also a piece。 Otherwise
a piece made up of three Nalu(that is, the standard "table 7-1" Nal_unit_type values are 2, 3, 4
three xNalu belongs to a piece);
2 coded stripe data split block a slice_data_partition_a_layer_rbsp ()
3 coded stripe data split block B slice_data_partition_b_layer_rbsp ()
4 coded stripe data split block C slice_data_partition_c_layer_rbsp ()(5), the above-mentioned
the size relationship between slices and nalu is not an abstract conceptual dependency。 From the concept of
Subordinate RelationshipOn the view,
NaluIn fact
It 's a set concept of a piece., for example: Nalu with the Nal_unit_type value of 5 in the standard "table 7-1" includes
I or SI tablets.
an image is divided according to the type of film that makes up it., can be divided into standard
8 types in "Table 7-5"。 The most common in our usual applications
These are actually the typesThe special case. For example:
What we normally call "I-frames" and "IDR frames",is actually
Primary_pic_type image with a value of 0, what we normally call "
P-Frame "is actually a special case of an image with a primary_pic_type value of 1，
our usual so-called "B-Frame" is actually a special case of an image with a primary_pic_type value of 2.
an image can be divided into two types according to the concept of：
IDR images and non-IDR images。 Whether an image is
IDR Imageis made up of the
The Nalu decision of the image, if the group
The Nalu of this image is the standard "table 7-1" with a Nal_unit_type value of 5 Nalu, then the
image as IDR image, otherwise the
non-IDR images。 Here are a few things to note:
(1), Nal_unit_type value of 5 Nalu will only appear in the IDR image, and all the Nalu in the IDR image are Nalu with a nal_unit_type value of 5;
(2), we make a
The type of the slice of the pictureTo differentiate the
whether the image is an IDR image is an errorOf For example:
all the slices in an image are I, which doesn't mean the image is an IDR image.。 Because I can also be from a nal_unit_type value of 1 Nalu is also non-IDR image may contain all I tablets. But the most common form that we usually get is that all the slices are the image of I and the IDR image. In fact, this time
IDR ImageConcept has also been embodied and minutely. However, the IDR images must all contain I or SI slices, but
only use the Nalu type to determine if the IDR image
An image from
1~n set of slicesComposition, and
each set of slicesAgain by one or
a number of slicesThe composition of a piece consists of a nalu or three nalu (if data is split).
decoding is always performed in the image decoding process by slices, and then reassemble the decoded macro block into an image as a set of slices. In this sense,
the chip is actually the largest decoding unit。
What types of macro blocks does a piece contain?
The standard "table 7-10" is the best description.
What are the types of an I macro block?
The standard "table 7-11" is the best description.
What are the types of a P-macro block?
The standard "table 7-13" is the best description.
What are the types of a B macro block?
The standard "table 7-14" is the best description.
What types of sub-macro blocks of a P-macro block are divided into?
The standard "table 7-17" is the best description.
What types of sub-macro blocks of a B macro block are divided into?
The standard "table 7-18" is the best description.
Images, frames, slices, nalu
