blob: 58f9a67360ff05051ccb4fdf98e0ec7a798c47e7 [file] [log] [blame]
/*
* Copyright 2020 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
// This program converts an image from stdin (e.g. a JPEG, PNG, etc.) to stdout
// (in the NIA/NIE format, a trivial image file format).
//
// The NIA/NIE file format specification is at:
// https://github.com/google/wuffs/blob/master/doc/spec/nie-spec.md
//
// Pass "-1" or "-first-frame-only" as a command line flag to output NIE (a
// still image) instead of NIA (an animated image). The output format (NIA or
// NIE) depends only on this flag's absence or presence, not on the stdin
// image's format.
//
// There are multiple codec implementations of any given image format. For
// example, as of May 2020, Chromium, Skia and Wuffs each have their own BMP
// decoder implementation. There is no standard "libbmp" that they all share.
// Comparing this program's output (or hashed output) to similar programs in
// other repositories can identify image inputs for which these decoders (or
// different versions of the same decoder) produce different output (pixels).
//
// An equivalent program (using the Chromium image codecs) is at:
// https://crrev.com/c/2210331
//
// An equivalent program (using the Wuffs image codecs) is at:
// https://github.com/google/wuffs/blob/master/example/convert-to-nia/convert-to-nia.c
#include <stdio.h>
#include <string.h>
#include "include/codec/SkCodec.h"
#include "include/core/SkBitmap.h"
#include "include/core/SkData.h"
#include "src/core/SkAutoMalloc.h"
static inline void set_u32le(uint8_t* ptr, uint32_t val) {
ptr[0] = val >> 0;
ptr[1] = val >> 8;
ptr[2] = val >> 16;
ptr[3] = val >> 24;
}
static inline void set_u64le(uint8_t* ptr, uint64_t val) {
ptr[0] = val >> 0;
ptr[1] = val >> 8;
ptr[2] = val >> 16;
ptr[3] = val >> 24;
ptr[4] = val >> 32;
ptr[5] = val >> 40;
ptr[6] = val >> 48;
ptr[7] = val >> 56;
}
static void write_nix_header(uint32_t magicU32le, uint32_t width, uint32_t height) {
uint8_t data[16];
set_u32le(data + 0, magicU32le);
set_u32le(data + 4, 0x346E62FF); // 4 bytes per pixel non-premul BGRA.
set_u32le(data + 8, width);
set_u32le(data + 12, height);
fwrite(data, 1, 16, stdout);
}
static bool write_nia_duration(uint64_t totalDurationMillis) {
// Flicks are NIA's unit of time. One flick (frame-tick) is 1 / 705_600_000
// of a second. See https://github.com/OculusVR/Flicks
static constexpr uint64_t flicksPerMilli = 705600;
if (totalDurationMillis > (INT64_MAX / flicksPerMilli)) {
// Converting from millis to flicks would overflow.
return false;
}
uint8_t data[8];
set_u64le(data + 0, totalDurationMillis * flicksPerMilli);
fwrite(data, 1, 8, stdout);
return true;
}
static void write_nie_pixels(uint32_t width, uint32_t height, const SkBitmap& bm) {
static constexpr size_t kBufferSize = 4096;
uint8_t buf[kBufferSize];
size_t n = 0;
for (uint32_t y = 0; y < height; y++) {
for (uint32_t x = 0; x < width; x++) {
SkColor c = bm.getColor(x, y);
buf[n++] = SkColorGetB(c);
buf[n++] = SkColorGetG(c);
buf[n++] = SkColorGetR(c);
buf[n++] = SkColorGetA(c);
if (n == kBufferSize) {
fwrite(buf, 1, n, stdout);
n = 0;
}
}
}
if (n > 0) {
fwrite(buf, 1, n, stdout);
}
}
static void write_nia_padding(uint32_t width, uint32_t height) {
// 4 bytes of padding when the width and height are both odd.
if (width & height & 1) {
uint8_t data[4];
set_u32le(data + 0, 0);
fwrite(data, 1, 4, stdout);
}
}
static void write_nia_footer(int repetitionCount, bool stillImage) {
uint8_t data[8];
if (stillImage || (repetitionCount == SkCodec::kRepetitionCountInfinite)) {
set_u32le(data + 0, 0);
} else {
// NIA's loop count and Skia's repetition count differ by one. See
// https://github.com/google/wuffs/blob/master/doc/spec/nie-spec.md#nii-footer
set_u32le(data + 0, 1 + repetitionCount);
}
set_u32le(data + 4, 0x80000000);
fwrite(data, 1, 8, stdout);
}
int main(int argc, char** argv) {
bool firstFrameOnly = false;
for (int a = 1; a < argc; a++) {
if ((strcmp(argv[a], "-1") == 0) || (strcmp(argv[a], "-first-frame-only") == 0)) {
firstFrameOnly = true;
break;
}
}
std::unique_ptr<SkCodec> codec(SkCodec::MakeFromData(SkData::MakeFromFILE(stdin)));
if (!codec) {
SkDebugf("Decode failed.\n");
return 1;
}
codec->getInfo().makeColorSpace(nullptr);
SkBitmap bm;
bm.allocPixels(codec->getInfo());
size_t bmByteSize = bm.computeByteSize();
// Cache a frame that future frames may depend on.
int cachedFrame = SkCodec::kNoFrame;
SkAutoMalloc cachedFramePixels;
uint64_t totalDurationMillis = 0;
const int frameCount = codec->getFrameCount();
if (frameCount == 0) {
SkDebugf("No frames.\n");
return 1;
}
// The SkCodec::getFrameInfo comment says that this vector will be empty
// for still (not animated) images, even though frameCount should be 1.
std::vector<SkCodec::FrameInfo> frameInfos = codec->getFrameInfo();
bool stillImage = frameInfos.empty();
for (int i = 0; i < frameCount; i++) {
SkCodec::Options opts;
opts.fFrameIndex = i;
if (!stillImage) {
int durationMillis = frameInfos[i].fDuration;
if (durationMillis < 0) {
SkDebugf("Negative animation duration.\n");
return 1;
}
totalDurationMillis += static_cast<uint64_t>(durationMillis);
if (totalDurationMillis > INT64_MAX) {
SkDebugf("Unsupported animation duration.\n");
return 1;
}
if ((cachedFrame != SkCodec::kNoFrame) &&
(cachedFrame == frameInfos[i].fRequiredFrame) && cachedFramePixels.get()) {
opts.fPriorFrame = cachedFrame;
memcpy(bm.getPixels(), cachedFramePixels.get(), bmByteSize);
}
}
if (!firstFrameOnly) {
if (i == 0) {
write_nix_header(0x41AFC36E, // "nïA" magic string as a u32le.
bm.width(), bm.height());
}
if (!write_nia_duration(totalDurationMillis)) {
SkDebugf("Unsupported animation duration.\n");
return 1;
}
}
const SkCodec::Result result =
codec->getPixels(codec->getInfo(), bm.getPixels(), bm.rowBytes(), &opts);
if ((result != SkCodec::kSuccess) && (result != SkCodec::kIncompleteInput)) {
SkDebugf("Decode frame pixels #%d failed.\n", i);
return 1;
}
// If the next frame depends on this one, store it in cachedFrame. It
// is possible that we may discard a frame that future frames depend
// on, but the codec will simply redecode the discarded frame.
if ((static_cast<size_t>(i + 1) < frameInfos.size()) &&
(frameInfos[i + 1].fRequiredFrame == i)) {
cachedFrame = i;
memcpy(cachedFramePixels.reset(bmByteSize), bm.getPixels(), bmByteSize);
}
int width = bm.width();
int height = bm.height();
write_nix_header(0x45AFC36E, // "nïE" magic string as a u32le.
width, height);
write_nie_pixels(width, height, bm);
if (result == SkCodec::kIncompleteInput) {
SkDebugf("Incomplete input.\n");
return 1;
}
if (firstFrameOnly) {
return 0;
}
write_nia_padding(width, height);
}
write_nia_footer(codec->getRepetitionCount(), stillImage);
return 0;
}