Skip to content

Commit

Permalink
Minor edits in Section 8 Profiles
Browse files Browse the repository at this point in the history 
SHA: 198515c
Reason: push, by wantehchang

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
  • Loading branch information
@wantehchang @github-actions
wantehchang and github-actions[bot] committed Oct 23, 2024
1 parent f212c59 commit ac43db1
Showing 1 changed file with 4 additions and 4 deletions.
8 changes: 4 additions & 4 deletions index.html
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1490,7 +1490,7 @@
</style>
<meta content="Bikeshed version 82ce88815, updated Thu Sep 7 16:33:55 2023 -0700" name="generator">
<link href="https://AOMediaCodec.github.io/av1-avif" rel="canonical">
<meta content="d81c366cdaae43dc1f02d3fb7cee1c7b21b5d340" name="document-revision">
<meta content="198515cb86afae7a298dc0465715483bfaec615c" name="document-revision">
<style>/* Boilerplate: style-autolinks */
.css.css, .property.property, .descriptor.descriptor {
color: var(--a-normal-text);
Expand Down Expand Up @@ -2874,7 +2874,7 @@ <h2 class="heading settled" data-level="7" id="file-constraints"><span class="se
<h2 class="heading settled" data-level="8" id="profiles"><span class="secno">8. </span><span class="content">Profiles</span><a class="self-link" href="#profiles"></a></h2>
<h3 class="heading settled" data-level="8.1" id="profiles-overview"><span class="secno">8.1. </span><span class="content">Overview</span><a class="self-link" href="#profiles-overview"></a></h3>
<p>The profiles defined in this section are for enabling interoperability between <a data-link-type="dfn" href="#av1-image-file-format" id="ref-for-av1-image-file-format①①">AV1 Image File Format</a> files and <a data-link-type="dfn" href="#av1-image-file-format" id="ref-for-av1-image-file-format①②">AV1 Image File Format</a> readers/parsers. A profile imposes a set of specific restrictions and is signaled by brands defined in this specification.</p>
<span id="assert-90b9bfa3">The <code><a data-link-type="dfn" href="https://www.iso.org/standard/68960.html" id="ref-for-something①⑥⑥">FileTypeBox</a></code> should declare at least one profile that enables decoding of the <a data-link-type="dfn" href="https://www.iso.org/standard/74417.html" id="ref-for-something①⑥⑦">primary image item</a>.</span> It is not an error for the encoder to include an auxiliary image that is not allowed by the specified profile(s). <span id="assert-951c6d0d">If <code>'<a data-link-type="dfn" href="#avif-image-sequence-brand-avis" id="ref-for-avif-image-sequence-brand-avis②">avis</a>'</code> is declared in the <code><a data-link-type="dfn" href="https://www.iso.org/standard/68960.html" id="ref-for-something①⑥⑧">FileTypeBox</a></code> and a profile is declared in the <code><a data-link-type="dfn" href="https://www.iso.org/standard/68960.html" id="ref-for-something①⑥⑨">FileTypeBox</a></code>, the profile shall also enable decoding of at least one image sequence track.</span> <span id="assert-8b7ce377">The profile should allow decoding of any associated auxiliary image sequence tracks, unless it is acceptable to decode the image sequence without its auxiliary image sequence tracks.</span>
<span id="assert-90b9bfa3">The <code><a data-link-type="dfn" href="https://www.iso.org/standard/68960.html" id="ref-for-something①⑥⑥">FileTypeBox</a></code> should declare at least one profile that enables decoding of the <a data-link-type="dfn" href="https://www.iso.org/standard/74417.html" id="ref-for-something①⑥⑦">primary image item</a>.</span> It is not an error for the encoder to include an auxiliary image that is not allowed by the specified profile(s). <span id="assert-951c6d0d">If <code>'<a data-link-type="dfn" href="#avif-image-sequence-brand-avis" id="ref-for-avif-image-sequence-brand-avis②">avis</a>'</code> is declared in the <code><a data-link-type="dfn" href="https://www.iso.org/standard/68960.html" id="ref-for-something①⑥⑧">FileTypeBox</a></code> and a profile is declared in the <code><a data-link-type="dfn" href="https://www.iso.org/standard/68960.html" id="ref-for-something①⑥⑨">FileTypeBox</a></code>, the profile shall also enable decoding of at least one image sequence track.</span> <span id="assert-564c67c4">The profile should allow decoding of any associated auxiliary image sequence tracks, unless it is acceptable to decode the image sequence track without its auxiliary image sequence tracks.</span>
<p>It is possible for a file compliant to this <a data-link-type="dfn" href="#av1-image-file-format" id="ref-for-av1-image-file-format①③">AV1 Image File Format</a> to not be able to declare an <a data-link-type="dfn" href="#avif" id="ref-for-avif⑥">AVIF</a> profile, if the corresponding AV1 encoding characteristics do not match any of the defined profiles.</p>
<p class="note" role="note"><span class="marker">NOTE:</span> <a data-link-type="biblio" href="#biblio-av1" title="AV1 Bitstream &amp; Decoding Process Specification">[AV1]</a> supports 3 bit depths: 8, 10 and 12 bits, and the maximum dimensions of a coded image is 65536x65536, when <code><a data-link-type="dfn" href="https://aomediacodec.github.io/av1-spec/av1-spec.pdf" id="ref-for-something①⑦⓪">seq_level_idx</a></code> is set to 31 (maximum parameters level).</p>
<div class="example" id="example-ee584b29"><a class="self-link" href="#example-ee584b29"></a>If an image is encoded with dimensions (respectively a bit depth) that exceed the maximum dimensions (respectively bit depth) required by the AV1 profile and level of the <a data-link-type="dfn" href="#avif" id="ref-for-avif⑦">AVIF</a> profiles defined in this specification, the file will only signal general <a data-link-type="dfn" href="#avif" id="ref-for-avif⑧">AVIF</a> brands.</div>
Expand All @@ -2896,8 +2896,8 @@ <h3 class="heading settled" data-level="8.2" id="baseline-profile"><span class="
<ul>
<li data-md>
<span id="assert-76bdbeb4">The AV1 profile shall be the Main Profile and the level shall be 5.1 or lower.</span>
<p class="note" role="note"><span class="marker">NOTE:</span> AV1 tiers are not constrained because timing is optional in image sequences and are not relevant in image items or collections.</p>
<p class="note" role="note"><span class="marker">NOTE:</span> Level 5.1 is chosen for the Baseline profile to ensure that no single coded image exceeds 4k resolution, as some decoder may not be able to handle larger images. More precisely, following <a data-link-type="biblio" href="#biblio-av1" title="AV1 Bitstream &amp; Decoding Process Specification">[AV1]</a> level definitions, coded image items compliant to the <a data-link-type="dfn" href="#avif-baseline-profile" id="ref-for-avif-baseline-profile">AVIF Baseline profile</a> may not have a number of pixels greater than 8912896, a width greater than 8192 or a height greater than 4352. It is still possible to use the Baseline profile to create larger images using a <a data-link-type="dfn" href="#grid-derived-image-item" id="ref-for-grid-derived-image-item①">grid derived image item</a>.</p>
<p class="note" role="note"><span class="marker">NOTE:</span> AV1 tiers are not constrained because timing is optional in image sequences and is not relevant in image items or collections.</p>
<p class="note" role="note"><span class="marker">NOTE:</span> Level 5.1 is chosen for the Baseline profile to ensure that no single coded image exceeds 4k resolution, as some decoders may not be able to handle larger images. More precisely, following <a data-link-type="biblio" href="#biblio-av1" title="AV1 Bitstream &amp; Decoding Process Specification">[AV1]</a> level definitions, coded image items compliant to the <a data-link-type="dfn" href="#avif-baseline-profile" id="ref-for-avif-baseline-profile">AVIF Baseline profile</a> may not have a number of pixels greater than 8912896, a width greater than 8192 or a height greater than 4352. It is still possible to use the Baseline profile to create larger images using a <a data-link-type="dfn" href="#grid-derived-image-item" id="ref-for-grid-derived-image-item①">grid derived image item</a>.</p>
</ul>
<div class="example" id="example-190506b9">
<a class="self-link" href="#example-190506b9"></a> A file containing items compliant with this profile is expected to list the following brands, in any order, in the <code><a data-link-type="dfn" href="https://www.iso.org/standard/68960.html" id="ref-for-something①⑦⑧">compatible_brands</a></code> of the <code><a data-link-type="dfn" href="https://www.iso.org/standard/68960.html" id="ref-for-something①⑦⑨">FileTypeBox</a></code>:
Expand Down

0 comments on commit ac43db1

Please sign in to comment.