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/*
* 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 <cstdio>
#include <string>
#include "aom/aom_codec.h"
#include "aom/aom_integer.h"
#include "aom_ports/mem_ops.h"
#include "av1/decoder/obu.h"
#include "tools/obu_parser.h"
namespace aom_tools {
// Basic OBU syntax
// 8 bits: Header
// 7
// forbidden bit
// 6,5,4,3
// type bits
// 2
// extension flag bit
// 1
// has size field bit
// 0
// reserved bit
const uint32_t kObuForbiddenBitMask = 0x1;
const uint32_t kObuForbiddenBitShift = 7;
const uint32_t kObuTypeBitsMask = 0xF;
const uint32_t kObuTypeBitsShift = 3;
const uint32_t kObuExtensionFlagBitMask = 0x1;
const uint32_t kObuExtensionFlagBitShift = 2;
const uint32_t kObuHasSizeFieldBitMask = 0x1;
const uint32_t kObuHasSizeFieldBitShift = 1;
// When extension flag bit is set:
// 8 bits: extension header
// 7,6,5
// temporal ID
// 4,3
// spatial ID
// 2,1,0
// reserved bits
const uint32_t kObuExtTemporalIdBitsMask = 0x7;
const uint32_t kObuExtTemporalIdBitsShift = 5;
const uint32_t kObuExtSpatialIdBitsMask = 0x3;
const uint32_t kObuExtSpatialIdBitsShift = 3;
bool ValidObuType(int obu_type) {
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: return true;
}
return false;
}
bool ParseObuHeader(uint8_t obu_header_byte, ObuHeader *obu_header) {
const int forbidden_bit =
(obu_header_byte >> kObuForbiddenBitShift) & kObuForbiddenBitMask;
if (forbidden_bit) {
fprintf(stderr, "Invalid OBU, forbidden bit set.\n");
return false;
}
obu_header->type = static_cast<OBU_TYPE>(
(obu_header_byte >> kObuTypeBitsShift) & kObuTypeBitsMask);
if (!ValidObuType(obu_header->type)) {
fprintf(stderr, "Invalid OBU type: %d.\n", obu_header->type);
return false;
}
obu_header->has_extension =
(obu_header_byte >> kObuExtensionFlagBitShift) & kObuExtensionFlagBitMask;
obu_header->has_size_field =
(obu_header_byte >> kObuHasSizeFieldBitShift) & kObuHasSizeFieldBitMask;
return true;
}
bool ParseObuExtensionHeader(uint8_t ext_header_byte, ObuHeader *obu_header) {
obu_header->temporal_layer_id =
(ext_header_byte >> kObuExtTemporalIdBitsShift) &
kObuExtTemporalIdBitsMask;
obu_header->spatial_layer_id =
(ext_header_byte >> kObuExtSpatialIdBitsShift) & kObuExtSpatialIdBitsMask;
return true;
}
void PrintObuHeader(const ObuHeader *header) {
printf(
" OBU type: %s\n"
" extension: %s\n",
aom_obu_type_to_string(static_cast<OBU_TYPE>(header->type)),
header->has_extension ? "yes" : "no");
if (header->has_extension) {
printf(
" temporal_id: %d\n"
" spatial_id: %d\n",
header->temporal_layer_id, header->temporal_layer_id);
}
}
bool DumpObu(const uint8_t *data, int length, int *obu_overhead_bytes) {
const int kObuHeaderSizeBytes = 1;
const int kMinimumBytesRequired = 1 + kObuHeaderSizeBytes;
int consumed = 0;
int obu_overhead = 0;
ObuHeader obu_header;
while (consumed < length) {
const int remaining = length - consumed;
if (remaining < kMinimumBytesRequired) {
fprintf(stderr,
"OBU parse error. Did not consume all data, %d bytes remain.\n",
remaining);
return false;
}
int obu_header_size = 0;
memset(&obu_header, 0, sizeof(obu_header));
const uint8_t obu_header_byte = *(data + consumed);
if (!ParseObuHeader(obu_header_byte, &obu_header)) {
fprintf(stderr, "OBU parsing failed at offset %d.\n", consumed);
return false;
}
++obu_overhead;
++obu_header_size;
if (obu_header.has_extension) {
const uint8_t obu_ext_header_byte =
*(data + consumed + kObuHeaderSizeBytes);
if (!ParseObuExtensionHeader(obu_ext_header_byte, &obu_header)) {
fprintf(stderr, "OBU extension parsing failed at offset %d.\n",
consumed + kObuHeaderSizeBytes);
return false;
}
++obu_overhead;
++obu_header_size;
}
PrintObuHeader(&obu_header);
uint64_t obu_size = 0;
size_t length_field_size = 0;
if (aom_uleb_decode(data + consumed + obu_header_size,
remaining - obu_header_size, &obu_size,
&length_field_size) != 0) {
fprintf(stderr, "OBU size parsing failed at offset %d.\n",
consumed + obu_header_size);
return false;
}
int current_obu_length = static_cast<int>(obu_size);
if (obu_header_size + static_cast<int>(length_field_size) +
current_obu_length >
remaining) {
fprintf(stderr, "OBU parsing failed: not enough OBU data.\n");
return false;
}
consumed += obu_header_size + static_cast<int>(length_field_size) +
current_obu_length;
printf(" length: %d\n",
static_cast<int>(obu_header_size + length_field_size +
current_obu_length));
}
if (obu_overhead_bytes != nullptr) *obu_overhead_bytes = obu_overhead;
printf(" TU size: %d\n", consumed);
return true;
}
} // namespace aom_tools
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