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technology/files/media/Codecs.md

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+---
+tags: ["meta"]
+obj: meta/collection
+---
+# List of Codecs
+## Video
+- [H.264](video/H.264.md)
+- [H.265](video/H.265.md)
+- [VP9](video/VP9.md)
+- [AV1](video/AV1.md)
+
+## Audio
+- [Opus](audio/Opus.md)
+- [FLAC](audio/FLAC.md)
+- [WAV](audio/WAV.md)
+
+## Images
+- [PNG](image/PNG.md)
+- [AVIF](image/AVIF.md)

technology/files/media/Matroska.md

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+---
+aliases: ["mkv"]
+website: https://matroska.org
+obj: concept
+---
+# Matroska
+The Matroska Multimedia Container is a free and open container format, a file format that can hold an unlimited number of video, audio, picture, or subtitle tracks in one file. It is a universal format for storing common multimedia content, like movies or TV shows. Matroska is similar in concept to other containers like AVI, MP4, or Advanced Systems Format (ASF), but is entirely open in specification, with implementations consisting mostly of open source software. Matroska file extensions are .mkv for video (which may include subtitles or audio), .mk3d for stereoscopic video, .mka for audio-only files (which may include subtitles), and .mks for subtitles only.
+Editing and creation of Matroska files can be done using [MKVToolnix](../../applications/media/MKVToolnix.md).
+
+| Name                     | Value                                  |
+| ------------------------ | -------------------------------------- |
+| Extension                | .mkv .mk3d .mka .mks                   |
+| [MIME](../MIME.md) | video/x-matroska <br> audio/x-matroska |
+| Website                  | https://matroska.org                   | 
+
+## Features
+
+**_Matroska_** is designed with the future in mind. It incorporates features you would expect from a modern container format, like:
+-   Fast seeking in the file
+-   Chapter entries
+-   Full metadata (tags) support
+-   Selectable subtitle/audio/video streams
+-   Modularly expandable
+-   Error resilience (can recover playback even when the stream is damaged)
+-   Streamable over the internet and local networks ([HTTP](../../internet/HTTP.md), CIFS, [FTP](../../internet/FTP.md), etc)
+-   _Menus (like DVDs have)_
+
+## What file extensions does Matroska use?
+-   `.mkv`: Used for files that contain at least one video track (usually with at least one audio track and optionally with subtitle tracks). This is the most commonly used extension.
+-   `.mka`: Used for audio only files, can contain any supported audio compression format, such as MP2, MP3, Vorbis, AAC, AC3, DTS, or PCM
+-   `.mk3d`: A special case of `.mkv` containing stereoscopic (3D) video
+-   `.mks`: Used for files that only contain subtitles

technology/files/media/audio/FLAC.md

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+---
+repo: https://gitlab.xiph.org/xiph/flac
+website: https://xiph.org/flac/
+obj: codec
+---
+# FLAC
+FLAC (Free Lossless Audio Codec) is an audio coding format for lossless compression of digital audio, developed by the Xiph.Org Foundation, and is also the name of the free software project producing the FLAC tools, the reference software package that includes a codec implementation. Digital audio compressed by FLAC's algorithm can typically be reduced to between 50 and 70 percent of its original size and decompresses to an identical copy of the original audio data.
+
+FLAC is an open format with royalty-free licensing and a reference implementation which is free software. FLAC has support for metadata tagging, album cover art, and fast seeking.
+
+| Name            | Value                             |
+| --------------- | --------------------------------- |
+| Initial Release | 2001-07-20                        |
+| Repository      | https://gitlab.xiph.org/xiph/flac |
+| Website         | https://xiph.org/flac/            |
+
+## Comparison to other formats
+FLAC is specifically designed for efficient packing of audio data, unlike general-purpose lossless algorithms such as DEFLATE, which are used in [ZIP](../../ZIP.md) and gzip. While [ZIP](../../ZIP.md) may reduce the size of a CD-quality audio file by 10–20%, FLAC is able to reduce the size of audio data by 40–50% by taking advantage of the characteristics of audio.
+The technical strengths of FLAC compared to other lossless formats lie in its ability to be streamed and decoded quickly, independent of compression level.
+Since FLAC is a lossless scheme, it is suitable as an archive format for owners of CDs and other media who wish to preserve their audio collections. If the original media are lost, damaged, or worn out, a FLAC copy of the audio tracks ensures that an exact duplicate of the original data can be recovered at any time. An exact restoration from a lossy copy (e.g., MP3) of the same data is impossible. FLAC being lossless means it is highly suitable for transcoding e.g. to MP3, without the normally associated transcoding quality loss between one lossy format and another. A CUE file can optionally be created when ripping a CD. If a CD is read and ripped perfectly to FLAC files, the CUE file allows later burning of an audio CD that is identical in audio data to the original CD, including track order and pregap, but excluding CD-Text and other additional data such as lyrics and CD+G graphics.

technology/files/media/audio/Opus.md

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+---
+website: https://opus-codec.org/
+obj: codec
+---
+# Opus
+Opus is a lossy audio coding format developed by the Xiph.Org Foundation and standardized by the Internet Engineering Task Force, designed to efficiently code speech and general audio in a single format, while remaining low-latency enough for real-time interactive communication and low-complexity enough for low-end embedded processors. Opus replaces both Vorbis and Speex for new applications, and several blind listening tests have ranked it higher-quality than any other standard audio format at any given bitrate until transparency is reached, including MP3, AAC, and HE-AAC.
+
+Opus combines the speech-oriented LPC-based SILK algorithm and the lower-latency MDCT-based CELT algorithm, switching between or combining them as needed for maximal efficiency. Bitrate, audio bandwidth, complexity, and algorithm can all be adjusted seamlessly in each frame. Opus has the low algorithmic delay (26.5 ms by default) necessary for use as part of a real-time communication link, networked music performances, and live lip sync; by trading-off quality or bitrate, the delay can be reduced down to 5 ms. Its delay is exceptionally low compared to competing [codecs](../Codecs.md), which require well over 100 ms, yet Opus performs very competitively with these formats in terms of quality per bitrate.
+
+As an open format standardized through RFC 6716, a reference implementation called libopus is available under the New BSD License. The reference has both fixed-point and floating-point optimizations for low- and high-end devices, with SIMD optimizations on platforms that support them. All known software patents that cover Opus are licensed under royalty-free terms. Opus is widely used as the voice-over-IP (VoIP) codec in applications such as Discord, WhatsApp, and the PlayStation 4.
+
+| Name      | Value                   |
+| --------- | ----------------------- |
+| Extension | .opus                   |
+| [MIME](../../MIME.md)      | audio/ogg<br>audio/opus |
+| Website   | https://opus-codec.org/ |
+

technology/files/media/audio/WAV.md

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+---
+obj: codec
+---
+# WAV
+Waveform Audio File Format (WAVE, or WAV due to its filename extension; pronounced "wave") is an audio file format standard, developed by IBM and Microsoft, for storing an audio bitstream on PCs. It is the main format used on Microsoft Windows systems for uncompressed audio. The usual bitstream encoding is the linear pulse-code modulation (LPCM) format.
+
+| Name      | Value                                  |
+| --------- | -------------------------------------- |
+| Extension | .wav<br>.wave                          |
+| [MIME](../../MIME.md)      | audio/x-wav<br>audio/wav<br>audio/wave |

technology/files/media/image/AVIF.md

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+---
+obj: codec
+website: https://aomediacodec.github.io/av1-avif
+---
+# AVIF
+AV1 Image File Format (AVIF) is an open, royalty-free image file format specification for storing images or image sequences compressed with AV1 in the HEIF container format. It competes with HEIC, which uses the same container format built upon ISOBMFF, but HEVC for compression. Version 1.0.0 of the AVIF specification was finalized in February 2019.
+
+| Name                | Value        |
+| ------------------- | ------------ |
+| Filename extension  | .avif        |
+| Internet media type | `image/avif` |
+
+## Features
+The AV1 Image File Format supports:
+- Multiple color spaces, including:
+    - HDR (with PQ or HLG transfer functions and BT.2020 color primaries, as part of BT.2100)
+    - SDR (with sRGB/ BT.709 / BT.601 or with wide color gamut
+    - Color space signaling via CICP (ITU-T H.273 and ISO/IEC 23091-2) or ICC profiles
+- Lossless compression and lossy compression
+- 8-, 10-, and 12-bit color depths
+- Monochrome (alpha/depth) or multi-components
+- 4:2:0, 4:2:2, 4:4:4 chroma subsampling and RGB
+- Film grain synthesis
+- Image sequences/animation
+
+## Usage
+
+**Convert from AVIF:**
+```shell
+avifdec [INPUT] [OUTPUT]
+```
+
+**Get information**
+```shell
+avifdec --info [INPUT]
+```
+
+**Convert to AVIF**
+```shell
+avifenc [OPTIONS] [INPUT] [OUTPUT]
+```
+
+_Flags:_
+```shell
+-j, --jobs <NUM> Number of threads
+-l, --lossless Lossless encoding
+```

technology/files/media/image/PNG.md

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+---
+obj: codec
+---
+# PNG
+Portable Network Graphics (PNG) is a raster-graphics file format that supports lossless data compression. PNG was developed as an improved, non-patented replacement for Graphics Interchange Format (GIF) — unofficially, the initials PNG stood for the recursive acronym "PNG's not GIF".
+
+PNG supports palette-based images (with palettes of 24-bit RGB or 32-bit RGBA colors), grayscale images (with or without an alpha channel for transparency), and full-color non-palette-based RGB or RGBA images. The PNG working group designed the format for transferring images on the Internet, not for professional-quality print graphics; therefore non-RGB color spaces such as CMYK are not supported. A PNG file contains a single image in an extensible structure of chunks, encoding the basic pixels and other information such as textual comments and integrity checks documented in RFC 2083.
+
+PNG files use the file extension PNG or png and are assigned [MIME](../../MIME.md) media type image/png. PNG was published as informational RFC 2083 in March 1997 and as an ISO/IEC 15948 standard in 2004.
+
+| Name         | Value                     |
+| ------------ | ------------------------- |
+| Extension    | .png                      |
+| [MIME](../../MIME.md)         | image/png                 |
+| Magic Number | `89 50 4e 47 0d 0a 1a 0a` |

technology/files/media/video/AV1.md

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+---
+obj: codec
+---
+# AV1
+AV1 is a royalty-free video codec designed to be an alternative to the widely used [H.264](H.264.md) and HEVC [codecs](../Codecs.md). It was developed by the Alliance for Open Media, a consortium of technology companies including Google, Mozilla, and Netflix.
+Encoding can be done with [ffmpeg](../../../applications/media/ffmpeg.md) or av1an.
+
+## Key Features
+AV1 includes a range of features designed to provide high-quality video compression while remaining open and accessible to all users:
+-   High compression efficiency: AV1 is designed to provide high-quality video compression while using less bandwidth than other [codecs](../Codecs.md). This makes it ideal for streaming video over the internet.
+-   Scalable video technology: AV1 includes scalable video technology that allows it to adjust the quality of video based on available bandwidth. This ensures that users always receive the best possible video quality for their network connection.
+-   Royalty-free: Unlike other [codecs](../Codecs.md), AV1 is completely royalty-free. This means that anyone can use it without having to pay fees or royalties.
+-   Wide range of applications: AV1 is suitable for a wide range of applications, including live streaming, video-on-demand services, and video conferencing.
+-   Open and accessible: AV1 is an open standard, meaning that anyone can use it and contribute to its development. This makes it accessible to users of all skill levels.
+
+## Advantages
+AV1 offers a number of advantages over other video [codecs](../Codecs.md):
+-   Higher quality video: AV1 provides higher quality video than other [codecs](../Codecs.md), even at lower bitrates.
+-   More efficient compression: AV1 provides more efficient compression than other [codecs](../Codecs.md), allowing for faster download and upload times.
+-   Better streaming performance: AV1 is designed for streaming video over the internet, and provides better streaming performance than other [codecs](../Codecs.md).
+-   Wide compatibility: AV1 is compatible with a wide range of devices and platforms, including desktop and mobile devices.
+

technology/files/media/video/H.264.md

@@ -0,0 +1,7 @@
+---
+obj: codec
+wiki: https://en.wikipedia.org/wiki/Advanced_Video_Coding
+---
+
+# H.264
+Advanced Video Coding (AVC), also referred to as H.264 or MPEG-4 Part 10, is a video compression standard based on block-oriented, motion-compensated coding. It supports a maximum resolution of 8K UHD.

technology/files/media/video/H.265.md

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+---
+obj: codec
+wiki: https://en.wikipedia.org/wiki/High_Efficiency_Video_Coding
+---
+# H.265
+High Efficiency Video Coding (HEVC), also known as H.265 and MPEG-H Part 2, is a video compression standard designed as part of the MPEG-H project as a successor to the widely used Advanced Video Coding (AVC, [H.264](H.264.md), or MPEG-4 Part 10). In comparison to AVC, HEVC offers from 25% to 50% better data compression at the same level of video quality, or substantially improved video quality at the same bit rate. It supports resolutions up to 8192×4320, including 8K UHD, and unlike the primarily 8-bit AVC, HEVC's higher fidelity Main 10 profile has been incorporated into nearly all supporting hardware.
+
+While AVC uses the integer discrete cosine transform (DCT) with 4×4 and 8×8 block sizes, HEVC uses both integer DCT and discrete sine transform (DST) with varied block sizes between 4×4 and 32×32. The High Efficiency Image Format (HEIF) is based on HEVC.

technology/files/media/video/VP9.md

@@ -0,0 +1,7 @@
+---
+website: https://www.webmproject.org/vp9/
+obj: codec
+---
+# VP9
+VP9 is an open and royalty-free video coding format developed by Google.
+VP9 is the successor to VP8 and competes mainly with MPEG's High Efficiency Video Coding (HEVC/[H.265](H.265.md)). At first, VP9 was mainly used on Google's video platform YouTube. The emergence of the Alliance for Open Media, and its support for the ongoing development of the successor [AV1](AV1.md), of which Google is a part, led to growing interest in the format.