Thanks for the review, Anton. Please find the updated patch attached.
BTW - what do you mean by "you should also forward the actual error code"?
Within the cuvid_handle_video_sequence() function in case of error,
function still returns 0 and sets internal context error, so I kept
behavior intact. Do I miss something?

пн, 5 июн. 2023 г. в 13:19, Anton Khirnov <anton@khirnov.net>:

> Quoting Roman Arzumanyan (2023-06-05 09:30:07)
> > Hello,
> >
> > This patch reduces vRAM usage by cuvid decoder implementation.
> > The number of surfaces used for decoding is updated within the parser
> > sequence decode callback.
> > Also the "surfaces" AVDictionary option specific to cuvid was removed in
> > favor of "extra_hw_surfaces".
>
> This can break existing workflows, you should deprecated the option
> instead and only remove it after some time has passed.
>
> >
> > vRAM consumption was tested on various videos and savings are between 1%
> > for 360p resolution up to 21% for some 1080p H.264 videos.
> > Decoding performance was tested on various H.264 and H.265 videos in
> > different resolutions from 360p and higher, no performance penalty was
> > found.
> >
> > From 32a1b016e88fa40b983318d4583750ef250a78d9 Mon Sep 17 00:00:00 2001
> > From: Roman Arzumanyan <r.arzumanyan@visionlabs.ai>
> > Date: Thu, 1 Jun 2023 11:17:39 +0300
> > Subject: [PATCH] libavcodec/cuviddec: determine DPB size from within
> cuvid
> >  parser
> >
> > ---
> >  libavcodec/cuviddec.c | 29 +++++++++++++++++++++++++++--
> >  1 file changed, 27 insertions(+), 2 deletions(-)
> >
> > diff --git a/libavcodec/cuviddec.c b/libavcodec/cuviddec.c
> > index 3d43bbd466..759ed49870 100644
> > --- a/libavcodec/cuviddec.c
> > +++ b/libavcodec/cuviddec.c
> > @@ -115,6 +115,12 @@ typedef struct CuvidParsedFrame
> >
> >  #define CHECK_CU(x) FF_CUDA_CHECK_DL(avctx, ctx->cudl, x)
> >
> > +// NV recommends [2;4] range
> > +#define CUVID_MAX_DISPLAY_DELAY (4)
> > +
> > +// Actual DPB size will be determined by parser.
> > +#define CUVID_DEFAULT_NUM_SURFACES (CUVID_MAX_DISPLAY_DELAY + 1)
> > +
> >  static int CUDAAPI cuvid_handle_video_sequence(void *opaque,
> CUVIDEOFORMAT* format)
> >  {
> >      AVCodecContext *avctx = opaque;
> > @@ -309,6 +315,25 @@ static int CUDAAPI cuvid_handle_video_sequence(void
> *opaque, CUVIDEOFORMAT* form
> >          return 0;
> >      }
> >
> > +    if (ctx->nb_surfaces < format->min_num_decode_surfaces + 3)
> > +        ctx->nb_surfaces = format->min_num_decode_surfaces + 3;
>
> FFMAX()
>
> > +
> > +    if (avctx->extra_hw_frames > 0)
> > +        ctx->nb_surfaces += avctx->extra_hw_frames;
> > +
> > +    if (0 > av_fifo_realloc2(ctx->frame_queue, ctx->nb_surfaces *
> sizeof(CuvidParsedFrame))) {
>
> this is the old deprecated AVFifoBuffer API, you cannot use it with
> AVFifo objects
>
> you should also forward the actual error code
>
> > +        av_log(avctx, AV_LOG_ERROR, "Failed to recreate frame queue on
> video sequence callback\n");
> > +        ctx->internal_error = AVERROR(EINVAL);
> > +        return 0;
> > +    }
> > +
> > +    ctx->key_frame = av_realloc_array(ctx->key_frame, ctx->nb_surfaces,
> sizeof(int));
> > +    if (!ctx->key_frame) {
> > +        av_log(avctx, AV_LOG_ERROR, "Failed to recreate key frame queue
> on video sequence callback\n");
> > +        ctx->internal_error = AVERROR(EINVAL);
>
> Leaks key_frame on failure and should be ENOMEM.
>
> --
> Anton Khirnov
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