Implement ISO BMFF support in Media Source.

media/mp4/box_reader.cc

+// Copyright (c) 2012 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 "media/mp4/box_reader.h"
+
+#include <algorithm>
+#include <map>
+#include <set>
+#include <string.h>

[acolwell GONE FROM CHROMIUM, 2012/06/08 16:10:38]

lint nit: Apparently C system headers must come before C++ system headers.
string.h must go before <algorithm>

[strobe_, 2012/06/11 18:44:21]

Done.

+
+#include "base/logging.h"
+#include "media/mp4/rcheck.h"
+#include "media/mp4/box_definitions.h"

[acolwell GONE FROM CHROMIUM, 2012/06/08 16:10:38]

lint nit: alphabetical order.

[strobe_, 2012/06/11 18:44:21]

Apparently I never learned my ABCs. Done.

+
+namespace media {
+namespace mp4 {
+
+bool BufferReader::Read1(uint8* v) {
+  RCHECK(HasBytes(1));
+  *v = buf_[pos_++];
+  return true;
+}
+
+// Internal implementation of multi-byte reads
+template<typename T> bool BufferReader::Read(T* v) {
+  RCHECK(HasBytes(sizeof(T)));
+
+  T tmp = 0;
+  for (size_t i = 0; i < sizeof(T); i++) {
+    tmp <<= 8;
+    tmp += buf_[pos_++];
+  }
+  *v = tmp;
+  return true;
+}
+
+bool BufferReader::Read2(uint16* v) { return Read(v); }
+bool BufferReader::Read2s(int16* v) { return Read(v); }
+bool BufferReader::Read4(uint32* v) { return Read(v); }
+bool BufferReader::Read4s(int32* v) { return Read(v); }
+bool BufferReader::Read8(uint64* v) { return Read(v); }
+bool BufferReader::Read8s(int64* v) { return Read(v); }
+
+bool BufferReader::ReadFourCC(FourCC* v) {
+  return Read4(reinterpret_cast<uint32*>(v));
+}
+
+bool BufferReader::ReadVec(std::vector<uint8>* vec, int count) {
+  RCHECK(HasBytes(count));
+  vec->clear();
+  vec->insert(vec->end(), buf_ + pos_, buf_ + pos_ + count);
+  pos_ += count;
+  return true;
+}
+
+bool BufferReader::SkipBytes(int bytes) {
+  RCHECK(HasBytes(bytes));
+  pos_ += bytes;
+  return true;
+}
+
+bool BufferReader::Read4Into8(uint64* v) {
+  uint32 tmp;
+  RCHECK(Read4(&tmp));
+  *v = tmp;
+  return true;
+}
+
+bool BufferReader::Read4sInto8s(int64* v) {
+  // Beware of the need for sign extension.
+  int32 tmp;
+  RCHECK(Read4s(&tmp));
+  *v = tmp;
+  return true;
+}
+
+
+BoxReader::BoxReader(const uint8* buf, const int size)
+  : BufferReader(buf, size), scanned_(false) {};

[acolwell GONE FROM CHROMIUM, 2012/06/08 16:10:38]

lint nit: on next line and remove ;

[strobe_, 2012/06/11 18:44:21]

Done.

+
+BoxReader::~BoxReader() {
+  if (scanned_ && !children_.empty()) {
+    for (auto itr = children_.begin(); itr != children_.end(); ++itr) {
+      DVLOG(1) << "Skipping unknown box: " << FourCCToString(itr->first);
+    }
+  }
+}
+
+BoxReader* BoxReader::ReadTopLevelBox(const uint8* buf,
+                                      const int buf_size,
+                                      bool* err) {
+  BoxReader* r = new BoxReader(buf, buf_size);

[acolwell GONE FROM CHROMIUM, 2012/06/08 16:10:38]

r-> reader.

[strobe_, 2012/06/11 18:44:21]

Done.

+  if (r->ReadHeader(err) && r->size() <= buf_size) {
+    return r;
+  }
+  delete r;
+  return NULL;
+}
+
+// static
+bool BoxReader::StartTopLevelBox(const uint8* buf,
+                                 const int buf_size,
+                                 FourCC* type,
+                                 int* box_size,
+                                 bool* err) {
+  BoxReader reader(buf, buf_size);
+  if (!reader.ReadHeader(err)) return false;
+  *type = reader.type();
+  *box_size = reader.size();
+  return true;
+}
+
+bool BoxReader::ScanChildren() {
+  DCHECK(!scanned_);
+  scanned_ = true;
+
+  bool err;
+  // TODO(strobe): Check or correct for multimap not inserting elements in
+  // consistent order.
+  while (pos() < size()) {
+    BoxReader child(&buf_[pos_], size_ - pos_);
+    if (!child.ReadHeader(&err)) break;
+
+    children_.insert(std::pair<FourCC, BoxReader>(child.type(), child));
+    pos_ += child.size();
+  }
+
+  DCHECK(!err);
+  return !err && pos() == size();
+}
+
+bool BoxReader::ReadChild(Box* child) {
+  DCHECK(scanned_);
+  // TODO(strobe): decide how to handle inappropriately repeated boxes.
+  // If we want to be as permissive as possible, we can ignore all
+  // boxes that need repeating. On the other hand, we may simply wish to be
+  // strict about the files that we accept.
+  FourCC child_type = child->BoxType();
+
+  auto itr = children_.find(child_type);
+  RCHECK(itr != children_.end());
+  DVLOG(2) << "Found a " << FourCCToString(child_type) << " box.";
+  RCHECK(child->Parse(&itr->second));
+  children_.erase(itr);
+  return true;
+}
+
+bool BoxReader::MaybeReadChild(Box* child) {
+  if (!children_.count(child->BoxType())) return true;
+  return ReadChild(child);
+}
+
+bool BoxReader::ReadFullBoxHeader() {
+  uint32 vflags;
+  RCHECK(Read4(&vflags));
+  version_ = vflags >> 24;
+  flags_ = vflags & 0xffffff;
+  return true;
+}
+
+bool BoxReader::ReadHeader(bool* err) {
+  uint64 size;
+  *err = false;
+
+  if (!HasBytes(8)) return false;
+  CHECK(Read4Into8(&size) && ReadFourCC(&type_));
+
+  if (size == 0) {
+    // Media Source specific: we do not support boxes that run to EOS.
+    *err = true;
+    return false;
+  } else if (size == 1) {
+    if (!HasBytes(8)) return false;
+    CHECK(Read8(&size));
+  }
+
+  // Implementation-specific: support for boxes larger than 2^31 has been
+  // removed.
+  if (size < static_cast<uint64>(pos_) ||
+      size > static_cast<uint64>(kint32max)) {
+    *err = true;
+    return false;
+  }
+
+  // Note that the pos_ head has advanced to the byte immediately after the
+  // header, which is where we want it.
+  size_ = size;
+  return true;
+}
+
+}  // namespace mp4
+}  // namespace media