Rename content to metadataPayload as it is more descriptive, add clarifying comments
diff --git a/src/write.c b/src/write.c
index d804be3..adb4151 100644
--- a/src/write.c
+++ b/src/write.c
@@ -75,8 +75,8 @@
uint16_t id;
uint8_t type[4];
avifCodec * codec; // only present on type==av01
- avifCodecEncodeOutput * encodeOutput; // AV1 sample data for image sequences
- avifRWData content; // OBU data on av01 items-based image, metadata payload for Exif/XMP
+ avifCodecEncodeOutput * encodeOutput; // AV1 sample data
+ avifRWData metadataPayload; // Exif/XMP data
avifBool alpha;
const char * infeName;
@@ -146,7 +146,7 @@
avifCodecDestroy(item->codec);
}
avifCodecEncodeOutputDestroy(item->encodeOutput);
- avifRWDataFree(&item->content);
+ avifRWDataFree(&item->metadataPayload);
avifArrayDestroy(&item->mdatFixups);
}
avifImageDestroy(data->imageMetadata);
@@ -292,20 +292,16 @@
for (uint32_t trakItemIndex = 0; trakItemIndex < encoder->data->items.count; ++trakItemIndex) {
avifEncoderItem * item = &encoder->data->items.item[trakItemIndex];
if (memcmp(item->type, "av01", 4) == 0) {
+ // Skip over all non-metadata items
continue;
}
- uint32_t contentSize = (uint32_t)item->content.size;
- if (item->encodeOutput->samples.count > 0) {
- contentSize = (uint32_t)item->encodeOutput->samples.sample[0].data.size;
- }
-
- avifRWStreamWriteU16(s, item->id); // unsigned int(16) item_ID;
- avifRWStreamWriteU16(s, 0); // unsigned int(16) data_reference_index;
- avifRWStreamWriteU16(s, 1); // unsigned int(16) extent_count;
- avifEncoderItemAddMdatFixup(item, s); //
- avifRWStreamWriteU32(s, 0 /* set later */); // unsigned int(offset_size*8) extent_offset;
- avifRWStreamWriteU32(s, contentSize); // unsigned int(length_size*8) extent_length;
+ avifRWStreamWriteU16(s, item->id); // unsigned int(16) item_ID;
+ avifRWStreamWriteU16(s, 0); // unsigned int(16) data_reference_index;
+ avifRWStreamWriteU16(s, 1); // unsigned int(16) extent_count;
+ avifEncoderItemAddMdatFixup(item, s); //
+ avifRWStreamWriteU32(s, 0 /* set later */); // unsigned int(offset_size*8) extent_offset;
+ avifRWStreamWriteU32(s, (uint32_t)item->metadataPayload.size); // unsigned int(length_size*8) extent_length;
}
avifRWStreamFinishBox(s, iloc);
@@ -412,10 +408,10 @@
exifItem->irefToID = encoder->data->primaryItemID;
exifItem->irefType = "cdsc";
- avifRWDataRealloc(&exifItem->content, sizeof(uint32_t) + image->exif.size);
+ avifRWDataRealloc(&exifItem->metadataPayload, sizeof(uint32_t) + image->exif.size);
exifTiffHeaderOffset = avifHTONL(exifTiffHeaderOffset);
- memcpy(exifItem->content.data, &exifTiffHeaderOffset, sizeof(uint32_t));
- memcpy(exifItem->content.data + sizeof(uint32_t), image->exif.data, image->exif.size);
+ memcpy(exifItem->metadataPayload.data, &exifTiffHeaderOffset, sizeof(uint32_t));
+ memcpy(exifItem->metadataPayload.data + sizeof(uint32_t), image->exif.data, image->exif.size);
}
if (image->xmp.size > 0) {
@@ -425,7 +421,7 @@
xmpItem->infeContentType = xmpContentType;
xmpItem->infeContentTypeSize = xmpContentTypeSize;
- avifRWDataSet(&xmpItem->content, image->xmp.data, image->xmp.size);
+ avifRWDataSet(&xmpItem->metadataPayload, image->xmp.data, image->xmp.size);
}
// -----------------------------------------------------------------------
@@ -571,8 +567,16 @@
for (uint32_t itemIndex = 0; itemIndex < encoder->data->items.count; ++itemIndex) {
avifEncoderItem * item = &encoder->data->items.item[itemIndex];
- uint32_t contentSize = (uint32_t)item->content.size;
+ uint32_t contentSize = (uint32_t)item->metadataPayload.size;
if (item->encodeOutput->samples.count > 0) {
+ // This is choosing sample 0's size as there are two cases here:
+ // * This is a single image, in which this is correct
+ // * This is an image sequence, but this file should still be a valid single-image avif,
+ // so there must still be a primary item pointing at a sync sample. Since the first
+ // frame of the image sequence is guaranteed to be a sync sample, it is chosen here.
+ //
+ // TODO: Offer the ability for an user to specify which frame in the sequence should
+ // become the primary item's image, and force that frame to be a keyframe.
contentSize = (uint32_t)item->encodeOutput->samples.sample[0].data.size;
}
@@ -922,7 +926,7 @@
avifBoxMarker mdat = avifRWStreamWriteBox(&s, "mdat", AVIF_BOX_SIZE_TBD);
for (uint32_t itemIndex = 0; itemIndex < encoder->data->items.count; ++itemIndex) {
avifEncoderItem * item = &encoder->data->items.item[itemIndex];
- if ((item->content.size == 0) && (item->encodeOutput->samples.count == 0)) {
+ if ((item->metadataPayload.size == 0) && (item->encodeOutput->samples.count == 0)) {
continue;
}
@@ -933,7 +937,7 @@
avifRWStreamWrite(&s, sample->data.data, sample->data.size);
}
} else {
- avifRWStreamWrite(&s, item->content.data, item->content.size);
+ avifRWStreamWrite(&s, item->metadataPayload.data, item->metadataPayload.size);
}
for (uint32_t fixupIndex = 0; fixupIndex < item->mdatFixups.count; ++fixupIndex) {
