gstreamer/gst-libs/gst/video/convertframe.c

/* Small helper element for format conversion
 * Copyright (C) 2005 Tim-Philipp Müller <tim centricular net>
 * Copyright (C) 2010 Brandon Lewis <brandon.lewis@collabora.co.uk>
 * Copyright (C) 2010 Edward Hervey <edward.hervey@collabora.co.uk>
 *
 * 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., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#include <string.h>
#include "video.h"

static gboolean
caps_are_raw (const GstCaps * caps)
{
  guint i, len;

  len = gst_caps_get_size (caps);

  for (i = 0; i < len; i++) {
    GstStructure *st = gst_caps_get_structure (caps, i);
    if (gst_structure_has_name (st, "video/x-raw-yuv") ||
        gst_structure_has_name (st, "video/x-raw-rgb"))
      return TRUE;
  }

  return FALSE;
}

static gboolean
create_element (const gchar * factory_name, GstElement ** element,
    GError ** err)
{
  *element = gst_element_factory_make (factory_name, NULL);
  if (*element)
    return TRUE;

  if (err && *err == NULL) {
    *err = g_error_new (GST_CORE_ERROR, GST_CORE_ERROR_MISSING_PLUGIN,
        "cannot create element '%s' - please check your GStreamer installation",
        factory_name);
  }

  return FALSE;
}

static GstElement *
get_encoder (const GstCaps * caps, GError ** err)
{
  GList *encoders = NULL;
  GList *filtered = NULL;
  GstElementFactory *factory = NULL;
  GstElement *encoder = NULL;

  encoders =
      gst_element_factory_list_get_elements (GST_ELEMENT_FACTORY_TYPE_ENCODER |
      GST_ELEMENT_FACTORY_TYPE_MEDIA_IMAGE, GST_RANK_NONE);

  if (encoders == NULL) {
    *err = g_error_new (GST_CORE_ERROR, GST_CORE_ERROR_MISSING_PLUGIN,
        "Cannot find any image encoder");
    goto fail;
  }

  GST_INFO ("got factory list %p", encoders);
  gst_plugin_feature_list_debug (encoders);

  filtered =
      gst_element_factory_list_filter (encoders, caps, GST_PAD_SRC, FALSE);
  GST_INFO ("got filtered list %p", filtered);

  if (filtered == NULL) {
    gchar *tmp = gst_caps_to_string (caps);
    *err = g_error_new (GST_CORE_ERROR, GST_CORE_ERROR_MISSING_PLUGIN,
        "Cannot find any image encoder for caps %s", tmp);
    g_free (tmp);
    goto fail;
  }

  gst_plugin_feature_list_debug (filtered);

  factory = (GstElementFactory *) filtered->data;

  GST_INFO ("got factory %p", factory);
  encoder = gst_element_factory_create (factory, NULL);

  GST_INFO ("created encoder element %p, %s", encoder,
      gst_element_get_name (encoder));

fail:
  if (encoders)
    gst_plugin_feature_list_free (encoders);
  if (filtered)
    gst_plugin_feature_list_free (filtered);

  return encoder;
}

/**
 * gst_video_convert_frame:
 * @buf: a #GstBuffer
 * @to_caps: the #GstCaps to convert to
 * @timeout: the maximum amount of time allowed for the processing.
 * @err: pointer to a #GError. Can be %NULL.
 *
 * Converts a raw video buffer into the specified output caps.
 *
 * The output caps can be any raw video formats or any image formats (jpeg, png, ...).
 *
 * The width, height and pixel-aspect-ratio can also be specified in the output caps.
 *
 * Returns: The converted #GstBuffer, or %NULL if an error happened (in which case @err
 * will point to the #GError).
 */
GstBuffer *
gst_video_convert_frame (GstBuffer * buf, const GstCaps * to_caps,
    GstClockTime timeout, GError ** err)
{
  GstElement *src = NULL, *csp = NULL, *vscale = NULL, *sink = NULL, *encoder =
      NULL, *pipeline;
  GstMessage *msg;
  GstBuffer *result = NULL;
  GError *error = NULL;
  GstBus *bus;
  GstCaps *from_caps;
  GstFlowReturn ret;

  g_return_val_if_fail (buf != NULL, NULL);
  g_return_val_if_fail (to_caps != NULL, NULL);
  g_return_val_if_fail (GST_BUFFER_CAPS (buf) != NULL, NULL);

  from_caps = GST_BUFFER_CAPS (buf);

  /* videoscale is here to correct for the pixel-aspect-ratio for us */
  GST_DEBUG ("creating elements");
  if (!create_element ("appsrc", &src, &error) ||
      !create_element ("ffmpegcolorspace", &csp, &error) ||
      !create_element ("videoscale", &vscale, &error) ||
      !create_element ("appsink", &sink, &error))
    goto no_elements;

  pipeline = gst_pipeline_new ("videoconvert-pipeline");
  if (pipeline == NULL)
    goto no_pipeline;

  /* Add black borders if necessary to keep the DAR */
  g_object_set (vscale, "add-borders", TRUE, NULL);

  GST_DEBUG ("adding elements");
  gst_bin_add_many (GST_BIN (pipeline), src, csp, vscale, sink, NULL);

  /* set caps */
  g_object_set (src, "caps", from_caps, NULL);
  g_object_set (sink, "caps", to_caps, NULL);

  /* FIXME: linking is still way too expensive, profile this properly */
  GST_DEBUG ("linking src->csp");
  if (!gst_element_link_pads (src, "src", csp, "sink"))
    goto link_failed;

  GST_DEBUG ("linking csp->vscale");
  if (!gst_element_link_pads (csp, "src", vscale, "sink"))
    goto link_failed;

  if (caps_are_raw (to_caps)) {
    GST_DEBUG ("linking vscale->sink");

    if (!gst_element_link_pads (vscale, "src", sink, "sink"))
      goto link_failed;
  } else {
    encoder = get_encoder (to_caps, &error);
    if (!encoder)
      goto no_encoder;
    gst_bin_add (GST_BIN (pipeline), encoder);

    GST_DEBUG ("linking vscale->encoder");
    if (!gst_element_link (vscale, encoder))
      goto link_failed;

    GST_DEBUG ("linking encoder->sink");
    if (!gst_element_link_pads (encoder, "src", sink, "sink"))
      goto link_failed;
  }

  /* now set the pipeline to the paused state, after we push the buffer into
   * appsrc, this should preroll the converted buffer in appsink */
  GST_DEBUG ("running conversion pipeline to caps %" GST_PTR_FORMAT, to_caps);
  gst_element_set_state (pipeline, GST_STATE_PAUSED);

  /* feed buffer in appsrc */
  GST_DEBUG ("feeding buffer %p, size %u, caps %" GST_PTR_FORMAT,
      buf, GST_BUFFER_SIZE (buf), from_caps);
  g_signal_emit_by_name (src, "push-buffer", buf, &ret);

  /* now see what happens. We either got an error somewhere or the pipeline
   * prerolled */
  bus = gst_element_get_bus (pipeline);
  msg = gst_bus_timed_pop_filtered (bus,
      timeout, GST_MESSAGE_ERROR | GST_MESSAGE_ASYNC_DONE);

  if (msg) {
    switch (GST_MESSAGE_TYPE (msg)) {
      case GST_MESSAGE_ASYNC_DONE:
      {
        /* we're prerolled, get the frame from appsink */
        g_signal_emit_by_name (sink, "pull-preroll", &result);

        if (result) {
          GST_DEBUG ("conversion successful: result = %p", result);
        } else {
          GST_ERROR ("prerolled but no result frame?!");
        }
        break;
      }
      case GST_MESSAGE_ERROR:{
        gchar *dbg = NULL;

        gst_message_parse_error (msg, &error, &dbg);
        if (error) {
          GST_ERROR ("Could not convert video frame: %s", error->message);
          GST_DEBUG ("%s [debug: %s]", error->message, GST_STR_NULL (dbg));
          if (err)
            *err = error;
          else
            g_error_free (error);
        }
        g_free (dbg);
        break;
      }
      default:{
        g_return_val_if_reached (NULL);
      }
    }
    gst_message_unref (msg);
  } else {
    GST_ERROR ("Could not convert video frame: timeout during conversion");
    if (err)
      *err = g_error_new (GST_CORE_ERROR, GST_CORE_ERROR_FAILED,
          "Could not convert video frame: timeout during conversion");
  }

  gst_element_set_state (pipeline, GST_STATE_NULL);
  gst_object_unref (bus);
  gst_object_unref (pipeline);

  return result;

  /* ERRORS */
no_encoder:
  {
    GST_ERROR ("could not find an encoder for provided caps");
    if (err)
      *err = error;
    else
      g_error_free (error);
    return NULL;
  }
no_elements:
  {
    if (src)
      gst_object_unref (src);
    if (csp)
      gst_object_unref (csp);
    if (vscale)
      gst_object_unref (vscale);
    if (sink)
      gst_object_unref (sink);
    GST_ERROR ("Could not convert video frame: %s", error->message);
    if (err)
      *err = error;
    else
      g_error_free (error);
    return NULL;
  }
no_pipeline:
  {
    GST_ERROR ("Could not convert video frame: no pipeline (unknown error)");
    if (err)
      *err = g_error_new (GST_CORE_ERROR, GST_CORE_ERROR_FAILED,
          "Could not convert video frame: no pipeline (unknown error)");
    return NULL;
  }
link_failed:
  {
    GST_ERROR ("Could not convert video frame: failed to link elements");
    if (err)
      *err = g_error_new (GST_CORE_ERROR, GST_CORE_ERROR_NEGOTIATION,
          "Could not convert video frame: failed to link elements");
    gst_object_unref (pipeline);
    return NULL;
  }
}