Support for parsing encrypted WebM streams by src.

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 <string>
 
+#include "base/base64.h"
 #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"
 #include "base/string_util.h"
 #include "base/time.h"
 #include "media/base/audio_decoder_config.h"
 #include "media/base/decoder_buffer.h"
 #include "media/base/limits.h"
 #include "media/base/media_switches.h"
 #include "media/base/video_decoder_config.h"
+#include "media/crypto/decryptor_helpers.h"
 #include "media/ffmpeg/ffmpeg_common.h"
 #include "media/filters/ffmpeg_glue.h"
 #include "media/filters/ffmpeg_h264_to_annex_b_bitstream_converter.h"
+#include "media/webm/webm_crypt_helpers.h"
 
 namespace media {
 
 //
 // FFmpegDemuxerStream
 //
 FFmpegDemuxerStream::FFmpegDemuxerStream(
     FFmpegDemuxer* demuxer,
     AVStream* stream)
     : demuxer_(demuxer),
@@ skipping 13 matching lines @@
       type_ = VIDEO;
       AVStreamToVideoDecoderConfig(stream, &video_config_);
       break;
     default:
       NOTREACHED();
       break;
   }
 
   // Calculate the duration.
   duration_ = ConvertStreamTimestamp(stream->time_base, stream->duration);
+
+  // *** DEBUG Until FFmpeg metadata "enck_key_id" is added for windows. ***
+  //av_dict_set(stream->metadata, "enc_key_id", "DEBUG_KEY_ID_REMOVE", 0);
+  // *** DEBUG Until FFmpeg metadata "enck_key_id" is added for windows. ***
+
+  // Only supports WebM for now.
+  AVDictionaryEntry *key = av_dict_get(stream->metadata, "enc_key_id", NULL, 0);
+  if (key) {
+    CHECK(key->value);

[xhwang, 2012/08/29 05:08:14]

Can a malformed file generate a |key| without value? Or does av_dict_get enforce
this is always true? We shouldn't crash on malformed files.

[fgalligan1, 2013/03/09 01:10:59]

Done.

+    base::StringPiece base64_key_id(key->value);
+    std::string enc_key_id;
+    base::Base64Decode(base64_key_id, &enc_key_id);
+    CHECK(!enc_key_id.empty());

[xhwang, 2012/08/29 05:08:14]

Same as above, add error handling code instead of crashing?

[fgalligan1, 2013/03/09 01:10:59]

Done.

[fgalligan1, 2013/03/09 01:10:59]

Done.

+    demuxer_->NeedKey(enc_key_id);
+    current_key_id_.assign(enc_key_id);
+  }
 }
 
 bool FFmpegDemuxerStream::HasPendingReads() {
   DCHECK(demuxer_->message_loop()->BelongsToCurrentThread());
   base::AutoLock auto_lock(lock_);
   DCHECK(!stopped_ || read_queue_.empty())
       << "Read queue should have been emptied if demuxing stream is stopped";
   return !read_queue_.empty();
 }
 
@@ skipping 10 matching lines @@
   scoped_refptr<DecoderBuffer> buffer;
   if (!packet.get()) {
     buffer = DecoderBuffer::CreateEOSBuffer();
   } else {
     // Convert the packet if there is a bitstream filter.
     if (packet->data && bitstream_converter_.get() &&
         !bitstream_converter_->ConvertPacket(packet.get())) {
       LOG(ERROR) << "Format converstion failed.";
     }
 
-    // If a packet is returned by FFmpeg's av_parser_parse2() the packet will
-    // reference inner memory of FFmpeg.  As such we should transfer the packet
-    // into memory we control.
-    buffer = DecoderBuffer::CopyFrom(packet->data, packet->size);
+    // TODO (fgalligan): Remove the WebM specific code to process an encrypted
+    // buffer. Create a generalized class or function that can be called that
+    // will work for all encrypted formats.
+    buffer = WebMCopyBufferCheckIfEncrypted(
+        packet->data,
+        packet->size,
+        reinterpret_cast<const uint8*>(current_key_id_.data()),
+        current_key_id_.size());
     buffer->SetTimestamp(ConvertStreamTimestamp(
         stream_->time_base, packet->pts));
     buffer->SetDuration(ConvertStreamTimestamp(
         stream_->time_base, packet->duration));
     if (buffer->GetTimestamp() != kNoTimestamp() &&
         last_packet_timestamp_ != kNoTimestamp() &&
         last_packet_timestamp_ < buffer->GetTimestamp()) {
       buffered_ranges_.Add(last_packet_timestamp_, buffer->GetTimestamp());
       demuxer_->message_loop()->PostTask(FROM_HERE, base::Bind(
           &FFmpegDemuxer::NotifyBufferingChanged, demuxer_));
@@ skipping 147 matching lines @@
     return kNoTimestamp();
 
   return ConvertFromTimeBase(time_base, timestamp);
 }
 
 //
 // FFmpegDemuxer
 //
 FFmpegDemuxer::FFmpegDemuxer(
     const scoped_refptr<base::MessageLoopProxy>& message_loop,
-    const scoped_refptr<DataSource>& data_source)
+    const scoped_refptr<DataSource>& data_source,
+    const FFmpegNeedKeyCB& need_key_cb)
     : host_(NULL),
       message_loop_(message_loop),
       format_context_(NULL),
       data_source_(data_source),
       read_event_(false, false),
       read_has_failed_(false),
       last_read_bytes_(0),
       read_position_(0),
       bitrate_(0),
       start_time_(kNoTimestamp()),
       audio_disabled_(false),
-      duration_known_(false) {
+      duration_known_(false),
+      need_key_cb_(need_key_cb) {
   DCHECK(message_loop_);
   DCHECK(data_source_);
 }
 
 FFmpegDemuxer::~FFmpegDemuxer() {
   // In this destructor, we clean up resources held by FFmpeg. It is ugly to
   // close the codec contexts here because the corresponding codecs are opened
   // in the decoder filters. By reaching this point, all filters should have
   // stopped, so this is the only safe place to do the global clean up.
   // TODO(hclam): close the codecs in the corresponding decoders.
@@ skipping 26 matching lines @@
 void FFmpegDemuxer::SetPlaybackRate(float playback_rate) {
   DCHECK(data_source_.get());
   data_source_->SetPlaybackRate(playback_rate);
 }
 
 void FFmpegDemuxer::OnAudioRendererDisabled() {
   message_loop_->PostTask(FROM_HERE, base::Bind(
       &FFmpegDemuxer::DisableAudioStreamTask, this));
 }
 
+void FFmpegDemuxer::NeedKey(const std::string& key_id) {
+  int key_id_size = key_id.size();
+  scoped_array<uint8> key_id_local(new uint8[key_id_size]);
+  memcpy(key_id_local.get(), key_id.data(), key_id_size);
+  need_key_cb_.Run(key_id_local.Pass(), key_id_size);

[xhwang, 2012/08/29 05:08:14]

Sad to see this conversion again. I think we need to address types we use for
initData eventually.

+}
+
 void FFmpegDemuxer::Initialize(DemuxerHost* host,
                                const PipelineStatusCB& status_cb) {
   message_loop_->PostTask(FROM_HERE, base::Bind(
       &FFmpegDemuxer::InitializeTask, this, host, status_cb));
 }
 
 scoped_refptr<DemuxerStream> FFmpegDemuxer::GetStream(
     DemuxerStream::Type type) {
   return GetFFmpegStream(type);
 }
@@ skipping 398 matching lines @@
   } else if (audio) {
     buffered = audio->GetBufferedRanges();
   } else if (video) {
     buffered = video->GetBufferedRanges();
   }
   for (size_t i = 0; i < buffered.size(); ++i)
     host_->AddBufferedTimeRange(buffered.start(i), buffered.end(i));
 }
 
 }  // namespace media