gstreamer/gst/subenc/gstwebvttenc.c

/* GStreamer
 * Copyright (C) <2008> Thijs Vermeir <thijsvermeir@gmail.com>
 * Copyright (C) 2011 David Schleef <ds@schleef.org>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <string.h>

#include "gstwebvttenc.h"

GST_DEBUG_CATEGORY_STATIC (webvttenc_debug);
#define GST_CAT_DEFAULT webvttenc_debug

enum
{
  ARG_0,
  ARG_TIMESTAMP,
  ARG_DURATION
};

static GstStaticPadTemplate src_template = GST_STATIC_PAD_TEMPLATE ("src",
    GST_PAD_SRC,
    GST_PAD_ALWAYS,
    GST_STATIC_CAPS ("text/vtt"));

static GstStaticPadTemplate sink_template = GST_STATIC_PAD_TEMPLATE ("sink",
    GST_PAD_SINK,
    GST_PAD_ALWAYS,
    GST_STATIC_CAPS ("text/x-raw, format = { pango-markup, utf8 }"));

static GstFlowReturn gst_webvtt_enc_chain (GstPad * pad, GstObject * parent,
    GstBuffer * buf);
static void gst_webvtt_enc_append_timestamp_to_string (GstClockTime timestamp,
    GString * str);
static void gst_webvtt_enc_get_property (GObject * object, guint prop_id,
    GValue * value, GParamSpec * pspec);
static void gst_webvtt_enc_reset (GstWebvttEnc * webvttenc);
static void gst_webvtt_enc_set_property (GObject * object, guint prop_id,
    const GValue * value, GParamSpec * pspec);

#define parent_class gst_webvtt_enc_parent_class
G_DEFINE_TYPE (GstWebvttEnc, gst_webvtt_enc, GST_TYPE_ELEMENT);

static void
gst_webvtt_enc_append_timestamp_to_string (GstClockTime timestamp,
    GString * str)
{
  guint h, m, s, ms;

  h = timestamp / (3600 * GST_SECOND);

  timestamp -= h * 3600 * GST_SECOND;
  m = timestamp / (60 * GST_SECOND);

  timestamp -= m * 60 * GST_SECOND;
  s = timestamp / GST_SECOND;

  timestamp -= s * GST_SECOND;
  ms = timestamp / GST_MSECOND;

  g_string_append_printf (str, "%02d:%02d:%02d.%03d", h, m, s, ms);
}

static GstFlowReturn
gst_webvtt_enc_chain (GstPad * pad, GstObject * parent, GstBuffer * buf)
{
  GstWebvttEnc *webvttenc = GST_WEBVTT_ENC (parent);
  GstClockTime ts, dur = GST_SECOND;
  GstBuffer *new_buffer;
  GstMapInfo map_info;
  GstFlowReturn ret;
  GString *s;
  gsize buf_size;

  if (!webvttenc->pushed_header) {
    const char *header = "WEBVTT\n\n";

    new_buffer = gst_buffer_new_wrapped (g_strdup (header), strlen (header));

    GST_BUFFER_PTS (new_buffer) = GST_CLOCK_TIME_NONE;
    GST_BUFFER_DURATION (new_buffer) = GST_CLOCK_TIME_NONE;

    ret = gst_pad_push (webvttenc->srcpad, new_buffer);

    if (ret != GST_FLOW_OK)
      goto out;

    webvttenc->pushed_header = TRUE;
  }

  gst_object_sync_values (GST_OBJECT (webvttenc), GST_BUFFER_PTS (buf));

  ts = GST_BUFFER_PTS (buf) + webvttenc->timestamp;
  if (GST_BUFFER_DURATION_IS_VALID (buf))
    dur = GST_BUFFER_DURATION (buf) + webvttenc->duration;
  else if (webvttenc->duration > 0)
    dur = webvttenc->duration;
  else
    dur = GST_SECOND;

  buf_size = gst_buffer_get_size (buf);
  s = g_string_sized_new (50 + buf_size + 1 + 1);

  /* start_time --> end_time */
  gst_webvtt_enc_append_timestamp_to_string (ts, s);
  g_string_append_printf (s, " --> ");
  gst_webvtt_enc_append_timestamp_to_string (ts + dur, s);
  g_string_append_c (s, '\n');

  /* text */
  if (gst_buffer_map (buf, &map_info, GST_MAP_READ)) {
    g_string_append_len (s, (const gchar *) map_info.data, map_info.size);
    gst_buffer_unmap (buf, &map_info);
  }

  g_string_append (s, "\n\n");

  buf_size = s->len;
  new_buffer = gst_buffer_new_wrapped (g_string_free (s, FALSE), buf_size);

  GST_BUFFER_TIMESTAMP (new_buffer) = GST_BUFFER_TIMESTAMP (buf);
  GST_BUFFER_DURATION (new_buffer) = GST_BUFFER_DURATION (buf);

  ret = gst_pad_push (webvttenc->srcpad, new_buffer);

out:

  gst_buffer_unref (buf);

  return ret;
}

static gboolean
gst_webvtt_enc_event (GstPad * pad, GstObject * parent, GstEvent * event)
{
  GstWebvttEnc *webvttenc = GST_WEBVTT_ENC (parent);
  gboolean ret;

  switch (GST_EVENT_TYPE (event)) {
    case GST_EVENT_CAPS:
    {
      GstCaps *caps;

      caps = gst_static_pad_template_get_caps (&src_template);
      gst_pad_set_caps (webvttenc->srcpad, caps);
      gst_caps_unref (caps);
      gst_event_unref (event);
      ret = TRUE;
      break;
    }
    default:
      ret = gst_pad_event_default (pad, parent, event);
      break;
  }

  return ret;
}

static void
gst_webvtt_enc_reset (GstWebvttEnc * webvttenc)
{
  webvttenc->counter = 1;
}

static GstStateChangeReturn
gst_webvtt_enc_change_state (GstElement * element, GstStateChange transition)
{
  GstStateChangeReturn ret;
  GstWebvttEnc *webvttenc = GST_WEBVTT_ENC (element);

  ret = GST_ELEMENT_CLASS (parent_class)->change_state (element, transition);
  if (ret == GST_STATE_CHANGE_FAILURE)
    return ret;

  switch (transition) {
    case GST_STATE_CHANGE_PAUSED_TO_READY:
      gst_webvtt_enc_reset (webvttenc);
      break;
    default:
      break;
  }

  return ret;
}

static void
gst_webvtt_enc_get_property (GObject * object,
    guint prop_id, GValue * value, GParamSpec * pspec)
{
  GstWebvttEnc *webvttenc;

  webvttenc = GST_WEBVTT_ENC (object);

  switch (prop_id) {
    case ARG_TIMESTAMP:
      g_value_set_int64 (value, webvttenc->timestamp);
      break;
    case ARG_DURATION:
      g_value_set_int64 (value, webvttenc->duration);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }
}

static void
gst_webvtt_enc_set_property (GObject * object,
    guint prop_id, const GValue * value, GParamSpec * pspec)
{

  GstWebvttEnc *webvttenc;

  webvttenc = GST_WEBVTT_ENC (object);

  switch (prop_id) {
    case ARG_TIMESTAMP:
      webvttenc->timestamp = g_value_get_int64 (value);
      break;
    case ARG_DURATION:
      webvttenc->duration = g_value_get_int64 (value);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }
}

static void
gst_webvtt_enc_class_init (GstWebvttEncClass * klass)
{
  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
  GstElementClass *element_class = GST_ELEMENT_CLASS (klass);

  gobject_class->set_property = GST_DEBUG_FUNCPTR (gst_webvtt_enc_set_property);
  gobject_class->get_property = GST_DEBUG_FUNCPTR (gst_webvtt_enc_get_property);

  element_class->change_state = GST_DEBUG_FUNCPTR (gst_webvtt_enc_change_state);

  g_object_class_install_property (gobject_class, ARG_TIMESTAMP,
      g_param_spec_int64 ("timestamp", "Offset for the starttime",
          "Offset for the starttime for the subtitles", G_MININT64, G_MAXINT64,
          0,
          G_PARAM_READWRITE | GST_PARAM_CONTROLLABLE | G_PARAM_STATIC_STRINGS));
  g_object_class_install_property (gobject_class, ARG_DURATION,
      g_param_spec_int64 ("duration", "Offset for the duration",
          "Offset for the duration of the subtitles", G_MININT64, G_MAXINT64,
          0,
          G_PARAM_READWRITE | GST_PARAM_CONTROLLABLE | G_PARAM_STATIC_STRINGS));

  gst_element_class_add_pad_template (element_class,
      gst_static_pad_template_get (&sink_template));
  gst_element_class_add_pad_template (element_class,
      gst_static_pad_template_get (&src_template));

  gst_element_class_set_static_metadata (element_class,
      "WebVTT encoder", "Codec/Encoder/Subtitle",
      "WebVTT subtitle encoder", "David Schleef <ds@schleef.org>");

  GST_DEBUG_CATEGORY_INIT (webvttenc_debug, "webvttenc", 0,
      "SubRip subtitle encoder");
}

static void
gst_webvtt_enc_init (GstWebvttEnc * webvttenc)
{
  gst_webvtt_enc_reset (webvttenc);

  webvttenc->srcpad = gst_pad_new_from_static_template (&src_template, "src");
  gst_element_add_pad (GST_ELEMENT (webvttenc), webvttenc->srcpad);
  webvttenc->sinkpad =
      gst_pad_new_from_static_template (&sink_template, "sink");
  gst_pad_set_chain_function (webvttenc->sinkpad,
      GST_DEBUG_FUNCPTR (gst_webvtt_enc_chain));
  gst_pad_set_event_function (webvttenc->sinkpad,
      GST_DEBUG_FUNCPTR (gst_webvtt_enc_event));
  gst_element_add_pad (GST_ELEMENT (webvttenc), webvttenc->sinkpad);
}