Support for parsing encrypted WebM streams by src.

media/filters/ffmpeg_demuxer.cc

Index: media/filters/ffmpeg_demuxer.cc
diff --git a/media/filters/ffmpeg_demuxer.cc b/media/filters/ffmpeg_demuxer.cc
index 535116ffebd3e4b000f1818ca44d84f8c8f1cc17..07972671b02b00a95fd466961ef1722790ff1ce2 100644
--- a/media/filters/ffmpeg_demuxer.cc
+++ b/media/filters/ffmpeg_demuxer.cc
@@ -7,6 +7,7 @@
 #include <algorithm>
 #include <string>
 
+#include "base/base64.h"
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/command_line.h"
@@ -20,9 +21,11 @@
 #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 {
 
@@ -56,6 +59,22 @@ FFmpegDemuxerStream::FFmpegDemuxerStream(
 
   // 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() {
@@ -86,10 +105,14 @@ void FFmpegDemuxerStream::EnqueuePacket(
       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(
@@ -257,7 +280,8 @@ base::TimeDelta FFmpegDemuxerStream::ConvertStreamTimestamp(
 //
 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),
@@ -269,7 +293,8 @@ FFmpegDemuxer::FFmpegDemuxer(
       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_);
 }
@@ -316,6 +341,13 @@ void FFmpegDemuxer::OnAudioRendererDisabled() {
       &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(