tag	02ab3e32f556a8c7409873c6894e8916fe3d7c4c
tagger	Joe Drago <joedrago@gmail.com>	Sat Nov 23 11:31:24 2019 -0800
object	f8d6142def7ca8af5cd207536c864d95ba25e8f1

commit	f8d6142def7ca8af5cd207536c864d95ba25e8f1	[log] [tgz]
author	Joe Drago <joedrago@gmail.com>	Sat Nov 23 11:31:01 2019 -0800
committer	Joe Drago <joedrago@gmail.com>	Sat Nov 23 11:31:01 2019 -0800
tree	876b8ff2a1b5ed48eef53331e24748aa293ab93c
parent	5932a057d95066729a3c787abfb8c3f3cf0d2315 [diff]

tree: 876b8ff2a1b5ed48eef53331e24748aa293ab93c

README.md

libavif

This library aims to be a friendly, portable C implementation of the AV1 Image File Format, as described here:

https://aomediacodec.github.io/av1-avif/

It is a work-in-progress, but can already encode and decode all AOM supported YUV formats and bit depths (with alpha).

For now, it is recommended that you checkout/use tagged releases instead of just using the master branch. I will regularly create new versions as bugfixes and features are added.

Usage

Basic Decoding (Single Image)

    #include "avif/avif.h"

    // point raw.data and raw.size to the contents of an .avif(s)
    avifROData raw;
    raw.data = ...;
    raw.size = ...;

    avifImage * image = avifImageCreateEmpty();
    avifDecoder * decoder = avifDecoderCreate();
    avifResult decodeResult = avifDecoderRead(decoder, image, &raw);
    if (decodeResult == AVIF_RESULT_OK) {
        // image is an independent copy of decoded data, decoder may be destroyed here

        ... image->width;
        ... image->height;
        ... image->depth;     // If >8, all plane ptrs below are uint16_t*
        ... image->yuvFormat; // U and V planes might be smaller than Y based on format,
                              // use avifGetPixelFormatInfo() to find out in a generic way

        // Option 1: Use YUV planes directly
        ... image->yuvPlanes;
        ... image->yuvRowBytes;

        // Option 2: Convert to RGB and use RGB planes
        avifImageYUVToRGB(image);
        ... image->rgbPlanes;
        ... image->rgbRowBytes;

        // Use alpha plane, if present
        if (image->alphaPlane) {
            ... image->alphaPlane;
            ... image->alphaRowBytes;
        }

        // Optional: query color profile
        if (image->profileFormat == AVIF_PROFILE_FORMAT_ICC) {
            // ICC profile present
            ... image->icc.data;
            ... image->icc.size;
        } else if (image->profileFormat == AVIF_PROFILE_FORMAT_NCLX) {
            // NCLX profile present
            ... image->nclx.colourPrimaries;
            ... image->nclx.transferCharacteristics;
            ... image->nclx.matrixCoefficients;
            ... image->nclx.fullRangeFlag;
        }

        // Optional: Exif and XMP metadata querying
        if(image->exif.size > 0) {
            // Parse Exif payload
            ... image->exif.data;
            ... image->exif.size;
        }
        if(image->xmp.size > 0) {
            // Parse XMP document
            ... image->xmp.data;
            ... image->xmp.size;
        }
    } else {
        printf("ERROR: Failed to decode: %s\n", avifResultToString(result));
    }

    avifImageDestroy(image);
    avifDecoderDestroy(decoder);

Advanced Decoding (Image Sequences & Avoiding Copies)

    #include "avif/avif.h"

    // point raw.data and raw.size to the contents of an .avif(s)
    avifROData raw;
    raw.data = ...;
    raw.size = ...;

    avifDecoder * decoder = avifDecoderCreate();
    avifResult decodeResult = avifDecoderParse(decoder, &raw);
    if (decodeResult == AVIF_RESULT_OK) {
        // Timing and frame information
        ... decoder->imageCount; // Total images expected to decode
        ... decoder->duration;   // Duration of entire sequence (seconds)

        for (;;) {
            avifResult nextImageResult = avifDecoderNextImage(decoder);
            if (nextImageResult == AVIF_RESULT_NO_IMAGES_REMAINING) {
                // No more images, bail out. Verify that you got the expected amount of images decoded.
                break;
            } else if (nextImageResult != AVIF_RESULT_OK) {
                printf("ERROR: Failed to decode all frames: %s\n", avifResultToString(nextImageResult));
                break;
            }

            // decoder->image now points at decoder owned planes, and the image itself
            // is also owned and dependent on decoder. decoder->image's data/pointers are
            // likely to be completely different after each call to avifDecoderNextImage().

            ... decoder->image->width;
            ... decoder->image->height;
            ... decoder->image->depth;     // If >8, all plane ptrs below are uint16_t*
            ... decoder->image->yuvFormat; // U and V planes might be smaller than Y based on format,
                                           // use avifGetPixelFormatInfo() to find out in a generic way

            // See Basic Decoding example for color profile and metadata querying

            // Option 1: Use YUV planes directly
            ... decoder->image->yuvPlanes;
            ... decoder->image->yuvRowBytes;

            // Option 2: Convert to RGB and use RGB planes
            avifImageYUVToRGB(decoder->image); // (this is legal to call on decoder->image)
            ... decoder->image->rgbPlanes;
            ... decoder->image->rgbRowBytes;

            // Use alpha plane, if present
            if (decoder->image->alphaPlane) {
                ... decoder->image->alphaPlane;
                ... decoder->image->alphaRowBytes;
            }

            // Timing and frame information
            ... decoder->imageIndex;           // Current index (0-based)
            ... decoder->imageTiming.pts;      // Current image's presentation timestamp (seconds)
            ... decoder->imageTiming.duration; // Current image's duration (seconds)

            // Optional: If you want to have a decoder-independent copy of image data
            avifImage * image = avifImageCreateEmpty();
            avifImageCopy(image, decoder->image);
            ... image;                         // do something with image
            avifImageDestroy(image);           // destroy later
        }
    } else {
        printf("ERROR: Failed to decode: %s\n", avifResultToString(result));
    }

    avifDecoderDestroy(decoder);

Encoding

    #include "avif/avif.h"

    int width = 32;
    int height = 32;
    int depth = 8;
    avifPixelFormat format = AVIF_PIXEL_FORMAT_YUV420;
    avifImage * image = avifImageCreate(width, height, depth, format);

    // Option 1: Populate YUV planes
    avifImageAllocatePlanes(image, AVIF_PLANES_YUV);
    ... image->yuvPlanes;
    ... image->yuvRowBytes;

    // Option 2: Populate RGB planes (if YUV planes are absent, RGB->YUV conversion will automatically happen)
    avifImageAllocatePlanes(image, AVIF_PLANES_RGB);
    ... image->rgbPlanes;
    ... image->rgbRowBytes;

    // Optional: Populate alpha plane
    avifImageAllocatePlanes(image, AVIF_PLANES_A);
    ... image->alphaPlane;
    ... image->alphaRowBytes;

    // Optional: Set color profile based on NCLX box
    avifNclxColorProfile nclx;
    nclx.colourPrimaries = AVIF_NCLX_COLOUR_PRIMARIES_BT709;
    nclx.transferCharacteristics = AVIF_NCLX_TRANSFER_CHARACTERISTICS_GAMMA22;
    nclx.matrixCoefficients = AVIF_NCLX_MATRIX_COEFFICIENTS_BT709;
    nclx.fullRangeFlag = AVIF_NCLX_FULL_RANGE;
    avifImageSetProfileNCLX(image, &nclx);

    // Optional: Set color profile based on ICC profile
    uint8_t * icc = ...;  // raw ICC profile data
    size_t iccSize = ...; // Length of raw ICC profile data
    avifImageSetProfileICC(image, icc, iccSize);

    // Optional: Set Exif and/or XMP metadata
    uint8_t * exif = ...;  // raw Exif payload
    size_t exifSize = ...; // Length of raw Exif payload
    avifImageSetMetadataExif(image, exif, exifSize);
    uint8_t * xmp = ...;  // raw XMP document
    size_t xmpSize = ...; // Length of raw XMP document
    avifImageSetMetadataXMP(image, xmp, xmpSize);

    avifRWData output = AVIF_DATA_EMPTY;
    avifEncoder * encoder = avifEncoderCreate();
    encoder->maxThreads = ...; // Choose max encoder threads, 1 to disable multithreading
    encoder->minQuantizer = AVIF_QUANTIZER_LOSSLESS;
    encoder->maxQuantizer = AVIF_QUANTIZER_LOSSLESS;
    avifResult encodeResult = avifEncoderWrite(encoder, image, &output);
    if (encodeResult == AVIF_RESULT_OK) {
        // output contains a valid .avif file's contents
        ... output.data;
        ... output.size;
    } else {
        printf("ERROR: Failed to encode: %s\n", avifResultToString(encodeResult));
    }
    avifImageDestroy(image);
    avifRWDataFree(&output);
    avifEncoderDestroy(encoder);

Build Notes

Building libavif requires CMake.

No AV1 codecs are enabled by default. Enable them by enabling any of the following CMake options:

AVIF_CODEC_AOM - requires CMake, NASM
AVIF_CODEC_DAV1D - requires Meson, Ninja, NASM
AVIF_CODEC_RAV1E - requires cargo (Rust), NASM

These libraries (in their C API form) must be externally available (discoverable via CMake‘s FIND_LIBRARY) to use them, or if libavif is a child CMake project, the appropriate CMake target must already exist by the time libavif’s CMake scripts are executed.

Local Builds

The ext/ subdirectory contains a handful of basic scripts which each pull down a known-good copy of an AV1 codec and make a local static library build. If you want to statically link any codec into your local build of libavif, building using one of these scripts and then enabling the associated AVIF_LOCAL_* is a convenient method.

If you want to build/install shared libraries for AV1 codecs, you can still peek inside of each script to see where the current known-good SHA is for each codec.

Prebuilt Library (Windows)

If you're building on Windows with VS2017 and want to try out libavif without going through the build process, static library builds for both Debug and Release are available on Appveyor.

License

Released under the BSD License.

Copyright 2019 Joe Drago. All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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