[FFmpeg-devel] [PATCH] avcodec/nvdec: don't free NVDECContext->bitstream

[Timo Rothenpieler]

On 06.02.2024 23:57, James Almer wrote:
> Ensure all hwaccels that allocate a buffer use NVDECContext->bitstream_internal.
> 
> Signed-off-by: James Almer <jamrial at gmail.com>
> ---
>   libavcodec/nvdec.c      | 2 +-
>   libavcodec/nvdec_h264.c | 4 ++--
>   libavcodec/nvdec_hevc.c | 4 ++--
>   3 files changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/libavcodec/nvdec.c b/libavcodec/nvdec.c
> index 27be644356..d13b790632 100644
> --- a/libavcodec/nvdec.c
> +++ b/libavcodec/nvdec.c
> @@ -259,8 +259,8 @@ int ff_nvdec_decode_uninit(AVCodecContext *avctx)
>   {
>       NVDECContext *ctx = avctx->internal->hwaccel_priv_data;
>   
> -    av_freep(&ctx->bitstream);
>       av_freep(&ctx->bitstream_internal);
> +    ctx->bitstream           = NULL;
>       ctx->bitstream_len       = 0;
>       ctx->bitstream_allocated = 0;
>   
> diff --git a/libavcodec/nvdec_h264.c b/libavcodec/nvdec_h264.c
> index f022619b64..8c72d5f4f7 100644
> --- a/libavcodec/nvdec_h264.c
> +++ b/libavcodec/nvdec_h264.c
> @@ -138,11 +138,11 @@ static int nvdec_h264_decode_slice(AVCodecContext *avctx, const uint8_t *buffer,
>       const H264SliceContext *sl = &h->slice_ctx[0];
>       void *tmp;
>   
> -    tmp = av_fast_realloc(ctx->bitstream, &ctx->bitstream_allocated,
> +    tmp = av_fast_realloc(ctx->bitstream_internal, &ctx->bitstream_allocated,
>                             ctx->bitstream_len + size + 3);
>       if (!tmp)
>           return AVERROR(ENOMEM);
> -    ctx->bitstream = tmp;
> +    ctx->bitstream = ctx->bitstream_internal = tmp;
>   
>       tmp = av_fast_realloc(ctx->slice_offsets, &ctx->slice_offsets_allocated,
>                             (ctx->nb_slices + 1) * sizeof(*ctx->slice_offsets));
> diff --git a/libavcodec/nvdec_hevc.c b/libavcodec/nvdec_hevc.c
> index b83d5edcf9..25319a1328 100644
> --- a/libavcodec/nvdec_hevc.c
> +++ b/libavcodec/nvdec_hevc.c
> @@ -274,11 +274,11 @@ static int nvdec_hevc_decode_slice(AVCodecContext *avctx, const uint8_t *buffer,
>       NVDECContext *ctx = avctx->internal->hwaccel_priv_data;
>       void *tmp;
>   
> -    tmp = av_fast_realloc(ctx->bitstream, &ctx->bitstream_allocated,
> +    tmp = av_fast_realloc(ctx->bitstream_internal, &ctx->bitstream_allocated,
>                             ctx->bitstream_len + size + 3);
>       if (!tmp)
>           return AVERROR(ENOMEM);
> -    ctx->bitstream = tmp;
> +    ctx->bitstream = ctx->bitstream_internal = tmp;
>   
>       tmp = av_fast_realloc(ctx->slice_offsets, &ctx->slice_offsets_allocated,
>                             (ctx->nb_slices + 1) * sizeof(*ctx->slice_offsets));

bitstream_internal was added for the av1 slice reconstructions.
Probably for the exact reason to avoid this confusion.

Looking at this some more... With this patch in place, there should 
never be a situation in which we want to free/freep ctx->bitstream?
So the freep() on it should probably be removed alongside, and replace 
with just setting it to NULL.