Function avifDecoderDecodeTiles

src/read.c:6729–6856

}

static avifResult avifDecoderDecodeTiles(avifDecoder * decoder, uint32_t nextImageIndex, avifTileInfo * info)
{
    const unsigned int oldDecodedTileCount = info->decodedTileCount;
    for (unsigned int tileIndex = oldDecodedTileCount; tileIndex < info->tileCount; ++tileIndex) {
        avifTile * tile = &decoder->data->tiles.tile[info->firstTileIndex + tileIndex];

        const avifDecodeSample * sample = &tile->input->samples.sample[nextImageIndex];
        if (sample->data.size < sample->size) {
            AVIF_ASSERT_OR_RETURN(decoder->allowIncremental);
            // Data is missing but there is no error yet. Output available pixel rows.
            return AVIF_RESULT_OK;
        }

        avifBool isLimitedRangeAlpha = AVIF_FALSE;
        tile->codec->maxThreads = decoder->maxThreads;
        tile->codec->imageSizeLimit = decoder->imageSizeLimit;
        tile->codec->imageDimensionLimit = decoder->imageDimensionLimit;
        if (!tile->codec->getNextImage(tile->codec, sample, avifIsAlpha(tile->input->itemCategory), &isLimitedRangeAlpha, tile->image)) {
            avifDiagnosticsPrintf(&decoder->diag, "tile->codec->getNextImage() failed");
            return avifGetErrorForItemCategory(tile->input->itemCategory);
        }

        // Section 2.3.4 of AV1 Codec ISO Media File Format Binding v1.2.0 says:
        //   the full_range_flag in the colr box shall match the color_range
        //   flag in the Sequence Header OBU.
        // See https://aomediacodec.github.io/av1-isobmff/v1.2.0.html#av1codecconfigurationbox-semantics.
        // If a 'colr' box of colour_type 'nclx' was parsed, a mismatch between
        // the 'colr' decoder->image->yuvRange and the AV1 OBU
        // tile->image->yuvRange should be treated as an error.
        // However codec_svt.c was not encoding the color_range field for
        // multiple years, so there probably are files in the wild that will
        // fail decoding if this is enforced. Thus this pattern is allowed.
        // Section 12.1.5.1 of ISO 14496-12 (ISOBMFF) says:
        //   If colour information is supplied in both this [colr] box, and also
        //   in the video bitstream, this box takes precedence, and over-rides
        //   the information in the bitstream.
        // So decoder->image->yuvRange is kept because it was either the 'colr'
        // value set when the 'colr' box was parsed, or it was the AV1 OBU value
        // extracted from the sequence header OBU of the first tile of the first
        // frame (if no 'colr' box of colour_type 'nclx' was found).

        // Alpha plane with limited range is not allowed by the latest revision
        // of the specification. However, it was allowed in version 1.0.0 of the
        // specification. To allow such files, simply convert the alpha plane to
        // full range.
        if (avifIsAlpha(tile->input->itemCategory) && isLimitedRangeAlpha) {
            avifResult result = avifImageLimitedToFullAlpha(tile->image);
            if (result != AVIF_RESULT_OK) {
                avifDiagnosticsPrintf(&decoder->diag, "avifImageLimitedToFullAlpha failed");
                return result;
            }
        }

        // Scale the decoded image so that it corresponds to this tile's output dimensions
        if ((tile->width != tile->image->width) || (tile->height != tile->image->height)) {
            if (avifImageScaleWithLimit(tile->image,
                                        tile->width,
                                        tile->height,