basevideodecoder: really and only set src pad caps whenever requested

... since subclass is expected to be wise enough to know when to do so.

ext/schroedinger/gstschrodec.c

@@ -382,9 +382,7 @@ parse_sequence_header (GstSchroDec * schro_dec, guint8 * data, int size)
     state->par_d = video_format.aspect_ratio_denominator;
     GST_DEBUG ("Pixel aspect ratio is %d/%d", state->par_n, state->par_d);
 
-    /* FIXME state points to what is actually in the decoder */
-    //gst_base_video_decoder_set_state (GST_BASE_VIDEO_DECODER (schro_dec),
-    //    state);
+    gst_base_video_decoder_set_src_caps (GST_BASE_VIDEO_DECODER (schro_dec));
   } else {
     GST_WARNING ("Failed to get frame rate from sequence header");
   }

ext/vp8/gstvp8dec.c

@@ -399,11 +399,11 @@ gst_vp8_dec_handle_frame (GstBaseVideoDecoder * decoder, GstVideoFrame * frame)
       return GST_FLOW_OK;
     }
 
-    /* should set size here */
     state->width = stream_info.w;
     state->height = stream_info.h;
     state->format = GST_VIDEO_FORMAT_I420;
     gst_vp8_dec_send_tags (dec);
+    gst_base_video_decoder_set_src_caps (decoder);
 
     caps = vpx_codec_get_caps (&vpx_codec_vp8_dx_algo);
 
@@ -445,21 +445,6 @@ gst_vp8_dec_handle_frame (GstBaseVideoDecoder * decoder, GstVideoFrame * frame)
   if (!GST_BUFFER_FLAG_IS_SET (frame->sink_buffer, GST_BUFFER_FLAG_DELTA_UNIT))
     gst_base_video_decoder_set_sync_point (decoder);
 
-#if 0
-  if (GST_PAD_CAPS (GST_BASE_VIDEO_CODEC_SRC_PAD (decoder)) == NULL) {
-    GstCaps *caps;
-
-    caps = gst_video_format_new_caps (decoder->state.format,
-        decoder->state.width, decoder->state.height,
-        decoder->state.fps_n, decoder->state.fps_d,
-        decoder->state.par_n, decoder->state.par_d);
-
-    GST_DEBUG ("setting caps %" GST_PTR_FORMAT, caps);
-
-    gst_pad_set_caps (GST_BASE_VIDEO_CODEC_SRC_PAD (decoder), caps);
-  }
-#endif
-
   deadline = gst_base_video_decoder_get_max_decode_time (decoder, frame);
   if (deadline < 0) {
     decoder_deadline = 1;

gst-libs/gst/video/gstbasevideodecoder.c

@@ -1245,7 +1245,6 @@ gst_base_video_decoder_finish_frame (GstBaseVideoDecoder * base_video_decoder,
     GST_BASE_VIDEO_CODEC (base_video_decoder)->time = GST_CLOCK_TIME_NONE;
   }
 
-  gst_base_video_decoder_set_src_caps (base_video_decoder);
   gst_buffer_set_caps (src_buffer,
       GST_PAD_CAPS (GST_BASE_VIDEO_CODEC_SRC_PAD (base_video_decoder)));
 
@@ -1583,9 +1582,6 @@ gst_base_video_decoder_set_src_caps (GstBaseVideoDecoder * base_video_decoder)
   g_return_val_if_fail (state->width != 0, FALSE);
   g_return_val_if_fail (state->height != 0, FALSE);
 
-  if (GST_PAD_CAPS (GST_BASE_VIDEO_CODEC_SRC_PAD (base_video_decoder)) != NULL)
-    return;
-
   /* sanitize */
   if (state->fps_d == 0) {
     state->fps_n = 0;
@@ -1599,9 +1595,6 @@ gst_base_video_decoder_set_src_caps (GstBaseVideoDecoder * base_video_decoder)
   caps = gst_video_format_new_caps (state->format,
       state->width, state->height,
       state->fps_n, state->fps_d, state->par_n, state->par_d);
-  /* arrange for derived info */
-  state->bytes_per_picture =
-      gst_video_format_get_size (state->format, state->width, state->height);
   gst_caps_set_simple (caps, "interlaced",
       G_TYPE_BOOLEAN, state->interlaced, NULL);
 
@@ -1610,9 +1603,12 @@ gst_base_video_decoder_set_src_caps (GstBaseVideoDecoder * base_video_decoder)
   ret =
       gst_pad_set_caps (GST_BASE_VIDEO_CODEC_SRC_PAD (base_video_decoder),
       caps);
-
   gst_caps_unref (caps);
 
+  /* arrange for derived info */
+  state->bytes_per_picture =
+      gst_video_format_get_size (state->format, state->width, state->height);
+
   return ret;
 }
 
@@ -1635,8 +1631,6 @@ gst_base_video_decoder_alloc_src_buffer (GstBaseVideoDecoder *
   int num_bytes;
   GstVideoState *state = &GST_BASE_VIDEO_CODEC (base_video_decoder)->state;
 
-  gst_base_video_decoder_set_src_caps (base_video_decoder);
-
   num_bytes = gst_video_format_get_size (state->format, state->width,
       state->height);
   GST_DEBUG ("alloc src buffer caps=%" GST_PTR_FORMAT,
@@ -1663,7 +1657,8 @@ gst_base_video_decoder_alloc_src_buffer (GstBaseVideoDecoder *
  *
  * Helper function that uses gst_pad_alloc_buffer_and_set_caps
  * to allocate a buffer to hold a video frame for @base_video_decoder's
- * current #GstVideoState.
+ * current #GstVideoState.  Subclass should already have configured video state
+ * and set src pad caps.
  *
  * Returns: result from pad alloc call
  */
@@ -1672,13 +1667,14 @@ gst_base_video_decoder_alloc_src_frame (GstBaseVideoDecoder *
     base_video_decoder, GstVideoFrame * frame)
 {
   GstFlowReturn flow_ret;
-  int num_bytes;
   GstVideoState *state = &GST_BASE_VIDEO_CODEC (base_video_decoder)->state;
+  int num_bytes = state->bytes_per_picture;
 
-  gst_base_video_decoder_set_src_caps (base_video_decoder);
+  g_return_val_if_fail (state->bytes_per_picture != 0, GST_FLOW_ERROR);
+  g_return_val_if_fail (GST_PAD_CAPS (GST_BASE_VIDEO_CODEC_SRC_PAD
+          (base_video_decoder)) != NULL, GST_FLOW_ERROR);
 
-  num_bytes = gst_video_format_get_size (state->format, state->width,
-      state->height);
+  GST_LOG_OBJECT (base_video_decoder, "alloc buffer size %d", num_bytes);
   flow_ret =
       gst_pad_alloc_buffer_and_set_caps (GST_BASE_VIDEO_CODEC_SRC_PAD
       (base_video_decoder), GST_BUFFER_OFFSET_NONE, num_bytes,

gst-libs/gst/video/gstbasevideodecoder.h

@@ -109,8 +109,6 @@ struct _GstBaseVideoDecoder
 
   /* need mark discont */
   gboolean          discont;
-  /* src caps set */
-  gboolean          have_src_caps;
 
   /* combine to yield (presentation) ts */
   GstClockTime      timestamp_offset;