From fbc9c3a8b286e7d08254cb189c644bb2d6525b48 Mon Sep 17 00:00:00 2001
From: Maire Reavy <mreavy@mozilla.com>
Date: Thu, 3 Jan 2013 18:37:55 -0500
Subject: [PATCH] bug 822956: Handle audio chunks that aren't 10ms in duration
 r=ekr

---
 .../src/mediapipeline/MediaPipeline.cpp       | 62 ++++++++++++++++++-
 .../src/mediapipeline/MediaPipeline.h         | 14 ++++-
 2 files changed, 72 insertions(+), 4 deletions(-)

diff --git a/media/webrtc/signaling/src/mediapipeline/MediaPipeline.cpp b/media/webrtc/signaling/src/mediapipeline/MediaPipeline.cpp
index 6affdc25a56..9e39712e2de 100644
--- a/media/webrtc/signaling/src/mediapipeline/MediaPipeline.cpp
+++ b/media/webrtc/signaling/src/mediapipeline/MediaPipeline.cpp
@@ -691,8 +691,66 @@ void MediaPipelineTransmit::PipelineListener::ProcessAudioChunk(
     }
   }
 
-  MOZ_MTLOG(PR_LOG_DEBUG, "Sending an audio frame");
-  conduit->SendAudioFrame(samples.get(), chunk.mDuration, rate, 0);
+  MOZ_ASSERT(!(rate%100)); // rate should be a multiple of 100
+
+  // Check if the rate has changed since the last time we came through
+  // I realize it may be overkill to check if the rate has changed, but
+  // I believe it is possible (e.g. if we change sources) and it costs us
+  // very little to handle this case
+
+  if (samplenum_10ms_ !=  rate/100) {
+    // Determine number of samples in 10 ms from the rate:
+    samplenum_10ms_ = rate/100;
+    // If we switch sample rates (e.g. if we switch codecs),
+    // we throw away what was in the sample_10ms_buffer at the old rate
+    samples_10ms_buffer_ = new int16_t[samplenum_10ms_];
+    buffer_current_ = 0;
+  }
+
+  // Vars to handle the non-sunny-day case (where the audio chunks
+  // we got are not multiples of 10ms OR there were samples left over
+  // from the last run)
+  int64_t chunk_remaining;
+  int64_t tocpy;
+  int16_t *samples_tmp = samples.get();
+
+  chunk_remaining = chunk.mDuration;
+
+  MOZ_ASSERT(chunk_remaining >= 0);
+
+  if (buffer_current_) {
+    tocpy = std::min(chunk_remaining, samplenum_10ms_ - buffer_current_);
+    memcpy(&samples_10ms_buffer_[buffer_current_], samples_tmp, tocpy * sizeof(int16_t));
+    buffer_current_ += tocpy;
+    samples_tmp += tocpy;
+    chunk_remaining -= tocpy;
+
+    if (buffer_current_ == samplenum_10ms_) {
+      // Send out the audio buffer we just finished filling
+      conduit->SendAudioFrame(samples_10ms_buffer_, samplenum_10ms_, rate, 0);
+      buffer_current_ = 0;
+    } else {
+      // We still don't have enough data to send a buffer
+      return;
+    }
+  }
+
+  // Now send (more) frames if there is more than 10ms of input left
+  tocpy = (chunk_remaining / samplenum_10ms_) * samplenum_10ms_;
+  if (tocpy > 0) {
+    conduit->SendAudioFrame(samples_tmp, tocpy, rate, 0);
+    samples_tmp += tocpy;
+    chunk_remaining = chunk.mDuration - tocpy;
+  }
+  // Copy what remains for the next run
+
+  MOZ_ASSERT(chunk_remaining < samplenum_10ms_);
+
+  if (chunk_remaining) {
+    memcpy(samples_10ms_buffer_, samples_tmp, chunk_remaining * sizeof(int16_t));
+    buffer_current_ = chunk_remaining;
+  }
+
 }
 
 #ifdef MOZILLA_INTERNAL_API
diff --git a/media/webrtc/signaling/src/mediapipeline/MediaPipeline.h b/media/webrtc/signaling/src/mediapipeline/MediaPipeline.h
index cf5c168256f..1cf472f9be1 100644
--- a/media/webrtc/signaling/src/mediapipeline/MediaPipeline.h
+++ b/media/webrtc/signaling/src/mediapipeline/MediaPipeline.h
@@ -253,9 +253,10 @@ class MediaPipelineTransmit : public MediaPipeline {
   class PipelineListener : public MediaStreamListener {
    public:
     PipelineListener(const RefPtr<MediaSessionConduit>& conduit)
-        : conduit_(conduit), active_(false) {}
+      : conduit_(conduit), active_(false), samples_10ms_buffer_(nullptr),  
+        buffer_current_(0), samplenum_10ms_(0){}
 
-    // XXX. This is not thread-safe but the hazard is just 
+    // XXX. This is not thread-safe but the hazard is just
     // that active_ = true takes a while to propagate. Revisit
     // when 823600 lands.
     void SetActive(bool active) { active_ = active; }
@@ -277,6 +278,15 @@ class MediaPipelineTransmit : public MediaPipeline {
 #endif
     RefPtr<MediaSessionConduit> conduit_;
     volatile bool active_;
+
+    // These vars handle breaking audio samples into exact 10ms chunks:
+    // The buffer of 10ms audio samples that we will send once full
+    // (can be carried over from one call to another).
+    nsAutoArrayPtr<int16_t> samples_10ms_buffer_;
+    // The location of the pointer within that buffer (in units of samples).
+    int64_t buffer_current_;
+    // The number of samples in a 10ms audio chunk.
+    int64_t samplenum_10ms_;
   };
 
  private: