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Fix return type of avifWriteToneMappedImagePayload (#2439)
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Also refactor avifWriteToneMappedImagePayload() into
avifWriteGainmapMetadata() which will be used by the HDR part of
SlimHEIF.
Add avifGainmapMetadataSize() which will be used by the HDR part of
SlimHEIF.
Add spec comments and references.
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@y-guyon
y-guyon authored Sep 24, 2024
1 parent 70862dc commit ca3e4be
Showing 1 changed file with 74 additions and 57 deletions.
131 changes: 74 additions & 57 deletions src/write.c
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Original file line number Diff line number Diff line change
Expand Up @@ -891,65 +891,85 @@ static avifResult avifWriteGridPayload(avifRWData * data, uint32_t gridCols, uin

#if defined(AVIF_ENABLE_EXPERIMENTAL_GAIN_MAP)

static avifBool avifWriteToneMappedImagePayload(avifRWData * data, const avifGainMapMetadata * metadata)
static avifBool avifGainmapMetadataIdenticalChannels(const avifGainMapMetadata * metadata)
{
avifRWStream s;
avifRWStreamStart(&s, data);
const uint8_t version = 0;
AVIF_CHECKRES(avifRWStreamWriteU8(&s, version));
return metadata->gainMapMinN[0] == metadata->gainMapMinN[1] && metadata->gainMapMinN[0] == metadata->gainMapMinN[2] &&
metadata->gainMapMinD[0] == metadata->gainMapMinD[1] && metadata->gainMapMinD[0] == metadata->gainMapMinD[2] &&
metadata->gainMapMaxN[0] == metadata->gainMapMaxN[1] && metadata->gainMapMaxN[0] == metadata->gainMapMaxN[2] &&
metadata->gainMapMaxD[0] == metadata->gainMapMaxD[1] && metadata->gainMapMaxD[0] == metadata->gainMapMaxD[2] &&
metadata->gainMapGammaN[0] == metadata->gainMapGammaN[1] && metadata->gainMapGammaN[0] == metadata->gainMapGammaN[2] &&
metadata->gainMapGammaD[0] == metadata->gainMapGammaD[1] && metadata->gainMapGammaD[0] == metadata->gainMapGammaD[2] &&
metadata->baseOffsetN[0] == metadata->baseOffsetN[1] && metadata->baseOffsetN[0] == metadata->baseOffsetN[2] &&
metadata->baseOffsetD[0] == metadata->baseOffsetD[1] && metadata->baseOffsetD[0] == metadata->baseOffsetD[2] &&
metadata->alternateOffsetN[0] == metadata->alternateOffsetN[1] &&
metadata->alternateOffsetN[0] == metadata->alternateOffsetN[2] &&
metadata->alternateOffsetD[0] == metadata->alternateOffsetD[1] &&
metadata->alternateOffsetD[0] == metadata->alternateOffsetD[2];
}

// Returns the number of bytes written by avifWriteGainmapMetadata().
static avifBool avifGainmapMetadataSize(const avifGainMapMetadata * metadata)
{
const uint8_t channelCount = avifGainmapMetadataIdenticalChannels(metadata) ? 1u : 3u;
return sizeof(uint16_t) * 2 + sizeof(uint8_t) + sizeof(uint32_t) * 4 + channelCount * sizeof(uint32_t) * 10;
}

static avifResult avifWriteGainmapMetadata(avifRWStream * s, const avifGainMapMetadata * metadata)
{
const size_t offset = avifRWStreamOffset(s);

// GainMapMetadata syntax as per clause C.2.2 of ISO 21496-1:

// GainMapVersion syntax as per clause C.2.2 of ISO 21496-1:
const uint16_t minimumVersion = 0;
AVIF_CHECKRES(avifRWStreamWriteU16(&s, minimumVersion));
AVIF_CHECKRES(avifRWStreamWriteBits(s, minimumVersion, 16)); // unsigned int(16) minimum_version;
const uint16_t writerVersion = 0;
AVIF_CHECKRES(avifRWStreamWriteU16(&s, writerVersion));

uint8_t flags = 0u;
// Always write three channels for now for simplicity.
// TODO(maryla): the draft says that this specifies the count of channels of the
// gain map. But tone mapping is done in RGB space so there are always three
// channels, even if the gain map is grayscale. Should this be revised?
const avifBool allChannelsIdentical =
metadata->gainMapMinN[0] == metadata->gainMapMinN[1] && metadata->gainMapMinN[0] == metadata->gainMapMinN[2] &&
metadata->gainMapMinD[0] == metadata->gainMapMinD[1] && metadata->gainMapMinD[0] == metadata->gainMapMinD[2] &&
metadata->gainMapMaxN[0] == metadata->gainMapMaxN[1] && metadata->gainMapMaxN[0] == metadata->gainMapMaxN[2] &&
metadata->gainMapMaxD[0] == metadata->gainMapMaxD[1] && metadata->gainMapMaxD[0] == metadata->gainMapMaxD[2] &&
metadata->gainMapGammaN[0] == metadata->gainMapGammaN[1] && metadata->gainMapGammaN[0] == metadata->gainMapGammaN[2] &&
metadata->gainMapGammaD[0] == metadata->gainMapGammaD[1] && metadata->gainMapGammaD[0] == metadata->gainMapGammaD[2] &&
metadata->baseOffsetN[0] == metadata->baseOffsetN[1] && metadata->baseOffsetN[0] == metadata->baseOffsetN[2] &&
metadata->baseOffsetD[0] == metadata->baseOffsetD[1] && metadata->baseOffsetD[0] == metadata->baseOffsetD[2] &&
metadata->alternateOffsetN[0] == metadata->alternateOffsetN[1] &&
metadata->alternateOffsetN[0] == metadata->alternateOffsetN[2] &&
metadata->alternateOffsetD[0] == metadata->alternateOffsetD[1] &&
metadata->alternateOffsetD[0] == metadata->alternateOffsetD[2];
const uint8_t channelCount = allChannelsIdentical ? 1u : 3u;
if (channelCount == 3) {
flags |= (1 << 7);
}
if (metadata->useBaseColorSpace) {
flags |= (1 << 6);
}
AVIF_CHECKRES(avifRWStreamWriteU8(&s, flags));

AVIF_CHECKRES(avifRWStreamWriteU32(&s, metadata->baseHdrHeadroomN));
AVIF_CHECKRES(avifRWStreamWriteU32(&s, metadata->baseHdrHeadroomD));
AVIF_CHECKRES(avifRWStreamWriteU32(&s, metadata->alternateHdrHeadroomN));
AVIF_CHECKRES(avifRWStreamWriteU32(&s, metadata->alternateHdrHeadroomD));

for (int c = 0; c < channelCount; ++c) {
AVIF_CHECKRES(avifRWStreamWriteU32(&s, (uint32_t)metadata->gainMapMinN[c]));
AVIF_CHECKRES(avifRWStreamWriteU32(&s, metadata->gainMapMinD[c]));
AVIF_CHECKRES(avifRWStreamWriteU32(&s, (uint32_t)metadata->gainMapMaxN[c]));
AVIF_CHECKRES(avifRWStreamWriteU32(&s, metadata->gainMapMaxD[c]));
AVIF_CHECKRES(avifRWStreamWriteU32(&s, metadata->gainMapGammaN[c]));
AVIF_CHECKRES(avifRWStreamWriteU32(&s, metadata->gainMapGammaD[c]));
AVIF_CHECKRES(avifRWStreamWriteU32(&s, (uint32_t)metadata->baseOffsetN[c]));
AVIF_CHECKRES(avifRWStreamWriteU32(&s, metadata->baseOffsetD[c]));
AVIF_CHECKRES(avifRWStreamWriteU32(&s, (uint32_t)metadata->alternateOffsetN[c]));
AVIF_CHECKRES(avifRWStreamWriteU32(&s, metadata->alternateOffsetD[c]));
}
AVIF_CHECKRES(avifRWStreamWriteBits(s, writerVersion, 16)); // unsigned int(16) writer_version;

if (minimumVersion == 0) {
const uint8_t channelCount = avifGainmapMetadataIdenticalChannels(metadata) ? 1u : 3u;
AVIF_CHECKRES(avifRWStreamWriteBits(s, channelCount == 3, 1)); // unsigned int(1) is_multichannel;
AVIF_CHECKRES(avifRWStreamWriteBits(s, metadata->useBaseColorSpace, 1)); // unsigned int(1) use_base_colour_space;
AVIF_CHECKRES(avifRWStreamWriteBits(s, 0, 6)); // unsigned int(6) reserved;

AVIF_CHECKRES(avifRWStreamWriteBits(s, metadata->baseHdrHeadroomN, 32)); // unsigned int(32) base_hdr_headroom_numerator;
AVIF_CHECKRES(avifRWStreamWriteBits(s, metadata->baseHdrHeadroomD, 32)); // unsigned int(32) base_hdr_headroom_denominator;
AVIF_CHECKRES(avifRWStreamWriteBits(s, metadata->alternateHdrHeadroomN, 32)); // unsigned int(32) alternate_hdr_headroom_numerator;
AVIF_CHECKRES(avifRWStreamWriteBits(s, metadata->alternateHdrHeadroomD, 32)); // unsigned int(32) alternate_hdr_headroom_denominator;

// GainMapChannel channels[channel_count];
for (int c = 0; c < channelCount; ++c) {
// GainMapChannel syntax as per clause C.2.2 of ISO 21496-1:
AVIF_CHECKRES(avifRWStreamWriteBits(s, (uint32_t)metadata->gainMapMinN[c], 32)); // int(32) gain_map_min_numerator;
AVIF_CHECKRES(avifRWStreamWriteBits(s, metadata->gainMapMinD[c], 32)); // unsigned int(32) gain_map_min_denominator;
AVIF_CHECKRES(avifRWStreamWriteBits(s, (uint32_t)metadata->gainMapMaxN[c], 32)); // int(32) gain_map_max_numerator;
AVIF_CHECKRES(avifRWStreamWriteBits(s, metadata->gainMapMaxD[c], 32)); // unsigned int(32) gain_map_max_denominator;
AVIF_CHECKRES(avifRWStreamWriteBits(s, metadata->gainMapGammaN[c], 32)); // unsigned int(32) gamma_numerator;
AVIF_CHECKRES(avifRWStreamWriteBits(s, metadata->gainMapGammaD[c], 32)); // unsigned int(32) gamma_denominator;
AVIF_CHECKRES(avifRWStreamWriteBits(s, (uint32_t)metadata->baseOffsetN[c], 32)); // int(32) base_offset_numerator;
AVIF_CHECKRES(avifRWStreamWriteBits(s, metadata->baseOffsetD[c], 32)); // unsigned int(32) base_offset_denominator;
AVIF_CHECKRES(avifRWStreamWriteBits(s, (uint32_t)metadata->alternateOffsetN[c], 32)); // int(32) alternate_offset_numerator;
AVIF_CHECKRES(avifRWStreamWriteBits(s, metadata->alternateOffsetD[c], 32)); // unsigned int(32) alternate_offset_denominator;
}
}

AVIF_ASSERT_OR_RETURN(avifRWStreamOffset(s) == offset + avifGainmapMetadataSize(metadata));
return AVIF_RESULT_OK;
}

static avifResult avifWriteToneMappedImagePayload(avifRWData * data, const avifGainMapMetadata * metadata)
{
avifRWStream s;
avifRWStreamStart(&s, data);
// ToneMapImage syntax as per section 6.6.2.4.2 of ISO/IEC 23008-12:2024
// amendment "Support for tone map derived image items and other improvements":
const uint8_t version = 0;
AVIF_CHECKRES(avifRWStreamWriteU8(&s, version)); // unsigned int(8) version = 0;
if (version == 0) {
AVIF_CHECKRES(avifWriteGainmapMetadata(&s, metadata)); // GainMapMetadata;
}
avifRWStreamFinishWrite(&s);
return AVIF_TRUE;
return AVIF_RESULT_OK;
}

size_t avifEncoderGetGainMapSizeBytes(avifEncoder * encoder)
Expand Down Expand Up @@ -1848,10 +1868,7 @@ static avifResult avifEncoderAddImageInternal(avifEncoder * encoder,
infeNameGainMap,
/*infeNameSize=*/strlen(infeNameGainMap) + 1,
/*cellIndex=*/0);
if (!avifWriteToneMappedImagePayload(&toneMappedItem->metadataPayload, &firstCell->gainMap->metadata)) {
avifDiagnosticsPrintf(&encoder->diag, "failed to write gain map metadata, some values may be negative or too large");
return AVIF_RESULT_ENCODE_GAIN_MAP_FAILED;
}
AVIF_CHECKRES(avifWriteToneMappedImagePayload(&toneMappedItem->metadataPayload, &firstCell->gainMap->metadata));
// Even though the 'tmap' item is related to the gain map, it represents a color image and its metadata is more similar to the color item.
toneMappedItem->itemCategory = AVIF_ITEM_COLOR;
uint16_t toneMappedItemID = toneMappedItem->id;
Expand Down

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