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.arzuman...@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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