> On Jan 27, 2020, at 12:59 AM, Carl Eugen Hoyos <ceffm...@gmail.com> wrote:
>
> Am So., 26. Jan. 2020 um 17:13 Uhr schrieb Zhao Zhili <quinkbl...@foxmail.com
> <mailto:quinkbl...@foxmail.com>>:
>>
>> ---
>> Or specify an upper limit on volume. What do you think?
>>
>> libavfilter/af_volume.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/libavfilter/af_volume.c b/libavfilter/af_volume.c
>> index 213c57195a..029925cbfb 100644
>> --- a/libavfilter/af_volume.c
>> +++ b/libavfilter/af_volume.c
>> @@ -200,7 +200,7 @@ static inline void scale_samples_s16(uint8_t *dst, const
>> uint8_t *src,
>> int16_t *smp_dst = (int16_t *)dst;
>> const int16_t *smp_src = (const int16_t *)src;
>> for (i = 0; i < nb_samples; i++)
>> - smp_dst[i] = av_clip_int16(((int64_t)smp_src[i] * volume + 128) >>
>> 8);
>> + smp_dst[i] = (int16_t)av_clip64(((int64_t)smp_src[i] * volume +
>> 128) >> 8, INT16_MIN, INT16_MAX);
>
> The cast looks unnecessary and confusing but if a limit works, it is likely
> simpler imo.
The function is supposed to handle smp_src[i] * volume > INT32_MAX, so the cast
is necessary.
case AV_SAMPLE_FMT_S16:
if (vol->volume_i < 0x10000)
vol->scale_samples = scale_samples_s16_small;
else
vol->scale_samples = scale_samples_s16;
break;
I'm not sure about the use case. Does the function suppose to handle
(((int64_t)smp_src[i] * volume + 128) >> 8) > INT32_MAX?
By the way, there is another overflow in set_volume():
if (vol->precision == PRECISION_FIXED) {
vol->volume_i = (int)(vol->volume * 256 + 0.5);
vol->volume = vol->volume_i / 256.0;
av_log(ctx, AV_LOG_VERBOSE, "volume_i:%d/255 ", vol->volume_i);
}
>
> Carl Eugen
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