Michael Niedermayer:
> This avoids some invalid shifts
>
> Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc>
> ---
> libavcodec/truespeech.c | 7 +++----
> 1 file changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/libavcodec/truespeech.c b/libavcodec/truespeech.c
> index d4ddfcbf9c..54352851b3 100644
> --- a/libavcodec/truespeech.c
> +++ b/libavcodec/truespeech.c
> @@ -132,8 +132,7 @@ static void truespeech_correlate_filter(TSContext *dec)
> if(i > 0){
> memcpy(tmp, dec->cvector, i * sizeof(*tmp));
> for(j = 0; j < i; j++)
> - dec->cvector[j] = ((tmp[i - j - 1] * dec->vector[i]) +
> - (dec->cvector[j] << 15) + 0x4000) >> 15;
> + dec->cvector[j] += (tmp[i - j - 1] * dec->vector[i] +
> 0x4000) >> 15;
> }
> dec->cvector[i] = (8 - dec->vector[i]) >> 3;
> }
> @@ -256,7 +255,7 @@ static void truespeech_synth(TSContext *dec, int16_t
> *out, int quart)
> int sum = 0;
> for(k = 0; k < 8; k++)
> sum += ptr0[k] * ptr1[k];
> - sum = (sum + (out[i] << 12) + 0x800) >> 12;
> + sum = out[i] + ((sum + 0x800) >> 12);
> out[i] = av_clip(sum, -0x7FFE, 0x7FFE);
> for(k = 7; k > 0; k--)
> ptr0[k] = ptr0[k - 1];
> @@ -274,7 +273,7 @@ static void truespeech_synth(TSContext *dec, int16_t
> *out, int quart)
> for(k = 7; k > 0; k--)
> ptr0[k] = ptr0[k - 1];
> ptr0[0] = out[i];
> - out[i] = ((out[i] << 12) - sum) >> 12;
> + out[i] += (- sum) >> 12;
> }
>
> for(i = 0; i < 8; i++)
>
LGTM.
- Andreas
PS: My first patch for this (never sent to the ML) was exactly as
yours until I dropped this approach because (x << shift) >> shift is
not the identity, but may change the high bits. Then I switched to
using multiplications and checked that they don't overflow, because
one factor is always an int16_t. At this point I should have realized
that my first approach was viable, but somehow didn't.
_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
To unsubscribe, visit link above, or email
ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
