Multiple standard XMP segments error when converting JPG #2919
Description
When using libultrahdr library and the ultrahdr_app. Specifically in API-4 mode where the SDR and gainmap are both normal JPGs. Attempting to convert those files with libavif will produce error:
XMP extraction failed: invalid multiple standard XMP segments
Generating a test UHDR image with the jpeg_image.jpeg from libultrahdr:
ultrahdr_app -m 0 -i jpeg_image.jpg -g jpeg_image.jpg -f metadata.cfg
I inserted some debug code in avifjpeg.c, it seems the for loop:
for (jpeg_saved_marker_ptr marker = cinfo.marker_list; marker != NULL; marker = marker->next) {
if ((marker->marker == (JPEG_APP0 + 1)) && (marker->data_length > AVIF_JPEG_STANDARD_XMP_TAG_LENGTH) &&
!memcmp(marker->data, AVIF_JPEG_STANDARD_XMP_TAG, AVIF_JPEG_STANDARD_XMP_TAG_LENGTH)) {
...}
Will find two AVIF_JPEG_STANDARD_XMP_TAG: "http://ns.adobe.com/xap/1.0/" in the sdr rendition, and two more in the stored gainmap.
As long as the lines below only run once per loop, the conversion is otherwise successful:
standardXMPData = marker->data + AVIF_JPEG_STANDARD_XMP_TAG_LENGTH;
standardXMPSize = (uint32_t)(marker->data_length - AVIF_JPEG_STANDARD_XMP_TAG_LENGTH);
The loop picks up double tags inside the paris_exif_xmp_gainmap_xxx.jpg files as well.
I can't see where the second tag is using "exiv2 -pS".
Is this check actually needed, or can the loop just break once the first marker is found?
if (standardXMPData) {
fprintf(stderr, "XMP extraction failed: invalid multiple standard XMP segments\n");
goto cleanup;
}