commit f3db34d06074bf777f50bbd5c9f16e95bd908053
author Sebastian Jansson <srte@webrtc.org> Fri May 24 07:34:00 2019
committer Commit Bot <commit-bot@chromium.org> Fri May 24 07:34:10 2019
tree d6a69a60e43fa8113337222c4732bbce43e1df70
parent 4c55c8953b759e9cc91ca5619077a11a98ac15d4

Revert "Cleanup of video packet overhead calculation."

This reverts commit 890bc3069cbababa19b40ec02684253d60e051b2.

Reason for revert: Div by zero.

Original change's description:
> Cleanup of video packet overhead calculation.
> 
> This CL updates the video packet overhead calculation to make it more
> clear. This prepares for future work on improving the accuracy of the
> calculation.
> 
> Bug: webrtc:9883
> Change-Id: I1d623a3e0de45be7b6e4a1f9e3cbe54fd2b8a45a
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/138077
> Commit-Queue: Sebastian Jansson <srte@webrtc.org>
> Reviewed-by: Erik Språng <sprang@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#28040}

TBR=sprang@webrtc.org,srte@webrtc.org

Change-Id: Icbdfc7b9252f8f9aa8e7e97b85b04171a27935e4
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: webrtc:9883
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/138212
Reviewed-by: Sebastian Jansson <srte@webrtc.org>
Commit-Queue: Sebastian Jansson <srte@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28049}

call/rtp_video_sender.cc

diff --git a/call/rtp_video_sender.cc b/call/rtp_video_sender.cc
index 115cd1f..bd56c33 100644
--- a/call/rtp_video_sender.cc
+++ b/call/rtp_video_sender.cc
@@ -188,13 +188,19 @@
       RTPSender::FecExtensionSizes(), rtp_state, clock);
 }
 
-DataRate CalculateMinOverheadRate(DataRate bitrate,
-                                  DataSize overhead_per_packet,
-                                  DataSize max_packet_size) {
-  TimeDelta packet_interval = max_packet_size / bitrate;
-  int packets_per_second =
-      rtc::dchecked_cast<int>(std::ceil(1 / packet_interval.seconds<double>()));
-  return packets_per_second * overhead_per_packet / TimeDelta::Seconds<1>();
+uint32_t CalculateOverheadRateBps(int packets_per_second,
+                                  size_t overhead_bytes_per_packet,
+                                  uint32_t max_overhead_bps) {
+  uint32_t overhead_bps =
+      static_cast<uint32_t>(8 * overhead_bytes_per_packet * packets_per_second);
+  return std::min(overhead_bps, max_overhead_bps);
+}
+
+int CalculatePacketRate(uint32_t bitrate_bps, size_t packet_size_bytes) {
+  size_t packet_size_bits = 8 * packet_size_bytes;
+  // Ceil for int value of bitrate_bps / packet_size_bits.
+  return static_cast<int>((bitrate_bps + packet_size_bits - 1) /
+                          packet_size_bits);
 }
 }  // namespace
 
@@ -680,17 +686,16 @@
                                       int framerate) {
   // Substract overhead from bitrate.
   rtc::CritScope lock(&crit_);
-  DataSize packet_overhead = DataSize::bytes(
-      overhead_bytes_per_packet_ + transport_overhead_bytes_per_packet_);
-  DataSize max_total_packet_size = DataSize::bytes(
-      rtp_config_.max_packet_size + transport_overhead_bytes_per_packet_);
   uint32_t payload_bitrate_bps = bitrate_bps;
   if (send_side_bwe_with_overhead_) {
-    DataRate overhead_rate = CalculateMinOverheadRate(
-        DataRate::bps(bitrate_bps), packet_overhead, max_total_packet_size);
-    // TODO(srte): We probably should not accept 0 payload bitrate here.
-    payload_bitrate_bps =
-        rtc::saturated_cast<uint32_t>(bitrate_bps - overhead_rate.bps());
+    uint32_t overhead_bps = CalculateOverheadRateBps(
+        CalculatePacketRate(
+            bitrate_bps,
+            rtp_config_.max_packet_size + transport_overhead_bytes_per_packet_),
+        overhead_bytes_per_packet_ + transport_overhead_bytes_per_packet_,
+        bitrate_bps);
+    RTC_DCHECK_LE(overhead_bps, bitrate_bps);
+    payload_bitrate_bps = bitrate_bps - overhead_bps;
   }
 
   // Get the encoder target rate. It is the estimated network rate -
@@ -711,16 +716,18 @@
 
   loss_mask_vector_.clear();
 
-  uint32_t encoder_overhead_rate_bps = 0;
-  if (send_side_bwe_with_overhead_) {
-    // TODO(srte): The packet size should probably match the one used above.
-    DataRate encoder_overhead_rate = CalculateMinOverheadRate(
-        DataRate::bps(encoder_target_rate_bps_), packet_overhead,
-        max_total_packet_size - DataSize::bytes(overhead_bytes_per_packet_));
-    encoder_overhead_rate_bps =
-        std::min(encoder_overhead_rate.bps<uint32_t>(),
-                 bitrate_bps - encoder_target_rate_bps_);
-  }
+  uint32_t encoder_overhead_rate_bps =
+      send_side_bwe_with_overhead_
+          ? CalculateOverheadRateBps(
+                CalculatePacketRate(encoder_target_rate_bps_,
+                                    rtp_config_.max_packet_size +
+                                        transport_overhead_bytes_per_packet_ -
+                                        overhead_bytes_per_packet_),
+                overhead_bytes_per_packet_ +
+                    transport_overhead_bytes_per_packet_,
+                bitrate_bps - encoder_target_rate_bps_)
+          : 0;
+
   // When the field trial "WebRTC-SendSideBwe-WithOverhead" is enabled
   // protection_bitrate includes overhead.
   const uint32_t media_rate = encoder_target_rate_bps_ +