/*

 * Copyright (c) 2017, Alliance for Open Media. All rights reserved

 *

 * This source code is subject to the terms of the BSD 2 Clause License and

 * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License

 * was not distributed with this source code in the LICENSE file, you can

 * obtain it at www.aomedia.org/license/software. If the Alliance for Open

 * Media Patent License 1.0 was not distributed with this source code in the

 * PATENTS file, you can obtain it at www.aomedia.org/license/patent.

 */

#include <assert.h>

#include "config/aom_config.h"

#include "config/aom_scale_rtcd.h"

#include "aom/aom_codec.h"

#include "aom_dsp/bitreader_buffer.h"

#include "aom_ports/mem_ops.h"

#include "av1/common/common.h"

#include "av1/common/obu_util.h"

#include "av1/common/timing.h"

#include "av1/decoder/decoder.h"

#include "av1/decoder/decodeframe.h"

#include "av1/decoder/obu.h"

aom_codec_err_t aom_get_num_layers_from_operating_point_idc(

    int operating_point_idc, unsigned int *number_spatial_layers,

    unsigned int *number_temporal_layers) {

  // derive number of spatial/temporal layers from operating_point_idc

  if (!number_spatial_layers || !number_temporal_layers)

    return AOM_CODEC_INVALID_PARAM;

  if (operating_point_idc == 0) {

    *number_temporal_layers = 1;

    *number_spatial_layers = 1;

  } else {

    *number_spatial_layers = 0;

    *number_temporal_layers = 0;

    for (int j = 0; j < MAX_NUM_SPATIAL_LAYERS; j++) {

      *number_spatial_layers +=

          (operating_point_idc >> (j + MAX_NUM_TEMPORAL_LAYERS)) & 0x1;

    }

    for (int j = 0; j < MAX_NUM_TEMPORAL_LAYERS; j++) {

      *number_temporal_layers += (operating_point_idc >> j) & 0x1;

    }

  }

  return AOM_CODEC_OK;

}

static int is_obu_in_current_operating_point(AV1Decoder *pbi,

                                             const ObuHeader *obu_header) {

  if (!pbi->current_operating_point || !obu_header->has_extension) {

    return 1;

  }

  if ((pbi->current_operating_point >> obu_header->temporal_layer_id) & 0x1 &&

      (pbi->current_operating_point >> (obu_header->spatial_layer_id + 8)) &

          0x1) {

    return 1;

  }

  return 0;

}

static int byte_alignment(AV1_COMMON *const cm,

                          struct aom_read_bit_buffer *const rb) {

  while (rb->bit_offset & 7) {

    if (aom_rb_read_bit(rb)) {

      cm->error->error_code = AOM_CODEC_CORRUPT_FRAME;

      return -1;

    }

  }

  return 0;

}

static uint32_t read_temporal_delimiter_obu() { return 0; }

// Returns a boolean that indicates success.

static int read_bitstream_level(AV1_LEVEL *seq_level_idx,

                                struct aom_read_bit_buffer *rb) {

  *seq_level_idx = aom_rb_read_literal(rb, LEVEL_BITS);

  if (!is_valid_seq_level_idx(*seq_level_idx)) return 0;

  return 1;

}

// Returns whether two sequence headers are consistent with each other.

// Note that the 'op_params' field is not compared per Section 7.5 in the spec:

//   Within a particular coded video sequence, the contents of

//   sequence_header_obu must be bit-identical each time the sequence header

//   appears except for the contents of operating_parameters_info.

static int are_seq_headers_consistent(const SequenceHeader *seq_params_old,

                                      const SequenceHeader *seq_params_new) {

  return !memcmp(seq_params_old, seq_params_new,

                 offsetof(SequenceHeader, op_params));

}

// On success, sets pbi->sequence_header_ready to 1 and returns the number of

// bytes read from 'rb'.

// On failure, sets pbi->common.error.error_code and returns 0.

static uint32_t read_sequence_header_obu(AV1Decoder *pbi,

                                         struct aom_read_bit_buffer *rb) {

  AV1_COMMON *const cm = &pbi->common;

  const uint32_t saved_bit_offset = rb->bit_offset;

  // Verify rb has been configured to report errors.

  assert(rb->error_handler);

  // Use a local variable to store the information as we decode. At the end,

  // if no errors have occurred, cm->seq_params is updated.

  SequenceHeader sh = *cm->seq_params;

  SequenceHeader *const seq_params = &sh;

  seq_params->profile = av1_read_profile(rb);

  if (seq_params->profile > CONFIG_MAX_DECODE_PROFILE) {

    pbi->error.error_code = AOM_CODEC_UNSUP_BITSTREAM;

    return 0;

  }

  // Still picture or not

  seq_params->still_picture = aom_rb_read_bit(rb);

  seq_params->reduced_still_picture_hdr = aom_rb_read_bit(rb);

  // Video must have reduced_still_picture_hdr = 0

  if (!seq_params->still_picture && seq_params->reduced_still_picture_hdr) {

    pbi->error.error_code = AOM_CODEC_UNSUP_BITSTREAM;

    return 0;

  }

  if (seq_params->reduced_still_picture_hdr) {

    seq_params->timing_info_present = 0;

    seq_params->decoder_model_info_present_flag = 0;

    seq_params->display_model_info_present_flag = 0;

    seq_params->operating_points_cnt_minus_1 = 0;

    seq_params->operating_point_idc[0] = 0;

    if (!read_bitstream_level(&seq_params->seq_level_idx[0], rb)) {

      pbi->error.error_code = AOM_CODEC_UNSUP_BITSTREAM;

      return 0;

    }

    seq_params->tier[0] = 0;

    seq_params->op_params[0].decoder_model_param_present_flag = 0;

    seq_params->op_params[0].display_model_param_present_flag = 0;

  } else {

    seq_params->timing_info_present = aom_rb_read_bit(rb);

    if (seq_params->timing_info_present) {

      av1_read_timing_info_header(&seq_params->timing_info, &pbi->error, rb);

      seq_params->decoder_model_info_present_flag = aom_rb_read_bit(rb);

      if (seq_params->decoder_model_info_present_flag)

        av1_read_decoder_model_info(&seq_params->decoder_model_info, rb);

    } else {

      seq_params->decoder_model_info_present_flag = 0;

    }

    seq_params->display_model_info_present_flag = aom_rb_read_bit(rb);

    seq_params->operating_points_cnt_minus_1 =

        aom_rb_read_literal(rb, OP_POINTS_CNT_MINUS_1_BITS);

    for (int i = 0; i < seq_params->operating_points_cnt_minus_1 + 1; i++) {

      seq_params->operating_point_idc[i] =

          aom_rb_read_literal(rb, OP_POINTS_IDC_BITS);

      if (!read_bitstream_level(&seq_params->seq_level_idx[i], rb)) {

        pbi->error.error_code = AOM_CODEC_UNSUP_BITSTREAM;

        return 0;

      }

      // This is the seq_level_idx[i] > 7 check in the spec. seq_level_idx 7

      // is equivalent to level 3.3.

      if (seq_params->seq_level_idx[i] >= SEQ_LEVEL_4_0)

        seq_params->tier[i] = aom_rb_read_bit(rb);

      else

        seq_params->tier[i] = 0;

      if (seq_params->decoder_model_info_present_flag) {

        seq_params->op_params[i].decoder_model_param_present_flag =

            aom_rb_read_bit(rb);

        if (seq_params->op_params[i].decoder_model_param_present_flag)

          av1_read_op_parameters_info(&seq_params->op_params[i],

                                      seq_params->decoder_model_info

                                          .encoder_decoder_buffer_delay_length,

                                      rb);

      } else {

        seq_params->op_params[i].decoder_model_param_present_flag = 0;

      }

      if (seq_params->timing_info_present &&

          (seq_params->timing_info.equal_picture_interval ||

           seq_params->op_params[i].decoder_model_param_present_flag)) {

        seq_params->op_params[i].bitrate = av1_max_level_bitrate(

            seq_params->profile, seq_params->seq_level_idx[i],

            seq_params->tier[i]);

        // Level with seq_level_idx = 31 returns a high "dummy" bitrate to pass

        // the check

        if (seq_params->op_params[i].bitrate == 0)

          aom_internal_error(&pbi->error, AOM_CODEC_UNSUP_BITSTREAM,

                             "AV1 does not support this combination of "

                             "profile, level, and tier.");

        // Buffer size in bits/s is bitrate in bits/s * 1 s

        seq_params->op_params[i].buffer_size = seq_params->op_params[i].bitrate;

      }

      if (seq_params->timing_info_present &&

          seq_params->timing_info.equal_picture_interval &&

          !seq_params->op_params[i].decoder_model_param_present_flag) {

        // When the decoder_model_parameters are not sent for this op, set

        // the default ones that can be used with the resource availability mode

        seq_params->op_params[i].decoder_buffer_delay = 70000;

        seq_params->op_params[i].encoder_buffer_delay = 20000;

        seq_params->op_params[i].low_delay_mode_flag = 0;

      }

      if (seq_params->display_model_info_present_flag) {

        seq_params->op_params[i].display_model_param_present_flag =

            aom_rb_read_bit(rb);

        if (seq_params->op_params[i].display_model_param_present_flag) {

          seq_params->op_params[i].initial_display_delay =

              aom_rb_read_literal(rb, 4) + 1;

          if (seq_params->op_params[i].initial_display_delay > 10)

            aom_internal_error(

                &pbi->error, AOM_CODEC_UNSUP_BITSTREAM,

                "AV1 does not support more than 10 decoded frames delay");

        } else {

          seq_params->op_params[i].initial_display_delay = 10;

        }

      } else {

        seq_params->op_params[i].display_model_param_present_flag = 0;

        seq_params->op_params[i].initial_display_delay = 10;

      }

    }

  }

  // This decoder supports all levels.  Choose operating point provided by

  // external means

  int operating_point = pbi->operating_point;

  if (operating_point < 0 ||

      operating_point > seq_params->operating_points_cnt_minus_1)

    operating_point = 0;

  pbi->current_operating_point =

      seq_params->operating_point_idc[operating_point];

  if (aom_get_num_layers_from_operating_point_idc(

          pbi->current_operating_point, &pbi->number_spatial_layers,

          &pbi->number_temporal_layers) != AOM_CODEC_OK) {

    pbi->error.error_code = AOM_CODEC_ERROR;

    return 0;

  }

  av1_read_sequence_header(cm, rb, seq_params);

  av1_read_color_config(rb, pbi->allow_lowbitdepth, seq_params, &pbi->error);

  if (!(seq_params->subsampling_x == 0 && seq_params->subsampling_y == 0) &&

      !(seq_params->subsampling_x == 1 && seq_params->subsampling_y == 1) &&

      !(seq_params->subsampling_x == 1 && seq_params->subsampling_y == 0)) {

    aom_internal_error(&pbi->error, AOM_CODEC_UNSUP_BITSTREAM,

                       "Only 4:4:4, 4:2:2 and 4:2:0 are currently supported, "

                       "%d %d subsampling is not supported.\n",

                       seq_params->subsampling_x, seq_params->subsampling_y);

  }

  seq_params->film_grain_params_present = aom_rb_read_bit(rb);

  if (av1_check_trailing_bits(pbi, rb) != 0) {

    // pbi->error.error_code is already set.

    return 0;

  }

  // If a sequence header has been decoded before, we check if the new

  // one is consistent with the old one.

  if (pbi->sequence_header_ready) {

    if (!are_seq_headers_consistent(cm->seq_params, seq_params))

      pbi->sequence_header_changed = 1;

  }

  *cm->seq_params = *seq_params;

  pbi->sequence_header_ready = 1;

  return ((rb->bit_offset - saved_bit_offset + 7) >> 3);

}

// On success, returns the frame header size. On failure, calls

// aom_internal_error and does not return. If show existing frame,

// also marks the data processing to end after the frame header.

static uint32_t read_frame_header_obu(AV1Decoder *pbi,

                                      struct aom_read_bit_buffer *rb,

                                      const uint8_t *data,

                                      const uint8_t **p_data_end,

                                      int trailing_bits_present) {

  const uint32_t hdr_size =

      av1_decode_frame_headers_and_setup(pbi, rb, trailing_bits_present);

  const AV1_COMMON *cm = &pbi->common;

  if (cm->show_existing_frame) {

    *p_data_end = data + hdr_size;

  }

  return hdr_size;

}

// On success, returns the tile group header size. On failure, calls

// aom_internal_error() and returns -1.

static int32_t read_tile_group_header(AV1Decoder *pbi,

                                      struct aom_read_bit_buffer *rb,

                                      int *start_tile, int *end_tile,

                                      int tile_start_implicit) {

  AV1_COMMON *const cm = &pbi->common;

  CommonTileParams *const tiles = &cm->tiles;

  uint32_t saved_bit_offset = rb->bit_offset;

  int tile_start_and_end_present_flag = 0;

  const int num_tiles = tiles->rows * tiles->cols;

  if (!tiles->large_scale && num_tiles > 1) {

    tile_start_and_end_present_flag = aom_rb_read_bit(rb);

    if (tile_start_implicit && tile_start_and_end_present_flag) {

      aom_internal_error(

          &pbi->error, AOM_CODEC_UNSUP_BITSTREAM,

          "For OBU_FRAME type obu tile_start_and_end_present_flag must be 0");

      return -1;

    }

  }

  if (tiles->large_scale || num_tiles == 1 ||

      !tile_start_and_end_present_flag) {

    *start_tile = 0;

    *end_tile = num_tiles - 1;

  } else {

    int tile_bits = tiles->log2_rows + tiles->log2_cols;

    *start_tile = aom_rb_read_literal(rb, tile_bits);

    *end_tile = aom_rb_read_literal(rb, tile_bits);

  }

  if (*start_tile != pbi->next_start_tile) {

    aom_internal_error(&pbi->error, AOM_CODEC_CORRUPT_FRAME,

                       "tg_start (%d) must be equal to %d", *start_tile,

                       pbi->next_start_tile);

    return -1;

  }

  if (*start_tile > *end_tile) {

    aom_internal_error(

        &pbi->error, AOM_CODEC_CORRUPT_FRAME,

        "tg_end (%d) must be greater than or equal to tg_start (%d)", *end_tile,

        *start_tile);

    return -1;

  }

  if (*end_tile >= num_tiles) {

    aom_internal_error(&pbi->error, AOM_CODEC_CORRUPT_FRAME,

                       "tg_end (%d) must be less than NumTiles (%d)", *end_tile,

                       num_tiles);

    return -1;

  }

  pbi->next_start_tile = (*end_tile == num_tiles - 1) ? 0 : *end_tile + 1;

  return ((rb->bit_offset - saved_bit_offset + 7) >> 3);

}

// On success, returns the tile group OBU size. On failure, sets

// pbi->common.error.error_code and returns 0.

static uint32_t read_one_tile_group_obu(

    AV1Decoder *pbi, struct aom_read_bit_buffer *rb, int is_first_tg,

    const uint8_t *data, const uint8_t *data_end, const uint8_t **p_data_end,

    int *is_last_tg, int tile_start_implicit) {

  AV1_COMMON *const cm = &pbi->common;

  int start_tile, end_tile;

  int32_t header_size, tg_payload_size;

  assert((rb->bit_offset & 7) == 0);

  assert(rb->bit_buffer + aom_rb_bytes_read(rb) == data);

  header_size = read_tile_group_header(pbi, rb, &start_tile, &end_tile,

                                       tile_start_implicit);

  if (header_size == -1 || byte_alignment(cm, rb)) return 0;

  data += header_size;

  av1_decode_tg_tiles_and_wrapup(pbi, data, data_end, p_data_end, start_tile,

                                 end_tile, is_first_tg);

  tg_payload_size = (uint32_t)(*p_data_end - data);

  *is_last_tg = end_tile == cm->tiles.rows * cm->tiles.cols - 1;

  return header_size + tg_payload_size;

}

static void alloc_tile_list_buffer(AV1Decoder *pbi) {

  // The resolution of the output frame is read out from the bitstream. The data

  // are stored in the order of Y plane, U plane and V plane. As an example, for

  // image format 4:2:0, the output frame of U plane and V plane is 1/4 of the

  // output frame.

  AV1_COMMON *const cm = &pbi->common;

  int tile_width, tile_height;

  av1_get_uniform_tile_size(cm, &tile_width, &tile_height);

  const int tile_width_in_pixels = tile_width * MI_SIZE;

  const int tile_height_in_pixels = tile_height * MI_SIZE;

  const int output_frame_width =

      (pbi->output_frame_width_in_tiles_minus_1 + 1) * tile_width_in_pixels;

  const int output_frame_height =

      (pbi->output_frame_height_in_tiles_minus_1 + 1) * tile_height_in_pixels;

  // The output frame is used to store the decoded tile list. The decoded tile

  // list has to fit into 1 output frame.

  assert((pbi->tile_count_minus_1 + 1) <=

         (pbi->output_frame_width_in_tiles_minus_1 + 1) *

             (pbi->output_frame_height_in_tiles_minus_1 + 1));

  // Allocate the tile list output buffer.

  // Note: if cm->seq_params->use_highbitdepth is 1 and

  // cm->seq_params->bit_depth is 8, we could allocate less memory, namely, 8

  // bits/pixel.

  if (aom_alloc_frame_buffer(&pbi->tile_list_outbuf, output_frame_width,

                             output_frame_height, cm->seq_params->subsampling_x,

                             cm->seq_params->subsampling_y,

                             (cm->seq_params->use_highbitdepth &&

                              (cm->seq_params->bit_depth > AOM_BITS_8)),

                             0, cm->features.byte_alignment))

    aom_internal_error(&pbi->error, AOM_CODEC_MEM_ERROR,

                       "Failed to allocate the tile list output buffer");

}

static void yv12_tile_copy(const YV12_BUFFER_CONFIG *src, int hstart1,

                           int hend1, int vstart1, int vend1,

                           YV12_BUFFER_CONFIG *dst, int hstart2, int vstart2,

                           int plane) {

  const int src_stride = (plane > 0) ? src->strides[1] : src->strides[0];

  const int dst_stride = (plane > 0) ? dst->strides[1] : dst->strides[0];

  int row, col;

  assert(src->flags & YV12_FLAG_HIGHBITDEPTH);

  assert(!(dst->flags & YV12_FLAG_HIGHBITDEPTH));

  const uint16_t *src16 =

      CONVERT_TO_SHORTPTR(src->buffers[plane] + vstart1 * src_stride + hstart1);

  uint8_t *dst8 = dst->buffers[plane] + vstart2 * dst_stride + hstart2;

  for (row = vstart1; row < vend1; ++row) {

    for (col = 0; col < (hend1 - hstart1); ++col) *dst8++ = (uint8_t)(*src16++);

    src16 += src_stride - (hend1 - hstart1);

    dst8 += dst_stride - (hend1 - hstart1);

  }

  return;

}

static void copy_decoded_tile_to_tile_list_buffer(AV1Decoder *pbi,

                                                  int tile_idx) {

  AV1_COMMON *const cm = &pbi->common;

  int tile_width, tile_height;

  av1_get_uniform_tile_size(cm, &tile_width, &tile_height);

  const int tile_width_in_pixels = tile_width * MI_SIZE;

  const int tile_height_in_pixels = tile_height * MI_SIZE;

  const int ssy = cm->seq_params->subsampling_y;

  const int ssx = cm->seq_params->subsampling_x;

  const int num_planes = av1_num_planes(cm);

  YV12_BUFFER_CONFIG *cur_frame = &cm->cur_frame->buf;

  const int tr = tile_idx / (pbi->output_frame_width_in_tiles_minus_1 + 1);

  const int tc = tile_idx % (pbi->output_frame_width_in_tiles_minus_1 + 1);

  int plane;

  // Copy decoded tile to the tile list output buffer.

  for (plane = 0; plane < num_planes; ++plane) {

    const int shift_x = plane > 0 ? ssx : 0;

    const int shift_y = plane > 0 ? ssy : 0;

    const int h = tile_height_in_pixels >> shift_y;

    const int w = tile_width_in_pixels >> shift_x;

    // src offset

    int vstart1 = pbi->dec_tile_row * h;

    int vend1 = vstart1 + h;

    int hstart1 = pbi->dec_tile_col * w;

    int hend1 = hstart1 + w;

    // dst offset

    int vstart2 = tr * h;

    int hstart2 = tc * w;

    if (cm->seq_params->use_highbitdepth &&

        cm->seq_params->bit_depth == AOM_BITS_8) {

      yv12_tile_copy(cur_frame, hstart1, hend1, vstart1, vend1,

                     &pbi->tile_list_outbuf, hstart2, vstart2, plane);

    } else {

      switch (plane) {

        case 0:

          aom_yv12_partial_copy_y(cur_frame, hstart1, hend1, vstart1, vend1,

                                  &pbi->tile_list_outbuf, hstart2, vstart2);

          break;

        case 1:

          aom_yv12_partial_copy_u(cur_frame, hstart1, hend1, vstart1, vend1,

                                  &pbi->tile_list_outbuf, hstart2, vstart2);

          break;

        case 2:

          aom_yv12_partial_copy_v(cur_frame, hstart1, hend1, vstart1, vend1,

                                  &pbi->tile_list_outbuf, hstart2, vstart2);

          break;

        default: assert(0);

      }

    }

  }

}

// Only called while large_scale_tile = 1.

//

// On success, returns the tile list OBU size. On failure, sets

// pbi->common.error.error_code and returns 0.

static uint32_t read_and_decode_one_tile_list(AV1Decoder *pbi,

                                              struct aom_read_bit_buffer *rb,

                                              const uint8_t *data,

                                              const uint8_t *data_end,

                                              const uint8_t **p_data_end,

                                              int *frame_decoding_finished) {

  AV1_COMMON *const cm = &pbi->common;

  uint32_t tile_list_payload_size = 0;

  const int num_tiles = cm->tiles.cols * cm->tiles.rows;

  const int start_tile = 0;

  const int end_tile = num_tiles - 1;

  int i = 0;

  // Process the tile list info.

  pbi->output_frame_width_in_tiles_minus_1 = aom_rb_read_literal(rb, 8);

  pbi->output_frame_height_in_tiles_minus_1 = aom_rb_read_literal(rb, 8);

  pbi->tile_count_minus_1 = aom_rb_read_literal(rb, 16);

  if (pbi->tile_count_minus_1 > MAX_TILES - 1) {

    pbi->error.error_code = AOM_CODEC_CORRUPT_FRAME;

    return 0;

  }

  // Allocate output frame buffer for the tile list.

  alloc_tile_list_buffer(pbi);

  uint32_t tile_list_info_bytes = 4;

  tile_list_payload_size += tile_list_info_bytes;

  data += tile_list_info_bytes;

  int tile_idx = 0;

  for (i = 0; i <= pbi->tile_count_minus_1; i++) {

    // Process 1 tile.

    // Reset the bit reader.

    rb->bit_offset = 0;

    rb->bit_buffer = data;

    // Read out the tile info.

    uint32_t tile_info_bytes = 5;

    // Set reference for each tile.

    int ref_idx = aom_rb_read_literal(rb, 8);

    if (ref_idx >= MAX_EXTERNAL_REFERENCES) {

      pbi->error.error_code = AOM_CODEC_CORRUPT_FRAME;

      return 0;

    }

    av1_set_reference_dec(cm, cm->remapped_ref_idx[0], 1,

                          &pbi->ext_refs.refs[ref_idx]);

    pbi->dec_tile_row = aom_rb_read_literal(rb, 8);

    pbi->dec_tile_col = aom_rb_read_literal(rb, 8);

    if (pbi->dec_tile_row < 0 || pbi->dec_tile_col < 0 ||

        pbi->dec_tile_row >= cm->tiles.rows ||

        pbi->dec_tile_col >= cm->tiles.cols) {

      pbi->error.error_code = AOM_CODEC_CORRUPT_FRAME;

      return 0;

    }

    pbi->coded_tile_data_size = aom_rb_read_literal(rb, 16) + 1;

    data += tile_info_bytes;

    if ((size_t)(data_end - data) < pbi->coded_tile_data_size) {

      pbi->error.error_code = AOM_CODEC_CORRUPT_FRAME;

      return 0;

    }

    av1_decode_tg_tiles_and_wrapup(pbi, data, data + pbi->coded_tile_data_size,

                                   p_data_end, start_tile, end_tile, 0);

    uint32_t tile_payload_size = (uint32_t)(*p_data_end - data);

    tile_list_payload_size += tile_info_bytes + tile_payload_size;

    // Update data ptr for next tile decoding.

    data = *p_data_end;

    assert(data <= data_end);

    // Copy the decoded tile to the tile list output buffer.

    copy_decoded_tile_to_tile_list_buffer(pbi, tile_idx);

    tile_idx++;

  }

  *frame_decoding_finished = 1;

  return tile_list_payload_size;

}

// Returns the last nonzero byte index in 'data'. If there is no nonzero byte in

// 'data', returns -1.

static int get_last_nonzero_byte_index(const uint8_t *data, size_t sz) {

  // Scan backward and return on the first nonzero byte.

  int i = (int)sz - 1;

  while (i >= 0 && data[i] == 0) {

    --i;

  }

  return i;

}

// Allocates metadata that was read and adds it to the decoders metadata array.

static void alloc_read_metadata(AV1Decoder *const pbi,

                                OBU_METADATA_TYPE metadata_type,

                                const uint8_t *data, size_t sz,

                                aom_metadata_insert_flags_t insert_flag) {

  if (!pbi->metadata) {

    pbi->metadata = aom_img_metadata_array_alloc(0);

    if (!pbi->metadata) {

      aom_internal_error(&pbi->error, AOM_CODEC_MEM_ERROR,

                         "Failed to allocate metadata array");

    }

  }

  aom_metadata_t *metadata =

      aom_img_metadata_alloc(metadata_type, data, sz, insert_flag);

  if (!metadata) {

    aom_internal_error(&pbi->error, AOM_CODEC_MEM_ERROR,

                       "Error allocating metadata");

  }

  aom_metadata_t **metadata_array =

      (aom_metadata_t **)realloc(pbi->metadata->metadata_array,

                                 (pbi->metadata->sz + 1) * sizeof(metadata));

  if (!metadata_array) {

    aom_img_metadata_free(metadata);

    aom_internal_error(&pbi->error, AOM_CODEC_MEM_ERROR,

                       "Error growing metadata array");

  }

  pbi->metadata->metadata_array = metadata_array;

  pbi->metadata->metadata_array[pbi->metadata->sz] = metadata;

  pbi->metadata->sz++;

}

// On failure, calls aom_internal_error() and does not return.

static void read_metadata_itut_t35(AV1Decoder *const pbi, const uint8_t *data,

                                   size_t sz) {

  if (sz == 0) {

    aom_internal_error(&pbi->error, AOM_CODEC_CORRUPT_FRAME,

                       "itu_t_t35_country_code is missing");

  }

  int country_code_size = 1;

  if (*data == 0xFF) {

    if (sz == 1) {

      aom_internal_error(&pbi->error, AOM_CODEC_CORRUPT_FRAME,

                         "itu_t_t35_country_code_extension_byte is missing");

    }

    ++country_code_size;

  }

  int end_index = get_last_nonzero_byte_index(data, sz);

  if (end_index < country_code_size) {

    aom_internal_error(&pbi->error, AOM_CODEC_CORRUPT_FRAME,

                       "No trailing bits found in ITU-T T.35 metadata OBU");

  }

  // itu_t_t35_payload_bytes is byte aligned. Section 6.7.2 of the spec says:

  //   itu_t_t35_payload_bytes shall be bytes containing data registered as

  //   specified in Recommendation ITU-T T.35.

  // Therefore the first trailing byte should be 0x80.

  if (data[end_index] != 0x80) {

    aom_internal_error(&pbi->error, AOM_CODEC_CORRUPT_FRAME,

                       "The last nonzero byte of the ITU-T T.35 metadata OBU "

                       "is 0x%02x, should be 0x80.",

                       data[end_index]);

  }

  alloc_read_metadata(pbi, OBU_METADATA_TYPE_ITUT_T35, data, end_index,

                      AOM_MIF_ANY_FRAME);

}

// On success, returns the number of bytes read from 'data'. On failure, calls

// aom_internal_error() and does not return.

static size_t read_metadata_hdr_cll(AV1Decoder *const pbi, const uint8_t *data,

                                    size_t sz) {

  const size_t kHdrCllPayloadSize = 4;

  if (sz < kHdrCllPayloadSize) {

    aom_internal_error(&pbi->error, AOM_CODEC_CORRUPT_FRAME,

                       "Incorrect HDR CLL metadata payload size");

  }

  alloc_read_metadata(pbi, OBU_METADATA_TYPE_HDR_CLL, data, kHdrCllPayloadSize,

                      AOM_MIF_ANY_FRAME);

  return kHdrCllPayloadSize;

}

// On success, returns the number of bytes read from 'data'. On failure, calls

// aom_internal_error() and does not return.

static size_t read_metadata_hdr_mdcv(AV1Decoder *const pbi, const uint8_t *data,

                                     size_t sz) {

  const size_t kMdcvPayloadSize = 24;

  if (sz < kMdcvPayloadSize) {

    aom_internal_error(&pbi->error, AOM_CODEC_CORRUPT_FRAME,

                       "Incorrect HDR MDCV metadata payload size");

  }

  alloc_read_metadata(pbi, OBU_METADATA_TYPE_HDR_MDCV, data, kMdcvPayloadSize,

                      AOM_MIF_ANY_FRAME);

  return kMdcvPayloadSize;

}

static void scalability_structure(struct aom_read_bit_buffer *rb) {

  const int spatial_layers_cnt_minus_1 = aom_rb_read_literal(rb, 2);

  const int spatial_layer_dimensions_present_flag = aom_rb_read_bit(rb);

  const int spatial_layer_description_present_flag = aom_rb_read_bit(rb);

  const int temporal_group_description_present_flag = aom_rb_read_bit(rb);

  // scalability_structure_reserved_3bits must be set to zero and be ignored by

  // decoders.

  aom_rb_read_literal(rb, 3);

  if (spatial_layer_dimensions_present_flag) {

    for (int i = 0; i <= spatial_layers_cnt_minus_1; i++) {

      aom_rb_read_literal(rb, 16);

      aom_rb_read_literal(rb, 16);

    }

  }

  if (spatial_layer_description_present_flag) {

    for (int i = 0; i <= spatial_layers_cnt_minus_1; i++) {

      aom_rb_read_literal(rb, 8);

    }

  }

  if (temporal_group_description_present_flag) {

    const int temporal_group_size = aom_rb_read_literal(rb, 8);

    for (int i = 0; i < temporal_group_size; i++) {

      aom_rb_read_literal(rb, 3);

      aom_rb_read_bit(rb);

      aom_rb_read_bit(rb);

      const int temporal_group_ref_cnt = aom_rb_read_literal(rb, 3);

      for (int j = 0; j < temporal_group_ref_cnt; j++) {

        aom_rb_read_literal(rb, 8);

      }

    }

  }

}

static void read_metadata_scalability(struct aom_read_bit_buffer *rb) {

  const int scalability_mode_idc = aom_rb_read_literal(rb, 8);

  if (scalability_mode_idc == SCALABILITY_SS) {

    scalability_structure(rb);

  }

}

static void read_metadata_timecode(struct aom_read_bit_buffer *rb) {

  aom_rb_read_literal(rb, 5);  // counting_type f(5)

  const int full_timestamp_flag =

      aom_rb_read_bit(rb);     // full_timestamp_flag f(1)

  aom_rb_read_bit(rb);         // discontinuity_flag (f1)

  aom_rb_read_bit(rb);         // cnt_dropped_flag f(1)

  aom_rb_read_literal(rb, 9);  // n_frames f(9)

  if (full_timestamp_flag) {

    aom_rb_read_literal(rb, 6);  // seconds_value f(6)

    aom_rb_read_literal(rb, 6);  // minutes_value f(6)

    aom_rb_read_literal(rb, 5);  // hours_value f(5)

  } else {

    const int seconds_flag = aom_rb_read_bit(rb);  // seconds_flag f(1)

    if (seconds_flag) {

      aom_rb_read_literal(rb, 6);                    // seconds_value f(6)

      const int minutes_flag = aom_rb_read_bit(rb);  // minutes_flag f(1)

      if (minutes_flag) {

        aom_rb_read_literal(rb, 6);                  // minutes_value f(6)

        const int hours_flag = aom_rb_read_bit(rb);  // hours_flag f(1)

        if (hours_flag) {

          aom_rb_read_literal(rb, 5);  // hours_value f(5)

        }

      }

    }

  }

  // time_offset_length f(5)

  const int time_offset_length = aom_rb_read_literal(rb, 5);

  if (time_offset_length) {

    // time_offset_value f(time_offset_length)

    aom_rb_read_literal(rb, time_offset_length);

  }

}

// Returns the last nonzero byte in 'data'. If there is no nonzero byte in

// 'data', returns 0.

//

// Call this function to check the following requirement in the spec:

//   This implies that when any payload data is present for this OBU type, at

//   least one byte of the payload data (including the trailing bit) shall not

//   be equal to 0.

static uint8_t get_last_nonzero_byte(const uint8_t *data, size_t sz) {

  // Scan backward and return on the first nonzero byte.

  size_t i = sz;

  while (i != 0) {

    --i;

    if (data[i] != 0) return data[i];

  }

  return 0;

}

// Checks the metadata for correct syntax but ignores the parsed metadata.

//

// On success, returns the number of bytes read from 'data'. On failure, sets

// pbi->common.error.error_code and returns 0, or calls aom_internal_error()

// and does not return.

static size_t read_metadata(AV1Decoder *pbi, const uint8_t *data, size_t sz) {

  size_t type_length;

  uint64_t type_value;

  if (aom_uleb_decode(data, sz, &type_value, &type_length) < 0) {

    pbi->error.error_code = AOM_CODEC_CORRUPT_FRAME;

    return 0;

  }

  const OBU_METADATA_TYPE metadata_type = (OBU_METADATA_TYPE)type_value;

  if (metadata_type == 0 || metadata_type >= 6) {

    // If metadata_type is reserved for future use or a user private value,

    // ignore the entire OBU and just check trailing bits.

    if (get_last_nonzero_byte(data + type_length, sz - type_length) == 0) {

      pbi->error.error_code = AOM_CODEC_CORRUPT_FRAME;

      return 0;

    }

    return sz;

  }

  if (metadata_type == OBU_METADATA_TYPE_ITUT_T35) {

    // read_metadata_itut_t35() checks trailing bits.

    read_metadata_itut_t35(pbi, data + type_length, sz - type_length);

    return sz;

  } else if (metadata_type == OBU_METADATA_TYPE_HDR_CLL) {

    size_t bytes_read =

        type_length +

        read_metadata_hdr_cll(pbi, data + type_length, sz - type_length);

    if (get_last_nonzero_byte(data + bytes_read, sz - bytes_read) != 0x80) {

      pbi->error.error_code = AOM_CODEC_CORRUPT_FRAME;

      return 0;

    }

    return sz;

  } else if (metadata_type == OBU_METADATA_TYPE_HDR_MDCV) {

    size_t bytes_read =

        type_length +

        read_metadata_hdr_mdcv(pbi, data + type_length, sz - type_length);

    if (get_last_nonzero_byte(data + bytes_read, sz - bytes_read) != 0x80) {

      pbi->error.error_code = AOM_CODEC_CORRUPT_FRAME;

      return 0;

    }

    return sz;

  }

  struct aom_read_bit_buffer rb;

  av1_init_read_bit_buffer(pbi, &rb, data + type_length, data + sz);

  if (metadata_type == OBU_METADATA_TYPE_SCALABILITY) {

    read_metadata_scalability(&rb);

  } else {

    assert(metadata_type == OBU_METADATA_TYPE_TIMECODE);

    read_metadata_timecode(&rb);

  }

  if (av1_check_trailing_bits(pbi, &rb) != 0) {

    // pbi->error.error_code is already set.

    return 0;

  }

  assert((rb.bit_offset & 7) == 0);

  return type_length + (rb.bit_offset >> 3);

}

// On success, returns 'sz'. On failure, sets pbi->common.error.error_code and

// returns 0.

static size_t read_padding(AV1_COMMON *const cm, const uint8_t *data,

                           size_t sz) {

  // The spec allows a padding OBU to be header-only (i.e., obu_size = 0). So

  // check trailing bits only if sz > 0.

  if (sz > 0) {

    // The payload of a padding OBU is byte aligned. Therefore the first

    // trailing byte should be 0x80. See https://crbug.com/aomedia/2393.

    const uint8_t last_nonzero_byte = get_last_nonzero_byte(data, sz);

    if (last_nonzero_byte != 0x80) {

      cm->error->error_code = AOM_CODEC_CORRUPT_FRAME;

      return 0;

    }

  }

  return sz;

}

// On success, returns a boolean that indicates whether the decoding of the

// current frame is finished. On failure, sets pbi->error.error_code and

// returns -1.

int aom_decode_frame_from_obus(struct AV1Decoder *pbi, const uint8_t *data,

                               const uint8_t *data_end,

                               const uint8_t **p_data_end) {

  AV1_COMMON *const cm = &pbi->common;

  int frame_decoding_finished = 0;

  int is_first_tg_obu_received = 1;

  // Whenever pbi->seen_frame_header is set to 1, frame_header is set to the

  // beginning of the frame_header_obu and frame_header_size is set to its

  // size. This allows us to check if a redundant frame_header_obu is a copy

  // of the previous frame_header_obu.

  //

  // Initialize frame_header to a dummy nonnull pointer, otherwise the Clang

  // Static Analyzer in clang 7.0.1 will falsely warn that a null pointer is

  // passed as an argument to a 'nonnull' parameter of memcmp(). The initial

  // value will not be used.

  const uint8_t *frame_header = data;

  uint32_t frame_header_size = 0;

  ObuHeader obu_header;

  memset(&obu_header, 0, sizeof(obu_header));

  pbi->seen_frame_header = 0;

  pbi->next_start_tile = 0;

  pbi->num_tile_groups = 0;

  if (data_end < data) {

    pbi->error.error_code = AOM_CODEC_CORRUPT_FRAME;

    return -1;

  }

  // Reset pbi->camera_frame_header_ready to 0 if cm->tiles.large_scale = 0.

  if (!cm->tiles.large_scale) pbi->camera_frame_header_ready = 0;

  // decode frame as a series of OBUs

  while (!frame_decoding_finished && pbi->error.error_code == AOM_CODEC_OK) {

    struct aom_read_bit_buffer rb;

    size_t payload_size = 0;

    size_t decoded_payload_size = 0;

    size_t obu_payload_offset = 0;

    size_t bytes_read = 0;

    const size_t bytes_available = data_end - data;

    if (bytes_available == 0 && !pbi->seen_frame_header) {

      *p_data_end = data;

      pbi->error.error_code = AOM_CODEC_OK;

      break;

    }

    aom_codec_err_t status =

        aom_read_obu_header_and_size(data, bytes_available, pbi->is_annexb,

                                     &obu_header, &payload_size, &bytes_read);

    if (status != AOM_CODEC_OK) {

      pbi->error.error_code = status;

      return -1;

    }

    // Record obu size header information.

    pbi->obu_size_hdr.data = data + obu_header.size;

    pbi->obu_size_hdr.size = bytes_read - obu_header.size;

    // Note: aom_read_obu_header_and_size() takes care of checking that this

    // doesn't cause 'data' to advance past 'data_end'.

    data += bytes_read;

    if ((size_t)(data_end - data) < payload_size) {

      pbi->error.error_code = AOM_CODEC_CORRUPT_FRAME;

      return -1;

    }

    cm->temporal_layer_id = obu_header.temporal_layer_id;

    cm->spatial_layer_id = obu_header.spatial_layer_id;

    if (obu_header.type != OBU_TEMPORAL_DELIMITER &&

        obu_header.type != OBU_SEQUENCE_HEADER) {

      // don't decode obu if it's not in current operating mode

      if (!is_obu_in_current_operating_point(pbi, &obu_header)) {

        data += payload_size;

        continue;

      }

    }

    av1_init_read_bit_buffer(pbi, &rb, data, data + payload_size);

    switch (obu_header.type) {

      case OBU_TEMPORAL_DELIMITER:

        decoded_payload_size = read_temporal_delimiter_obu();

        if (pbi->seen_frame_header) {

          // A new temporal unit has started, but the frame in the previous

          // temporal unit is incomplete.

          pbi->error.error_code = AOM_CODEC_CORRUPT_FRAME;

          return -1;

        }

        break;

      case OBU_SEQUENCE_HEADER:

        decoded_payload_size = read_sequence_header_obu(pbi, &rb);

        if (pbi->error.error_code != AOM_CODEC_OK) return -1;

        // The sequence header should not change in the middle of a frame.

        if (pbi->sequence_header_changed && pbi->seen_frame_header) {

          pbi->error.error_code = AOM_CODEC_CORRUPT_FRAME;

          return -1;

        }

        break;

      case OBU_FRAME_HEADER:

      case OBU_REDUNDANT_FRAME_HEADER:

      case OBU_FRAME:

        if (obu_header.type == OBU_REDUNDANT_FRAME_HEADER) {

          if (!pbi->seen_frame_header) {

            pbi->error.error_code = AOM_CODEC_CORRUPT_FRAME;

            return -1;

          }

        } else {

          // OBU_FRAME_HEADER or OBU_FRAME.

          if (pbi->seen_frame_header) {

            pbi->error.error_code = AOM_CODEC_CORRUPT_FRAME;

            return -1;

          }

        }

        // Only decode first frame header received

        if (!pbi->seen_frame_header ||

            (cm->tiles.large_scale && !pbi->camera_frame_header_ready)) {

          frame_header_size = read_frame_header_obu(

              pbi, &rb, data, p_data_end, obu_header.type != OBU_FRAME);

          frame_header = data;

          pbi->seen_frame_header = 1;

          if (!pbi->ext_tile_debug && cm->tiles.large_scale)

            pbi->camera_frame_header_ready = 1;

        } else {

          // Verify that the frame_header_obu is identical to the original

          // frame_header_obu.

          if (frame_header_size > payload_size ||

              memcmp(data, frame_header, frame_header_size) != 0) {

            pbi->error.error_code = AOM_CODEC_CORRUPT_FRAME;

            return -1;

          }

          assert(rb.bit_offset == 0);

          rb.bit_offset = 8 * frame_header_size;

        }

        decoded_payload_size = frame_header_size;

        pbi->frame_header_size = frame_header_size;

        cm->cur_frame->temporal_id = obu_header.temporal_layer_id;

        cm->cur_frame->spatial_id = obu_header.spatial_layer_id;

        if (cm->show_existing_frame) {

          if (obu_header.type == OBU_FRAME) {

            pbi->error.error_code = AOM_CODEC_UNSUP_BITSTREAM;