Add Common Encryption support to BMFF, including subsample decryption.

media/mp4/mp4_stream_parser.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/mp4/mp4_stream_parser.h"
 
 #include "base/callback.h"
 #include "base/callback_helpers.h"
 #include "base/logging.h"
 #include "base/time.h"
@@ skipping 155 matching lines @@
       }
     }
     RCHECK(desc_idx > 0);
     desc_idx -= 1;  // BMFF descriptor index is one-based
 
     if (track->media.handler.type == kAudio && !audio_config.IsValidConfig()) {
       RCHECK(!samp_descr.audio_entries.empty());
 
       // It is not uncommon to find otherwise-valid files with incorrect sample
       // description indices, so we fail gracefully in that case.
-      if (static_cast<uint32>(desc_idx) >= samp_descr.audio_entries.size())
+      if (desc_idx >= samp_descr.audio_entries.size())
         desc_idx = 0;
       const AudioSampleEntry& entry = samp_descr.audio_entries[desc_idx];
       const AAC& aac = entry.esds.aac;
 
-      // TODO(strobe): We accept all format values, pending clarification on
-      // the formats used for encrypted media (http://crbug.com/132351).
-      //  RCHECK(entry.format == FOURCC_MP4A ||
-      //         (entry.format == FOURCC_ENCA &&
-      //          entry.sinf.format.format == FOURCC_MP4A));
+      RCHECK(entry.format == FOURCC_MP4A ||
+             (entry.format == FOURCC_ENCA &&
+              entry.sinf.format.format == FOURCC_MP4A));
+      RCHECK(EmitKeyNeeded(entry.sinf.info.track_encryption));
 
       // Check if it is MPEG4 AAC defined in ISO 14496 Part 3.
       RCHECK(entry.esds.object_type == kISO_14496_3);
       audio_config.Initialize(kCodecAAC, entry.samplesize,
                               aac.channel_layout(), aac.frequency(),
                               NULL, 0, false);
 
       has_audio_ = true;
       audio_track_id_ = track->header.track_id;
     }
     if (track->media.handler.type == kVideo && !video_config.IsValidConfig()) {
       RCHECK(!samp_descr.video_entries.empty());
-      if (static_cast<uint32>(desc_idx) >= samp_descr.video_entries.size())
+      if (desc_idx >= samp_descr.video_entries.size())
         desc_idx = 0;
       const VideoSampleEntry& entry = samp_descr.video_entries[desc_idx];
 
-      //  RCHECK(entry.format == FOURCC_AVC1 ||
-      //         (entry.format == FOURCC_ENCV &&
-      //          entry.sinf.format.format == FOURCC_AVC1));
+      RCHECK(entry.format == FOURCC_AVC1 ||
+             (entry.format == FOURCC_ENCV &&
+              entry.sinf.format.format == FOURCC_AVC1));
+      RCHECK(EmitKeyNeeded(entry.sinf.info.track_encryption));
 
       // TODO(strobe): Recover correct crop box
       video_config.Initialize(kCodecH264, H264PROFILE_MAIN,  VideoFrame::YV12,
                               gfx::Size(entry.width, entry.height),
                               gfx::Rect(0, 0, entry.width, entry.height),
                               // Framerate of zero is provided to signal that
                               // the decoder should trust demuxer timestamps
                               0, 1,
                               entry.pixel_aspect.h_spacing,
                               entry.pixel_aspect.v_spacing,
                               // No decoder-specific buffer needed for AVC;
                               // SPS/PPS are embedded in the video stream
                               NULL, 0, false);
       has_video_ = true;
       video_track_id_ = track->header.track_id;
     }
   }
 
   // TODO(strobe): For now, we avoid sending new configs on a new
   // reinitialization segment, and instead simply embed the updated parameter
-  // sets into the video stream. The conditional should be removed when
-  // http://crbug.com/122913 is fixed.
+  // sets into the video stream.  The conditional should be removed when
+  // http://crbug.com/122913 is fixed.  (We detect whether we've already sent
+  // configs by looking at init_cb_ instead of config_cb_, because init_cb_
+  // should only be fired once even after that bug is fixed.)
   if (!init_cb_.is_null())
     RCHECK(config_cb_.Run(audio_config, video_config));
 
   base::TimeDelta duration;
   if (moov_->extends.header.fragment_duration > 0) {
-    duration = TimeDeltaFromFrac(moov_->extends.header.fragment_duration,
-                                 moov_->header.timescale);
+    duration = TimeDeltaFromRational(moov_->extends.header.fragment_duration,
+                                     moov_->header.timescale);
   } else if (moov_->header.duration > 0) {
-    duration = TimeDeltaFromFrac(moov_->header.duration,
-                                 moov_->header.timescale);
+    duration = TimeDeltaFromRational(moov_->header.duration,
+                                     moov_->header.timescale);
   } else {
     duration = kInfiniteDuration();
   }
 
   if (!init_cb_.is_null())
     base::ResetAndReturn(&init_cb_).Run(true, duration);
   return true;
 }
 
 bool MP4StreamParser::ParseMoof(BoxReader* reader) {
   RCHECK(moov_.get());  // Must already have initialization segment
   MovieFragment moof;
   RCHECK(moof.Parse(reader));
   RCHECK(runs_->Init(moof));
   new_segment_cb_.Run(runs_->GetMinDecodeTimestamp());
   ChangeState(kEmittingSamples);
   return true;
 }
 
+bool MP4StreamParser::EmitKeyNeeded(const TrackEncryption& track_encryption) {
+  // TODO(strobe): Send the correct value for initData. The format of initData
+  // has not yet been defined; see
+  // https://www.w3.org/Bugs/Public/show_bug.cgi?id=17673.
+  if (!track_encryption.is_encrypted) return true;
+  scoped_array<uint8> kid(new uint8[track_encryption.default_kid.size()]);
+  memcpy(kid.get(), &track_encryption.default_kid[0],
+         track_encryption.default_kid.size());
+  return need_key_cb_.Run(kid.Pass(), track_encryption.default_kid.size());
+}
+
+bool MP4StreamParser::PrepareAVCBuffer(
+    const AVCDecoderConfigurationRecord& avc_config,
+    std::vector<uint8>* frame_buf,
+    std::vector<SubsampleEntry>* subsamples) const {
+  // Convert the AVC NALU length fields to Annex B headers, as expected by
+  // decoding libraries. Since this may enlarge the size of the buffer, we also
+  // update the clear byte count for each subsample if encryption is used.
+  RCHECK(AVC::ConvertFrameToAnnexB(avc_config.length_size, frame_buf));
+  if (!subsamples->empty()) {
+    const int nalu_size_diff = 4 - avc_config.length_size;
+    size_t expected_size = runs_->sample_size() +
+        subsamples->size() * nalu_size_diff;
+    RCHECK(frame_buf->size() == expected_size);
+    for (size_t i = 0; i < subsamples->size(); i++)
+      (*subsamples)[i].clear_bytes += nalu_size_diff;
+  }
+
+  if (runs_->is_keyframe()) {
+    // If this is a keyframe, we (re-)inject SPS and PPS headers at the start of
+    // a frame. If subsample info is present, we also update the clear byte
+    // count for that first subsample.
+    std::vector<uint8> param_sets;
+    RCHECK(AVC::ConvertParameterSetsToAnnexB(avc_config, &param_sets));

[ddorwin, 2012/07/24 01:00:10]

This is a bit confusing because "ParameterSets" would seem to be the input from
the function name, but param_sets is an output parameter. If avc_config contains
"paramater sets" and param_sets is AnnexB format, I guess that's fine, but a
little confusing to read.

[strobe_, 2012/07/25 01:05:13]

I see your point. Suggestions for alternative name?
GetAnnexBParameterSetsFromConfig?

[ddorwin, 2012/07/25 07:13:47]

Convert[Config]ToAnnexB[ParameterSets]()
"Config" is complete but maybe unnecessary. PamaremterSets is probably a good
idea but could be dropped.

[strobe_, 2012/07/25 21:12:36]

Done.

+    frame_buf->insert(frame_buf->begin(),
+                      param_sets.begin(), param_sets.end());
+    if (!subsamples->empty())
+      (*subsamples)[0].clear_bytes += param_sets.size();
+  }
+  return true;
+}
+
 bool MP4StreamParser::EnqueueSample(BufferQueue* audio_buffers,
                                     BufferQueue* video_buffers,
                                     bool* err) {
-  if (!runs_->RunIsValid()) {
+  if (!runs_->IsRunValid()) {
     // Flush any buffers we've gotten in this chunk so that buffers don't
     // cross NewSegment() calls
     *err = !SendAndFlushSamples(audio_buffers, video_buffers);
     if (*err) return false;
     ChangeState(kParsingBoxes);
     return true;
   }
 
-  if (!runs_->SampleIsValid()) {
+  if (!runs_->IsSampleValid()) {
     runs_->AdvanceRun();
     return true;
   }
 
   DCHECK(!(*err));
 
   const uint8* buf;
-  int size;
-  queue_.Peek(&buf, &size);
-  if (!size) return false;
+  int buf_size;
+  queue_.Peek(&buf, &buf_size);
+  if (!buf_size) return false;
 
   bool audio = has_audio_ && audio_track_id_ == runs_->track_id();
   bool video = has_video_ && video_track_id_ == runs_->track_id();
 
   // Skip this entire track if it's not one we're interested in
   if (!audio && !video) runs_->AdvanceRun();
 
-  queue_.PeekAt(runs_->sample_offset() + moof_head_, &buf, &size);
-  if (size < runs_->sample_size()) return false;
+  // Attempt to cache the auxiliary information first. Aux info is usually
+  // placed in a contiguous block before the sample data, rather than being
+  // interleaved. If we didn't cache it, this would require that we retain the
+  // start of the segment buffer while reading samples. Aux info is typically
+  // quite small compared to sample data, so this pattern is useful on
+  // memory-constrained devices where the source buffer consumes a substantial
+  // portion of the total system memory.
+  if (runs_->AuxInfoNeedsToBeCached()) {
+    queue_.PeekAt(runs_->aux_info_offset() + moof_head_, &buf, &buf_size);
+    if (buf_size < runs_->aux_info_size()) return false;
+    *err = !runs_->CacheAuxInfo(buf, buf_size);
+    return !*err;
+  }
+
+  queue_.PeekAt(runs_->sample_offset() + moof_head_, &buf, &buf_size);
+  if (buf_size < runs_->sample_size()) return false;
+
+  scoped_ptr<DecryptConfig> decrypt_config;
+  if (runs_->is_encrypted())
+    decrypt_config = runs_->GetDecryptConfig();
 
   std::vector<uint8> frame_buf(buf, buf + runs_->sample_size());
   if (video) {
-    const AVCDecoderConfigurationRecord& avc_config =
-        runs_->video_description().avcc;
-    RCHECK(AVC::ConvertToAnnexB(avc_config.length_size, &frame_buf));
-    if (runs_->is_keyframe())
-      RCHECK(AVC::InsertParameterSets(avc_config, &frame_buf));
+    std::vector<SubsampleEntry> subsamples;
+    if (decrypt_config.get())
+      subsamples = decrypt_config->subsamples();
+    RCHECK(PrepareAVCBuffer(runs_->video_description().avcc,
+                            &frame_buf, &subsamples));
+    if (!subsamples.empty()) {
+      decrypt_config.reset(new DecryptConfig(
+          decrypt_config->key_id(),
+          decrypt_config->iv(),
+          decrypt_config->checksum(),
+          decrypt_config->data_offset(),
+          subsamples));
+    }
   }
 
   if (audio) {
     const AAC& aac = runs_->audio_description().esds.aac;
     RCHECK(aac.ConvertEsdsToADTS(&frame_buf));
   }
 
   scoped_refptr<StreamParserBuffer> stream_buf =
     StreamParserBuffer::CopyFrom(&frame_buf[0], frame_buf.size(),
                                  runs_->is_keyframe());
 
+  if (runs_->is_encrypted())
+    stream_buf->SetDecryptConfig(decrypt_config.Pass());
+
   stream_buf->SetDuration(runs_->duration());
   stream_buf->SetTimestamp(runs_->cts());
   stream_buf->SetDecodeTimestamp(runs_->dts());
 
   DVLOG(3) << "Pushing frame: aud=" << audio
            << ", key=" << runs_->is_keyframe()
            << ", dur=" << runs_->duration().InMilliseconds()
            << ", dts=" << runs_->dts().InMilliseconds()
            << ", cts=" << runs_->cts().InMilliseconds()
            << ", size=" << runs_->sample_size();
@@ skipping 48 matching lines @@
   return true;
 }
 
 void MP4StreamParser::ChangeState(State new_state) {
   DVLOG(2) << "Changing state: " << new_state;
   state_ = new_state;
 }
 
 }  // namespace mp4
 }  // namespace media