[FFmpeg-devel] [PATCH] avcodec/dxvenc: Use proper alignment, write endian-independent output

[Sean McGovern]

Hi,

On Mon, Feb 26, 2024 at 6:48 PM Andreas Rheinhardt
<andreas.rheinhardt at outlook.com> wrote:
>
> Fixes the dxv3enc-dxt1 FATE test with UBSan.
>
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at outlook.com>
> ---
> I have not actually tested whether the output is actually wrong
> on BE systems. Would be nice if someone could.
>
>  libavcodec/dxvenc.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/libavcodec/dxvenc.c b/libavcodec/dxvenc.c
> index 1ce2b1d014..3f28fb696a 100644
> --- a/libavcodec/dxvenc.c
> +++ b/libavcodec/dxvenc.c
> @@ -149,7 +149,7 @@ typedef struct DXVEncContext {
>          } else {                                                              \
>              op = 0;                                                           \
>          }                                                                     \
> -        *value |= (op << (state * 2));                                        \
> +        AV_WL32(value, AV_RL32(value) | (op << (state * 2)));                 \
>          state++;                                                              \
>      } while (0)
>
> @@ -157,7 +157,7 @@ static int dxv_compress_dxt1(AVCodecContext *avctx)
>  {
>      DXVEncContext *ctx = avctx->priv_data;
>      PutByteContext *pbc = &ctx->pbc;
> -    uint32_t *value;
> +    void *value;
>      uint32_t color, lut, idx, color_idx, lut_idx, prev_pos, state = 16, pos = 2, op = 0;
>
>      ht_init(ctx->color_lookback_ht);

Confirming that this does fix the failing test on a big-endian PowerPC
+ Altivec virtual machine.

Thanks,
Sean McGovern