Bug 1891082 - Implement CodecChangeMonitor for AAC in MediaChangeMonitor r=media-playback-reviewers,padenot

This patch implements a `CodecChangeMonitor` specifically for *AAC*
format, which will later be integrated into the `MediaChangeMonitor`.
The `CheckForChange` function within `CodecChangeMonitor` is designed to
detect changes in the data format and signal `MediaChangeMonitor` to
re-create and re-initialize the underlying decoder accordingly.

When the data stream format changes from *ADTS* to *AAC*, the
`CodecChangeMonitor` will add an AAC-specific configuration that is
missing in *ADTS* for proper decoder configuration. Conversely, when the
format switches from *AAC* to *ADTS*, it will reconfigure the decoder
without the AAC-specific configuration.

Depends on D219147

Differential Revision: https://phabricator.services.mozilla.com/D220505

Author: ChunMinChang

dom/media/platforms/wrappers/MediaChangeMonitor.cpp

@@ -6,6 +6,7 @@
 
 #include "MediaChangeMonitor.h"
 
+#include "Adts.h"
 #include "AnnexB.h"
 #include "H264.h"
 #include "H265.h"
@@ -588,6 +589,73 @@ class AV1ChangeMonitor : public MediaChangeMonitor::CodecChangeMonitor {
 };
 #endif
 
+class AACCodecChangeMonitor : public MediaChangeMonitor::CodecChangeMonitor {
+ public:
+  explicit AACCodecChangeMonitor(const AudioInfo& aInfo)
+      : mCurrentConfig(aInfo), mIsADTS(IsADTS(aInfo)) {}
+
+  bool CanBeInstantiated() const override { return true; }
+
+  MediaResult CheckForChange(MediaRawData* aSample) override {
+    bool isADTS =
+        ADTS::FrameHeader::MatchesSync(Span{aSample->Data(), aSample->Size()});
+    if (isADTS != mIsADTS) {
+      if (mIsADTS) {
+        if (!MakeAACSpecificConfig()) {
+          LOG("Failed to make AAC specific config");
+          return MediaResult(NS_ERROR_DOM_MEDIA_DECODE_ERR);
+        }
+        LOG("Reconfiguring decoder adts -> raw aac, with maked AAC specific "
+            "config: %zu bytes",
+            mCurrentConfig.mCodecSpecificConfig
+                .as<AudioCodecSpecificBinaryBlob>()
+                .mBinaryBlob->Length());
+      } else {
+        LOG("Reconfiguring decoder raw aac -> adts");
+        // Remove AAC specific config to configure a ADTS decoder.
+        mCurrentConfig.mCodecSpecificConfig =
+            AudioCodecSpecificVariant{NoCodecSpecificData{}};
+      }
+
+      mIsADTS = isADTS;
+      return MediaResult(NS_ERROR_DOM_MEDIA_NEED_NEW_DECODER);
+    }
+    return NS_OK;
+  }
+
+  const TrackInfo& Config() const override { return mCurrentConfig; }
+
+  MediaResult PrepareSample(MediaDataDecoder::ConversionRequired aConversion,
+                            MediaRawData* aSample,
+                            bool aNeedKeyFrame) override {
+    return NS_OK;
+  }
+
+ private:
+  static bool IsADTS(const AudioInfo& aInfo) {
+    return !aInfo.mCodecSpecificConfig.is<AacCodecSpecificData>() &&
+           !aInfo.mCodecSpecificConfig.is<AudioCodecSpecificBinaryBlob>();
+  }
+
+  bool MakeAACSpecificConfig() {
+    MOZ_ASSERT(IsADTS(mCurrentConfig));
+    // If profile is not set, default to AAC-LC
+    const uint8_t aacObjectType =
+        mCurrentConfig.mProfile ? mCurrentConfig.mProfile : 2;
+    auto r = ADTS::MakeSpecificConfig(aacObjectType, mCurrentConfig.mRate,
+                                      mCurrentConfig.mChannels);
+    if (r.isErr()) {
+      return false;
+    }
+    mCurrentConfig.mCodecSpecificConfig =
+        AudioCodecSpecificVariant{AudioCodecSpecificBinaryBlob{r.unwrap()}};
+    return true;
+  }
+
+  AudioInfo mCurrentConfig;
+  bool mIsADTS;
+};
+
 MediaChangeMonitor::MediaChangeMonitor(
     PDMFactory* aPDMFactory,
     UniquePtr<CodecChangeMonitor>&& aCodecChangeMonitor,