[FFmpeg-devel] [PATCH 2/2] libavcodec/sanm: codec47: apply top offset also to diff buffers

[Manuel Lauss]

Hello,

Ping?

On Fri, Nov 8, 2024 at 12:51 PM Manuel Lauss <manuel.lauss at gmail.com> wrote:
>
> SAN FRME objects specify width/height as well as offsets from top/left.
> These offsets need to be taken into account for the diff buffers
> as well.  Fixes playback of all SAN videos of "Shadows of the Empire",
> which have a constant top offset of 60 (640x272 video on a 640x480 window)
> and show tons of ghosting and block artifacts.
>
> Signed-off-by: Manuel Lauss <manuel.lauss at gmail.com>
> ---
>  libavcodec/sanm.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/libavcodec/sanm.c b/libavcodec/sanm.c
> index fcf6234d8a..8bcffb1e90 100644
> --- a/libavcodec/sanm.c
> +++ b/libavcodec/sanm.c
> @@ -913,8 +913,8 @@ static int old_codec47(SANMVideoContext *ctx, int top,
>      int i, j;
>      ptrdiff_t stride = ctx->pitch;
>      uint8_t *dst   = (uint8_t *)ctx->frm0 + left + top * stride;
> -    uint8_t *prev1 = (uint8_t *)ctx->frm1;
> -    uint8_t *prev2 = (uint8_t *)ctx->frm2;
> +    uint8_t *prev1 = (uint8_t *)ctx->frm1 + left + top * stride;
> +    uint8_t *prev2 = (uint8_t *)ctx->frm2 + left + top * stride;
>      uint8_t auxcol[2];
>      int tbl_pos = bytestream2_tell(&ctx->gb);
>      int seq     = bytestream2_get_le16(&ctx->gb);
> @@ -940,8 +940,8 @@ static int old_codec47(SANMVideoContext *ctx, int top,
>      }
>      if (!seq) {
>          ctx->prev_seq = -1;
> -        memset(prev1, auxcol[0], ctx->height * stride);
> -        memset(prev2, auxcol[1], ctx->height * stride);
> +        memset(prev1, auxcol[0], (ctx->height - top) * stride);
> +        memset(prev2, auxcol[1], (ctx->height - top) * stride);
>      }
>
>      switch (compr) {
> --
> 2.47.0
>