blob: 9ef8ae86c6c7793016afd172f2a1e723ea86049f [file] [log] [blame]
// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <stdint.h>
#include <limits>
#include <map>
#include <memory>
#include <vector>
#include "base/compiler_specific.h"
#include "base/logging.h"
#include "base/numerics/safe_conversions.h"
#include "media/base/media_export.h"
#include "media/base/media_log.h"
#include "media/formats/mp4/fourccs.h"
#include "media/formats/mp4/parse_result.h"
#include "media/formats/mp4/rcheck.h"
namespace media {
namespace mp4 {
enum DisplayMatrixSize {
kDisplayMatrixWidth = 3,
kDisplayMatrixHeight = 3,
kDisplayMatrixDimension = kDisplayMatrixHeight * kDisplayMatrixWidth
using DisplayMatrix = int32_t[kDisplayMatrixDimension];
class BoxReader;
struct MEDIA_EXPORT Box {
virtual ~Box();
// Parse errors may be logged using the BoxReader's media log.
virtual bool Parse(BoxReader* reader) = 0;
virtual FourCC BoxType() const = 0;
class MEDIA_EXPORT BufferReader {
BufferReader(const uint8_t* buf, const size_t buf_size)
: buf_(buf), buf_size_(buf_size), pos_(0) {
bool HasBytes(size_t count) {
// As the size of a box is implementation limited to 2^31, fail if
// attempting to check for too many bytes.
const size_t impl_limit =
return pos_ <= buf_size_ && count <= impl_limit &&
count <= buf_size_ - pos_;
// Read a value from the stream, performing endian correction, and advance the
// stream pointer.
bool Read1(uint8_t* v) WARN_UNUSED_RESULT;
bool Read2(uint16_t* v) WARN_UNUSED_RESULT;
bool Read2s(int16_t* v) WARN_UNUSED_RESULT;
bool Read4(uint32_t* v) WARN_UNUSED_RESULT;
bool Read4s(int32_t* v) WARN_UNUSED_RESULT;
bool Read8(uint64_t* v) WARN_UNUSED_RESULT;
bool Read8s(int64_t* v) WARN_UNUSED_RESULT;
bool ReadFourCC(FourCC* v) WARN_UNUSED_RESULT;
bool ReadVec(std::vector<uint8_t>* t, uint64_t count) WARN_UNUSED_RESULT;
// These variants read a 4-byte integer of the corresponding signedness and
// store it in the 8-byte return type.
bool Read4Into8(uint64_t* v) WARN_UNUSED_RESULT;
bool Read4sInto8s(int64_t* v) WARN_UNUSED_RESULT;
// Advance the stream by this many bytes.
bool SkipBytes(uint64_t nbytes) WARN_UNUSED_RESULT;
const uint8_t* buffer() const { return buf_; }
// Returns the size of the buffer. This may not match the size specified
// in the mp4 box header and could be less than the box size when the full box
// has not been appended. Always consult buffer_size() to avoid OOB reads.
// See BoxReader::box_size().
size_t buffer_size() const { return buf_size_; }
size_t pos() const { return pos_; }
const uint8_t* buf_;
size_t buf_size_;
size_t pos_;
template<typename T> bool Read(T* t) WARN_UNUSED_RESULT;
class MEDIA_EXPORT BoxReader : public BufferReader {
BoxReader(const BoxReader& other);
// Create a BoxReader from a buffer. If the result is kOk, then |out_reader|
// will be set, otherwise |out_reader| will be unchanged.
// |buf| is retained but not owned, and must outlive the BoxReader instance.
static ParseResult ReadTopLevelBox(const uint8_t* buf,
const size_t buf_size,
MediaLog* media_log,
std::unique_ptr<BoxReader>* out_reader)
// Read the box header from the current buffer, and return its type and size.
// This function returns kNeedMoreData if the box is incomplete, even if the
// box header is complete.
// |buf| is not retained.
static ParseResult StartTopLevelBox(const uint8_t* buf,
const size_t buf_size,
MediaLog* media_log,
FourCC* out_type,
size_t* out_box_size) WARN_UNUSED_RESULT;
// Create a BoxReader from a buffer. |buf| must be the complete buffer, as
// errors are returned when sufficient data is not available. |buf| can start
// with any type of box -- it does not have to be IsValidTopLevelBox().
// |buf| is retained but not owned, and must outlive the BoxReader instance.
static BoxReader* ReadConcatentatedBoxes(const uint8_t* buf,
const size_t buf_size,
MediaLog* media_log);
// Returns true if |type| is recognized to be a top-level box, false
// otherwise. This returns true for some boxes which we do not parse.
// Helpful in debugging misaligned appends.
static bool IsValidTopLevelBox(const FourCC& type, MediaLog* media_log);
// Scan through all boxes within the current box, starting at the current
// buffer position. Must be called before any of the *Child functions work.
bool ScanChildren() WARN_UNUSED_RESULT;
// Return true if child with type |child.BoxType()| exists.
bool HasChild(Box* child) WARN_UNUSED_RESULT;
// Read exactly one child box from the set of children. The type of the child
// will be determined by the BoxType() method of |child|.
bool ReadChild(Box* child) WARN_UNUSED_RESULT;
// Read one child if available. Returns false on error, true on successful
// read or on child absent.
bool MaybeReadChild(Box* child) WARN_UNUSED_RESULT;
// ISO-BMFF streams files use a 3x3 matrix consisting of 6 16.16 fixed point
// decimals and 3 2.30 fixed point decimals.
bool ReadDisplayMatrix(DisplayMatrix matrix);
// Read at least one child. False means error or no such child present.
template<typename T> bool ReadChildren(
std::vector<T>* children) WARN_UNUSED_RESULT;
// Read any number of children. False means error.
template<typename T> bool MaybeReadChildren(
std::vector<T>* children) WARN_UNUSED_RESULT;
// Read all children, regardless of FourCC. This is used from exactly one box,
// corresponding to a rather significant inconsistency in the BMFF spec.
// Note that this method is mutually exclusive with ScanChildren() and
// ReadAllChildrenAndCheckFourCC().
template <typename T>
bool ReadAllChildren(std::vector<T>* children) WARN_UNUSED_RESULT;
// Read all children and verify that the FourCC matches what is expected.
// Returns true if all children are successfully parsed and have the correct
// box type for |T|. Note that this method is mutually exclusive with
// ScanChildren() and ReadAllChildren().
template <typename T>
bool ReadAllChildrenAndCheckFourCC(std::vector<T>* children)
// Populate the values of 'version()' and 'flags()' from a full box header.
// Many boxes, but not all, use these values. This call should happen after
// the box has been initialized, and does not re-read the main box header.
bool ReadFullBoxHeader() WARN_UNUSED_RESULT;
size_t box_size() const {
return box_size_;
FourCC type() const { return type_; }
uint8_t version() const { return version_; }
uint32_t flags() const { return flags_; }
MediaLog* media_log() const { return media_log_; }
// Create a BoxReader from |buf|. |is_EOS| should be true if |buf| is
// complete stream (i.e. no additional data is expected to be appended).
BoxReader(const uint8_t* buf,
const size_t buf_size,
MediaLog* media_log,
bool is_EOS);
// Must be called immediately after init.
ParseResult ReadHeader() WARN_UNUSED_RESULT;
// Read all children, optionally checking FourCC. Returns true if all
// children are successfully parsed and, if |check_box_type|, have the
// correct box type for |T|. Note that this method is mutually exclusive
// with ScanChildren().
template <typename T>
bool ReadAllChildrenInternal(std::vector<T>* children, bool check_box_type);
MediaLog* media_log_;
size_t box_size_;
bool box_size_known_;
FourCC type_;
uint8_t version_;
uint32_t flags_;
typedef std::multimap<FourCC, BoxReader> ChildMap;
// The set of child box FourCCs and their corresponding buffer readers. Only
// valid if scanned_ is true.
ChildMap children_;
bool scanned_;
// True if the buffer provided to the reader is the complete stream.
const bool is_EOS_;
// Template definitions
template<typename T> bool BoxReader::ReadChildren(std::vector<T>* children) {
RCHECK(MaybeReadChildren(children) && !children->empty());
return true;
template<typename T>
bool BoxReader::MaybeReadChildren(std::vector<T>* children) {
FourCC child_type = (*children)[0].BoxType();
ChildMap::iterator start_itr = children_.lower_bound(child_type);
ChildMap::iterator end_itr = children_.upper_bound(child_type);
children->resize(std::distance(start_itr, end_itr));
typename std::vector<T>::iterator child_itr = children->begin();
for (ChildMap::iterator itr = start_itr; itr != end_itr; ++itr) {
children_.erase(start_itr, end_itr);
DVLOG(2) << "Found " << children->size() << " "
<< FourCCToString(child_type) << " boxes.";
return true;
template <typename T>
bool BoxReader::ReadAllChildren(std::vector<T>* children) {
return ReadAllChildrenInternal(children, false);
template <typename T>
bool BoxReader::ReadAllChildrenAndCheckFourCC(std::vector<T>* children) {
return ReadAllChildrenInternal(children, true);
template <typename T>
bool BoxReader::ReadAllChildrenInternal(std::vector<T>* children,
bool check_box_type) {
scanned_ = true;
// Must know our box size before attempting to parse child boxes.
DCHECK_LE(pos_, box_size_);
while (pos_ < box_size_) {
BoxReader child_reader(&buf_[pos_], box_size_ - pos_, media_log_, is_EOS_);
if (child_reader.ReadHeader() != ParseResult::kOk)
return false;
T child;
RCHECK(!check_box_type || child_reader.type() == child.BoxType());
pos_ += child_reader.box_size();
DCHECK_EQ(pos_, box_size_);
return true;
} // namespace mp4
} // namespace media