avcodec/h264: implement new decode_params callback for PPS/SPS

This callback will be used by the VideoToolbox H264 hwaccel so that it
can receive SPS and PPS NALUs. VideoToolbox requires PPS changes to be
fed into the decoder session, and for the session to be recreated when
the SPS changes.
Signed-off-by: Aman Gupta <aman@tmm1.net>

libavcodec/h264dec.c

@@ -713,6 +713,14 @@ static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size)
             break;
         case H264_NAL_SPS: {
             GetBitContext tmp_gb = nal->gb;
+            if (avctx->hwaccel && avctx->hwaccel->decode_params) {
+                ret = avctx->hwaccel->decode_params(avctx,
+                                                    nal->type,
+                                                    nal->raw_data,
+                                                    nal->raw_size);
+                if (ret < 0)
+                    goto end;
+            }
             if (ff_h264_decode_seq_parameter_set(&tmp_gb, avctx, &h->ps, 0) >= 0)
                 break;
             av_log(h->avctx, AV_LOG_DEBUG,
@@ -724,6 +732,14 @@ static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size)
             break;
         }
         case H264_NAL_PPS:
+            if (avctx->hwaccel && avctx->hwaccel->decode_params) {
+                ret = avctx->hwaccel->decode_params(avctx,
+                                                    nal->type,
+                                                    nal->raw_data,
+                                                    nal->raw_size);
+                if (ret < 0)
+                    goto end;
+            }
             ret = ff_h264_decode_picture_parameter_set(&nal->gb, avctx, &h->ps,
                                                        nal->size_bits);
             if (ret < 0 && (h->avctx->err_recognition & AV_EF_EXPLODE))