blob: 342f2ad73b03464bc2ffb67183ce97edd6038914 [file] [log] [blame]
// Copyright 2021 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "media/video/h265_nalu_parser.h"
#include <stddef.h>
#include <algorithm>
#include <cmath>
#include <cstring>
#include "base/cxx17_backports.h"
#include "base/logging.h"
#include "media/base/decrypt_config.h"
namespace media {
namespace {
// Converts [|start|, |end|) range with |encrypted_ranges| into a vector of
// SubsampleEntry. |encrypted_ranges| must be with in the range defined by
// |start| and |end|.
// It is OK to pass in empty |encrypted_ranges|; this will return a vector
// with single SubsampleEntry with clear_bytes set to the size of the buffer.
std::vector<SubsampleEntry> EncryptedRangesToSubsampleEntry(
const uint8_t* start,
const uint8_t* end,
const Ranges<const uint8_t*>& encrypted_ranges) {
std::vector<SubsampleEntry> subsamples(encrypted_ranges.size());
const uint8_t* cur = start;
for (size_t i = 0; i < encrypted_ranges.size(); ++i) {
const uint8_t* encrypted_start = encrypted_ranges.start(i);
DCHECK_GE(encrypted_start, cur)
<< "Encrypted range started before the current buffer pointer.";
subsamples[i].clear_bytes = encrypted_start - cur;
const uint8_t* encrypted_end = encrypted_ranges.end(i);
subsamples[i].cypher_bytes = encrypted_end - encrypted_start;
cur = encrypted_end;
DCHECK_LE(cur, end) << "Encrypted range is outside the buffer range.";
}
// If there is more data in the buffer but not covered by encrypted_ranges,
// then it must be in the clear.
if (cur < end)
subsamples.emplace_back(end - cur, 0);
return subsamples;
}
} // namespace
#define READ_BITS_OR_RETURN(num_bits, out) \
do { \
int _out; \
if (!br_.ReadBits(num_bits, &_out)) { \
DVLOG(1) \
<< "Error in stream: unexpected EOS while trying to read " #out; \
return kInvalidStream; \
} \
*out = _out; \
} while (0)
#define TRUE_OR_RETURN(a) \
do { \
if (!(a)) { \
DVLOG(1) << "Error in stream: invalid value, expected " << #a; \
return kInvalidStream; \
} \
} while (0)
H265NALU::H265NALU() {
memset(reinterpret_cast<void*>(this), 0, sizeof(*this));
}
H265NaluParser::H265NaluParser() {
Reset();
}
H265NaluParser::~H265NaluParser() {}
void H265NaluParser::Reset() {
stream_ = NULL;
bytes_left_ = 0;
encrypted_ranges_.clear();
previous_nalu_range_.clear();
}
void H265NaluParser::SetStream(const uint8_t* stream, off_t stream_size) {
std::vector<SubsampleEntry> subsamples;
SetEncryptedStream(stream, stream_size, subsamples);
}
void H265NaluParser::SetEncryptedStream(
const uint8_t* stream,
off_t stream_size,
const std::vector<SubsampleEntry>& subsamples) {
DCHECK(stream);
DCHECK_GT(stream_size, 0);
stream_ = stream;
bytes_left_ = stream_size;
previous_nalu_range_.clear();
encrypted_ranges_.clear();
const uint8_t* start = stream;
const uint8_t* stream_end = stream_ + bytes_left_;
for (size_t i = 0; i < subsamples.size() && start < stream_end; ++i) {
start += subsamples[i].clear_bytes;
const uint8_t* end =
std::min(start + subsamples[i].cypher_bytes, stream_end);
encrypted_ranges_.Add(start, end);
start = end;
}
}
bool H265NaluParser::LocateNALU(off_t* nalu_size, off_t* start_code_size) {
// Find the start code of next NALU.
off_t nalu_start_off = 0;
off_t annexb_start_code_size = 0;
if (!H264Parser::FindStartCodeInClearRanges(
stream_, bytes_left_, encrypted_ranges_, &nalu_start_off,
&annexb_start_code_size)) {
DVLOG(4) << "Could not find start code, end of stream?";
return false;
}
// Move the stream to the beginning of the NALU (pointing at the start code).
stream_ += nalu_start_off;
bytes_left_ -= nalu_start_off;
const uint8_t* nalu_data = stream_ + annexb_start_code_size;
off_t max_nalu_data_size = bytes_left_ - annexb_start_code_size;
if (max_nalu_data_size <= 0) {
DVLOG(3) << "End of stream";
return false;
}
// Find the start code of next NALU;
// if successful, |nalu_size_without_start_code| is the number of bytes from
// after previous start code to before this one;
// if next start code is not found, it is still a valid NALU since there
// are some bytes left after the first start code: all the remaining bytes
// belong to the current NALU.
off_t next_start_code_size = 0;
off_t nalu_size_without_start_code = 0;
if (!H264Parser::FindStartCodeInClearRanges(
nalu_data, max_nalu_data_size, encrypted_ranges_,
&nalu_size_without_start_code, &next_start_code_size)) {
nalu_size_without_start_code = max_nalu_data_size;
}
*nalu_size = nalu_size_without_start_code + annexb_start_code_size;
*start_code_size = annexb_start_code_size;
return true;
}
H265NaluParser::Result H265NaluParser::AdvanceToNextNALU(H265NALU* nalu) {
off_t start_code_size;
off_t nalu_size_with_start_code;
if (!LocateNALU(&nalu_size_with_start_code, &start_code_size)) {
DVLOG(4) << "Could not find next NALU, bytes left in stream: "
<< bytes_left_;
return kEOStream;
}
DCHECK(nalu);
nalu->data = stream_ + start_code_size;
nalu->size = nalu_size_with_start_code - start_code_size;
DVLOG(4) << "NALU found: size=" << nalu_size_with_start_code;
// Initialize bit reader at the start of found NALU.
if (!br_.Initialize(nalu->data, nalu->size))
return kEOStream;
// Move parser state to after this NALU, so next time AdvanceToNextNALU
// is called, we will effectively be skipping it;
// other parsing functions will use the position saved
// in bit reader for parsing, so we don't have to remember it here.
stream_ += nalu_size_with_start_code;
bytes_left_ -= nalu_size_with_start_code;
// Read NALU header, skip the forbidden_zero_bit, but check for it.
int data;
READ_BITS_OR_RETURN(1, &data);
TRUE_OR_RETURN(data == 0);
READ_BITS_OR_RETURN(6, &nalu->nal_unit_type);
READ_BITS_OR_RETURN(6, &nalu->nuh_layer_id);
READ_BITS_OR_RETURN(3, &nalu->nuh_temporal_id_plus1);
DVLOG(4) << "NALU type: " << static_cast<int>(nalu->nal_unit_type)
<< " at: " << reinterpret_cast<const void*>(nalu->data)
<< " size: " << nalu->size;
previous_nalu_range_.clear();
previous_nalu_range_.Add(nalu->data, nalu->data + nalu->size);
return kOk;
}
std::vector<SubsampleEntry> H265NaluParser::GetCurrentSubsamples() {
DCHECK_EQ(previous_nalu_range_.size(), 1u)
<< "This should only be called after a "
"successful call to AdvanceToNextNalu()";
auto intersection = encrypted_ranges_.IntersectionWith(previous_nalu_range_);
return EncryptedRangesToSubsampleEntry(
previous_nalu_range_.start(0), previous_nalu_range_.end(0), intersection);
}
} // namespace media