Cast: Clarify the unit of bitrate

chrome/renderer/media/cast_rtp_stream.cc

 // Copyright 2013 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 "chrome/renderer/media/cast_rtp_stream.h"
 
 #include "base/bind.h"
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "base/memory/weak_ptr.h"
@@ skipping 16 matching lines @@
 #include "ui/gfx/geometry/size.h"
 
 using media::cast::AudioSenderConfig;
 using media::cast::VideoSenderConfig;
 
 namespace {
 
 const char kCodecNameOpus[] = "OPUS";
 const char kCodecNameVp8[] = "VP8";
 
+// To convert from kilobits per second to bits to per second.
+const int kBitrateMultiplier = 1000;
+
 // This constant defines the number of sets of audio data to buffer
 // in the FIFO. If input audio and output data have different resampling
 // rates then buffer is necessary to avoid audio glitches.
 // See CastAudioSink::ResampleData() and CastAudioSink::OnSetFormat()
 // for more defaults.
 const int kBufferAudioData = 2;
 
 CastRtpPayloadParams DefaultOpusPayload() {
   CastRtpPayloadParams payload;
   payload.ssrc = 1;
   payload.feedback_ssrc = 1;
   payload.payload_type = 127;
   payload.codec_name = kCodecNameOpus;
   payload.clock_rate = 48000;
   payload.channels = 2;
+  // The value is 0 which means VBR.
   payload.min_bitrate = payload.max_bitrate =
       media::cast::kDefaultAudioEncoderBitrate;
   return payload;
 }
 
 CastRtpPayloadParams DefaultVp8Payload() {
   CastRtpPayloadParams payload;
   payload.ssrc = 11;
   payload.feedback_ssrc = 12;
   payload.payload_type = 96;
   payload.codec_name = kCodecNameVp8;
   payload.clock_rate = 90000;
   payload.width = 1280;
   payload.height = 720;
-  payload.min_bitrate = 50 * 1000;
-  payload.max_bitrate = 2000 * 1000;
+  payload.min_bitrate = 50;
+  payload.max_bitrate = 2000;
   return payload;
 }
 
 std::vector<CastRtpParams> SupportedAudioParams() {
   // TODO(hclam): Fill in more codecs here.
   std::vector<CastRtpParams> supported_params;
   supported_params.push_back(CastRtpParams(DefaultOpusPayload()));
   return supported_params;
 }
 
 std::vector<CastRtpParams> SupportedVideoParams() {
   // TODO(hclam): Fill in H264 here.
   std::vector<CastRtpParams> supported_params;
   supported_params.push_back(CastRtpParams(DefaultVp8Payload()));
   return supported_params;
 }
 
 bool ToAudioSenderConfig(const CastRtpParams& params,
                          AudioSenderConfig* config) {
   config->sender_ssrc = params.payload.ssrc;
   config->incoming_feedback_ssrc = params.payload.feedback_ssrc;
   config->rtp_config.payload_type = params.payload.payload_type;
   config->use_external_encoder = false;
   config->frequency = params.payload.clock_rate;
   config->channels = params.payload.channels;
-  config->bitrate = params.payload.max_bitrate;
+  config->bitrate = params.payload.max_bitrate * kBitrateMultiplier;
   config->codec = media::cast::transport::kPcm16;
   if (params.payload.codec_name == kCodecNameOpus)
     config->codec = media::cast::transport::kOpus;
   else
     return false;
   return true;
 }
 
 bool ToVideoSenderConfig(const CastRtpParams& params,
                          VideoSenderConfig* config) {
   config->sender_ssrc = params.payload.ssrc;
   config->incoming_feedback_ssrc = params.payload.feedback_ssrc;
   config->rtp_config.payload_type = params.payload.payload_type;
   config->use_external_encoder = false;
   config->width = params.payload.width;
   config->height = params.payload.height;
-  config->min_bitrate = config->start_bitrate = params.payload.min_bitrate;
-  config->max_bitrate = params.payload.max_bitrate;
+  config->min_bitrate = config->start_bitrate =
+      params.payload.min_bitrate * kBitrateMultiplier;
+  config->max_bitrate = params.payload.max_bitrate * kBitrateMultiplier;
   if (params.payload.codec_name == kCodecNameVp8)
     config->codec = media::cast::transport::kVp8;
   else
     return false;
   return true;
 }
 
 }  // namespace
 
 // This class receives MediaStreamTrack events and video frames from a
@@ skipping 322 matching lines @@
 }
 
 void CastRtpStream::DidEncounterError(const std::string& message) {
   // Save the WeakPtr first because the error callback might delete this object.
   base::WeakPtr<CastRtpStream> ptr = weak_factory_.GetWeakPtr();
   error_callback_.Run(message);
   content::RenderThread::Get()->GetMessageLoop()->PostTask(
       FROM_HERE,
       base::Bind(&CastRtpStream::Stop, ptr));
 }