1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
|
// Copyright 2014 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/cast/sender/external_video_encoder.h"
#include <cmath>
#include "base/bind.h"
#include "base/debug/crash_logging.h"
#include "base/debug/dump_without_crashing.h"
#include "base/format_macros.h"
#include "base/logging.h"
#include "base/memory/scoped_vector.h"
#include "base/memory/shared_memory.h"
#include "base/message_loop/message_loop.h"
#include "base/metrics/histogram.h"
#include "base/strings/stringprintf.h"
#include "media/base/video_frame.h"
#include "media/base/video_types.h"
#include "media/base/video_util.h"
#include "media/cast/cast_config.h"
#include "media/cast/cast_defines.h"
#include "media/cast/logging/logging_defines.h"
#include "media/cast/net/cast_transport_config.h"
#include "media/cast/sender/vp8_quantizer_parser.h"
#include "media/filters/h264_parser.h"
namespace {
enum { MAX_H264_QUANTIZER = 51 };
static const size_t kOutputBufferCount = 3;
} // namespace
namespace media {
namespace cast {
// Container for the associated data of a video frame being processed.
struct InProgressFrameEncode {
// The source content to encode.
const scoped_refptr<VideoFrame> video_frame;
// The reference time for this frame.
const base::TimeTicks reference_time;
// The callback to run when the result is ready.
const VideoEncoder::FrameEncodedCallback frame_encoded_callback;
// The target encode bit rate.
const int target_bit_rate;
// The real-world encode start time. This is used to compute the encoded
// frame's |deadline_utilization| and so it uses the real-world clock instead
// of the CastEnvironment clock, the latter of which might be simulated.
const base::TimeTicks start_time;
InProgressFrameEncode(const scoped_refptr<VideoFrame>& v_frame,
base::TimeTicks r_time,
VideoEncoder::FrameEncodedCallback callback,
int bit_rate)
: video_frame(v_frame),
reference_time(r_time),
frame_encoded_callback(callback),
target_bit_rate(bit_rate),
start_time(base::TimeTicks::Now()) {}
};
// Owns a VideoEncoderAccelerator instance and provides the necessary adapters
// to encode media::VideoFrames and emit media::cast::EncodedFrames. All
// methods must be called on the thread associated with the given
// SingleThreadTaskRunner, except for the task_runner() accessor.
class ExternalVideoEncoder::VEAClientImpl
: public VideoEncodeAccelerator::Client,
public base::RefCountedThreadSafe<VEAClientImpl> {
public:
VEAClientImpl(
const scoped_refptr<CastEnvironment>& cast_environment,
const scoped_refptr<base::SingleThreadTaskRunner>& encoder_task_runner,
scoped_ptr<media::VideoEncodeAccelerator> vea,
int max_frame_rate,
const StatusChangeCallback& status_change_cb,
const CreateVideoEncodeMemoryCallback& create_video_encode_memory_cb)
: cast_environment_(cast_environment),
task_runner_(encoder_task_runner),
max_frame_rate_(max_frame_rate),
status_change_cb_(status_change_cb),
create_video_encode_memory_cb_(create_video_encode_memory_cb),
video_encode_accelerator_(vea.Pass()),
encoder_active_(false),
next_frame_id_(0u),
key_frame_encountered_(false),
codec_profile_(media::VIDEO_CODEC_PROFILE_UNKNOWN),
key_frame_quantizer_parsable_(false),
requested_bit_rate_(-1),
has_seen_zero_length_encoded_frame_(false) {}
base::SingleThreadTaskRunner* task_runner() const {
return task_runner_.get();
}
void Initialize(const gfx::Size& frame_size,
VideoCodecProfile codec_profile,
int start_bit_rate,
uint32 first_frame_id) {
DCHECK(task_runner_->RunsTasksOnCurrentThread());
requested_bit_rate_ = start_bit_rate;
encoder_active_ = video_encode_accelerator_->Initialize(
media::PIXEL_FORMAT_I420, frame_size, codec_profile, start_bit_rate,
this);
next_frame_id_ = first_frame_id;
codec_profile_ = codec_profile;
UMA_HISTOGRAM_BOOLEAN("Cast.Sender.VideoEncodeAcceleratorInitializeSuccess",
encoder_active_);
cast_environment_->PostTask(
CastEnvironment::MAIN,
FROM_HERE,
base::Bind(status_change_cb_,
encoder_active_ ? STATUS_INITIALIZED :
STATUS_CODEC_INIT_FAILED));
}
void SetBitRate(int bit_rate) {
DCHECK(task_runner_->RunsTasksOnCurrentThread());
requested_bit_rate_ = bit_rate;
video_encode_accelerator_->RequestEncodingParametersChange(bit_rate,
max_frame_rate_);
}
void EncodeVideoFrame(
const scoped_refptr<media::VideoFrame>& video_frame,
const base::TimeTicks& reference_time,
bool key_frame_requested,
const VideoEncoder::FrameEncodedCallback& frame_encoded_callback) {
DCHECK(task_runner_->RunsTasksOnCurrentThread());
if (!encoder_active_)
return;
in_progress_frame_encodes_.push_back(InProgressFrameEncode(
video_frame, reference_time, frame_encoded_callback,
requested_bit_rate_));
// BitstreamBufferReady will be called once the encoder is done.
video_encode_accelerator_->Encode(video_frame, key_frame_requested);
}
protected:
void NotifyError(VideoEncodeAccelerator::Error error) final {
DCHECK(task_runner_->RunsTasksOnCurrentThread());
DCHECK(error != VideoEncodeAccelerator::kInvalidArgumentError &&
error != VideoEncodeAccelerator::kIllegalStateError);
encoder_active_ = false;
cast_environment_->PostTask(
CastEnvironment::MAIN,
FROM_HERE,
base::Bind(status_change_cb_, STATUS_CODEC_RUNTIME_ERROR));
// TODO(miu): Force-flush all |in_progress_frame_encodes_| immediately so
// pending frames do not become stuck, freezing VideoSender.
}
// Called to allocate the input and output buffers.
void RequireBitstreamBuffers(unsigned int input_count,
const gfx::Size& input_coded_size,
size_t output_buffer_size) final {
DCHECK(task_runner_->RunsTasksOnCurrentThread());
// TODO(miu): Investigate why we are ignoring |input_count| (4) and instead
// using |kOutputBufferCount| (3) here.
for (size_t j = 0; j < kOutputBufferCount; ++j) {
create_video_encode_memory_cb_.Run(
output_buffer_size,
base::Bind(&VEAClientImpl::OnCreateSharedMemory, this));
}
}
// Encoder has encoded a frame and it's available in one of the output
// buffers. Package the result in a media::cast::EncodedFrame and post it
// to the Cast MAIN thread via the supplied callback.
void BitstreamBufferReady(int32 bitstream_buffer_id,
size_t payload_size,
bool key_frame) final {
DCHECK(task_runner_->RunsTasksOnCurrentThread());
if (bitstream_buffer_id < 0 ||
bitstream_buffer_id >= static_cast<int32>(output_buffers_.size())) {
NOTREACHED();
VLOG(1) << "BitstreamBufferReady(): invalid bitstream_buffer_id="
<< bitstream_buffer_id;
NotifyError(media::VideoEncodeAccelerator::kPlatformFailureError);
return;
}
base::SharedMemory* output_buffer = output_buffers_[bitstream_buffer_id];
if (payload_size > output_buffer->mapped_size()) {
NOTREACHED();
VLOG(1) << "BitstreamBufferReady(): invalid payload_size = "
<< payload_size;
NotifyError(media::VideoEncodeAccelerator::kPlatformFailureError);
return;
}
if (key_frame)
key_frame_encountered_ = true;
if (!key_frame_encountered_) {
// Do not send video until we have encountered the first key frame.
// Save the bitstream buffer in |stream_header_| to be sent later along
// with the first key frame.
//
// TODO(miu): Should |stream_header_| be an std::ostringstream for
// performance reasons?
stream_header_.append(static_cast<const char*>(output_buffer->memory()),
payload_size);
} else if (!in_progress_frame_encodes_.empty()) {
const InProgressFrameEncode& request = in_progress_frame_encodes_.front();
scoped_ptr<SenderEncodedFrame> encoded_frame(new SenderEncodedFrame());
encoded_frame->dependency = key_frame ? EncodedFrame::KEY :
EncodedFrame::DEPENDENT;
encoded_frame->frame_id = next_frame_id_++;
if (key_frame)
encoded_frame->referenced_frame_id = encoded_frame->frame_id;
else
encoded_frame->referenced_frame_id = encoded_frame->frame_id - 1;
encoded_frame->rtp_timestamp = TimeDeltaToRtpDelta(
request.video_frame->timestamp(), kVideoFrequency);
encoded_frame->reference_time = request.reference_time;
if (!stream_header_.empty()) {
encoded_frame->data = stream_header_;
stream_header_.clear();
}
encoded_frame->data.append(
static_cast<const char*>(output_buffer->memory()), payload_size);
// If FRAME_DURATION metadata was provided in the source VideoFrame,
// compute the utilization metrics.
base::TimeDelta frame_duration;
if (request.video_frame->metadata()->GetTimeDelta(
media::VideoFrameMetadata::FRAME_DURATION, &frame_duration) &&
frame_duration > base::TimeDelta()) {
// Compute deadline utilization as the real-world time elapsed divided
// by the frame duration.
const base::TimeDelta processing_time =
base::TimeTicks::Now() - request.start_time;
encoded_frame->deadline_utilization =
processing_time.InSecondsF() / frame_duration.InSecondsF();
const double actual_bit_rate =
encoded_frame->data.size() * 8.0 / frame_duration.InSecondsF();
DCHECK_GT(request.target_bit_rate, 0);
const double bitrate_utilization =
actual_bit_rate / request.target_bit_rate;
double quantizer = QuantizerEstimator::NO_RESULT;
// If the quantizer can be parsed from the key frame, try to parse
// the following delta frames as well.
// Otherwise, switch back to entropy estimation for the key frame
// and all the following delta frames.
if (key_frame || key_frame_quantizer_parsable_) {
if (codec_profile_ == media::VP8PROFILE_ANY) {
quantizer = ParseVp8HeaderQuantizer(
reinterpret_cast<const uint8*>(encoded_frame->data.data()),
encoded_frame->data.size());
} else if (codec_profile_ == media::H264PROFILE_MAIN) {
quantizer = GetH264FrameQuantizer(
reinterpret_cast<const uint8*>(encoded_frame->data.data()),
encoded_frame->data.size());
} else {
NOTIMPLEMENTED();
}
if (quantizer < 0) {
LOG(ERROR) << "Unable to parse quantizer from encoded "
<< (key_frame ? "key" : "delta")
<< " frame, id=" << encoded_frame->frame_id;
if (key_frame) {
key_frame_quantizer_parsable_ = false;
quantizer = quantizer_estimator_.EstimateForKeyFrame(
*request.video_frame);
}
} else {
if (key_frame) {
key_frame_quantizer_parsable_ = true;
}
}
} else {
quantizer =
quantizer_estimator_.EstimateForDeltaFrame(*request.video_frame);
}
if (quantizer >= 0) {
const double max_quantizer =
codec_profile_ == media::VP8PROFILE_ANY
? static_cast<int>(QuantizerEstimator::MAX_VP8_QUANTIZER)
: static_cast<int>(MAX_H264_QUANTIZER);
encoded_frame->lossy_utilization =
bitrate_utilization * (quantizer / max_quantizer);
}
} else {
quantizer_estimator_.Reset();
}
// TODO(miu): Determine when/why encoding can produce zero-length data,
// which causes crypto crashes. http://crbug.com/519022
if (!has_seen_zero_length_encoded_frame_ && encoded_frame->data.empty()) {
has_seen_zero_length_encoded_frame_ = true;
const char kZeroEncodeDetails[] = "zero-encode-details";
const std::string details = base::StringPrintf(
("%c/%c,id=%" PRIu32 ",rtp=%" PRIu32 ",br=%d,q=%" PRIuS
",act=%c,ref=%d"),
codec_profile_ == media::VP8PROFILE_ANY ? 'V' : 'H',
key_frame ? 'K' : 'D', encoded_frame->frame_id,
encoded_frame->rtp_timestamp, request.target_bit_rate / 1000,
in_progress_frame_encodes_.size(), encoder_active_ ? 'Y' : 'N',
static_cast<int>(encoded_frame->referenced_frame_id % 1000));
base::debug::SetCrashKeyValue(kZeroEncodeDetails, details);
// Please forward crash reports to http://crbug.com/519022:
base::debug::DumpWithoutCrashing();
base::debug::ClearCrashKey(kZeroEncodeDetails);
}
encoded_frame->encode_completion_time =
cast_environment_->Clock()->NowTicks();
cast_environment_->PostTask(
CastEnvironment::MAIN,
FROM_HERE,
base::Bind(request.frame_encoded_callback,
base::Passed(&encoded_frame)));
in_progress_frame_encodes_.pop_front();
} else {
VLOG(1) << "BitstreamBufferReady(): no encoded frame data available";
}
// We need to re-add the output buffer to the encoder after we are done
// with it.
video_encode_accelerator_->UseOutputBitstreamBuffer(media::BitstreamBuffer(
bitstream_buffer_id,
output_buffers_[bitstream_buffer_id]->handle(),
output_buffers_[bitstream_buffer_id]->mapped_size()));
}
private:
friend class base::RefCountedThreadSafe<VEAClientImpl>;
~VEAClientImpl() final {
// According to the media::VideoEncodeAccelerator interface, Destroy()
// should be called instead of invoking its private destructor.
task_runner_->PostTask(
FROM_HERE,
base::Bind(&media::VideoEncodeAccelerator::Destroy,
base::Unretained(video_encode_accelerator_.release())));
}
// Note: This method can be called on any thread.
void OnCreateSharedMemory(scoped_ptr<base::SharedMemory> memory) {
task_runner_->PostTask(FROM_HERE,
base::Bind(&VEAClientImpl::OnReceivedSharedMemory,
this,
base::Passed(&memory)));
}
void OnReceivedSharedMemory(scoped_ptr<base::SharedMemory> memory) {
DCHECK(task_runner_->RunsTasksOnCurrentThread());
output_buffers_.push_back(memory.Pass());
// Wait until all requested buffers are received.
if (output_buffers_.size() < kOutputBufferCount)
return;
// Immediately provide all output buffers to the VEA.
for (size_t i = 0; i < output_buffers_.size(); ++i) {
video_encode_accelerator_->UseOutputBitstreamBuffer(
media::BitstreamBuffer(static_cast<int32>(i),
output_buffers_[i]->handle(),
output_buffers_[i]->mapped_size()));
}
}
// Parse H264 SPS, PPS, and Slice header, and return the averaged frame
// quantizer in the range of [0, 51], or -1 on parse error.
double GetH264FrameQuantizer(const uint8* encoded_data, off_t size) {
DCHECK(encoded_data);
if (!size)
return -1;
h264_parser_.SetStream(encoded_data, size);
double total_quantizer = 0;
int num_slices = 0;
while (true) {
H264NALU nalu;
H264Parser::Result res = h264_parser_.AdvanceToNextNALU(&nalu);
if (res == H264Parser::kEOStream)
break;
if (res != H264Parser::kOk)
return -1;
switch (nalu.nal_unit_type) {
case H264NALU::kIDRSlice:
case H264NALU::kNonIDRSlice: {
H264SliceHeader slice_header;
if (h264_parser_.ParseSliceHeader(nalu, &slice_header) !=
H264Parser::kOk)
return -1;
const H264PPS* pps =
h264_parser_.GetPPS(slice_header.pic_parameter_set_id);
if (!pps)
return -1;
++num_slices;
int slice_quantizer =
26 +
((slice_header.IsSPSlice() || slice_header.IsSISlice())
? pps->pic_init_qs_minus26 + slice_header.slice_qs_delta
: pps->pic_init_qp_minus26 + slice_header.slice_qp_delta);
DCHECK_GE(slice_quantizer, 0);
DCHECK_LE(slice_quantizer, MAX_H264_QUANTIZER);
total_quantizer += slice_quantizer;
break;
}
case H264NALU::kSPS: {
int id;
if (h264_parser_.ParseSPS(&id) != H264Parser::kOk)
return -1;
break;
}
case H264NALU::kPPS: {
int id;
if (h264_parser_.ParsePPS(&id) != H264Parser::kOk)
return -1;
break;
}
default:
// Skip other NALUs.
break;
}
}
return (num_slices == 0) ? -1 : (total_quantizer / num_slices);
}
const scoped_refptr<CastEnvironment> cast_environment_;
const scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
const int max_frame_rate_;
const StatusChangeCallback status_change_cb_; // Must be run on MAIN thread.
const CreateVideoEncodeMemoryCallback create_video_encode_memory_cb_;
scoped_ptr<media::VideoEncodeAccelerator> video_encode_accelerator_;
bool encoder_active_;
uint32 next_frame_id_;
bool key_frame_encountered_;
std::string stream_header_;
VideoCodecProfile codec_profile_;
bool key_frame_quantizer_parsable_;
H264Parser h264_parser_;
// Shared memory buffers for output with the VideoAccelerator.
ScopedVector<base::SharedMemory> output_buffers_;
// FIFO list.
std::list<InProgressFrameEncode> in_progress_frame_encodes_;
// The requested encode bit rate for the next frame.
int requested_bit_rate_;
// Used to compute utilization metrics for each frame.
QuantizerEstimator quantizer_estimator_;
// Set to true once a frame with zero-length encoded data has been
// encountered.
// TODO(miu): Remove after discovering cause. http://crbug.com/519022
bool has_seen_zero_length_encoded_frame_;
DISALLOW_COPY_AND_ASSIGN(VEAClientImpl);
};
// static
bool ExternalVideoEncoder::IsSupported(const VideoSenderConfig& video_config) {
if (video_config.codec != CODEC_VIDEO_VP8 &&
video_config.codec != CODEC_VIDEO_H264)
return false;
// TODO(miu): "Layering hooks" are needed to be able to query outside of
// libmedia, to determine whether the system provides a hardware encoder. For
// now, assume that this was already checked by this point.
// http://crbug.com/454029
return video_config.use_external_encoder;
}
ExternalVideoEncoder::ExternalVideoEncoder(
const scoped_refptr<CastEnvironment>& cast_environment,
const VideoSenderConfig& video_config,
const gfx::Size& frame_size,
uint32 first_frame_id,
const StatusChangeCallback& status_change_cb,
const CreateVideoEncodeAcceleratorCallback& create_vea_cb,
const CreateVideoEncodeMemoryCallback& create_video_encode_memory_cb)
: cast_environment_(cast_environment),
create_video_encode_memory_cb_(create_video_encode_memory_cb),
frame_size_(frame_size),
bit_rate_(video_config.start_bitrate),
key_frame_requested_(false),
weak_factory_(this) {
DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
DCHECK_GT(video_config.max_frame_rate, 0);
DCHECK(!frame_size_.IsEmpty());
DCHECK(!status_change_cb.is_null());
DCHECK(!create_vea_cb.is_null());
DCHECK(!create_video_encode_memory_cb_.is_null());
DCHECK_GT(bit_rate_, 0);
create_vea_cb.Run(
base::Bind(&ExternalVideoEncoder::OnCreateVideoEncodeAccelerator,
weak_factory_.GetWeakPtr(),
video_config,
first_frame_id,
status_change_cb));
}
ExternalVideoEncoder::~ExternalVideoEncoder() {
}
bool ExternalVideoEncoder::EncodeVideoFrame(
const scoped_refptr<media::VideoFrame>& video_frame,
const base::TimeTicks& reference_time,
const FrameEncodedCallback& frame_encoded_callback) {
DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
DCHECK(!frame_encoded_callback.is_null());
if (!client_ || video_frame->visible_rect().size() != frame_size_)
return false;
client_->task_runner()->PostTask(FROM_HERE,
base::Bind(&VEAClientImpl::EncodeVideoFrame,
client_,
video_frame,
reference_time,
key_frame_requested_,
frame_encoded_callback));
key_frame_requested_ = false;
return true;
}
void ExternalVideoEncoder::SetBitRate(int new_bit_rate) {
DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
DCHECK_GT(new_bit_rate, 0);
bit_rate_ = new_bit_rate;
if (!client_)
return;
client_->task_runner()->PostTask(
FROM_HERE, base::Bind(&VEAClientImpl::SetBitRate, client_, bit_rate_));
}
void ExternalVideoEncoder::GenerateKeyFrame() {
DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
key_frame_requested_ = true;
}
void ExternalVideoEncoder::OnCreateVideoEncodeAccelerator(
const VideoSenderConfig& video_config,
uint32 first_frame_id,
const StatusChangeCallback& status_change_cb,
scoped_refptr<base::SingleThreadTaskRunner> encoder_task_runner,
scoped_ptr<media::VideoEncodeAccelerator> vea) {
DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
// The callback will be invoked with null pointers in the case where the
// system does not support or lacks the resources to provide GPU-accelerated
// video encoding.
if (!encoder_task_runner || !vea) {
cast_environment_->PostTask(
CastEnvironment::MAIN,
FROM_HERE,
base::Bind(status_change_cb, STATUS_CODEC_INIT_FAILED));
return;
}
VideoCodecProfile codec_profile;
switch (video_config.codec) {
case CODEC_VIDEO_VP8:
codec_profile = media::VP8PROFILE_ANY;
break;
case CODEC_VIDEO_H264:
codec_profile = media::H264PROFILE_MAIN;
break;
case CODEC_VIDEO_FAKE:
NOTREACHED() << "Fake software video encoder cannot be external";
// ...flow through to next case...
default:
cast_environment_->PostTask(
CastEnvironment::MAIN,
FROM_HERE,
base::Bind(status_change_cb, STATUS_UNSUPPORTED_CODEC));
return;
}
DCHECK(!client_);
client_ = new VEAClientImpl(cast_environment_,
encoder_task_runner,
vea.Pass(),
video_config.max_frame_rate,
status_change_cb,
create_video_encode_memory_cb_);
client_->task_runner()->PostTask(FROM_HERE,
base::Bind(&VEAClientImpl::Initialize,
client_,
frame_size_,
codec_profile,
bit_rate_,
first_frame_id));
}
SizeAdaptableExternalVideoEncoder::SizeAdaptableExternalVideoEncoder(
const scoped_refptr<CastEnvironment>& cast_environment,
const VideoSenderConfig& video_config,
const StatusChangeCallback& status_change_cb,
const CreateVideoEncodeAcceleratorCallback& create_vea_cb,
const CreateVideoEncodeMemoryCallback& create_video_encode_memory_cb)
: SizeAdaptableVideoEncoderBase(cast_environment,
video_config,
status_change_cb),
create_vea_cb_(create_vea_cb),
create_video_encode_memory_cb_(create_video_encode_memory_cb) {}
SizeAdaptableExternalVideoEncoder::~SizeAdaptableExternalVideoEncoder() {}
scoped_ptr<VideoEncoder> SizeAdaptableExternalVideoEncoder::CreateEncoder() {
return scoped_ptr<VideoEncoder>(new ExternalVideoEncoder(
cast_environment(),
video_config(),
frame_size(),
last_frame_id() + 1,
CreateEncoderStatusChangeCallback(),
create_vea_cb_,
create_video_encode_memory_cb_));
}
QuantizerEstimator::QuantizerEstimator() {}
QuantizerEstimator::~QuantizerEstimator() {}
void QuantizerEstimator::Reset() {
last_frame_pixel_buffer_.reset();
}
double QuantizerEstimator::EstimateForKeyFrame(const VideoFrame& frame) {
if (!CanExamineFrame(frame))
return NO_RESULT;
// If the size of the frame is different from the last frame, allocate a new
// buffer. The buffer only needs to be a fraction of the size of the entire
// frame, since the entropy analysis only examines a subset of each frame.
const gfx::Size size = frame.visible_rect().size();
const int rows_in_subset =
std::max(1, size.height() * FRAME_SAMPLING_PERCENT / 100);
if (last_frame_size_ != size || !last_frame_pixel_buffer_) {
last_frame_pixel_buffer_.reset(new uint8[size.width() * rows_in_subset]);
last_frame_size_ = size;
}
// Compute a histogram where each bucket represents the number of times two
// neighboring pixels were different by a specific amount. 511 buckets are
// needed, one for each integer in the range [-255,255].
int histogram[511];
memset(histogram, 0, sizeof(histogram));
const int row_skip = size.height() / rows_in_subset;
int y = 0;
for (int i = 0; i < rows_in_subset; ++i, y += row_skip) {
const uint8* const row_begin = frame.visible_data(VideoFrame::kYPlane) +
y * frame.stride(VideoFrame::kYPlane);
const uint8* const row_end = row_begin + size.width();
int left_hand_pixel_value = static_cast<int>(*row_begin);
for (const uint8* p = row_begin + 1; p < row_end; ++p) {
const int right_hand_pixel_value = static_cast<int>(*p);
const int difference = right_hand_pixel_value - left_hand_pixel_value;
const int histogram_index = difference + 255;
++histogram[histogram_index];
left_hand_pixel_value = right_hand_pixel_value; // For next iteration.
}
// Copy the row of pixels into the buffer. This will be used when
// generating histograms for future delta frames.
memcpy(last_frame_pixel_buffer_.get() + i * size.width(),
row_begin,
size.width());
}
// Estimate a quantizer value depending on the difference data in the
// histogram and return it.
const int num_samples = (size.width() - 1) * rows_in_subset;
return ToQuantizerEstimate(ComputeEntropyFromHistogram(
histogram, arraysize(histogram), num_samples));
}
double QuantizerEstimator::EstimateForDeltaFrame(const VideoFrame& frame) {
if (!CanExamineFrame(frame))
return NO_RESULT;
// If the size of the |frame| has changed, no difference can be examined.
// In this case, process this frame as if it were a key frame.
const gfx::Size size = frame.visible_rect().size();
if (last_frame_size_ != size || !last_frame_pixel_buffer_)
return EstimateForKeyFrame(frame);
const int rows_in_subset =
std::max(1, size.height() * FRAME_SAMPLING_PERCENT / 100);
// Compute a histogram where each bucket represents the number of times the
// same pixel in this frame versus the last frame was different by a specific
// amount. 511 buckets are needed, one for each integer in the range
// [-255,255].
int histogram[511];
memset(histogram, 0, sizeof(histogram));
const int row_skip = size.height() / rows_in_subset;
int y = 0;
for (int i = 0; i < rows_in_subset; ++i, y += row_skip) {
const uint8* const row_begin = frame.visible_data(VideoFrame::kYPlane) +
y * frame.stride(VideoFrame::kYPlane);
const uint8* const row_end = row_begin + size.width();
uint8* const last_frame_row_begin =
last_frame_pixel_buffer_.get() + i * size.width();
for (const uint8* p = row_begin, *q = last_frame_row_begin; p < row_end;
++p, ++q) {
const int difference = static_cast<int>(*p) - static_cast<int>(*q);
const int histogram_index = difference + 255;
++histogram[histogram_index];
}
// Copy the row of pixels into the buffer. This will be used when
// generating histograms for future delta frames.
memcpy(last_frame_row_begin, row_begin, size.width());
}
// Estimate a quantizer value depending on the difference data in the
// histogram and return it.
const int num_samples = size.width() * rows_in_subset;
return ToQuantizerEstimate(ComputeEntropyFromHistogram(
histogram, arraysize(histogram), num_samples));
}
// static
bool QuantizerEstimator::CanExamineFrame(const VideoFrame& frame) {
DCHECK_EQ(8, VideoFrame::PlaneHorizontalBitsPerPixel(frame.format(),
VideoFrame::kYPlane));
return media::IsYuvPlanar(frame.format()) &&
!frame.visible_rect().IsEmpty();
}
// static
double QuantizerEstimator::ComputeEntropyFromHistogram(const int* histogram,
size_t num_buckets,
int num_samples) {
#if defined(OS_ANDROID)
// Android does not currently provide a log2() function in their C++ standard
// library. This is a substitute.
const auto log2 = [](double num) -> double {
return log(num) / 0.69314718055994528622676398299518041312694549560546875;
};
#endif
DCHECK_LT(0, num_samples);
double entropy = 0.0;
for (size_t i = 0; i < num_buckets; ++i) {
const double probability = static_cast<double>(histogram[i]) / num_samples;
if (probability > 0.0)
entropy = entropy - probability * log2(probability);
}
return entropy;
}
// static
double QuantizerEstimator::ToQuantizerEstimate(double shannon_entropy) {
DCHECK_GE(shannon_entropy, 0.0);
// This math is based on an analysis of data produced by running a wide range
// of mirroring content in a Cast streaming session on a Chromebook Pixel
// (2013 edition). The output from the Pixel's built-in hardware encoder was
// compared to an identically-configured software implementation (libvpx)
// running alongside. Based on an analysis of the data, the following linear
// mapping seems to produce reasonable VP8 quantizer values from the
// |shannon_entropy| values.
//
// TODO(miu): Confirm whether this model and value work well on other
// platforms.
const double kEntropyAtMaxQuantizer = 7.5;
const double slope =
(MAX_VP8_QUANTIZER - MIN_VP8_QUANTIZER) / kEntropyAtMaxQuantizer;
const double quantizer = std::min<double>(
MAX_VP8_QUANTIZER, MIN_VP8_QUANTIZER + slope * shannon_entropy);
return quantizer;
}
} // namespace cast
} // namespace media
|