1 files changed, 147 insertions, 0 deletions
diff --git a/third_party/aom/av1/common/obu_util.c b/third_party/aom/av1/common/obu_util.c
new file mode 100644
index 0000000000..823b700b13
--- /dev/null
+++ b/third_party/aom/av1/common/obu_util.c
@@ -0,0 +1,147 @@
+/*
+ * Copyright (c) 2018, 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 "av1/common/obu_util.h"
+
+#include "aom_dsp/bitreader_buffer.h"
+
+// Returns 1 when OBU type is valid, and 0 otherwise.
+static int valid_obu_type(int obu_type) {
+  int valid_type = 0;
+  switch (obu_type) {
+    case OBU_SEQUENCE_HEADER:
+    case OBU_TEMPORAL_DELIMITER:
+    case OBU_FRAME_HEADER:
+    case OBU_TILE_GROUP:
+    case OBU_METADATA:
+    case OBU_FRAME:
+    case OBU_REDUNDANT_FRAME_HEADER:
+    case OBU_TILE_LIST:
+    case OBU_PADDING: valid_type = 1; break;
+    default: break;
+  }
+  return valid_type;
+}
+
+static aom_codec_err_t read_obu_size(const uint8_t *data,
+                                     size_t bytes_available,
+                                     size_t *const obu_size,
+                                     size_t *const length_field_size) {
+  uint64_t u_obu_size = 0;
+  if (aom_uleb_decode(data, bytes_available, &u_obu_size, length_field_size) !=
+      0) {
+    return AOM_CODEC_CORRUPT_FRAME;
+  }
+
+  if (u_obu_size > UINT32_MAX) return AOM_CODEC_CORRUPT_FRAME;
+  *obu_size = (size_t)u_obu_size;
+  return AOM_CODEC_OK;
+}
+
+// Parses OBU header and stores values in 'header'.
+static aom_codec_err_t read_obu_header(struct aom_read_bit_buffer *rb,
+                                       int is_annexb, ObuHeader *header) {
+  if (!rb || !header) return AOM_CODEC_INVALID_PARAM;
+
+  const ptrdiff_t bit_buffer_byte_length = rb->bit_buffer_end - rb->bit_buffer;
+  if (bit_buffer_byte_length < 1) return AOM_CODEC_CORRUPT_FRAME;
+
+  header->size = 1;
+
+  if (aom_rb_read_bit(rb) != 0) {
+    // Forbidden bit. Must not be set.
+    return AOM_CODEC_CORRUPT_FRAME;
+  }
+
+  header->type = (OBU_TYPE)aom_rb_read_literal(rb, 4);
+
+  if (!valid_obu_type(header->type)) return AOM_CODEC_CORRUPT_FRAME;
+
+  header->has_extension = aom_rb_read_bit(rb);
+  header->has_size_field = aom_rb_read_bit(rb);
+
+  if (!header->has_size_field && !is_annexb) {
+    // section 5 obu streams must have obu_size field set.
+    return AOM_CODEC_UNSUP_BITSTREAM;
+  }
+
+  if (aom_rb_read_bit(rb) != 0) {
+    // obu_reserved_1bit must be set to 0.
+    return AOM_CODEC_CORRUPT_FRAME;
+  }
+
+  if (header->has_extension) {
+    if (bit_buffer_byte_length == 1) return AOM_CODEC_CORRUPT_FRAME;
+
+    header->size += 1;
+    header->temporal_layer_id = aom_rb_read_literal(rb, 3);
+    header->spatial_layer_id = aom_rb_read_literal(rb, 2);
+    if (aom_rb_read_literal(rb, 3) != 0) {
+      // extension_header_reserved_3bits must be set to 0.
+      return AOM_CODEC_CORRUPT_FRAME;
+    }
+  }
+
+  return AOM_CODEC_OK;
+}
+
+aom_codec_err_t aom_read_obu_header(uint8_t *buffer, size_t buffer_length,
+                                    size_t *consumed, ObuHeader *header,
+                                    int is_annexb) {
+  if (buffer_length < 1 || !consumed || !header) return AOM_CODEC_INVALID_PARAM;
+
+  // TODO(tomfinegan): Set the error handler here and throughout this file, and
+  // confirm parsing work done via aom_read_bit_buffer is successful.
+  struct aom_read_bit_buffer rb = { buffer, buffer + buffer_length, 0, NULL,
+                                    NULL };
+  aom_codec_err_t parse_result = read_obu_header(&rb, is_annexb, header);
+  if (parse_result == AOM_CODEC_OK) *consumed = header->size;
+  return parse_result;
+}
+
+aom_codec_err_t aom_read_obu_header_and_size(const uint8_t *data,
+                                             size_t bytes_available,
+                                             int is_annexb,
+                                             ObuHeader *obu_header,
+                                             size_t *const payload_size,
+                                             size_t *const bytes_read) {
+  size_t length_field_size = 0, obu_size = 0;
+  aom_codec_err_t status;
+
+  if (is_annexb) {
+    // Size field comes before the OBU header, and includes the OBU header
+    status =
+        read_obu_size(data, bytes_available, &obu_size, &length_field_size);
+
+    if (status != AOM_CODEC_OK) return status;
+  }
+
+  struct aom_read_bit_buffer rb = { data + length_field_size,
+                                    data + bytes_available, 0, NULL, NULL };
+
+  status = read_obu_header(&rb, is_annexb, obu_header);
+  if (status != AOM_CODEC_OK) return status;
+
+  if (is_annexb) {
+    // Derive the payload size from the data we've already read
+    if (obu_size < obu_header->size) return AOM_CODEC_CORRUPT_FRAME;
+
+    *payload_size = obu_size - obu_header->size;
+  } else {
+    // Size field comes after the OBU header, and is just the payload size
+    status = read_obu_size(data + obu_header->size,
+                           bytes_available - obu_header->size, payload_size,
+                           &length_field_size);
+    if (status != AOM_CODEC_OK) return status;
+  }
+
+  *bytes_read = length_field_size + obu_header->size;
+  return AOM_CODEC_OK;
+}