set min: number of decoded surfaces to non-zero value for ffmpeg based decoding (#627)

[ROCm/rocdecode commit: d9690d1715]

projects/rocdecode/src/rocdecode-host/avcodec/avcodec_videodecoder.cpp

@@ -388,7 +388,8 @@ rocDecStatus AvcodecVideoDecoder::NotifyNewSequence(AVFrame *p_frame) {
     p_video_format->bit_depth_luma_minus8 = BitDepthFromPixelFormat(dec_context_->pix_fmt) - 8;
     p_video_format->bit_depth_chroma_minus8 = p_video_format->bit_depth_luma_minus8;
     p_video_format->progressive_sequence = !p_frame->interlaced_frame;
-    p_video_format->min_num_decode_surfaces = dec_context_->delay + dec_context_->max_b_frames;
+    //number of decode surfaces are internal and not exposed in avcodec based decoding. Setting some value for sanity
+    p_video_format->min_num_decode_surfaces = dec_frames_.size();
     p_video_format->coded_width = p_frame->linesize[0];
     p_video_format->coded_height = p_frame->height;
     p_video_format->chroma_format = AVPixelFormat2rocDecVideoChromaFormat(dec_context_->pix_fmt);