avcodec/nvdec: make explicit copy of frames unless user requested oth…

…erwise

libavcodec/nvdec.c

@@ -51,6 +51,8 @@ typedef struct NVDECDecoder {
 
  CudaFunctions *cudl;
  CuvidFunctions *cvdl;
+
+ int unsafe_output;
 } NVDECDecoder;
 
 typedef struct NVDECFramePool {
@@ -344,6 +346,8 @@ int ff_nvdec_decode_init(AVCodecContext *avctx)
  int cuvid_codec_type, cuvid_chroma_format, chroma_444;
  int ret = 0;
 
+ int unsafe_output = !!(avctx->hwaccel_flags & AV_HWACCEL_FLAG_UNSAFE_OUTPUT);
+
  sw_desc = av_pix_fmt_desc_get(avctx->sw_pix_fmt);
  if (!sw_desc)
  return AVERROR_BUG;
@@ -402,7 +406,7 @@ int ff_nvdec_decode_init(AVCodecContext *avctx)
  params.CodecType = cuvid_codec_type;
  params.ChromaFormat = cuvid_chroma_format;
  params.ulNumDecodeSurfaces = frames_ctx->initial_pool_size;
- params.ulNumOutputSurfaces = frames_ctx->initial_pool_size;
+ params.ulNumOutputSurfaces = unsafe_output ? frames_ctx->initial_pool_size : 1;
 
  ret = nvdec_decoder_create(&ctx->decoder_ref, frames_ctx->device_ref, &params, avctx);
  if (ret < 0) {
@@ -417,6 +421,7 @@ int ff_nvdec_decode_init(AVCodecContext *avctx)
  }
 
  decoder = (NVDECDecoder*)ctx->decoder_ref->data;
+ decoder->unsafe_output = unsafe_output;
  decoder->real_hw_frames_ref = real_hw_frames_ref;
  real_hw_frames_ref = NULL;
 
@@ -554,7 +559,11 @@ static int nvdec_retrieve_data(void *logctx, AVFrame *frame)
 
 finish:
  CHECK_CU(decoder->cudl->cuCtxPopCurrent(&dummy));
- return ret;
+
+ if (ret < 0 || decoder->unsafe_output)
+ return ret;
+
+ return av_frame_make_writable(frame);
 }
 
 int ff_nvdec_start_frame(AVCodecContext *avctx, AVFrame *frame)