Clarify comments about non-grid images with alpha
In this case, the alpha plane also needs to be a non-grid auxiliary
image. I use the term "single tile" instead of "non-grid" to match the
existing comments.
diff --git a/src/read.c b/src/read.c
index 36a9058..0c0fb89 100644
--- a/src/read.c
+++ b/src/read.c
@@ -3369,8 +3369,9 @@
static avifBool avifTilesCanBeDecodedWithSameAV1Decoder(avifDecoderData * data)
{
if (data->color.tileCount == 1 && data->alpha.tileCount == 1) {
- // Single tile image with alpha plane. In this case each tile needs its own decoder since the planes will be "stolen".
- // Stealing either the color or the alpha plane will invalidate the other one when decode is called the second time.
+ // Single tile image with single tile alpha plane. In this case each tile needs its own decoder since the planes will be
+ // "stolen". Stealing either the color or the alpha plane will invalidate the other one when decode is called the second
+ // time.
return AVIF_FALSE;
}
const uint8_t firstTileOperatingPoint = data->tiles.tile[0].operatingPoint;
@@ -3407,8 +3408,8 @@
// and do not allow it to be changed later).
// - All the tiles must have the same value for allLayers (because AV1 decoders take allLayers once at initialization
// and do not allow it to be changed later).
- // - If the image has a single tile, it must not have an alpha plane (in this case we will steal the planes from the
- // decoder, so we cannot use the same decoder for both the color and the alpha planes).
+ // - If the image has a single tile, it must not have a single tile alpha plane (in this case we will steal the planes
+ // from the decoder, so we cannot use the same decoder for both the color and the alpha planes).
// Otherwise, we will use |tiles.count| decoder instances (one instance for each tile).
avifBool canUseSingleDecoder = (data->tiles.count == 1) ||
(decoder->imageCount == 1 && avifTilesCanBeDecodedWithSameAV1Decoder(data));
