Add UMA stats for audio/video containers.

media/filters/ffmpeg_glue.cc

 // Copyright (c) 2012 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 "media/filters/ffmpeg_glue.h"
 
 #include "base/lazy_instance.h"
 #include "base/logging.h"
+#include "base/metrics/sparse_histogram.h"
 #include "base/synchronization/lock.h"
+#include "media/base/container_names.h"
 #include "media/ffmpeg/ffmpeg_common.h"
 
 namespace media {
 
 // Internal buffer size used by AVIO for reading.
 // TODO(dalecurtis): Experiment with this buffer size and measure impact on
 // performance.  Currently we want to use 32kb to preserve existing behavior
 // with the previous URLProtocol based approach.
 enum { kBufferSize = 32 * 1024 };
 
@@ skipping 128 matching lines @@
   format_context_->pb = avio_context_.get();
 }
 
 bool FFmpegGlue::OpenContext() {
   DCHECK(!open_called_) << "OpenContext() should't be called twice.";
 
   // If avformat_open_input() is called we have to take a slightly different
   // destruction path to avoid double frees.
   open_called_ = true;
 
+  // Attempt to recognize the container by looking at the first few bytes of the
+  // stream. The stream position is left unchanged.
+  scoped_ptr<uint8[]> buffer(new uint8[8192]);

[acolwell GONE FROM CHROMIUM, 2013/05/22 21:03:14]

nit: Could std::vector<uint8> work here? If so then you can replace the 8192
below w/ buffer.size() so we only have the constant here once.

[jrummell, 2013/05/22 23:59:46]

Done.

+
+  int64 pos = AVIOSeekOperation(avio_context_.get()->opaque, 0, SEEK_CUR);
+  AVIOSeekOperation(avio_context_.get()->opaque, 0, SEEK_SET);
+  int numRead =
+      AVIOReadOperation(avio_context_.get()->opaque, buffer.get(), 8192);
+  AVIOSeekOperation(avio_context_.get()->opaque, pos, SEEK_SET);
+  if (numRead > 0) {
+    // < 0 means Read failed
+    container_names::MediaContainerName container =
+        container_names::DetermineContainer(buffer.get(), numRead);
+    UMA_HISTOGRAM_SPARSE_SLOWLY("Media.DetectedContainer", container);
+  }
+
   // By passing NULL for the filename (second parameter) we are telling FFmpeg
   // to use the AVIO context we setup from the AVFormatContext structure.
   return avformat_open_input(&format_context_, NULL, NULL, NULL) == 0;
 }
 
 FFmpegGlue::~FFmpegGlue() {
   // In the event of avformat_open_input() failure, FFmpeg may sometimes free
   // our AVFormatContext behind the scenes, but leave the buffer alive.  It will
   // helpfully set |format_context_| to NULL in this case.
   if (!format_context_) {
@@ skipping 27 matching lines @@
         avcodec_close(stream->codec);
       }
     }
   }
 
   avformat_close_input(&format_context_);
   av_free(avio_context_->buffer);
 }
 
 }  // namespace media