Andreas Rheinhardt:
> The allocated buffer of an AVFrame need not be height * linesize
> big. In case there is padding between lines, the last line need
> not have this padding. Pathological examples exist with height == 1
> (where linesize is not really meaningful); non-pathological examples
> are produced by the separatefields filter, which simply offsets
> the pointers and doubles linesize, so that the frame created from
> the bottom field has only height - 1 lines with padding (containing
> the top field) and one line without padding.
>
> The mpegvideo encoders sometimes copy the input frames for padding/
> alignment reasons and when doing so, there is a fast path in which
> everything is copied with one memcpy() of height * linesize. And
> this is wrong as explained above. Use av_image_copy_plane() instead
> of our ad-hoc code for copying.
>
> Fixes ticket #10754 (discovered by Zeng Yunxiang).
>
> (The above discussion presupposes linesize > 0 and would need some
> adaptation for negative linesizes; the code removed seems even more
> buggy for negative linesizes.)
>
> Signed-off-by: Andreas Rheinhardt <andreas.rheinha...@outlook.com>
> ---
> 1. One could also use av_image_copy().
> 2. The "direct" (non-copy) path only ensures a height mod 16, yet
> the non-direct mode sometimes pads to 32 (for non-progressive mpeg2).
> Seems fishy.
>
> libavcodec/mpegvideo_enc.c | 19 ++++---------------
> 1 file changed, 4 insertions(+), 15 deletions(-)
>
> diff --git a/libavcodec/mpegvideo_enc.c b/libavcodec/mpegvideo_enc.c
> index 6d2d417454..fac9bb7ae7 100644
> --- a/libavcodec/mpegvideo_enc.c
> +++ b/libavcodec/mpegvideo_enc.c
> @@ -36,6 +36,7 @@
> #include <stdint.h>
>
> #include "libavutil/emms.h"
> +#include "libavutil/imgutils.h"
> #include "libavutil/internal.h"
> #include "libavutil/intmath.h"
> #include "libavutil/mathematics.h"
> @@ -1201,28 +1202,16 @@ static int load_input_picture(MpegEncContext *s,
> const AVFrame *pic_arg)
> int w = s->width >> h_shift;
> int h = s->height >> v_shift;
> const uint8_t *src = pic_arg->data[i];
> - uint8_t *dst = pic->f->data[i];
> + uint8_t *dst = pic->f->data[i] + !s->avctx->rc_buffer_size *
> INPLACE_OFFSET;
> int vpad = 16;
>
> + av_image_copy_plane(dst, dst_stride, src, src_stride, w, h);
> +
> if ( s->codec_id == AV_CODEC_ID_MPEG2VIDEO
> && !s->progressive_sequence
> && FFALIGN(s->height, 32) - s->height > 16)
> vpad = 32;
>
> - if (!s->avctx->rc_buffer_size)
> - dst += INPLACE_OFFSET;
> -
> - if (src_stride == dst_stride)
> - memcpy(dst, src, src_stride * h);
> - else {
> - int h2 = h;
> - uint8_t *dst2 = dst;
> - while (h2--) {
> - memcpy(dst2, src, w);
> - dst2 += dst_stride;
> - src += src_stride;
> - }
> - }
> if ((s->width & 15) || (s->height & (vpad-1))) {
> s->mpvencdsp.draw_edges(dst, dst_stride,
> w, h,
Will apply this patch tomorrow unless there are objections.
- Andreas
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