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shaka-packager/packager/media/formats/mp4/mp4_media_parser.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 "packager/media/formats/mp4/mp4_media_parser.h"
#include <limits>
#include "packager/base/callback.h"
#include "packager/base/callback_helpers.h"
#include "packager/base/logging.h"
#include "packager/base/memory/ref_counted.h"
#include "packager/base/strings/string_number_conversions.h"
#include "packager/media/base/aes_encryptor.h"
#include "packager/media/base/audio_stream_info.h"
#include "packager/media/base/buffer_reader.h"
#include "packager/media/base/decrypt_config.h"
#include "packager/media/base/key_source.h"
#include "packager/media/base/media_sample.h"
#include "packager/media/base/video_stream_info.h"
#include "packager/media/file/file.h"
#include "packager/media/file/file_closer.h"
#include "packager/media/formats/mp4/box_definitions.h"
#include "packager/media/formats/mp4/box_reader.h"
#include "packager/media/formats/mp4/es_descriptor.h"
#include "packager/media/formats/mp4/rcheck.h"
#include "packager/media/formats/mp4/track_run_iterator.h"
namespace {
uint64_t Rescale(uint64_t time_in_old_scale,
uint32_t old_scale,
uint32_t new_scale) {
return (static_cast<double>(time_in_old_scale) / old_scale) * new_scale;
}
const char kWidevineKeySystemId[] = "edef8ba979d64acea3c827dcd51d21ed";
} // namespace
namespace edash_packager {
namespace media {
namespace mp4 {
MP4MediaParser::MP4MediaParser()
: state_(kWaitingForInit), moof_head_(0), mdat_tail_(0) {}
MP4MediaParser::~MP4MediaParser() {
STLDeleteValues(&decryptor_map_);
}
void MP4MediaParser::Init(const InitCB& init_cb,
const NewSampleCB& new_sample_cb,
KeySource* decryption_key_source) {
DCHECK_EQ(state_, kWaitingForInit);
DCHECK(init_cb_.is_null());
DCHECK(!init_cb.is_null());
DCHECK(!new_sample_cb.is_null());
ChangeState(kParsingBoxes);
init_cb_ = init_cb;
new_sample_cb_ = new_sample_cb;
decryption_key_source_ = decryption_key_source;
}
void MP4MediaParser::Reset() {
queue_.Reset();
runs_.reset();
moof_head_ = 0;
mdat_tail_ = 0;
}
void MP4MediaParser::Flush() {
DCHECK_NE(state_, kWaitingForInit);
Reset();
ChangeState(kParsingBoxes);
}
bool MP4MediaParser::Parse(const uint8_t* buf, int size) {
DCHECK_NE(state_, kWaitingForInit);
if (state_ == kError)
return false;
queue_.Push(buf, size);
bool result, err = false;
do {
if (state_ == kParsingBoxes) {
result = ParseBox(&err);
} else {
DCHECK_EQ(kEmittingSamples, state_);
result = EnqueueSample(&err);
if (result) {
int64_t max_clear = runs_->GetMaxClearOffset() + moof_head_;
err = !ReadAndDiscardMDATsUntil(max_clear);
}
}
} while (result && !err);
if (err) {
DLOG(ERROR) << "Error while parsing MP4";
moov_.reset();
Reset();
ChangeState(kError);
return false;
}
return true;
}
bool MP4MediaParser::LoadMoov(const std::string& file_path) {
scoped_ptr<File, FileCloser> file(
File::OpenWithNoBuffering(file_path.c_str(), "r"));
if (!file) {
LOG(ERROR) << "Unable to open media file '" << file_path << "'";
return false;
}
if (!file->Seek(0)) {
LOG(WARNING) << "Filesystem does not support seeking on file '" << file_path
<< "'";
return false;
}
uint64_t file_position(0);
bool mdat_seen(false);
while (true) {
const uint32_t kBoxHeaderReadSize(16);
std::vector<uint8_t> buffer(kBoxHeaderReadSize);
int64_t bytes_read = file->Read(&buffer[0], kBoxHeaderReadSize);
if (bytes_read == 0) {
LOG(ERROR) << "Could not find 'moov' box in file '" << file_path << "'";
return false;
}
if (bytes_read < kBoxHeaderReadSize) {
LOG(ERROR) << "Error reading media file '" << file_path << "'";
return false;
}
uint64_t box_size;
FourCC box_type;
bool err;
if (!BoxReader::StartTopLevelBox(&buffer[0], kBoxHeaderReadSize, &box_type,
&box_size, &err)) {
LOG(ERROR) << "Could not start top level box from file '" << file_path
<< "'";
return false;
}
if (box_type == FOURCC_MDAT) {
mdat_seen = true;
} else if (box_type == FOURCC_MOOV) {
if (!mdat_seen) {
// 'moov' is before 'mdat'. Nothing to do.
break;
}
// 'mdat' before 'moov'. Read and parse 'moov'.
if (!Parse(&buffer[0], bytes_read)) {
LOG(ERROR) << "Error parsing mp4 file '" << file_path << "'";
return false;
}
uint64_t bytes_to_read = box_size - bytes_read;
buffer.resize(bytes_to_read);
while (bytes_to_read > 0) {
bytes_read = file->Read(&buffer[0], bytes_to_read);
if (bytes_read <= 0) {
LOG(ERROR) << "Error reading 'moov' contents from file '" << file_path
<< "'";
return false;
}
if (!Parse(&buffer[0], bytes_read)) {
LOG(ERROR) << "Error parsing mp4 file '" << file_path << "'";
return false;
}
bytes_to_read -= bytes_read;
}
queue_.Reset(); // So that we don't need to adjust data offsets.
mdat_tail_ = 0; // So it will skip boxes until mdat.
break; // Done.
}
file_position += box_size;
if (!file->Seek(file_position)) {
LOG(ERROR) << "Error skipping box in mp4 file '" << file_path << "'";
return false;
}
}
return true;
}
bool MP4MediaParser::ParseBox(bool* err) {
const uint8_t* buf;
int size;
queue_.Peek(&buf, &size);
if (!size)
return false;
scoped_ptr<BoxReader> reader(BoxReader::ReadTopLevelBox(buf, size, err));
if (reader.get() == NULL)
return false;
if (reader->type() == FOURCC_MDAT) {
// The code ends up here only if a MOOV box is not yet seen.
DCHECK(!moov_);
NOTIMPLEMENTED() << " Files with MDAT before MOOV is not supported yet.";
*err = true;
return false;
}
// Set up mdat offset for ReadMDATsUntil().
mdat_tail_ = queue_.head() + reader->size();
if (reader->type() == FOURCC_MOOV) {
*err = !ParseMoov(reader.get());
} else if (reader->type() == FOURCC_MOOF) {
moof_head_ = queue_.head();
*err = !ParseMoof(reader.get());
// Return early to avoid evicting 'moof' data from queue. Auxiliary info may
// be located anywhere in the file, including inside the 'moof' itself.
// (Since 'default-base-is-moof' is mandated, no data references can come
// before the head of the 'moof', so keeping this box around is sufficient.)
return !(*err);
} else {
VLOG(2) << "Skipping top-level box: " << FourCCToString(reader->type());
}
queue_.Pop(reader->size());
return !(*err);
}
bool MP4MediaParser::ParseMoov(BoxReader* reader) {
if (moov_)
return true; // Already parsed the 'moov' box.
moov_.reset(new Movie);
RCHECK(moov_->Parse(reader));
runs_.reset();
std::vector<scoped_refptr<StreamInfo> > streams;
for (std::vector<Track>::const_iterator track = moov_->tracks.begin();
track != moov_->tracks.end(); ++track) {
const uint32_t timescale = track->media.header.timescale;
// Calculate duration (based on timescale).
uint64_t duration = 0;
if (track->media.header.duration > 0) {
duration = track->media.header.duration;
} else if (moov_->extends.header.fragment_duration > 0) {
DCHECK(moov_->header.timescale != 0);
duration = Rescale(moov_->extends.header.fragment_duration,
moov_->header.timescale,
timescale);
} else if (moov_->header.duration > 0 &&
moov_->header.duration != std::numeric_limits<uint64_t>::max()) {
DCHECK(moov_->header.timescale != 0);
duration =
Rescale(moov_->header.duration, moov_->header.timescale, timescale);
}
const SampleDescription& samp_descr =
track->media.information.sample_table.description;
size_t desc_idx = 0;
// Read sample description index from mvex if it exists otherwise read
// from the first entry in Sample To Chunk box.
if (moov_->extends.tracks.size() > 0) {
for (size_t t = 0; t < moov_->extends.tracks.size(); t++) {
const TrackExtends& trex = moov_->extends.tracks[t];
if (trex.track_id == track->header.track_id) {
desc_idx = trex.default_sample_description_index;
break;
}
}
} else {
const std::vector<ChunkInfo>& chunk_info =
track->media.information.sample_table.sample_to_chunk.chunk_info;
RCHECK(chunk_info.size() > 0);
desc_idx = chunk_info[0].sample_description_index;
}
RCHECK(desc_idx > 0);
desc_idx -= 1; // BMFF descriptor index is one-based
if (track->media.handler.type == kAudio) {
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 (desc_idx >= samp_descr.audio_entries.size())
desc_idx = 0;
const AudioSampleEntry& entry = samp_descr.audio_entries[desc_idx];
if (!(entry.format == FOURCC_MP4A || entry.format == FOURCC_EAC3 ||
(entry.format == FOURCC_ENCA &&
entry.sinf.format.format == FOURCC_MP4A))) {
LOG(ERROR) << "Unsupported audio format 0x"
<< std::hex << entry.format << " in stsd box.";
return false;
}
ObjectType audio_type = entry.esds.es_descriptor.object_type();
DVLOG(1) << "audio_type " << std::hex << audio_type;
if (audio_type == kForbidden && entry.format == FOURCC_EAC3) {
audio_type = kEAC3;
}
AudioCodec codec = kUnknownAudioCodec;
uint8_t num_channels = 0;
uint32_t sampling_frequency = 0;
uint8_t audio_object_type = 0;
std::vector<uint8_t> extra_data;
// Check if it is MPEG4 AAC defined in ISO 14496 Part 3 or
// supported MPEG2 AAC variants.
if (entry.esds.es_descriptor.IsAAC()) {
codec = kCodecAAC;
const AACAudioSpecificConfig& aac_audio_specific_config =
entry.esds.aac_audio_specific_config;
num_channels = aac_audio_specific_config.num_channels();
sampling_frequency = aac_audio_specific_config.frequency();
audio_object_type = aac_audio_specific_config.audio_object_type();
extra_data = entry.esds.es_descriptor.decoder_specific_info();
} else if (audio_type == kEAC3) {
codec = kCodecEAC3;
num_channels = entry.channelcount;
sampling_frequency = entry.samplerate;
} else {
LOG(ERROR) << "Unsupported audio object type 0x"
<< std::hex << audio_type << " in esds.";
return false;
}
bool is_encrypted = entry.sinf.info.track_encryption.is_encrypted;
DVLOG(1) << "is_audio_track_encrypted_: " << is_encrypted;
streams.push_back(new AudioStreamInfo(
track->header.track_id,
timescale,
duration,
codec,
AudioStreamInfo::GetCodecString(codec, audio_object_type),
track->media.header.language,
entry.samplesize,
num_channels,
sampling_frequency,
extra_data.size() ? &extra_data[0] : NULL,
extra_data.size(),
is_encrypted));
}
if (track->media.handler.type == kVideo) {
RCHECK(!samp_descr.video_entries.empty());
if (desc_idx >= samp_descr.video_entries.size())
desc_idx = 0;
const VideoSampleEntry& entry = samp_descr.video_entries[desc_idx];
if (!(entry.format == FOURCC_AVC1 ||
(entry.format == FOURCC_ENCV &&
entry.sinf.format.format == FOURCC_AVC1))) {
LOG(ERROR) << "Unsupported video format 0x"
<< std::hex << entry.format << " in stsd box.";
return false;
}
const std::string codec_string =
VideoStreamInfo::GetCodecString(kCodecH264,
entry.avcc.profile_indication,
entry.avcc.profile_compatibility,
entry.avcc.avc_level);
bool is_encrypted = entry.sinf.info.track_encryption.is_encrypted;
DVLOG(1) << "is_video_track_encrypted_: " << is_encrypted;
streams.push_back(new VideoStreamInfo(track->header.track_id,
timescale,
duration,
kCodecH264,
codec_string,
track->media.header.language,
entry.width,
entry.height,
0, // trick_play_rate
entry.avcc.length_size,
&entry.avcc.data[0],
entry.avcc.data.size(),
is_encrypted));
}
}
init_cb_.Run(streams);
if (!FetchKeysIfNecessary(moov_->pssh))
return false;
runs_.reset(new TrackRunIterator(moov_.get()));
RCHECK(runs_->Init());
ChangeState(kEmittingSamples);
return true;
}
bool MP4MediaParser::ParseMoof(BoxReader* reader) {
// Must already have initialization segment.
RCHECK(moov_.get());
MovieFragment moof;
RCHECK(moof.Parse(reader));
if (!runs_)
runs_.reset(new TrackRunIterator(moov_.get()));
RCHECK(runs_->Init(moof));
if (!FetchKeysIfNecessary(moof.pssh))
return false;
ChangeState(kEmittingSamples);
return true;
}
bool MP4MediaParser::FetchKeysIfNecessary(
const std::vector<ProtectionSystemSpecificHeader>& headers) {
if (headers.empty())
return true;
// An error will be returned later if the samples need to be decrypted.
if (!decryption_key_source_)
return true;
// TODO(tinskip): Pass in raw 'pssh' boxes to FetchKeys. This will allow
// supporting multiple keysystems. Move this to KeySource.
std::vector<uint8_t> widevine_system_id;
base::HexStringToBytes(kWidevineKeySystemId, &widevine_system_id);
for (std::vector<ProtectionSystemSpecificHeader>::const_iterator iter =
headers.begin(); iter != headers.end(); ++iter) {
if (iter->system_id == widevine_system_id) {
Status status = decryption_key_source_->FetchKeys(iter->data);
if (!status.ok()) {
LOG(ERROR) << "Error fetching decryption keys: " << status;
return false;
}
return true;
}
}
LOG(ERROR) << "No viable 'pssh' box found for content decryption.";
return false;
}
bool MP4MediaParser::EnqueueSample(bool* err) {
if (!runs_->IsRunValid()) {
// Remain in kEnqueueingSamples state, discarding data, until the end of
// the current 'mdat' box has been appended to the queue.
if (!queue_.Trim(mdat_tail_))
return false;
ChangeState(kParsingBoxes);
return true;
}
if (!runs_->IsSampleValid()) {
runs_->AdvanceRun();
return true;
}
DCHECK(!(*err));
const uint8_t* buf;
int buf_size;
queue_.Peek(&buf, &buf_size);
if (!buf_size)
return false;
// Skip this entire track if it is not audio nor video.
if (!runs_->is_audio() && !runs_->is_video())
runs_->AdvanceRun();
// 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;
}
int64_t sample_offset = runs_->sample_offset() + moof_head_;
queue_.PeekAt(sample_offset, &buf, &buf_size);
if (buf_size < runs_->sample_size()) {
if (sample_offset < queue_.head()) {
LOG(ERROR) << "Incorrect sample offset " << sample_offset
<< " < " << queue_.head();
*err = true;
}
return false;
}
scoped_refptr<MediaSample> stream_sample(MediaSample::CopyFrom(
buf, runs_->sample_size(), runs_->is_keyframe()));
if (runs_->is_encrypted()) {
scoped_ptr<DecryptConfig> decrypt_config = runs_->GetDecryptConfig();
if (!decrypt_config ||
!DecryptSampleBuffer(decrypt_config.get(),
stream_sample->writable_data(),
stream_sample->data_size())) {
*err = true;
LOG(ERROR) << "Cannot decrypt samples.";
return false;
}
}
stream_sample->set_dts(runs_->dts());
stream_sample->set_pts(runs_->cts());
stream_sample->set_duration(runs_->duration());
DVLOG(3) << "Pushing frame: "
<< ", key=" << runs_->is_keyframe()
<< ", dur=" << runs_->duration()
<< ", dts=" << runs_->dts()
<< ", cts=" << runs_->cts()
<< ", size=" << runs_->sample_size();
if (!new_sample_cb_.Run(runs_->track_id(), stream_sample)) {
*err = true;
LOG(ERROR) << "Failed to process the sample.";
return false;
}
runs_->AdvanceSample();
return true;
}
bool MP4MediaParser::DecryptSampleBuffer(const DecryptConfig* decrypt_config,
uint8_t* buffer,
size_t buffer_size) {
DCHECK(decrypt_config);
DCHECK(buffer);
if (!decryption_key_source_) {
LOG(ERROR) << "Encrypted media sample encountered, but decryption is not "
"enabled";
return false;
}
// Get the encryptor object.
AesCtrEncryptor* encryptor;
DecryptorMap::iterator found = decryptor_map_.find(decrypt_config->key_id());
if (found == decryptor_map_.end()) {
// Create new AesCtrEncryptor
EncryptionKey key;
Status status(decryption_key_source_->GetKey(decrypt_config->key_id(),
&key));
if (!status.ok()) {
LOG(ERROR) << "Error retrieving decryption key: " << status;
return false;
}
scoped_ptr<AesCtrEncryptor> new_encryptor(new AesCtrEncryptor);
if (!new_encryptor->InitializeWithIv(key.key, decrypt_config->iv())) {
LOG(ERROR) << "Failed to initialize AesCtrEncryptor for decryption.";
return false;
}
encryptor = new_encryptor.release();
decryptor_map_[decrypt_config->key_id()] = encryptor;
} else {
encryptor = found->second;
}
if (!encryptor->SetIv(decrypt_config->iv())) {
LOG(ERROR) << "Invalid initialization vector.";
return false;
}
if (decrypt_config->subsamples().empty()) {
// Sample not encrypted using subsample encryption. Decrypt whole.
if (!encryptor->Decrypt(buffer, buffer_size, buffer)) {
LOG(ERROR) << "Error during bulk sample decryption.";
return false;
}
return true;
}
// Subsample decryption.
const std::vector<SubsampleEntry>& subsamples = decrypt_config->subsamples();
uint8_t* current_ptr = buffer;
const uint8_t* buffer_end = buffer + buffer_size;
current_ptr += decrypt_config->data_offset();
if (current_ptr > buffer_end) {
LOG(ERROR) << "Subsample data_offset too large.";
return false;
}
for (std::vector<SubsampleEntry>::const_iterator iter = subsamples.begin();
iter != subsamples.end();
++iter) {
if ((current_ptr + iter->clear_bytes + iter->cipher_bytes) > buffer_end) {
LOG(ERROR) << "Subsamples overflow sample buffer.";
return false;
}
current_ptr += iter->clear_bytes;
if (!encryptor->Decrypt(current_ptr, iter->cipher_bytes, current_ptr)) {
LOG(ERROR) << "Error decrypting subsample buffer.";
return false;
}
current_ptr += iter->cipher_bytes;
}
return true;
}
bool MP4MediaParser::ReadAndDiscardMDATsUntil(const int64_t offset) {
bool err = false;
while (mdat_tail_ < offset) {
const uint8_t* buf;
int size;
queue_.PeekAt(mdat_tail_, &buf, &size);
FourCC type;
uint64_t box_sz;
if (!BoxReader::StartTopLevelBox(buf, size, &type, &box_sz, &err))
break;
mdat_tail_ += box_sz;
}
queue_.Trim(std::min(mdat_tail_, offset));
return !err;
}
void MP4MediaParser::ChangeState(State new_state) {
DVLOG(2) << "Changing state: " << new_state;
state_ = new_state;
}
} // namespace mp4
} // namespace media
} // namespace edash_packager
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