Re: [FFmpeg-devel] [PATCH 2/2] avcodec/apedec: Fix 48khz 24bit below insane level

[Paul B Mahol <onemda@gmail.com>]

On Fri, Aug 25, 2023 at 5:13 PM Michael Niedermayer <michael@niedermayer.cc>
wrote:

> Fixes: Ticket9816
> Fixes: vlc.ape and APE_48K_24bit_2CH_02_01.ape
>
> Regression since: ed0001482a74b60f3d5bc5cd7e304c9d65b2fcd5.
>
> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> ---
>  libavcodec/apedec.c | 15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/libavcodec/apedec.c b/libavcodec/apedec.c
> index 7bad8500e1..b1cceb9395 100644
> --- a/libavcodec/apedec.c
> +++ b/libavcodec/apedec.c
> @@ -1184,7 +1184,9 @@ static void predictor_decode_mono_3930(APEContext
> *ctx, int count)
>  static av_always_inline int predictor_update_filter(APEPredictor64 *p,
>                                                      const int decoded,
> const int filter,
>                                                      const int delayA,
> const int delayB,
> -                                                    const int adaptA,
> const int adaptB)
> +                                                    const int adaptA,
> const int adaptB,
> +                                                    int compression_level
> +                                                   )
>

Why on ')' separate line?


>  {
>      int64_t predictionA, predictionB;
>      int32_t sign;
> @@ -1212,7 +1214,12 @@ static av_always_inline int
> predictor_update_filter(APEPredictor64 *p,
>                    p->buf[delayB - 3] * p->coeffsB[filter][3] +
>                    p->buf[delayB - 4] * p->coeffsB[filter][4];
>
> -    p->lastA[filter] = decoded + ((int64_t)((uint64_t)predictionA +
> (predictionB >> 1)) >> 10);
> +    if (compression_level < COMPRESSION_LEVEL_INSANE) {
> +        predictionA = (int32_t)predictionA;
> +        predictionB = (int32_t)predictionB;
> +        p->lastA[filter] = decoded + ((int32_t)(predictionA +
> (predictionB >> 1)) >> 10);
> +    } else
> +        p->lastA[filter] = decoded + ((int64_t)((uint64_t)predictionA +
> (predictionB >> 1)) >> 10);
>

Please make {} block.


>      p->filterA[filter] = p->lastA[filter] + ((int64_t)(p->filterA[filter]
> * 31ULL) >> 5);
>
>      sign = APESIGN(decoded);
> @@ -1240,10 +1247,10 @@ static void
> predictor_decode_stereo_3950(APEContext *ctx, int count)
>      while (count--) {
>          /* Predictor Y */
>          *decoded0 = predictor_update_filter(p, *decoded0, 0, YDELAYA,
> YDELAYB,
> -                                            YADAPTCOEFFSA, YADAPTCOEFFSB);
> +                                            YADAPTCOEFFSA, YADAPTCOEFFSB,
> ctx->compression_level);
>          decoded0++;
>          *decoded1 = predictor_update_filter(p, *decoded1, 1, XDELAYA,
> XDELAYB,
> -                                            XADAPTCOEFFSA, XADAPTCOEFFSB);
> +                                            XADAPTCOEFFSA, XADAPTCOEFFSB,
> ctx->compression_level);
>          decoded1++;
>
>          /* Combined */
> --
> 2.17.1
>
>
OK with that style fixed, assuming it fixes that ticket and is still
bitexact with both files.



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