Fix up missing timestamps in FFmpegDemuxer.

media/filters/ffmpeg_demuxer.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_demuxer.h"
 
 #include <algorithm>
 #include <memory>
 #include <set>
 #include <utility>
@@ skipping 258 matching lines @@
       video_config_(video_config.release()),
       type_(UNKNOWN),
       liveness_(LIVENESS_UNKNOWN),
       end_of_stream_(false),
       last_packet_timestamp_(kNoTimestamp),
       last_packet_duration_(kNoTimestamp),
       video_rotation_(VIDEO_ROTATION_0),
       is_enabled_(true),
       waiting_for_keyframe_(false),
       aborted_(false),
-      fixup_negative_timestamps_(false) {
+      fixup_negative_timestamps_(false),
+      warned_about_missing_timestamps_(false) {
   DCHECK(demuxer_);
 
   bool is_encrypted = false;
   int rotation = 0;
   AVDictionaryEntry* rotation_entry = NULL;
 
   // Determine our media format.
   switch (stream->codecpar->codec_type) {
     case AVMEDIA_TYPE_AUDIO:
       DCHECK(audio_config_.get() && !video_config_.get());
@@ skipping 230 matching lines @@
         // nearest millisecond.  See enable_negative_timestamp_fixups().
         DCHECK_LE(-std::ceil(FramesToTimeDelta(
                                  audio_decoder_config().codec_delay(),
                                  audio_decoder_config().samples_per_second())
                                  .InMillisecondsF()),
                   stream_timestamp.InMillisecondsF());
       }
     }
   } else {
     // If this happens on the first packet, decoders will throw an error.
-    buffer->set_timestamp(kNoTimestamp);
+    // Just try zero.  crbug.com/665305 .
+    if (!warned_about_missing_timestamps_) {
+      LOG(WARNING) << "No timestamp provided for initial buffer";
+      warned_about_missing_timestamps_ = true;
+    }
+    buffer->set_timestamp(base::TimeDelta());
   }
 
   if (last_packet_timestamp_ != kNoTimestamp) {
     // FFmpeg doesn't support chained ogg correctly.  Instead of guaranteeing
     // continuity across links in the chain it uses the timestamp information
     // from each link directly.  Doing so can lead to timestamps which appear to
     // go backwards in time.
     //
     // If the new link starts with a negative timestamp or a timestamp less than
     // the original (positive) |start_time|, we will get a negative timestamp
     // here.  It's also possible FFmpeg returns kNoTimestamp here if it's not
     // able to work out a timestamp using the previous link and the next.
     //
     // Fixing chained ogg is non-trivial, so for now just reuse the last good
     // timestamp.  The decoder will rewrite the timestamps to be sample accurate
     // later.  See http://crbug.com/396864.
-    if (fixup_negative_timestamps_ &&
-        (buffer->timestamp() == kNoTimestamp ||
+    //
+    // Whether we're fixing up timestamps or not, if we have no timestamp, then
+    // use the last timestamp instead.  This can happen if bad media causes
+    // ffmpeg to fail to provide a timestamp.  crbug.com/665305
+    if (buffer->timestamp() == kNoTimestamp ||
+        (fixup_negative_timestamps_ &&
          buffer->timestamp() < last_packet_timestamp_)) {
+      if (!fixup_negative_timestamps_ && !warned_about_missing_timestamps_) {

[liberato (no reviews please), 2016/12/12 22:24:48]

"!fixup..." to prevent a warning when we wouldn't have before.  no idea if we
actually care about this.

+        LOG(WARNING) << "No timestamp provided for buffer";
+        warned_about_missing_timestamps_ = true;
+      }
       buffer->set_timestamp(last_packet_timestamp_ +
                             (last_packet_duration_ != kNoTimestamp
                                  ? last_packet_duration_
                                  : base::TimeDelta::FromMicroseconds(1)));
     }
 
-    // The demuxer should always output positive timestamps.
+    // The demuxer should always output non-negative timestamps.  If it output
+    // no timestamp, then we should have already fixed that up.
+    DCHECK(buffer->timestamp() != kNoTimestamp);
     DCHECK(buffer->timestamp() >= base::TimeDelta());
-    DCHECK(buffer->timestamp() != kNoTimestamp);
 
     if (last_packet_timestamp_ < buffer->timestamp()) {
       buffered_ranges_.Add(last_packet_timestamp_, buffer->timestamp());
       demuxer_->NotifyBufferingChanged();
     }
   }
 
   if (packet.get()->flags & AV_PKT_FLAG_KEY)
     buffer->set_is_key_frame(true);
 
@@ skipping 1235 matching lines @@
 
 void FFmpegDemuxer::SetLiveness(DemuxerStream::Liveness liveness) {
   DCHECK(task_runner_->BelongsToCurrentThread());
   for (const auto& stream : streams_) {
     if (stream)
       stream->SetLiveness(liveness);
   }
 }
 
 }  // namespace media