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c3df2a24e5
* Add custom quality factors and quantizer bitrate mode (closes #327) * Fix quantizer mode fallback and per-frame quantizer edge cases * Clean up quantizer mode tests * Quantizer implementation * Add quality tests * Improve conversion codec error message, make test more lenient * Add quantizer support blog post --------- Co-authored-by: Vanilagy <[email protected]>
49 lines
2.2 KiB
Markdown
49 lines
2.2 KiB
Markdown
---
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description: Advanced Video Coding (H.264) video codec definition, defining legal codec strings, decoder configs, and packet data formats.
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---
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<script setup>
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import { VPBadge } from 'vitepress/theme'
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</script>
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<VPBadge type="info" text="Video codec" />
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# AVC (H.264) codec registration
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## Description
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The Advanced Video Coding (H.264) video codec, specified in [Rec. ITU-T H.264](https://www.itu.int/rec/T-REC-H.264) / [ISO/IEC 14496-10](https://www.iso.org/standard/87574.html).
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An AVC bitstream can have either of two formats:
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- _Canonical_ (length-prefixed), as defined in [ISO/IEC 14496-15](https://www.iso.org/standard/89118.html) Section 5.3.2. Here, video parameter sets (SPS/PPS) are provided out-of-band.
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- _Annex B_, as defined in [Rec. ITU-T H.264](https://www.itu.int/rec/T-REC-H.264) Annex B. Here, video parameter sets (SPS/PPS) must be provided in-band in the respective NALUs.
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All packets within the bitstream must have the same format.
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## Codec ID
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```ts
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'avc'
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```
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## `EncodedPacket` data
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The packet's data must be an access unit as defined in [Rec. ITU-T H.264](https://www.itu.int/rec/T-REC-H.264) Section 7.4.1.2, in either _canonical_ or _Annex B_ format.
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## `EncodedPacket` type
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If the packet's type is `'key'`, then the packet is expected to contain a primary coded picture from which decoding can begin. Additionally, if the bitstream's format is _Annex B_, then this packet is also expected to contain the necessary video parameter sets to initialize the decoder.
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## `VideoDecoderConfig` codec string
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The full codec string begins with the prefix `'avc1.'` or `'avc3.'`, with a suffix of 6 characters as described respectively in Section 3.4 of [RFC 6381](https://www.rfc-editor.org/rfc/rfc6381) and Section 5.4.1 of [ISO/IEC 14496-15](https://www.iso.org/standard/89118.html).
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## `VideoDecoderConfig` description
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If the bitstream is in the _canonical_ (length-prefixed) format, `description` must be an `AVCDecoderConfigurationRecord` as defined in [ISO/IEC 14496-15](https://www.iso.org/standard/89118.html) Section 5.3.3.1.
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If the bitstream is in the _Annex B_ format, `description` must be undefined.
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## Quantizer range
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AVC has quantizer support and supports quantizer values in the range [0, 51]. |