From cffbc80aca49fb6f6373c27c369b3f20d88b22ae Mon Sep 17 00:00:00 2001
From: Jean-Yves Avenard <jyavenard@mozilla.com>
Date: Thu, 22 Oct 2020 12:40:29 +0000
Subject: [PATCH] Bug 1672311 - Implement audio trimming for batch jobs.
 r=padenot

Differential Revision: https://phabricator.services.mozilla.com/D94280
---
 dom/media/platforms/wrappers/AudioTrimmer.cpp | 71 +++++++++++++------
 dom/media/platforms/wrappers/AudioTrimmer.h   |  7 +-
 2 files changed, 53 insertions(+), 25 deletions(-)

diff --git a/dom/media/platforms/wrappers/AudioTrimmer.cpp b/dom/media/platforms/wrappers/AudioTrimmer.cpp
index deed07a28961..46dcb05a5e55 100644
--- a/dom/media/platforms/wrappers/AudioTrimmer.cpp
+++ b/dom/media/platforms/wrappers/AudioTrimmer.cpp
@@ -24,27 +24,8 @@ RefPtr<MediaDataDecoder::DecodePromise> AudioTrimmer::Decode(
     MediaRawData* aSample) {
   MOZ_ASSERT(mThread->IsOnCurrentThread(),
              "We're not on the thread we were first initialized on");
-  // A compress sample indicates that it needs to be trimmed after decoding by
-  // having its mOriginalPresentationWindow member set; in which case
-  // mOriginalPresentationWindow contains the original time and duration of the
-  // frame set by the demuxer and mTime and mDuration set to what it should be
-  // after trimming.
   RefPtr<MediaRawData> sample = aSample;
-  if (sample->mOriginalPresentationWindow) {
-    LOG("sample[%" PRId64 ",%" PRId64 "] has trimming info ([%" PRId64
-        ",%" PRId64 "]",
-        sample->mOriginalPresentationWindow->mStart.ToMicroseconds(),
-        sample->mOriginalPresentationWindow->mEnd.ToMicroseconds(),
-        sample->mTime.ToMicroseconds(), sample->GetEndTime().ToMicroseconds());
-    mTrimmers.AppendElement(
-        Some(TimeInterval(sample->mTime, sample->GetEndTime())));
-    sample->mTime = sample->mOriginalPresentationWindow->mStart;
-    sample->mDuration = sample->mOriginalPresentationWindow->Length();
-  } else {
-    LOG("sample[%" PRId64 ",%" PRId64 "] no trimming information",
-        sample->mTime.ToMicroseconds(), sample->GetEndTime().ToMicroseconds());
-    mTrimmers.AppendElement(Nothing());
-  }
+  PrepareTrimmers(sample);
   RefPtr<AudioTrimmer> self = this;
   RefPtr<DecodePromise> p = mDecoder->Decode(sample)->Then(
       GetCurrentSerialEventTarget(), __func__,
@@ -69,8 +50,7 @@ RefPtr<MediaDataDecoder::DecodePromise> AudioTrimmer::Drain() {
   RefPtr<DecodePromise> p = mDecoder->Drain()->Then(
       GetCurrentSerialEventTarget(), __func__,
       [self = RefPtr{this}](DecodePromise::ResolveOrRejectValue&& aValue) {
-        auto p = self->HandleDecodedResult(std::move(aValue), nullptr);
-        return p;
+        return self->HandleDecodedResult(std::move(aValue), nullptr);
       });
   return p;
 }
@@ -178,6 +158,53 @@ RefPtr<MediaDataDecoder::DecodePromise> AudioTrimmer::HandleDecodedResult(
   return DecodePromise::CreateAndResolve(std::move(results), __func__);
 }
 
+RefPtr<MediaDataDecoder::DecodePromise> AudioTrimmer::DecodeBatch(
+    nsTArray<RefPtr<MediaRawData>>&& aSamples) {
+  MOZ_ASSERT(mThread->IsOnCurrentThread(),
+             "We're not on the thread we were first initialized on");
+  LOG("DecodeBatch");
+
+  for (auto&& sample : aSamples) {
+    PrepareTrimmers(sample);
+  }
+  RefPtr<DecodePromise> p =
+      mDecoder->DecodeBatch(std::move(aSamples))
+          ->Then(GetCurrentSerialEventTarget(), __func__,
+                 [self = RefPtr{this}](
+                     DecodePromise::ResolveOrRejectValue&& aValue) {
+                   // If the decoder returned less samples than what we fed it.
+                   // We can assume that this is due to the decoder encoding
+                   // delay and that all decoded frames have been shifted by n =
+                   // compressedSamples.Length() - decodedSamples.Length() and
+                   // that the first n compressed samples returned nothing.
+                   return self->HandleDecodedResult(std::move(aValue), nullptr);
+                 });
+  return p;
+}
+
+void AudioTrimmer::PrepareTrimmers(MediaRawData* aRaw) {
+  // A compress sample indicates that it needs to be trimmed after decoding by
+  // having its mOriginalPresentationWindow member set; in which case
+  // mOriginalPresentationWindow contains the original time and duration of
+  // the frame set by the demuxer and mTime and mDuration set to what it
+  // should be after trimming.
+  if (aRaw->mOriginalPresentationWindow) {
+    LOG("sample[%" PRId64 ",%" PRId64 "] has trimming info ([%" PRId64
+        ",%" PRId64 "]",
+        aRaw->mOriginalPresentationWindow->mStart.ToMicroseconds(),
+        aRaw->mOriginalPresentationWindow->mEnd.ToMicroseconds(),
+        aRaw->mTime.ToMicroseconds(), aRaw->GetEndTime().ToMicroseconds());
+    mTrimmers.AppendElement(
+        Some(TimeInterval(aRaw->mTime, aRaw->GetEndTime())));
+    aRaw->mTime = aRaw->mOriginalPresentationWindow->mStart;
+    aRaw->mDuration = aRaw->mOriginalPresentationWindow->Length();
+  } else {
+    LOG("sample[%" PRId64 ",%" PRId64 "] no trimming information",
+        aRaw->mTime.ToMicroseconds(), aRaw->GetEndTime().ToMicroseconds());
+    mTrimmers.AppendElement(Nothing());
+  }
+}
+
 }  // namespace mozilla
 
 #undef LOG
diff --git a/dom/media/platforms/wrappers/AudioTrimmer.h b/dom/media/platforms/wrappers/AudioTrimmer.h
index 82cf7ae9d277..dd7ac1a57bcb 100644
--- a/dom/media/platforms/wrappers/AudioTrimmer.h
+++ b/dom/media/platforms/wrappers/AudioTrimmer.h
@@ -24,9 +24,7 @@ class AudioTrimmer : public MediaDataDecoder {
   RefPtr<DecodePromise> Decode(MediaRawData* aSample) override;
   bool CanDecodeBatch() const override { return mDecoder->CanDecodeBatch(); }
   RefPtr<DecodePromise> DecodeBatch(
-      nsTArray<RefPtr<MediaRawData>>&& aSamples) override {
-    return mDecoder->DecodeBatch(std::move(aSamples));
-  }
+      nsTArray<RefPtr<MediaRawData>>&& aSamples) override;
   RefPtr<DecodePromise> Drain() override;
   RefPtr<FlushPromise> Flush() override;
   RefPtr<ShutdownPromise> Shutdown() override;
@@ -37,8 +35,11 @@ class AudioTrimmer : public MediaDataDecoder {
   ConversionRequired NeedsConversion() const override;
 
  private:
+  // Apply trimming information on decoded data. aRaw can be null as it's only
+  // used for logging purposes.
   RefPtr<DecodePromise> HandleDecodedResult(
       DecodePromise::ResolveOrRejectValue&& aValue, MediaRawData* aRaw);
+  void PrepareTrimmers(MediaRawData* aRaw);
   const RefPtr<MediaDataDecoder> mDecoder;
   nsCOMPtr<nsISerialEventTarget> mThread;
   AutoTArray<Maybe<media::TimeInterval>, 2> mTrimmers;