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shaka-packager/media/mp4/track_run_iterator.cc

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// 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/track_run_iterator.h"
#include <algorithm>
#include "media/base/buffer_reader.h"
#include "media/mp4/chunk_info_iterator.h"
#include "media/mp4/composition_offset_iterator.h"
#include "media/mp4/decoding_time_iterator.h"
#include "media/mp4/rcheck.h"
#include "media/mp4/sync_sample_iterator.h"
namespace media {
namespace mp4 {
struct SampleInfo {
int size;
int duration;
int cts_offset;
bool is_keyframe;
};
struct TrackRunInfo {
uint32 track_id;
std::vector<SampleInfo> samples;
int64 timescale;
int64 start_dts;
int64 sample_start_offset;
bool is_audio;
const AudioSampleEntry* audio_description;
const VideoSampleEntry* video_description;
int64 aux_info_start_offset; // Only valid if aux_info_total_size > 0.
int aux_info_default_size;
std::vector<uint8> aux_info_sizes; // Populated if default_size == 0.
int aux_info_total_size;
TrackRunInfo();
~TrackRunInfo();
};
TrackRunInfo::TrackRunInfo()
: track_id(0),
timescale(-1),
start_dts(-1),
sample_start_offset(-1),
is_audio(false),
aux_info_start_offset(-1),
aux_info_default_size(0),
aux_info_total_size(0) {}
TrackRunInfo::~TrackRunInfo() {}
TrackRunIterator::TrackRunIterator(const Movie* moov)
: moov_(moov), sample_dts_(0), sample_offset_(0) {
CHECK(moov);
}
TrackRunIterator::~TrackRunIterator() {}
static void PopulateSampleInfo(const TrackExtends& trex,
const TrackFragmentHeader& tfhd,
const TrackFragmentRun& trun,
const uint32 i,
SampleInfo* sample_info) {
if (i < trun.sample_sizes.size()) {
sample_info->size = trun.sample_sizes[i];
} else if (tfhd.default_sample_size > 0) {
sample_info->size = tfhd.default_sample_size;
} else {
sample_info->size = trex.default_sample_size;
}
if (i < trun.sample_durations.size()) {
sample_info->duration = trun.sample_durations[i];
} else if (tfhd.default_sample_duration > 0) {
sample_info->duration = tfhd.default_sample_duration;
} else {
sample_info->duration = trex.default_sample_duration;
}
if (i < trun.sample_composition_time_offsets.size()) {
sample_info->cts_offset = trun.sample_composition_time_offsets[i];
} else {
sample_info->cts_offset = 0;
}
uint32 flags;
if (i < trun.sample_flags.size()) {
flags = trun.sample_flags[i];
} else if (tfhd.flags & TrackFragmentHeader::kDefaultSampleFlagsPresentMask) {
flags = tfhd.default_sample_flags;
} else {
flags = trex.default_sample_flags;
}
sample_info->is_keyframe = !(flags & TrackFragmentHeader::kNonKeySampleMask);
}
// In well-structured encrypted media, each track run will be immediately
// preceded by its auxiliary information; this is the only optimal storage
// pattern in terms of minimum number of bytes from a serial stream needed to
// begin playback. It also allows us to optimize caching on memory-constrained
// architectures, because we can cache the relatively small auxiliary
// information for an entire run and then discard data from the input stream,
// instead of retaining the entire 'mdat' box.
//
// We optimize for this situation (with no loss of generality) by sorting track
// runs during iteration in order of their first data offset (either sample data
// or auxiliary data).
class CompareMinTrackRunDataOffset {
public:
bool operator()(const TrackRunInfo& a, const TrackRunInfo& b) {
int64 a_aux = a.aux_info_total_size ? a.aux_info_start_offset : kint64max;
int64 b_aux = b.aux_info_total_size ? b.aux_info_start_offset : kint64max;
int64 a_lesser = std::min(a_aux, a.sample_start_offset);
int64 a_greater = std::max(a_aux, a.sample_start_offset);
int64 b_lesser = std::min(b_aux, b.sample_start_offset);
int64 b_greater = std::max(b_aux, b.sample_start_offset);
if (a_lesser == b_lesser)
return a_greater < b_greater;
return a_lesser < b_lesser;
}
};
bool TrackRunIterator::Init() {
runs_.clear();
for (std::vector<Track>::const_iterator trak = moov_->tracks.begin();
trak != moov_->tracks.end(); ++trak) {
const SampleDescription& stsd =
trak->media.information.sample_table.description;
if (stsd.type != kAudio && stsd.type != kVideo) {
DVLOG(1) << "Skipping unhandled track type";
continue;
}
// Edit list is ignored.
// We may consider supporting the single edit with a nonnegative media time
// if it is required. Just need to pass the media_time to Muxer and
// generate the edit list.
const std::vector<EditListEntry>& edits = trak->edit.list.edits;
if (!edits.empty()) {
if (edits.size() > 1)
DVLOG(1) << "Multi-entry edit box detected.";
LOG(INFO) << "Edit list with media time " << edits[0].media_time
<< " ignored.";
}
DecodingTimeIterator decoding_time(
trak->media.information.sample_table.decoding_time_to_sample);
CompositionOffsetIterator composition_offset(
trak->media.information.sample_table.composition_time_to_sample);
bool has_composition_offset = composition_offset.IsValid();
ChunkInfoIterator chunk_info(
trak->media.information.sample_table.sample_to_chunk);
SyncSampleIterator sync_sample(
trak->media.information.sample_table.sync_sample);
// Skip processing saiz and saio boxes for non-fragmented mp4 as we
// don't support encrypted non-fragmented mp4.
const SampleSize& sample_size =
trak->media.information.sample_table.sample_size;
const std::vector<uint64>& chunk_offset_vector =
trak->media.information.sample_table.chunk_large_offset.offsets;
int64 run_start_dts = 0;
int64 run_data_offset = 0;
uint32 num_samples = sample_size.sample_count;
uint32 num_chunks = chunk_offset_vector.size();
// Check that total number of samples match.
DCHECK_EQ(num_samples, decoding_time.NumSamples());
if (has_composition_offset)
DCHECK_EQ(num_samples, composition_offset.NumSamples());
if (num_chunks > 0)
DCHECK_EQ(num_samples, chunk_info.NumSamples(1, num_chunks));
DCHECK_GE(num_chunks, chunk_info.LastFirstChunk());
if (num_samples > 0) {
// Verify relevant tables are not empty.
RCHECK(decoding_time.IsValid());
RCHECK(chunk_info.IsValid());
}
uint32 sample_index = 0;
for (uint32 chunk_index = 0; chunk_index < num_chunks; ++chunk_index) {
RCHECK(chunk_info.current_chunk() == chunk_index + 1);
TrackRunInfo tri;
tri.track_id = trak->header.track_id;
tri.timescale = trak->media.header.timescale;
tri.start_dts = run_start_dts;
tri.sample_start_offset = chunk_offset_vector[chunk_index];
uint32 desc_idx = chunk_info.sample_description_index();
RCHECK(desc_idx > 0); // Descriptions are one-indexed in the file.
desc_idx -= 1;
tri.is_audio = (stsd.type == kAudio);
if (tri.is_audio) {
RCHECK(!stsd.audio_entries.empty());
if (desc_idx > stsd.audio_entries.size())
desc_idx = 0;
tri.audio_description = &stsd.audio_entries[desc_idx];
// We don't support encrypted non-fragmented mp4 for now.
RCHECK(!tri.audio_description->sinf.info.track_encryption.is_encrypted);
} else {
RCHECK(!stsd.video_entries.empty());
if (desc_idx > stsd.video_entries.size())
desc_idx = 0;
tri.video_description = &stsd.video_entries[desc_idx];
// We don't support encrypted non-fragmented mp4 for now.
RCHECK(!tri.video_description->sinf.info.track_encryption.is_encrypted);
}
uint32 samples_per_chunk = chunk_info.samples_per_chunk();
tri.samples.resize(samples_per_chunk);
for (uint32 k = 0; k < samples_per_chunk; ++k) {
SampleInfo& sample = tri.samples[k];
sample.size = sample_size.sample_size != 0
? sample_size.sample_size
: sample_size.sizes[sample_index];
sample.duration = decoding_time.sample_delta();
sample.cts_offset =
has_composition_offset ? composition_offset.sample_offset() : 0;
sample.is_keyframe = sync_sample.IsSyncSample();
run_start_dts += sample.duration;
// Advance to next sample. Should success except for last sample.
++sample_index;
RCHECK(chunk_info.AdvanceSample() && sync_sample.AdvanceSample());
if (sample_index == num_samples) {
// We should hit end of tables for decoding time and composition
// offset.
RCHECK(!decoding_time.AdvanceSample());
if (has_composition_offset)
RCHECK(!composition_offset.AdvanceSample());
} else {
RCHECK(decoding_time.AdvanceSample());
if (has_composition_offset)
RCHECK(composition_offset.AdvanceSample());
}
}
runs_.push_back(tri);
}
}
std::sort(runs_.begin(), runs_.end(), CompareMinTrackRunDataOffset());
run_itr_ = runs_.begin();
ResetRun();
return true;
}
bool TrackRunIterator::Init(const MovieFragment& moof) {
runs_.clear();
for (size_t i = 0; i < moof.tracks.size(); i++) {
const TrackFragment& traf = moof.tracks[i];
const Track* trak = NULL;
for (size_t t = 0; t < moov_->tracks.size(); t++) {
if (moov_->tracks[t].header.track_id == traf.header.track_id)
trak = &moov_->tracks[t];
}
RCHECK(trak);
const TrackExtends* trex = NULL;
for (size_t t = 0; t < moov_->extends.tracks.size(); t++) {
if (moov_->extends.tracks[t].track_id == traf.header.track_id)
trex = &moov_->extends.tracks[t];
}
RCHECK(trex);
const SampleDescription& stsd =
trak->media.information.sample_table.description;
if (stsd.type != kAudio && stsd.type != kVideo) {
DVLOG(1) << "Skipping unhandled track type";
continue;
}
size_t desc_idx = traf.header.sample_description_index;
if (!desc_idx)
desc_idx = trex->default_sample_description_index;
RCHECK(desc_idx > 0); // Descriptions are one-indexed in the file
desc_idx -= 1;
int64 run_start_dts = traf.decode_time.decode_time;
int sample_count_sum = 0;
for (size_t j = 0; j < traf.runs.size(); j++) {
const TrackFragmentRun& trun = traf.runs[j];
TrackRunInfo tri;
tri.track_id = traf.header.track_id;
tri.timescale = trak->media.header.timescale;
tri.start_dts = run_start_dts;
tri.sample_start_offset = trun.data_offset;
tri.is_audio = (stsd.type == kAudio);
if (tri.is_audio) {
RCHECK(!stsd.audio_entries.empty());
if (desc_idx > stsd.audio_entries.size())
desc_idx = 0;
tri.audio_description = &stsd.audio_entries[desc_idx];
} else {
RCHECK(!stsd.video_entries.empty());
if (desc_idx > stsd.video_entries.size())
desc_idx = 0;
tri.video_description = &stsd.video_entries[desc_idx];
}
// Collect information from the auxiliary_offset entry with the same index
// in the 'saiz' container as the current run's index in the 'trun'
// container, if it is present.
if (traf.auxiliary_offset.offsets.size() > j) {
// There should be an auxiliary info entry corresponding to each sample
// in the auxiliary offset entry's corresponding track run.
RCHECK(traf.auxiliary_size.sample_count >=
sample_count_sum + trun.sample_count);
tri.aux_info_start_offset = traf.auxiliary_offset.offsets[j];
tri.aux_info_default_size =
traf.auxiliary_size.default_sample_info_size;
if (tri.aux_info_default_size == 0) {
const std::vector<uint8>& sizes =
traf.auxiliary_size.sample_info_sizes;
tri.aux_info_sizes.insert(
tri.aux_info_sizes.begin(),
sizes.begin() + sample_count_sum,
sizes.begin() + sample_count_sum + trun.sample_count);
}
// If the default info size is positive, find the total size of the aux
// info block from it, otherwise sum over the individual sizes of each
// aux info entry in the aux_offset entry.
if (tri.aux_info_default_size) {
tri.aux_info_total_size =
tri.aux_info_default_size * trun.sample_count;
} else {
tri.aux_info_total_size = 0;
for (size_t k = 0; k < trun.sample_count; k++) {
tri.aux_info_total_size += tri.aux_info_sizes[k];
}
}
} else {
tri.aux_info_start_offset = -1;
tri.aux_info_total_size = 0;
}
tri.samples.resize(trun.sample_count);
for (size_t k = 0; k < trun.sample_count; k++) {
PopulateSampleInfo(*trex, traf.header, trun, k, &tri.samples[k]);
run_start_dts += tri.samples[k].duration;
}
runs_.push_back(tri);
sample_count_sum += trun.sample_count;
}
}
std::sort(runs_.begin(), runs_.end(), CompareMinTrackRunDataOffset());
run_itr_ = runs_.begin();
ResetRun();
return true;
}
void TrackRunIterator::AdvanceRun() {
++run_itr_;
ResetRun();
}
void TrackRunIterator::ResetRun() {
if (!IsRunValid())
return;
sample_dts_ = run_itr_->start_dts;
sample_offset_ = run_itr_->sample_start_offset;
sample_itr_ = run_itr_->samples.begin();
cenc_info_.clear();
}
void TrackRunIterator::AdvanceSample() {
DCHECK(IsSampleValid());
sample_dts_ += sample_itr_->duration;
sample_offset_ += sample_itr_->size;
++sample_itr_;
}
// This implementation only indicates a need for caching if CENC auxiliary
// info is available in the stream.
bool TrackRunIterator::AuxInfoNeedsToBeCached() {
DCHECK(IsRunValid());
return is_encrypted() && aux_info_size() > 0 && cenc_info_.size() == 0;
}
// TODO(kqyang): Revisit later. We might not need to cache cenc info.
// This implementation currently only caches CENC auxiliary info.
bool TrackRunIterator::CacheAuxInfo(const uint8* buf, int buf_size) {
RCHECK(AuxInfoNeedsToBeCached() && buf_size >= aux_info_size());
cenc_info_.resize(run_itr_->samples.size());
int64 pos = 0;
for (size_t i = 0; i < run_itr_->samples.size(); i++) {
int info_size = run_itr_->aux_info_default_size;
if (!info_size)
info_size = run_itr_->aux_info_sizes[i];
BufferReader reader(buf + pos, info_size);
RCHECK(cenc_info_[i].Parse(track_encryption().default_iv_size, &reader));
pos += info_size;
}
return true;
}
bool TrackRunIterator::IsRunValid() const { return run_itr_ != runs_.end(); }
bool TrackRunIterator::IsSampleValid() const {
return IsRunValid() && (sample_itr_ != run_itr_->samples.end());
}
// Because tracks are in sorted order and auxiliary information is cached when
// returning samples, it is guaranteed that no data will be required before the
// lesser of the minimum data offset of this track and the next in sequence.
// (The stronger condition - that no data is required before the minimum data
// offset of this track alone - is not guaranteed, because the BMFF spec does
// not have any inter-run ordering restrictions.)
int64 TrackRunIterator::GetMaxClearOffset() {
int64 offset = kint64max;
if (IsSampleValid()) {
offset = std::min(offset, sample_offset_);
if (AuxInfoNeedsToBeCached())
offset = std::min(offset, aux_info_offset());
}
if (run_itr_ != runs_.end()) {
std::vector<TrackRunInfo>::const_iterator next_run = run_itr_ + 1;
if (next_run != runs_.end()) {
offset = std::min(offset, next_run->sample_start_offset);
if (next_run->aux_info_total_size)
offset = std::min(offset, next_run->aux_info_start_offset);
}
}
if (offset == kint64max)
return 0;
return offset;
}
uint32 TrackRunIterator::track_id() const {
DCHECK(IsRunValid());
return run_itr_->track_id;
}
bool TrackRunIterator::is_encrypted() const {
DCHECK(IsRunValid());
return track_encryption().is_encrypted;
}
int64 TrackRunIterator::aux_info_offset() const {
return run_itr_->aux_info_start_offset;
}
int TrackRunIterator::aux_info_size() const {
return run_itr_->aux_info_total_size;
}
bool TrackRunIterator::is_audio() const {
DCHECK(IsRunValid());
return run_itr_->is_audio;
}
const AudioSampleEntry& TrackRunIterator::audio_description() const {
DCHECK(is_audio());
DCHECK(run_itr_->audio_description);
return *run_itr_->audio_description;
}
const VideoSampleEntry& TrackRunIterator::video_description() const {
DCHECK(!is_audio());
DCHECK(run_itr_->video_description);
return *run_itr_->video_description;
}
int64 TrackRunIterator::sample_offset() const {
DCHECK(IsSampleValid());
return sample_offset_;
}
int TrackRunIterator::sample_size() const {
DCHECK(IsSampleValid());
return sample_itr_->size;
}
int64 TrackRunIterator::dts() const {
DCHECK(IsSampleValid());
return sample_dts_;
}
int64 TrackRunIterator::cts() const {
DCHECK(IsSampleValid());
return sample_dts_ + sample_itr_->cts_offset;
}
int64 TrackRunIterator::duration() const {
DCHECK(IsSampleValid());
return sample_itr_->duration;
}
bool TrackRunIterator::is_keyframe() const {
DCHECK(IsSampleValid());
return sample_itr_->is_keyframe;
}
const TrackEncryption& TrackRunIterator::track_encryption() const {
if (is_audio())
return audio_description().sinf.info.track_encryption;
return video_description().sinf.info.track_encryption;
}
scoped_ptr<DecryptConfig> TrackRunIterator::GetDecryptConfig() {
size_t sample_idx = sample_itr_ - run_itr_->samples.begin();
DCHECK(sample_idx < cenc_info_.size());
const FrameCENCInfo& cenc_info = cenc_info_[sample_idx];
DCHECK(is_encrypted() && !AuxInfoNeedsToBeCached());
const size_t total_size_of_subsamples = cenc_info.GetTotalSizeOfSubsamples();
if (total_size_of_subsamples != 0 &&
total_size_of_subsamples != static_cast<size_t>(sample_size())) {
LOG(ERROR) << "Incorrect CENC subsample size.";
return scoped_ptr<DecryptConfig>();
}
const std::vector<uint8>& kid = track_encryption().default_kid;
return scoped_ptr<DecryptConfig>(new DecryptConfig(
std::string(reinterpret_cast<const char*>(&kid[0]), kid.size()),
std::string(cenc_info.iv().begin(), cenc_info.iv().end()),
0, // No offset to start of media data in MP4 using CENC.
cenc_info.subsamples()));
}
} // namespace mp4
} // namespace media
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