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Layered encoding support
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Layered image can be encoded by calling avifEncoderAddImage() multiple
times, one layer per call.
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@tongyuantongyu
tongyuantongyu authored Jan 20, 2023
1 parent 7c4c2d4 commit 5d16f1f
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Showing 12 changed files with 602 additions and 148 deletions.
1 change: 1 addition & 0 deletions CHANGELOG.md
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Expand Up @@ -23,6 +23,7 @@ avifEncoder struct.
minQuantizer, maxQuantizer, minQuantizerAlpha, and maxQuantizerAlpha
initialized to the default values.
* Add the public API function avifImageIsOpaque() in avif.h.
* Add experimental API for progressive AVIF encoding.

### Changed
* Exif and XMP metadata is exported to PNG and JPEG files by default,
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62 changes: 47 additions & 15 deletions include/avif/avif.h
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Expand Up @@ -99,6 +99,9 @@ typedef int avifBool;
// to handle this case however they want.
#define AVIF_REPETITION_COUNT_UNKNOWN -2

// The number of spatial layers in AV1, with spatial_id = 0..3.
#define AVIF_MAX_AV1_LAYER_COUNT 4

typedef enum avifPlanesFlag
{
AVIF_PLANES_YUV = (1 << 0),
Expand Down Expand Up @@ -344,6 +347,15 @@ typedef struct avifDiagnostics

AVIF_API void avifDiagnosticsClearError(avifDiagnostics * diag);

// ---------------------------------------------------------------------------
// Fraction utility

typedef struct avifFraction
{
int32_t n;
int32_t d;
} avifFraction;

// ---------------------------------------------------------------------------
// Optional transformation structs

Expand Down Expand Up @@ -1067,6 +1079,12 @@ AVIF_API avifResult avifDecoderNthImageMaxExtent(const avifDecoder * decoder, ui
struct avifEncoderData;
struct avifCodecSpecificOptions;

typedef struct avifScalingMode
{
avifFraction horizontal;
avifFraction vertical;
} avifScalingMode;

// Notes:
// * If avifEncoderWrite() returns AVIF_RESULT_OK, output must be freed with avifRWDataFree()
// * If (maxThreads < 2), multithreading is disabled
Expand All @@ -1087,6 +1105,8 @@ struct avifCodecSpecificOptions;
// image in less bytes. AVIF_SPEED_DEFAULT means "Leave the AV1 codec to its default speed settings"./
// If avifEncoder uses rav1e, the speed value is directly passed through (0-10). If libaom is used,
// a combination of settings are tweaked to simulate this speed range.
// * Extra layer count: [0 - (AVIF_MAX_AV1_LAYER_COUNT-1)]. Non-zero value indicates a layered
// (progressive) image.
// * Some encoder settings can be changed after encoding starts. Changes will take effect in the next
// call to avifEncoderAddImage().
typedef struct avifEncoder
Expand All @@ -1097,12 +1117,13 @@ typedef struct avifEncoder
// settings (see Notes above)
int maxThreads;
int speed;
int keyframeInterval; // How many frames between automatic forced keyframes; 0 to disable (default).
uint64_t timescale; // timescale of the media (Hz)
int repetitionCount; // Number of times the image sequence should be repeated. This can also be set to
// AVIF_REPETITION_COUNT_INFINITE for infinite repetitions. Only applicable for image sequences.
// Essentially, if repetitionCount is a non-negative integer `n`, then the image sequence should be
// played back `n + 1` times. Defaults to AVIF_REPETITION_COUNT_INFINITE.
int keyframeInterval; // How many frames between automatic forced keyframes; 0 to disable (default).
uint64_t timescale; // timescale of the media (Hz)
int repetitionCount; // Number of times the image sequence should be repeated. This can also be set to
// AVIF_REPETITION_COUNT_INFINITE for infinite repetitions. Only applicable for image sequences.
// Essentially, if repetitionCount is a non-negative integer `n`, then the image sequence should be
// played back `n + 1` times. Defaults to AVIF_REPETITION_COUNT_INFINITE.
uint32_t extraLayerCount; // EXPERIMENTAL: Non-zero value encodes layered image.

// changeable encoder settings
int quality;
Expand All @@ -1114,6 +1135,7 @@ typedef struct avifEncoder
int tileRowsLog2;
int tileColsLog2;
avifBool autoTiling;
avifScalingMode scalingMode;

// stats from the most recent write
avifIOStats ioStats;
Expand All @@ -1137,26 +1159,36 @@ typedef enum avifAddImageFlag
// Force this frame to be a keyframe (sync frame).
AVIF_ADD_IMAGE_FLAG_FORCE_KEYFRAME = (1 << 0),

// Use this flag when encoding a single image. Signals "still_picture" to AV1 encoders, which
// tweaks various compression rules. This is enabled automatically when using the
// avifEncoderWrite() single-image encode path.
// Use this flag when encoding a single frame, single layer image.
// Signals "still_picture" to AV1 encoders, which tweaks various compression rules.
// This is enabled automatically when using the avifEncoderWrite() single-image encode path.
AVIF_ADD_IMAGE_FLAG_SINGLE = (1 << 1)
} avifAddImageFlag;
typedef uint32_t avifAddImageFlags;

// Multi-function alternative to avifEncoderWrite() for image sequences.
// Multi-function alternative to avifEncoderWrite() for advanced features.
//
// Usage / function call order is:
// * avifEncoderCreate()
// * Set encoder->timescale (Hz) correctly
// * avifEncoderAddImage() ... [repeatedly; at least once]
// OR
// * avifEncoderAddImageGrid() [exactly once, AVIF_ADD_IMAGE_FLAG_SINGLE is assumed]
// - Still image:
// * avifEncoderAddImage() [exactly once]
// - Still image grid:
// * avifEncoderAddImageGrid() [exactly once, AVIF_ADD_IMAGE_FLAG_SINGLE is assumed]
// - Image sequence:
// * Set encoder->timescale (Hz) correctly
// * avifEncoderAddImage() ... [repeatedly; at least once]
// - Still layered image:
// * Set encoder->extraLayerCount correctly
// * avifEncoderAddImage() ... [exactly encoder->extraLayerCount+1 times]
// - Still layered grid:
// * Set encoder->extraLayerCount correctly
// * avifEncoderAddImageGrid() ... [exactly encoder->extraLayerCount+1 times]
// * avifEncoderFinish()
// * avifEncoderDestroy()
//

// durationInTimescales is ignored if AVIF_ADD_IMAGE_FLAG_SINGLE is set in addImageFlags.
// durationInTimescales is ignored if AVIF_ADD_IMAGE_FLAG_SINGLE is set in addImageFlags,
// or if we are encoding a layered image.
AVIF_API avifResult avifEncoderAddImage(avifEncoder * encoder, const avifImage * image, uint64_t durationInTimescales, avifAddImageFlags addImageFlags);
AVIF_API avifResult avifEncoderAddImageGrid(avifEncoder * encoder,
uint32_t gridCols,
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6 changes: 6 additions & 0 deletions include/avif/internal.h
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Expand Up @@ -72,6 +72,11 @@ void avifArrayPush(void * arrayStruct, void * element);
void avifArrayPop(void * arrayStruct);
void avifArrayDestroy(void * arrayStruct);

void avifFractionSimplify(avifFraction * f);
avifBool avifFractionCD(avifFraction * a, avifFraction * b);
avifBool avifFractionAdd(avifFraction a, avifFraction b, avifFraction * result);
avifBool avifFractionSub(avifFraction a, avifFraction b, avifFraction * result);

void avifImageSetDefaults(avifImage * image);
// Copies all fields that do not need to be freed/allocated from srcImage to dstImage.
void avifImageCopyNoAlloc(avifImage * dstImage, const avifImage * srcImage);
Expand Down Expand Up @@ -288,6 +293,7 @@ typedef enum avifEncoderChange
AVIF_ENCODER_CHANGE_TILE_COLS_LOG2 = (1u << 5),
AVIF_ENCODER_CHANGE_QUANTIZER = (1u << 6),
AVIF_ENCODER_CHANGE_QUANTIZER_ALPHA = (1u << 7),
AVIF_ENCODER_CHANGE_SCALING_MODE = (1u << 8),

AVIF_ENCODER_CHANGE_CODEC_SPECIFIC = (1u << 31)
} avifEncoderChange;
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138 changes: 24 additions & 114 deletions src/avif.c
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Expand Up @@ -563,15 +563,9 @@ void avifRGBImageFreePixels(avifRGBImage * rgb)
// ---------------------------------------------------------------------------
// avifCropRect

typedef struct clapFraction
static avifFraction calcCenter(int32_t dim)
{
int32_t n;
int32_t d;
} clapFraction;

static clapFraction calcCenter(int32_t dim)
{
clapFraction f;
avifFraction f;
f.n = dim >> 1;
f.d = 1;
if ((dim % 2) != 0) {
Expand All @@ -581,95 +575,11 @@ static clapFraction calcCenter(int32_t dim)
return f;
}

// |a| and |b| hold int32_t values. The int64_t type is used so that we can negate INT32_MIN without
// overflowing int32_t.
static int64_t calcGCD(int64_t a, int64_t b)
{
if (a < 0) {
a *= -1;
}
if (b < 0) {
b *= -1;
}
while (b != 0) {
int64_t r = a % b;
a = b;
b = r;
}
return a;
}

static void clapFractionSimplify(clapFraction * f)
{
int64_t gcd = calcGCD(f->n, f->d);
if (gcd > 1) {
f->n = (int32_t)(f->n / gcd);
f->d = (int32_t)(f->d / gcd);
}
}

static avifBool overflowsInt32(int64_t x)
{
return (x < INT32_MIN) || (x > INT32_MAX);
}

// Make the fractions have a common denominator
static avifBool clapFractionCD(clapFraction * a, clapFraction * b)
{
clapFractionSimplify(a);
clapFractionSimplify(b);
if (a->d != b->d) {
const int64_t ad = a->d;
const int64_t bd = b->d;
const int64_t anNew = a->n * bd;
const int64_t adNew = a->d * bd;
const int64_t bnNew = b->n * ad;
const int64_t bdNew = b->d * ad;
if (overflowsInt32(anNew) || overflowsInt32(adNew) || overflowsInt32(bnNew) || overflowsInt32(bdNew)) {
return AVIF_FALSE;
}
a->n = (int32_t)anNew;
a->d = (int32_t)adNew;
b->n = (int32_t)bnNew;
b->d = (int32_t)bdNew;
}
return AVIF_TRUE;
}

static avifBool clapFractionAdd(clapFraction a, clapFraction b, clapFraction * result)
{
if (!clapFractionCD(&a, &b)) {
return AVIF_FALSE;
}

const int64_t resultN = (int64_t)a.n + b.n;
if (overflowsInt32(resultN)) {
return AVIF_FALSE;
}
result->n = (int32_t)resultN;
result->d = a.d;

clapFractionSimplify(result);
return AVIF_TRUE;
}

static avifBool clapFractionSub(clapFraction a, clapFraction b, clapFraction * result)
{
if (!clapFractionCD(&a, &b)) {
return AVIF_FALSE;
}

const int64_t resultN = (int64_t)a.n - b.n;
if (overflowsInt32(resultN)) {
return AVIF_FALSE;
}
result->n = (int32_t)resultN;
result->d = a.d;

clapFractionSimplify(result);
return AVIF_TRUE;
}

static avifBool avifCropRectIsValid(const avifCropRect * cropRect, uint32_t imageW, uint32_t imageH, avifPixelFormat yuvFormat, avifDiagnostics * diag)

{
Expand Down Expand Up @@ -755,32 +665,32 @@ avifBool avifCropRectConvertCleanApertureBox(avifCropRect * cropRect,
avifDiagnosticsPrintf(diag, "[Strict] image width %u or height %u is greater than INT32_MAX", imageW, imageH);
return AVIF_FALSE;
}
clapFraction uncroppedCenterX = calcCenter((int32_t)imageW);
clapFraction uncroppedCenterY = calcCenter((int32_t)imageH);
avifFraction uncroppedCenterX = calcCenter((int32_t)imageW);
avifFraction uncroppedCenterY = calcCenter((int32_t)imageH);

clapFraction horizOff;
avifFraction horizOff;
horizOff.n = horizOffN;
horizOff.d = horizOffD;
clapFraction croppedCenterX;
if (!clapFractionAdd(uncroppedCenterX, horizOff, &croppedCenterX)) {
avifFraction croppedCenterX;
if (!avifFractionAdd(uncroppedCenterX, horizOff, &croppedCenterX)) {
avifDiagnosticsPrintf(diag, "[Strict] croppedCenterX overflowed");
return AVIF_FALSE;
}

clapFraction vertOff;
avifFraction vertOff;
vertOff.n = vertOffN;
vertOff.d = vertOffD;
clapFraction croppedCenterY;
if (!clapFractionAdd(uncroppedCenterY, vertOff, &croppedCenterY)) {
avifFraction croppedCenterY;
if (!avifFractionAdd(uncroppedCenterY, vertOff, &croppedCenterY)) {
avifDiagnosticsPrintf(diag, "[Strict] croppedCenterY overflowed");
return AVIF_FALSE;
}

clapFraction halfW;
avifFraction halfW;
halfW.n = clapW;
halfW.d = 2;
clapFraction cropX;
if (!clapFractionSub(croppedCenterX, halfW, &cropX)) {
avifFraction cropX;
if (!avifFractionSub(croppedCenterX, halfW, &cropX)) {
avifDiagnosticsPrintf(diag, "[Strict] cropX overflowed");
return AVIF_FALSE;
}
Expand All @@ -789,11 +699,11 @@ avifBool avifCropRectConvertCleanApertureBox(avifCropRect * cropRect,
return AVIF_FALSE;
}

clapFraction halfH;
avifFraction halfH;
halfH.n = clapH;
halfH.d = 2;
clapFraction cropY;
if (!clapFractionSub(croppedCenterY, halfH, &cropY)) {
avifFraction cropY;
if (!avifFractionSub(croppedCenterY, halfH, &cropY)) {
avifDiagnosticsPrintf(diag, "[Strict] cropY overflowed");
return AVIF_FALSE;
}
Expand Down Expand Up @@ -831,8 +741,8 @@ avifBool avifCleanApertureBoxConvertCropRect(avifCleanApertureBox * clap,
avifDiagnosticsPrintf(diag, "[Strict] image width %u or height %u is greater than INT32_MAX", imageW, imageH);
return AVIF_FALSE;
}
clapFraction uncroppedCenterX = calcCenter((int32_t)imageW);
clapFraction uncroppedCenterY = calcCenter((int32_t)imageH);
avifFraction uncroppedCenterX = calcCenter((int32_t)imageW);
avifFraction uncroppedCenterY = calcCenter((int32_t)imageH);

if ((cropRect->width > INT32_MAX) || (cropRect->height > INT32_MAX)) {
avifDiagnosticsPrintf(diag,
Expand All @@ -841,28 +751,28 @@ avifBool avifCleanApertureBoxConvertCropRect(avifCleanApertureBox * clap,
cropRect->height);
return AVIF_FALSE;
}
clapFraction croppedCenterX = calcCenter((int32_t)cropRect->width);
avifFraction croppedCenterX = calcCenter((int32_t)cropRect->width);
const int64_t croppedCenterXN = croppedCenterX.n + (int64_t)cropRect->x * croppedCenterX.d;
if (overflowsInt32(croppedCenterXN)) {
avifDiagnosticsPrintf(diag, "[Strict] croppedCenterX overflowed");
return AVIF_FALSE;
}
croppedCenterX.n = (int32_t)croppedCenterXN;
clapFraction croppedCenterY = calcCenter((int32_t)cropRect->height);
avifFraction croppedCenterY = calcCenter((int32_t)cropRect->height);
const int64_t croppedCenterYN = croppedCenterY.n + (int64_t)cropRect->y * croppedCenterY.d;
if (overflowsInt32(croppedCenterYN)) {
avifDiagnosticsPrintf(diag, "[Strict] croppedCenterY overflowed");
return AVIF_FALSE;
}
croppedCenterY.n = (int32_t)croppedCenterYN;

clapFraction horizOff;
if (!clapFractionSub(croppedCenterX, uncroppedCenterX, &horizOff)) {
avifFraction horizOff;
if (!avifFractionSub(croppedCenterX, uncroppedCenterX, &horizOff)) {
avifDiagnosticsPrintf(diag, "[Strict] horizOff overflowed");
return AVIF_FALSE;
}
clapFraction vertOff;
if (!clapFractionSub(croppedCenterY, uncroppedCenterY, &vertOff)) {
avifFraction vertOff;
if (!avifFractionSub(croppedCenterY, uncroppedCenterY, &vertOff)) {
avifDiagnosticsPrintf(diag, "[Strict] vertOff overflowed");
return AVIF_FALSE;
}
Expand Down
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