Re: [FFmpeg-devel] [PATCH 06/13] avcodec/mpegvideo_enc: Don't overallocate arrays

From: Michael Niedermayer <michael@niedermayer.cc>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: Re: [FFmpeg-devel] [PATCH 06/13] avcodec/mpegvideo_enc: Don't overallocate arrays
Date: Sat, 7 Oct 2023 18:33:13 +0200
Message-ID: <20231007163313.GP3543730@pb2> (raw)
In-Reply-To: <AS8P250MB0744E573A29753776E0FA3578FC9A@AS8P250MB0744.EURP250.PROD.OUTLOOK.COM>

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On Fri, Oct 06, 2023 at 04:46:29AM +0200, Andreas Rheinhardt wrote:
> Only entries 0..max_b_frames are ever used.
> 
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
> ---
>  libavcodec/mpegvideo_enc.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/libavcodec/mpegvideo_enc.c b/libavcodec/mpegvideo_enc.c
> index 1e0aed8db9..c06fdd08fe 100644
> --- a/libavcodec/mpegvideo_enc.c
> +++ b/libavcodec/mpegvideo_enc.c
> @@ -819,8 +819,8 @@ av_cold int ff_mpv_encode_init(AVCodecContext *avctx)
>          !FF_ALLOCZ_TYPED_ARRAY(s->q_intra_matrix16,        32) ||
>          !FF_ALLOCZ_TYPED_ARRAY(s->q_chroma_intra_matrix16, 32) ||
>          !FF_ALLOCZ_TYPED_ARRAY(s->q_inter_matrix16,        32) ||
> -        !FF_ALLOCZ_TYPED_ARRAY(s->input_picture,           MAX_PICTURE_COUNT) ||
> -        !FF_ALLOCZ_TYPED_ARRAY(s->reordered_input_picture, MAX_PICTURE_COUNT))
> +        !FF_ALLOCZ_TYPED_ARRAY(s->input_picture,           MAX_B_FRAMES + 1) ||
> +        !FF_ALLOCZ_TYPED_ARRAY(s->reordered_input_picture, MAX_B_FRAMES + 1))
>          return AVERROR(ENOMEM);
>  
>      /* Allocate MV tables; the MV and MB tables will be copied
> @@ -1231,7 +1231,7 @@ static int load_input_picture(MpegEncContext *s, const AVFrame *pic_arg)
>      }
>  
>      /* shift buffer entries */
> -    for (i = flush_offset; i < MAX_PICTURE_COUNT /*s->encoding_delay + 1*/; i++)
> +    for (int i = flush_offset; i <= MAX_B_FRAMES; i++)
>          s->input_picture[i - flush_offset] = s->input_picture[i];
>  
>      s->input_picture[encoding_delay] = pic;
> @@ -1450,9 +1450,9 @@ static int select_input_picture(MpegEncContext *s)
>  {
>      int i, ret;
>  
> -    for (i = 1; i < MAX_PICTURE_COUNT; i++)
> +    for (int i = 1; i <= MAX_B_FRAMES; i++)
>          s->reordered_input_picture[i - 1] = s->reordered_input_picture[i];

I see the addition of "int" and that seems neither needed nor
explained why in the commit message

thx

[...]
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Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

"I am not trying to be anyone's saviour, I'm trying to think about the
 future and not be sad" - Elon Musk

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