Replace media::Limits struct with media::limits namespace and update documentation.

media/filters/ffmpeg_demuxer.cc

 // Copyright (c) 2011 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 "base/bind.h"
 #include "base/callback.h"
 #include "base/command_line.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop.h"
 #include "base/stl_util.h"
@@ skipping 501 matching lines @@
     return;
   }
   if (format_context_->duration != static_cast<int64_t>(AV_NOPTS_VALUE)) {
     // If there is a duration value in the container use that to find the
     // maximum between it and the duration from A/V streams.
     const AVRational av_time_base = {1, AV_TIME_BASE};
     max_duration =
         std::max(max_duration,
                  ConvertFromTimeBase(av_time_base, format_context_->duration));
   } else {
-    // The duration is not a valid value. Assume that this is a live stream
-    // and set duration to the maximum int64 number to represent infinity.
-    max_duration = base::TimeDelta::FromMicroseconds(
-        Limits::kMaxTimeInMicroseconds);
+    // The duration is unknown, in which case this is likely a live stream.
+    max_duration = base::TimeDelta::FromMicroseconds(limits::kInfiniteDuration);
   }
 
   // Some demuxers, like WAV, do not put timestamps on their frames. We
   // assume the the start time is 0.
   if (start_time_ == kNoTimestamp)
     start_time_ = base::TimeDelta();
 
   // Good to go: set the duration and bitrate and notify we're done
   // initializing.
   if (host())
@@ skipping 16 matching lines @@
 
   // Then try to sum the bitrates individually per stream.
   int bitrate = 0;
   for (size_t i = 0; i < format_context_->nb_streams; ++i) {
     AVCodecContext* codec_context = format_context_->streams[i]->codec;
     bitrate += codec_context->bit_rate;
   }
   if (bitrate > 0)
     return bitrate;
 
-  // If there isn't a bitrate set in the container or streams, but there is a
-  // valid duration, approximate the bitrate using the duration.
-  if (max_duration_.InMilliseconds() > 0 &&
-      max_duration_.InMicroseconds() < Limits::kMaxTimeInMicroseconds) {
-    int64 filesize_in_bytes;
-    if (GetSize(&filesize_in_bytes))
-      return 8000 * filesize_in_bytes / max_duration_.InMilliseconds();
-  }
+  // See if we can approximate the bitrate as long as we have a filesize and
+  // valid duration.
+  int64 filesize_in_bytes;
+  if (max_duration_.InMicroseconds() <= 0 ||
+      max_duration_.InMicroseconds() == limits::kInfiniteDuration ||
+      !GetSize(&filesize_in_bytes))
+    return 0;

[Ami GONE FROM CHROMIUM, 2011/12/07 01:04:48]

Need braces.

[scherkus (not reviewing), 2011/12/07 05:56:56]

Done.

 
-  // Bitrate could not be determined.
-  return 0;
+  // Do math in floating point as we'd overflow an int64 if the filesize was
+  // larger than ~1073GB.
+  double bytes = filesize_in_bytes;
+  double duration = max_duration_.InMicroseconds();
+  return bytes * 8000000.0 / duration;

[Ami GONE FROM CHROMIUM, 2011/12/07 01:04:48]

Personally I prefer 8e6 to counting zeros, but I don't think that's a
chromium-dev majority opinion.

[scherkus (not reviewing), 2011/12/07 05:56:56]

I like my zeros!

also my efforts to prevent overflow are somewhat futile considering we truncate
to int :~(

 }
 
 bool FFmpegDemuxer::IsLocalSource() {
   return local_source_;
 }
 
 bool FFmpegDemuxer::IsSeekable() {
   return !IsStreaming();
 }
 
@@ skipping 149 matching lines @@
   read_event_.Wait();
   return last_read_bytes_;
 }
 
 void FFmpegDemuxer::SignalReadCompleted(size_t size) {
   last_read_bytes_ = size;
   read_event_.Signal();
 }
 
 }  // namespace media