src/transcoder/transcoder.cpp

/*
 * Strawberry Music Player
 * This file was part of Clementine.
 * Copyright 2010, David Sansome <me@davidsansome.com>
 * Copyright 2018-2021, Jonas Kvinge <jonas@jkvinge.net>
 *
 * Strawberry is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Strawberry is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Strawberry.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include "config.h"

#include <glib.h>
#include <glib/gtypes.h>
#include <cstdlib>
#include <memory>
#include <algorithm>
#include <gst/gst.h>

#include <QtGlobal>
#include <QThread>
#include <QCoreApplication>
#include <QStandardPaths>
#include <QByteArray>
#include <QDir>
#include <QFileInfo>
#include <QList>
#include <QMap>
#include <QVariant>
#include <QString>
#include <QSettings>
#include <QtDebug>

#include "core/logging.h"
#include "core/signalchecker.h"
#include "transcoder.h"

int Transcoder::JobFinishedEvent::sEventType = -1;

TranscoderPreset::TranscoderPreset(const Song::FileType filetype, const QString &name, const QString &extension, const QString &codec_mimetype, const QString &muxer_mimetype)
    : filetype_(filetype),
      name_(name),
      extension_(extension),
      codec_mimetype_(codec_mimetype),
      muxer_mimetype_(muxer_mimetype) {}


GstElement *Transcoder::CreateElement(const QString &factory_name, GstElement *bin, const QString &name) {

  GstElement *ret = gst_element_factory_make(factory_name.toLatin1().constData(), name.isNull() ? factory_name.toLatin1().constData() : name.toLatin1().constData());

  if (ret && bin) gst_bin_add(GST_BIN(bin), ret);

  if (!ret) {
    emit LogLine(tr("Could not create the GStreamer element \"%1\" - make sure you have all the required GStreamer plugins installed").arg(factory_name));
  }
  else {
    SetElementProperties(factory_name, G_OBJECT(ret));
  }

  return ret;

}

struct SuitableElement {

  explicit SuitableElement(const QString &name = QString(), int rank = 0) : name_(name), rank_(rank) {}

  bool operator<(const SuitableElement &other) const {
    return rank_ < other.rank_;
  }

  QString name_;
  int rank_;

};

GstElement *Transcoder::CreateElementForMimeType(const QString &element_type, const QString &mime_type, GstElement *bin) {

  if (mime_type.isEmpty()) return nullptr;

  // HACK: Force mp4mux because it doesn't set any useful src caps
  if (mime_type == "audio/mp4") {
    emit LogLine(QString("Using '%1' (rank %2)").arg("mp4mux").arg(-1));
    return CreateElement("mp4mux", bin);
  }

  // Keep track of all the suitable elements we find and figure out which is the best at the end.
  QList<SuitableElement> suitable_elements_;

  // The caps we're trying to find
  GstCaps *target_caps = gst_caps_from_string(mime_type.toUtf8().constData());

  GstRegistry *registry = gst_registry_get();
  GList *const features = gst_registry_get_feature_list(registry, GST_TYPE_ELEMENT_FACTORY);

  for (GList *f = features; f; f = g_list_next(f)) {
    GstElementFactory *factory = GST_ELEMENT_FACTORY(f->data);

    // Is this the right type of plugin?
    if (QString(gst_element_factory_get_klass(factory)).contains(element_type)) {
      const GList *const templates = gst_element_factory_get_static_pad_templates(factory);
      for (const GList *t = templates; t; t = g_list_next(t)) {
        // Only interested in source pads
        GstStaticPadTemplate *pad_template = reinterpret_cast<GstStaticPadTemplate*>(t->data);
        if (pad_template->direction != GST_PAD_SRC) continue;

        // Does this pad support the mime type we want?
        GstCaps *caps = gst_static_pad_template_get_caps(pad_template);
        GstCaps *intersection = gst_caps_intersect(caps, target_caps);

        if (intersection) {
          if (!gst_caps_is_empty(intersection)) {
            int rank = gst_plugin_feature_get_rank(GST_PLUGIN_FEATURE(factory));
            QString name = GST_OBJECT_NAME(factory);

            if (name.startsWith("ffmux") || name.startsWith("ffenc"))
              rank = -1;  // ffmpeg usually sucks

            suitable_elements_ << SuitableElement(name, rank);
          }
          gst_caps_unref(intersection);
        }
      }
    }
  }

  gst_plugin_feature_list_free(features);
  gst_caps_unref(target_caps);

  if (suitable_elements_.isEmpty()) return nullptr;

  // Sort by rank
  std::sort(suitable_elements_.begin(), suitable_elements_.end());
  const SuitableElement &best = suitable_elements_.last();

  emit LogLine(QString("Using '%1' (rank %2)").arg(best.name_).arg(best.rank_));

  if (best.name_ == "lamemp3enc") {
    // Special case: we need to add xingmux and id3v2mux to the pipeline when using lamemp3enc because it doesn't write the VBR or ID3v2 headers itself.

    emit LogLine("Adding xingmux and id3v2mux to the pipeline");

    // Create the bin
    GstElement *mp3bin = gst_bin_new("mp3bin");
    gst_bin_add(GST_BIN(bin), mp3bin);

    // Create the elements
    GstElement *lame = CreateElement("lamemp3enc", mp3bin);
    GstElement *xing = CreateElement("xingmux", mp3bin);
    GstElement *id3v2 = CreateElement("id3v2mux", mp3bin);

    if (!lame || !xing || !id3v2) {
      return nullptr;
    }

    // Link the elements together
    gst_element_link_many(lame, xing, id3v2, nullptr);

    // Link the bin's ghost pads to the elements on each end
    GstPad *pad = gst_element_get_static_pad(lame, "sink");
    gst_element_add_pad(mp3bin, gst_ghost_pad_new("sink", pad));
    gst_object_unref(GST_OBJECT(pad));

    pad = gst_element_get_static_pad(id3v2, "src");
    gst_element_add_pad(mp3bin, gst_ghost_pad_new("src", pad));
    gst_object_unref(GST_OBJECT(pad));

    return mp3bin;
  }
  else {
    return CreateElement(best.name_, bin);
  }
}

Transcoder::JobFinishedEvent::JobFinishedEvent(JobState *state, bool success)
    : QEvent(QEvent::Type(sEventType)), state_(state), success_(success) {}

void Transcoder::JobState::PostFinished(const bool success) {

  if (success) {
    emit parent_->LogLine(tr("Successfully written %1").arg(QDir::toNativeSeparators(job_.output)));
  }

  QCoreApplication::postEvent(parent_, new Transcoder::JobFinishedEvent(this, success));

}

Transcoder::Transcoder(QObject *parent, const QString &settings_postfix)
    : QObject(parent),
      max_threads_(QThread::idealThreadCount()),
      settings_postfix_(settings_postfix) {

  if (JobFinishedEvent::sEventType == -1)
    JobFinishedEvent::sEventType = QEvent::registerEventType();

  // Initialize some settings for the lamemp3enc element.
  QSettings s;
  s.beginGroup("Transcoder/lamemp3enc" + settings_postfix_);

  if (s.value("target").isNull()) {
    s.setValue("target", 1);  // 1 == bitrate
  }
  if (s.value("cbr").isNull()) {
    s.setValue("cbr", false);
  }

}

QList<TranscoderPreset> Transcoder::GetAllPresets() {

  QList<TranscoderPreset> ret;
  ret << PresetForFileType(Song::FileType_WAV);
  ret << PresetForFileType(Song::FileType_FLAC);
  ret << PresetForFileType(Song::FileType_WavPack);
  ret << PresetForFileType(Song::FileType_OggFlac);
  ret << PresetForFileType(Song::FileType_OggVorbis);
  ret << PresetForFileType(Song::FileType_OggOpus);
  ret << PresetForFileType(Song::FileType_OggSpeex);
  ret << PresetForFileType(Song::FileType_MPEG);
  ret << PresetForFileType(Song::FileType_MP4);
  ret << PresetForFileType(Song::FileType_ASF);
  return ret;

}

TranscoderPreset Transcoder::PresetForFileType(const Song::FileType filetype) {

  switch (filetype) {
    case Song::FileType_WAV:
      return TranscoderPreset(filetype, "Wav",                    "wav",  QString(), "audio/x-wav");
    case Song::FileType_FLAC:
      return TranscoderPreset(filetype, "FLAC",                   "flac", "audio/x-flac");
    case Song::FileType_WavPack:
      return TranscoderPreset(filetype, "WavPack",                "wv",   "audio/x-wavpack");
    case Song::FileType_OggFlac:
      return TranscoderPreset(filetype, "Ogg FLAC",               "ogg",  "audio/x-flac", "application/ogg");
    case Song::FileType_OggVorbis:
      return TranscoderPreset(filetype, "Ogg Vorbis",             "ogg",  "audio/x-vorbis", "application/ogg");
    case Song::FileType_OggOpus:
      return TranscoderPreset(filetype, "Ogg Opus",               "opus", "audio/x-opus", "application/ogg");
    case Song::FileType_OggSpeex:
      return TranscoderPreset(filetype, "Ogg Speex",              "spx",  "audio/x-speex", "application/ogg");
    case Song::FileType_MPEG:
      return TranscoderPreset(filetype, "MP3",                    "mp3",  "audio/mpeg, mpegversion=(int)1, layer=(int)3");
    case Song::FileType_MP4:
      return TranscoderPreset(filetype, "M4A AAC",                "mp4",  "audio/mpeg, mpegversion=(int)4", "audio/mp4");
    case Song::FileType_ASF:
      return TranscoderPreset(filetype, "Windows Media audio",    "wma",  "audio/x-wma", "video/x-ms-asf");
    default:
      qLog(Warning) << "Unsupported format in PresetForFileType:" << filetype;
      return TranscoderPreset();
  }

}

Song::FileType Transcoder::PickBestFormat(const QList<Song::FileType> &supported) {

  if (supported.isEmpty()) return Song::FileType_Unknown;

  QList<Song::FileType> best_formats;
  best_formats << Song::FileType_FLAC;
  best_formats << Song::FileType_OggFlac;
  best_formats << Song::FileType_WavPack;

  for (Song::FileType type : best_formats) {
    if (supported.isEmpty() || supported.contains(type)) return type;
  }

  return supported[0];

}

QString Transcoder::GetFile(const QString &input, const TranscoderPreset &preset, const QString &output) {

  QFileInfo fileinfo_output;

  if (!output.isEmpty()) {
    fileinfo_output.setFile(output);
  }

  if (!fileinfo_output.isFile() || fileinfo_output.filePath().isEmpty() || fileinfo_output.path().isEmpty() || fileinfo_output.fileName().isEmpty() || fileinfo_output.suffix().isEmpty()) {
    QFileInfo fileinfo_input(input);
    QString temp_dir = QStandardPaths::writableLocation(QStandardPaths::CacheLocation) + "/transcoder";
    if (!QDir(temp_dir).exists()) QDir().mkpath(temp_dir);
    QString filename = fileinfo_input.completeBaseName() + "." + preset.extension_;
    fileinfo_output.setFile(temp_dir + "/" + filename);
  }

  // Never overwrite existing files
  if (fileinfo_output.exists()) {
    QString path = fileinfo_output.path();
    QString filename = fileinfo_output.completeBaseName();
    QString suffix = fileinfo_output.suffix();
    for (int i = 0;; ++i) {
      QString new_filename = QString("%1/%2-%3.%4").arg(path, filename).arg(i).arg(suffix);
      fileinfo_output.setFile(new_filename);
      if (!fileinfo_output.exists()) {
        break;
      }

    }
  }

  return fileinfo_output.filePath();
}

void Transcoder::AddJob(const QString &input, const TranscoderPreset &preset, const QString &output) {

  Job job;
  job.input = input;
  job.preset = preset;
  job.output = output;
  queued_jobs_ << job;

}

void Transcoder::Start() {

  emit LogLine(tr("Transcoding %1 files using %2 threads").arg(queued_jobs_.count()).arg(max_threads()));

  forever {
    StartJobStatus status = MaybeStartNextJob();
    if (status == AllThreadsBusy || status == NoMoreJobs) break;
  }

}

Transcoder::StartJobStatus Transcoder::MaybeStartNextJob() {

  if (current_jobs_.count() >= max_threads()) return AllThreadsBusy;
  if (queued_jobs_.isEmpty()) {
    if (current_jobs_.isEmpty()) {
      emit AllJobsComplete();
    }

    return NoMoreJobs;
  }

  Job job = queued_jobs_.takeFirst();
  if (StartJob(job)) {
    return StartedSuccessfully;
  }

  emit JobComplete(job.input, job.output, false);
  return FailedToStart;

}

void Transcoder::NewPadCallback(GstElement*, GstPad *pad, gpointer data) {

  JobState *state = reinterpret_cast<JobState*>(data);
  GstPad *const audiopad = gst_element_get_static_pad(state->convert_element_, "sink");

  if (GST_PAD_IS_LINKED(audiopad)) {
    qLog(Debug) << "audiopad is already linked, unlinking old pad";
    gst_pad_unlink(audiopad, GST_PAD_PEER(audiopad));
  }

  gst_pad_link(pad, audiopad);
  gst_object_unref(audiopad);

}

GstBusSyncReply Transcoder::BusCallbackSync(GstBus*, GstMessage *msg, gpointer data) {

  JobState *state = reinterpret_cast<JobState*>(data);
  switch (GST_MESSAGE_TYPE(msg)) {
    case GST_MESSAGE_EOS:
      state->PostFinished(true);
      break;

    case GST_MESSAGE_ERROR:
      state->ReportError(msg);
      state->PostFinished(false);
      break;

    default:
      break;
  }

  return GST_BUS_PASS;

}

void Transcoder::JobState::ReportError(GstMessage *msg) const {

  GError *error = nullptr;
  gchar *debugs = nullptr;

  gst_message_parse_error(msg, &error, &debugs);
  QString message = QString::fromLocal8Bit(error->message);

  g_error_free(error);
  free(debugs);

  emit parent_->LogLine(tr("Error processing %1: %2").arg(QDir::toNativeSeparators(job_.input), message));

}

bool Transcoder::StartJob(const Job &job) {

  std::shared_ptr<JobState> state = std::make_shared<JobState>(job, this);

  emit LogLine(tr("Starting %1").arg(QDir::toNativeSeparators(job.input)));

  // Create the pipeline.
  // This should be a scoped_ptr, but scoped_ptr doesn't support custom destructors.
  state->pipeline_ = gst_pipeline_new("pipeline");
  if (!state->pipeline_) return false;

  // Create all the elements
  GstElement *src      = CreateElement("filesrc", state->pipeline_);
  GstElement *decode   = CreateElement("decodebin", state->pipeline_);
  GstElement *convert  = CreateElement("audioconvert", state->pipeline_);
  GstElement *resample = CreateElement("audioresample", state->pipeline_);
  GstElement *codec    = CreateElementForMimeType("Codec/Encoder/Audio", job.preset.codec_mimetype_, state->pipeline_);
  GstElement *muxer    = CreateElementForMimeType("Codec/Muxer", job.preset.muxer_mimetype_, state->pipeline_);
  GstElement *sink     = CreateElement("filesink", state->pipeline_);

  if (!src || !decode || !convert || !sink) return false;

  if (!codec && !job.preset.codec_mimetype_.isEmpty()) {
    emit LogLine(tr("Couldn't find an encoder for %1, check you have the correct GStreamer plugins installed").arg(job.preset.codec_mimetype_));
    return false;
  }

  if (!muxer && !job.preset.muxer_mimetype_.isEmpty()) {
    emit LogLine(tr("Couldn't find a muxer for %1, check you have the correct GStreamer plugins installed").arg(job.preset.muxer_mimetype_));
    return false;
  }

  // Join them together
  gst_element_link(src, decode);
  if (codec && muxer) gst_element_link_many(convert, resample, codec, muxer, sink, nullptr);
  else if (codec) gst_element_link_many(convert, resample, codec, sink, nullptr);
  else if (muxer) gst_element_link_many(convert, resample, muxer, sink, nullptr);

  // Set properties
  g_object_set(src, "location", job.input.toUtf8().constData(), nullptr);
  g_object_set(sink, "location", job.output.toUtf8().constData(), nullptr);

  // Set callbacks
  state->convert_element_ = convert;

  CHECKED_GCONNECT(decode, "pad-added", &NewPadCallback, state.get());
  gst_bus_set_sync_handler(gst_pipeline_get_bus(GST_PIPELINE(state->pipeline_)), BusCallbackSync, state.get(), nullptr);

  // Start the pipeline
  gst_element_set_state(state->pipeline_, GST_STATE_PLAYING);

  // GStreamer now transcodes in another thread, so we can return now and do something else.
  // Keep the JobState object around.  It'll post an event to our event loop when it finishes.
  current_jobs_ << state;

  return true;

}

Transcoder::JobState::~JobState() {

  if (pipeline_) {
    gst_element_set_state(pipeline_, GST_STATE_NULL);
    gst_object_unref(pipeline_);
  }

}

bool Transcoder::event(QEvent *e) {

  if (e->type() == JobFinishedEvent::sEventType) {
    JobFinishedEvent *finished_event = static_cast<JobFinishedEvent*>(e);

    // Find this job in the list
    JobStateList::iterator it = current_jobs_.begin();
    for (; it != current_jobs_.end(); ++it) {
      if (it->get() == finished_event->state_) break;
    }
    if (it == current_jobs_.end()) {
      // Couldn't find it, maybe GStreamer gave us an event after we'd destroyed the pipeline?
      return true;
    }

    QString input = (*it)->job_.input;
    QString output = (*it)->job_.output;

    // Remove event handlers from the gstreamer pipeline so they don't get called after the pipeline is shutting down
    gst_bus_set_sync_handler(gst_pipeline_get_bus(GST_PIPELINE(finished_event->state_->pipeline_)), nullptr, nullptr, nullptr);

    // Remove it from the list - this will also destroy the GStreamer pipeline
    current_jobs_.erase(it);  // clazy:exclude=strict-iterators

    // Emit the finished signal
    emit JobComplete(input, output, finished_event->success_);

    // Start some more jobs
    MaybeStartNextJob();

    return true;
  }

  return QObject::event(e);

}

void Transcoder::Cancel() {

  // Remove all pending jobs
  queued_jobs_.clear();

  // Stop the running ones
  JobStateList::iterator it = current_jobs_.begin();
  while (it != current_jobs_.end()) {
    std::shared_ptr<JobState> state(*it);

    // Remove event handlers from the gstreamer pipeline so they don't get called after the pipeline is shutting down
    gst_bus_set_sync_handler(gst_pipeline_get_bus(GST_PIPELINE(state->pipeline_)), nullptr, nullptr, nullptr);

    // Stop the pipeline
    if (gst_element_set_state(state->pipeline_, GST_STATE_NULL) == GST_STATE_CHANGE_ASYNC) {
      // Wait for it to finish stopping...
      gst_element_get_state(state->pipeline_, nullptr, nullptr, GST_CLOCK_TIME_NONE);
    }

    // Remove the job, this destroys the GStreamer pipeline too
    it = current_jobs_.erase(it);  // clazy:exclude=strict-iterators
  }

}

QMap<QString, float> Transcoder::GetProgress() const {

  QMap<QString, float> ret;

  for (const auto &state : current_jobs_) {
    if (!state->pipeline_) continue;

    gint64 position = 0;
    gint64 duration = 0;

    gst_element_query_position(state->pipeline_, GST_FORMAT_TIME, &position);
    gst_element_query_duration(state->pipeline_, GST_FORMAT_TIME, &duration);

    ret[state->job_.input] = static_cast<float>(position) / duration;
  }

  return ret;

}

void Transcoder::SetElementProperties(const QString &name, GObject *object) {

  QSettings s;
  s.beginGroup("Transcoder/" + name + settings_postfix_);

  guint properties_count = 0;
  GParamSpec **properties = g_object_class_list_properties(G_OBJECT_GET_CLASS(object), &properties_count);

  for (uint i = 0; i < properties_count; ++i) {
    GParamSpec *property = properties[i];

    const QVariant value = s.value(property->name);
    if (value.isNull()) continue;

    emit LogLine(QString("Setting %1 property: %2 = %3").arg(name, property->name, value.toString()));

    switch (property->value_type) {
      case G_TYPE_DOUBLE:
        g_object_set(object, property->name, value.toDouble(), nullptr);
        break;
      case G_TYPE_FLOAT:
        g_object_set(object, property->name, value.toFloat(), nullptr);
        break;
      case G_TYPE_BOOLEAN:
        g_object_set(object, property->name, value.toInt(), nullptr);
        break;
      case G_TYPE_INT:
      default:
        g_object_set(object, property->name, value.toInt(), nullptr);
        break;
    }
  }

  g_free(properties);

}