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

[Michael Niedermayer]

On Mon, Oct 09, 2023 at 02:30:21PM +0200, Andreas Rheinhardt wrote:
> Andreas Rheinhardt:
> > Michael Niedermayer:
> >> 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 at 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
> >>
> > 
> > It's part of the general switch to the loop-based iterators wherever
> > possible (it is better because it automatically indicates that the value
> > at the end of the loop doesn't matter and it also allows to more easily
> > move blocks of code around). I always use them when I touch a loop.
> > 
> > If it matters: That i in the outer scope survives this patchset, but it
> > won't survive for long.
> > 
> 
> Are you ok with this patch

ok


> and the rest of the patchset?  I'd like to
> apply it tomorrow unless there are objections.

i have no objections




thx

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Dictatorship naturally arises out of democracy, and the most aggravated
form of tyranny and slavery out of the most extreme liberty. -- Plato
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