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// Copyright (c) 2012 The WebM project authors. All Rights Reserved.
//
// Use of this source code is governed by a BSD-style license
// that can be found in the LICENSE file in the root of the source
// tree. An additional intellectual property rights grant can be found
// in the file PATENTS. All contributing project authors may
// be found in the AUTHORS file in the root of the source tree.
//
// This sample application demonstrates how to use the matroska parser
// library, which allows clients to handle a matroska format file.
#include "sample_muxer_metadata.h"
#include <cstdio>
#include <string>
#include "mkvmuxer/mkvmuxer.h"
#include "webvtt/vttreader.h"
SampleMuxerMetadata::SampleMuxerMetadata() : segment_(NULL) {}
bool SampleMuxerMetadata::Init(mkvmuxer::Segment* segment) {
if (segment == NULL || segment_ != NULL)
return false;
segment_ = segment;
return true;
}
bool SampleMuxerMetadata::Load(const char* file, Kind kind) {
if (kind == kChapters)
return LoadChapters(file);
uint64_t track_num;
if (!AddTrack(kind, &track_num)) {
printf("Unable to add track for WebVTT file \"%s\"\n", file);
return false;
}
return Parse(file, kind, track_num);
}
bool SampleMuxerMetadata::AddChapters() {
typedef cue_list_t::const_iterator iter_t;
iter_t i = chapter_cues_.begin();
const iter_t j = chapter_cues_.end();
while (i != j) {
const cue_t& chapter = *i++;
if (!AddChapter(chapter))
return false;
}
return true;
}
bool SampleMuxerMetadata::Write(int64_t time_ns) {
typedef cues_set_t::iterator iter_t;
iter_t i = cues_set_.begin();
const iter_t j = cues_set_.end();
while (i != j) {
const cues_set_t::value_type& v = *i;
if (time_ns >= 0 && v > time_ns)
return true; // nothing else to do just yet
if (!v.Write(segment_)) {
printf("\nCould not add metadata.\n");
return false; // error
}
cues_set_.erase(i++);
}
return true;
}
bool SampleMuxerMetadata::LoadChapters(const char* file) {
if (!chapter_cues_.empty()) {
printf("Support for more than one chapters file is not yet implemented\n");
return false;
}
cue_list_t cues;
if (!ParseChapters(file, &cues))
return false;
// TODO(matthewjheaney): support more than one chapters file
chapter_cues_.swap(cues);
return true;
}
bool SampleMuxerMetadata::ParseChapters(const char* file,
cue_list_t* cues_ptr) {
cue_list_t& cues = *cues_ptr;
cues.clear();
libwebvtt::VttReader r;
int e = r.Open(file);
if (e) {
printf("Unable to open WebVTT file: \"%s\"\n", file);
return false;
}
libwebvtt::Parser p(&r);
e = p.Init();
if (e < 0) { // error
printf("Error parsing WebVTT file: \"%s\"\n", file);
return false;
}
libwebvtt::Time t;
t.hours = -1;
for (;;) {
cue_t c;
e = p.Parse(&c);
if (e < 0) { // error
printf("Error parsing WebVTT file: \"%s\"\n", file);
return false;
}
if (e > 0) // EOF
return true;
if (c.start_time < t) {
printf("bad WebVTT cue timestamp (out-of-order)\n");
return false;
}
if (c.stop_time < c.start_time) {
printf("bad WebVTT cue timestamp (stop < start)\n");
return false;
}
t = c.start_time;
cues.push_back(c);
}
}
bool SampleMuxerMetadata::AddChapter(const cue_t& cue) {
// TODO(matthewjheaney): support language and country
mkvmuxer::Chapter* const chapter = segment_->AddChapter();
if (chapter == NULL) {
printf("Unable to add chapter\n");
return false;
}
if (cue.identifier.empty()) {
chapter->set_id(NULL);
} else {
const char* const id = cue.identifier.c_str();
if (!chapter->set_id(id)) {
printf("Unable to set chapter id\n");
return false;
}
}
typedef libwebvtt::presentation_t time_ms_t;
const time_ms_t start_time_ms = cue.start_time.presentation();
const time_ms_t stop_time_ms = cue.stop_time.presentation();
enum { kNsPerMs = 1000000 };
const uint64_t start_time_ns = start_time_ms * kNsPerMs;
const uint64_t stop_time_ns = stop_time_ms * kNsPerMs;
chapter->set_time(*segment_, start_time_ns, stop_time_ns);
typedef libwebvtt::Cue::payload_t::const_iterator iter_t;
iter_t i = cue.payload.begin();
const iter_t j = cue.payload.end();
std::string title;
for (;;) {
title += *i++;
if (i == j)
break;
enum { kLF = '\x0A' };
title += kLF;
}
if (!chapter->add_string(title.c_str(), NULL, NULL)) {
printf("Unable to set chapter title\n");
return false;
}
return true;
}
bool SampleMuxerMetadata::AddTrack(Kind kind, uint64_t* track_num) {
*track_num = 0;
// Track number value 0 means "let muxer choose track number"
mkvmuxer::Track* const track = segment_->AddTrack(0);
if (track == NULL) // error
return false;
// Return the track number value chosen by the muxer
*track_num = track->number();
int type;
const char* codec_id;
switch (kind) {
case kSubtitles:
type = 0x11;
codec_id = "D_WEBVTT/SUBTITLES";
break;
case kCaptions:
type = 0x11;
codec_id = "D_WEBVTT/CAPTIONS";
break;
case kDescriptions:
type = 0x21;
codec_id = "D_WEBVTT/DESCRIPTIONS";
break;
case kMetadata:
type = 0x21;
codec_id = "D_WEBVTT/METADATA";
break;
default:
return false;
}
track->set_type(type);
track->set_codec_id(codec_id);
// TODO(matthewjheaney): set name and language
return true;
}
bool SampleMuxerMetadata::Parse(const char* file, Kind /* kind */,
uint64_t track_num) {
libwebvtt::VttReader r;
int e = r.Open(file);
if (e) {
printf("Unable to open WebVTT file: \"%s\"\n", file);
return false;
}
libwebvtt::Parser p(&r);
e = p.Init();
if (e < 0) { // error
printf("Error parsing WebVTT file: \"%s\"\n", file);
return false;
}
SortableCue cue;
cue.track_num = track_num;
libwebvtt::Time t;
t.hours = -1;
for (;;) {
cue_t& c = cue.cue;
e = p.Parse(&c);
if (e < 0) { // error
printf("Error parsing WebVTT file: \"%s\"\n", file);
return false;
}
if (e > 0) // EOF
return true;
if (c.start_time >= t) {
t = c.start_time;
} else {
printf("bad WebVTT cue timestamp (out-of-order)\n");
return false;
}
if (c.stop_time < c.start_time) {
printf("bad WebVTT cue timestamp (stop < start)\n");
return false;
}
cues_set_.insert(cue);
}
}
void SampleMuxerMetadata::MakeFrame(const cue_t& c, std::string* pf) {
pf->clear();
WriteCueIdentifier(c.identifier, pf);
WriteCueSettings(c.settings, pf);
WriteCuePayload(c.payload, pf);
}
void SampleMuxerMetadata::WriteCueIdentifier(const std::string& identifier,
std::string* pf) {
pf->append(identifier);
pf->push_back('\x0A'); // LF
}
void SampleMuxerMetadata::WriteCueSettings(const cue_t::settings_t& settings,
std::string* pf) {
if (settings.empty()) {
pf->push_back('\x0A'); // LF
return;
}
typedef cue_t::settings_t::const_iterator iter_t;
iter_t i = settings.begin();
const iter_t j = settings.end();
for (;;) {
const libwebvtt::Setting& setting = *i++;
pf->append(setting.name);
pf->push_back(':');
pf->append(setting.value);
if (i == j)
break;
pf->push_back(' '); // separate settings with whitespace
}
pf->push_back('\x0A'); // LF
}
void SampleMuxerMetadata::WriteCuePayload(const cue_t::payload_t& payload,
std::string* pf) {
typedef cue_t::payload_t::const_iterator iter_t;
iter_t i = payload.begin();
const iter_t j = payload.end();
while (i != j) {
const std::string& line = *i++;
pf->append(line);
pf->push_back('\x0A'); // LF
}
}
bool SampleMuxerMetadata::SortableCue::Write(mkvmuxer::Segment* segment) const {
// Cue start time expressed in milliseconds
const int64_t start_ms = cue.start_time.presentation();
// Cue start time expressed in nanoseconds (MKV time)
const int64_t start_ns = start_ms * 1000000;
// Cue stop time expressed in milliseconds
const int64_t stop_ms = cue.stop_time.presentation();
// Cue stop time expressed in nanonseconds
const int64_t stop_ns = stop_ms * 1000000;
// Metadata blocks always specify the block duration.
const int64_t duration_ns = stop_ns - start_ns;
std::string frame;
MakeFrame(cue, &frame);
typedef const uint8_t* data_t;
const data_t buf = reinterpret_cast<data_t>(frame.data());
const uint64_t len = frame.length();
mkvmuxer::Frame muxer_frame;
if (!muxer_frame.Init(buf, len))
return 0;
muxer_frame.set_track_number(track_num);
muxer_frame.set_timestamp(start_ns);
muxer_frame.set_duration(duration_ns);
muxer_frame.set_is_key(true); // All metadata frames are keyframes.
return segment->AddGenericFrame(&muxer_frame);
}