gstbasetransform.c

gnash 在pc和嵌入式下开发需要的源码

  gboolean ret;

  klass = GST_BASE_TRANSFORM_GET_CLASS (trans);

  GST_DEBUG_OBJECT (trans, "asked to transform size %d for caps %"
      GST_PTR_FORMAT " to size for caps %" GST_PTR_FORMAT " in direction %s",
      size, caps, othercaps, direction == GST_PAD_SRC ? "SRC" : "SINK");

  /* if there is a custom transform function, use this */
  if (klass->transform_size) {
    ret = klass->transform_size (trans, direction, caps, size, othercaps,
        othersize);
  } else {
    if (!gst_base_transform_get_unit_size (trans, caps, &inunitsize))
      goto no_in_size;

    GST_DEBUG_OBJECT (trans, "input size %d, input unit size %d", size,
        inunitsize);

    if (inunitsize == 0 || (size % inunitsize != 0))
      goto no_multiple;

    units = size / inunitsize;
    if (!gst_base_transform_get_unit_size (trans, othercaps, &outunitsize))
      goto no_out_size;

    *othersize = units * outunitsize;
    GST_DEBUG_OBJECT (trans, "transformed size to %d", *othersize);

    ret = TRUE;
  }
  return ret;

  /* ERRORS */
no_in_size:
  {
    GST_DEBUG_OBJECT (trans, "could not get in_size");
    g_warning ("could not get in_size");
    return FALSE;
  }
no_multiple:
  {
    GST_DEBUG_OBJECT (trans, "Size %u is not a multiple of unit size %u", size,
        inunitsize);
    g_warning ("Size %u is not a multiple of unit size %u", size, inunitsize);
    return FALSE;
  }
no_out_size:
  {
    GST_DEBUG_OBJECT (trans, "could not get out_size");
    g_warning ("could not get out_size");
    return FALSE;
  }
}

static GstCaps *
gst_base_transform_getcaps (GstPad * pad)
{
  GstBaseTransform *trans;
  GstPad *otherpad;
  GstCaps *caps;

  trans = GST_BASE_TRANSFORM (gst_pad_get_parent (pad));

  otherpad = (pad == trans->srcpad) ? trans->sinkpad : trans->srcpad;

  /* we can do what the peer can */
  caps = gst_pad_peer_get_caps (otherpad);
  if (caps) {
    GstCaps *temp;
    const GstCaps *templ;

    GST_DEBUG_OBJECT (pad, "peer caps  %" GST_PTR_FORMAT, caps);

    /* filtered against our padtemplate */
    templ = gst_pad_get_pad_template_caps (otherpad);
    GST_DEBUG_OBJECT (pad, "our template  %" GST_PTR_FORMAT, templ);
    temp = gst_caps_intersect (caps, templ);
    GST_DEBUG_OBJECT (pad, "intersected %" GST_PTR_FORMAT, temp);
    gst_caps_unref (caps);
    /* then see what we can transform this to */
    caps = gst_base_transform_transform_caps (trans,
        GST_PAD_DIRECTION (otherpad), temp);
    GST_DEBUG_OBJECT (pad, "transformed  %" GST_PTR_FORMAT, caps);
    gst_caps_unref (temp);
    if (caps == NULL)
      goto done;

    /* and filter against the template again */
    templ = gst_pad_get_pad_template_caps (pad);
    GST_DEBUG_OBJECT (pad, "our template  %" GST_PTR_FORMAT, templ);
    temp = gst_caps_intersect (caps, templ);
    GST_DEBUG_OBJECT (pad, "intersected %" GST_PTR_FORMAT, temp);
    gst_caps_unref (caps);
    /* this is what we can do */
    caps = temp;
  } else {
    /* no peer, our padtemplate is enough then */
    caps = gst_caps_copy (gst_pad_get_pad_template_caps (pad));
  }

done:
  GST_DEBUG_OBJECT (trans, "returning  %" GST_PTR_FORMAT, caps);

  gst_object_unref (trans);

  return caps;
}

/* function triggered when the in and out caps are negotiated and need
 * to be configured in the subclass. */
static gboolean
gst_base_transform_configure_caps (GstBaseTransform * trans, GstCaps * in,
    GstCaps * out)
{
  gboolean ret = TRUE;
  GstBaseTransformClass *klass;

  klass = GST_BASE_TRANSFORM_GET_CLASS (trans);

  /* clear the cache */
  gst_caps_replace (&trans->cache_caps1, NULL);
  gst_caps_replace (&trans->cache_caps2, NULL);

  /* If we've a transform_ip method and same input/output caps, set in_place
   * by default. If for some reason the sub-class prefers using a transform
   * function, it can clear the in place flag in the set_caps */
  gst_base_transform_set_in_place (trans,
      klass->transform_ip && trans->have_same_caps);

  /* Set the passthrough if the class wants passthrough_on_same_caps
   * and we have the same caps on each pad */
  if (klass->passthrough_on_same_caps)
    gst_base_transform_set_passthrough (trans, trans->have_same_caps);

  /* now configure the element with the caps */
  if (klass->set_caps) {
    GST_DEBUG_OBJECT (trans, "Calling set_caps method to setup caps");
    ret = klass->set_caps (trans, in, out);
  }

  trans->negotiated = ret;

  return ret;
}

/* called when new caps arrive on the sink or source pad */
static gboolean
gst_base_transform_setcaps (GstPad * pad, GstCaps * caps)
{
  GstBaseTransform *trans;
  GstBaseTransformClass *klass;
  GstPad *otherpad, *otherpeer;
  GstCaps *othercaps = NULL;
  gboolean ret = TRUE;
  gboolean peer_checked = FALSE;

  trans = GST_BASE_TRANSFORM (gst_pad_get_parent (pad));
  klass = GST_BASE_TRANSFORM_GET_CLASS (trans);

  otherpad = (pad == trans->srcpad) ? trans->sinkpad : trans->srcpad;
  otherpeer = gst_pad_get_peer (otherpad);

  /* if we get called recursively, we bail out now to avoid an
   * infinite loop. */
  if (GST_PAD_IS_IN_SETCAPS (otherpad))
    goto done;

  /* caps must be fixed here */
  if (!gst_caps_is_fixed (caps))
    goto unfixed_caps;

  /* see how we can transform the input caps. */
  othercaps = gst_base_transform_transform_caps (trans,
      GST_PAD_DIRECTION (pad), caps);

  /* The caps we can actually output is the intersection of the transformed
   * caps with the pad template for the pad */
  if (othercaps) {
    GstCaps *intersect;
    const GstCaps *templ_caps;

    templ_caps = gst_pad_get_pad_template_caps (otherpad);
    intersect = gst_caps_intersect (othercaps, templ_caps);

    gst_caps_unref (othercaps);
    othercaps = intersect;
  }

  /* check if transform is empty */
  if (!othercaps || gst_caps_is_empty (othercaps))
    goto no_transform;

  /* if the othercaps are not fixed, we need to fixate them, first attempt
   * is by attempting passthrough if the othercaps are a superset of caps. */
  if (!gst_caps_is_fixed (othercaps)) {
    GstCaps *temp;

    GST_DEBUG_OBJECT (trans,
        "transform returned non fixed  %" GST_PTR_FORMAT, othercaps);

    /* see if the target caps are a superset of the source caps, in this
     * case we can try to perform passthrough */
    temp = gst_caps_intersect (othercaps, caps);
    GST_DEBUG_OBJECT (trans, "intersect returned %" GST_PTR_FORMAT, temp);
    if (temp) {
      if (!gst_caps_is_empty (temp) && otherpeer) {
        GST_DEBUG_OBJECT (trans, "try passthrough with %" GST_PTR_FORMAT, caps);
        /* try passthrough. we know it's fixed, because caps is fixed */
        if (gst_pad_accept_caps (otherpeer, caps)) {
          GST_DEBUG_OBJECT (trans, "peer accepted %" GST_PTR_FORMAT, caps);
          /* peer accepted unmodified caps, we free the original non-fixed
           * caps and work with the passthrough caps */
          gst_caps_unref (othercaps);
          othercaps = gst_caps_ref (caps);
          /* mark that we checked othercaps with the peer, this
           * makes sure we don't call accept_caps again with these same
           * caps */
          peer_checked = TRUE;
        } else {
          GST_DEBUG_OBJECT (trans,
              "peer did not accept %" GST_PTR_FORMAT, caps);
        }
      }
      gst_caps_unref (temp);
    }
  }

  /* second attempt at fixation is done by intersecting with
   * the peer caps */
  if (!gst_caps_is_fixed (othercaps) && otherpeer) {
    /* intersect against what the peer can do */
    GstCaps *peercaps;
    GstCaps *intersect;

    GST_DEBUG_OBJECT (trans, "othercaps now %" GST_PTR_FORMAT, othercaps);

    peercaps = gst_pad_get_caps (otherpeer);
    intersect = gst_caps_intersect (peercaps, othercaps);
    gst_caps_unref (peercaps);
    gst_caps_unref (othercaps);
    othercaps = intersect;
    peer_checked = FALSE;

    GST_DEBUG_OBJECT (trans,
        "filtering against peer yields %" GST_PTR_FORMAT, othercaps);
  }

  if (gst_caps_is_empty (othercaps))
    goto no_transform_possible;

  /* third attempt at fixation, call the fixate vmethod and
   * ultimately call the pad fixate function. */
  if (!gst_caps_is_fixed (othercaps)) {
    GstCaps *temp;

    GST_DEBUG_OBJECT (trans,
        "trying to fixate %" GST_PTR_FORMAT " on pad %s:%s",
        othercaps, GST_DEBUG_PAD_NAME (otherpad));

    /* since we have no other way to fixate left, we might as well just take
     * the first of the caps list and fixate that */

    /* FIXME: when fixating using the vmethod, it might make sense to fixate
     * each of the caps; but Wim doesn't see a use case for that yet */
    temp = gst_caps_copy_nth (othercaps, 0);
    gst_caps_unref (othercaps);
    othercaps = temp;
    peer_checked = FALSE;

    if (klass->fixate_caps) {
      GST_DEBUG_OBJECT (trans, "trying to fixate %" GST_PTR_FORMAT
          " using caps %" GST_PTR_FORMAT
          " on pad %s:%s using fixate_caps vmethod", othercaps, caps,
          GST_DEBUG_PAD_NAME (otherpad));
      klass->fixate_caps (trans, GST_PAD_DIRECTION (pad), caps, othercaps);
    }
    /* if still not fixed, no other option but to let the default pad fixate
     * function do its job */
    if (!gst_caps_is_fixed (othercaps)) {
      GST_DEBUG_OBJECT (trans, "trying to fixate %" GST_PTR_FORMAT
          " on pad %s:%s using gst_pad_fixate_caps", othercaps,
          GST_DEBUG_PAD_NAME (otherpad));
      gst_pad_fixate_caps (otherpad, othercaps);
    }
    GST_DEBUG_OBJECT (trans, "after fixating %" GST_PTR_FORMAT, othercaps);
  }

  /* caps should be fixed now, if not we have to fail. */
  if (!gst_caps_is_fixed (othercaps))
    goto could_not_fixate;

  /* and peer should accept, don't check again if we already checked the
   * othercaps against the peer. */
  if (!peer_checked && otherpeer && !gst_pad_accept_caps (otherpeer, othercaps))
    goto peer_no_accept;

  GST_DEBUG_OBJECT (trans, "Input caps were %" GST_PTR_FORMAT
      ", and got final caps %" GST_PTR_FORMAT, caps, othercaps);

  trans->have_same_caps = gst_caps_is_equal (caps, othercaps);
  GST_DEBUG_OBJECT (trans, "have_same_caps: %d", trans->have_same_caps);

  /* see if we have to configure the element now */
  if (!trans->delay_configure) {
    GstCaps *incaps, *outcaps;

    /* make sure in and out caps are correct */
    if (pad == trans->sinkpad) {
      incaps = caps;
      outcaps = othercaps;
    } else {
      incaps = othercaps;
      outcaps = caps;
    }
    /* call configure now */
    if (!(ret = gst_base_transform_configure_caps (trans, incaps, outcaps)))
      goto failed_configure;
  } else {
    /* set pending configure, the configure will happen later with the
     * caps we set on the pads above. */
    trans->pending_configure = TRUE;
  }

  /* we know this will work, we implement the setcaps */
  gst_pad_set_caps (otherpad, othercaps);

  if (pad == trans->srcpad && trans->priv->pad_mode == GST_ACTIVATE_PULL) {
    ret &= gst_pad_set_caps (otherpeer, othercaps);
    if (!ret) {
      GST_INFO_OBJECT (trans, "otherpeer setcaps(%" GST_PTR_FORMAT ") failed",
          othercaps);
    }
  }

done:
  if (otherpeer)
    gst_object_unref (otherpeer);
  if (othercaps)
    gst_caps_unref (othercaps);

  trans->negotiated = ret;

  gst_object_unref (trans);

  return ret;

  /* ERRORS */
unfixed_caps:
  {
    GST_DEBUG_OBJECT (trans, "caps are not fixed  %" GST_PTR_FORMAT, caps);
    ret = FALSE;
    goto done;
  }
no_transform:
  {
    GST_DEBUG_OBJECT (trans,
        "transform returned useless  %" GST_PTR_FORMAT, othercaps);
    ret = FALSE;
    goto done;
  }
no_transform_possible:
  {
    GST_DEBUG_OBJECT (trans,
        "transform could not transform %" GST_PTR_FORMAT
        " in anything we support", caps);
    ret = FALSE;
    goto done;
  }
could_not_fixate:
  {
    GST_ERROR_OBJECT (trans, "FAILED to fixate %" GST_PTR_FORMAT, othercaps);
    ret = FALSE;
    goto done;
  }
peer_no_accept:
  {
    GST_DEBUG_OBJECT (trans, "FAILED to get peer of %" GST_PTR_FORMAT
        " to accept %" GST_PTR_FORMAT, otherpad, othercaps);
    ret = FALSE;
    goto done;
  }
failed_configure:
  {
    GST_DEBUG_OBJECT (trans, "FAILED to configure caps %" GST_PTR_FORMAT
        " to accept %" GST_PTR_FORMAT, otherpad, othercaps);
    ret = FALSE;
    goto done;
  }
}

/* Allocate a buffer using gst_pad_alloc_buffer
 *
 * This function does not do renegotiation on the source pad
 *
 * The output buffer is always writable. outbuf can be equal to
 * inbuf, the caller should be prepared for this and perform 
 * appropriate refcounting.
 */
static GstFlowReturn
gst_base_transform_prepare_output_buffer (GstBaseTransform * trans,
    GstBuffer * in_buf, gint out_size, GstCaps * out_caps, GstBuffer ** out_buf)
{
  GstBaseTransformClass *bclass;
  GstFlowReturn ret = GST_FLOW_OK;
  gboolean copy_inbuf = FALSE;

  bclass = GST_BASE_TRANSFORM_GET_CLASS (trans);

  /* we cannot reconfigure the element yet as we are still processing
   * the old buffer. We will therefore delay the reconfiguration of the
   * element until we have processed this last buffer. */
  trans->delay_configure = TRUE;

  /* out_caps is the caps of the src pad gathered through the GST_PAD_CAPS 
     macro. If a set_caps occurs during this function this caps will become
     invalid. We want to keep them during preparation of the output buffer. */
  if (out_caps)
    gst_caps_ref (out_caps);

  /* see if the subclass wants to alloc a buffer */
  if (bclass->prepare_output_buffer) {
    ret =
        bclass->prepare_output_buffer (trans, in_buf, out_size, out_caps,
        out_buf);
    if (ret != GST_FLOW_OK)
      goto done;

    /* decrease refcount again if vmethod returned refcounted in_buf. This
     * is because we need to make sure that the buffer is writable for the
     * in_place transform. The docs of the vmethod say that you should return
     * a reffed inbuf, which is exactly what we don't want :), oh well.. */
    if (in_buf == *out_buf)
      gst_buffer_unref (in_buf);
  }

  /* See if we want to prepare the buffer for in place output */
  if (*out_buf == NULL && GST_BUFFER_SIZE (in_buf) == out_size
      && bclass->transform_ip) {
    if (gst_buffer_is_writable (in_buf)) {
      if (trans->have_same_caps) {
        /* Input buffer is already writable and caps are the same, return input as
         * output buffer. We don't take an additional ref since that would make the
         * output buffer not writable anymore. Caller should be prepared to deal
         * with proper refcounting of input/output buffers. */
        *out_buf = in_buf;
        GST_LOG_OBJECT (trans, "reuse input buffer");
      } else {
        /* Writable buffer, but need to change caps => subbuffer */
        *out_buf = gst_buffer_create_sub (in_buf, 0, GST_BUFFER_SIZE (in_buf));
        gst_caps_replace (&GST_BUFFER_CAPS (*out_buf), out_caps);
        GST_LOG_OBJECT (trans, "created sub-buffer of input buffer");
      }
      /* we are done now */
      goto done;
    } else {
      /* Make a writable buffer below and copy the data */
      copy_inbuf = TRUE;
      GST_LOG_OBJECT (trans, "need to copy input buffer to new output buffer");
    }
  }

  if (*out_buf == NULL) {
    /* Sub-class didn't already provide a buffer for us. Make one */
    ret = gst_pad_alloc_buffer (trans->srcpad,
        GST_BUFFER_OFFSET (in_buf), out_size, out_caps, out_buf);
    if (ret != GST_FLOW_OK || *out_buf == NULL)
      goto done;

    /* allocated buffer could be of different caps than what we requested */
    if (G_UNLIKELY (!gst_caps_is_equal (out_caps, GST_BUFFER_CAPS (*out_buf)))) {
      /* FIXME, it is possible we can reconfigure the transform with new caps at this
       * point but for now we just create a buffer ourselves */
      gst_buffer_unref (*out_buf);
      *out_buf = gst_buffer_new_and_alloc (out_size);
      gst_buffer_set_caps (*out_buf, out_caps);
    }
  }

  /* If the output buffer metadata is modifiable, copy timestamps and
   * buffer flags */
  if (*out_buf != in_buf && gst_buffer_is_metadata_writable (*out_buf)) {

    if (copy_inbuf && gst_buffer_is_writable (*out_buf))
      memcpy (GST_BUFFER_DATA (*out_buf), GST_BUFFER_DATA (in_buf), out_size);

    gst_buffer_copy_metadata (*out_buf, in_buf,
        GST_BUFFER_COPY_FLAGS | GST_BUFFER_COPY_TIMESTAMPS);