struct heif_error vvdec_decode_image()

in libheif/plugins/decoder_vvdec.cc [176:326]

• 109 lines of code
• 20 McCabe index (conditional complexity)

struct heif_error vvdec_decode_image(void* decoder_raw, struct heif_image** out_img)
{
  auto* decoder = (struct vvdec_decoder*) decoder_raw;

  vvdecFrame* frame = nullptr;

  // --- prepare AU payload with maximum NALU size

  size_t max_payload_size = 0;
  for (const auto& nalu : decoder->nalus) {
    max_payload_size = std::max(max_payload_size, nalu.size());
  }

  if (decoder->au == nullptr || max_payload_size > (size_t) decoder->au->payloadSize) {
    if (decoder->au) {
      vvdec_accessUnit_free(decoder->au);
    }

    decoder->au = vvdec_accessUnit_alloc();
    vvdec_accessUnit_default(decoder->au);
    vvdec_accessUnit_alloc_payload(decoder->au, (int)max_payload_size);
  }

  // --- feed NALUs into decoder, flush when done

  for (int i = 0;; i++) {
    int ret;

    if (i < (int) decoder->nalus.size()) {
      const auto& nalu = decoder->nalus[i];

      memcpy(decoder->au->payload, nalu.data(), nalu.size());
      decoder->au->payloadUsedSize = (int) nalu.size();

      ret = vvdec_decode(decoder->decoder, decoder->au, &frame);
    }
    else {
      ret = vvdec_flush(decoder->decoder, &frame);
    }

    if (ret != VVDEC_OK && ret != VVDEC_EOF && ret != VVDEC_TRY_AGAIN) {
      return {heif_error_Decoder_plugin_error, heif_suberror_Unspecified, "vvdec decoding error"};
    }

    if (frame) {
      break;
    }

    if (ret == VVDEC_EOF) {
      return {heif_error_Decoder_plugin_error, heif_suberror_Unspecified, "no frame decoded"};
    }
  }


  decoder->nalus.clear();

  // --- convert decoded frame to heif_image

  heif_chroma chroma;
  heif_colorspace colorspace;

  if (frame->colorFormat == VVDEC_CF_YUV400_PLANAR) {
    chroma = heif_chroma_monochrome;
    colorspace = heif_colorspace_monochrome;
  }
  else {
    if (frame->colorFormat == VVDEC_CF_YUV444_PLANAR) {
      chroma = heif_chroma_444;
    }
    else if (frame->colorFormat == VVDEC_CF_YUV422_PLANAR) {
      chroma = heif_chroma_422;
    }
    else {
      chroma = heif_chroma_420;
    }
    colorspace = heif_colorspace_YCbCr;
  }

  struct heif_image* heif_img = nullptr;
  struct heif_error err = heif_image_create((int)frame->width,
                                            (int)frame->height,
                                            colorspace,
                                            chroma,
                                            &heif_img);
  if (err.code != heif_error_Ok) {
    assert(heif_img == nullptr);
    return err;
  }


  // --- read nclx parameters from decoded AV1 bitstream

#if 0
  heif_color_profile_nclx nclx;
  nclx.version = 1;
  HEIF_WARN_OR_FAIL(decoder->strict_decoding, heif_img, heif_nclx_color_profile_set_color_primaries(&nclx, static_cast<uint16_t>(img->cp)), { heif_image_release(heif_img); });
  HEIF_WARN_OR_FAIL(decoder->strict_decoding, heif_img, heif_nclx_color_profile_set_transfer_characteristics(&nclx, static_cast<uint16_t>(img->tc)), { heif_image_release(heif_img); });
  HEIF_WARN_OR_FAIL(decoder->strict_decoding, heif_img, heif_nclx_color_profile_set_matrix_coefficients(&nclx, static_cast<uint16_t>(img->mc)), { heif_image_release(heif_img); });
  nclx.full_range_flag = (img->range == AOM_CR_FULL_RANGE);
  heif_image_set_nclx_color_profile(heif_img, &nclx);
#endif

  // --- transfer data from vvdecFrame to HeifPixelImage

  heif_channel channel2plane[3] = {
      heif_channel_Y,
      heif_channel_Cb,
      heif_channel_Cr
  };


  int num_planes = (chroma == heif_chroma_monochrome ? 1 : 3);

  for (int c = 0; c < num_planes; c++) {
    int bpp = (int)frame->bitDepth;

    const auto& plane = frame->planes[c];
    const uint8_t* data = plane.ptr;
    int stride = (int)plane.stride;

    int w = (int)plane.width;
    int h = (int)plane.height;

    err = heif_image_add_plane(heif_img, channel2plane[c], w, h, bpp);
    if (err.code != heif_error_Ok) {
      heif_image_release(heif_img);
      return err;
    }

    int dst_stride;
    uint8_t* dst_mem = heif_image_get_plane(heif_img, channel2plane[c], &dst_stride);

    int bytes_per_pixel = (bpp + 7) / 8;

    for (int y = 0; y < h; y++) {
      memcpy(dst_mem + y * dst_stride, data + y * stride, w * bytes_per_pixel);
    }

#if 0
      std::cout << "DATA " << c << " " << w << " " << h << " bpp:" << bpp << "\n";
      std::cout << write_raw_data_as_hex(dst_mem, w*h, {}, {});
      std::cout << "---\n";
#endif
  }

  *out_img = heif_img;

  vvdec_frame_unref(decoder->decoder, frame);

  return err;
}