[FFmpeg-devel] Re: [PATCH] libavfilter: Fix incorrect ebur128 peak calculation.

[Tobias Rapp via ffmpeg-devel <ffmpeg-devel@ffmpeg.org>]

On 17/11/2025 16:01, Niklas Haas wrote:

> On Monday, November 17th, 2025 at 3:48 PM, Tobias Rapp via ffmpeg-devel <ffmpeg-devel@ffmpeg.org> wrote:
>>
>> On 11/11/2025 03:33, Michael Niedermayer via ffmpeg-devel wrote:
>>
>>> Hi
>>>
>>> adding niklas to the CC so its not missed
>>> but i agree the patch LGTM
>>>
>>> On Tue, Nov 04, 2025 at 08:52:36PM +0100, Nicolas George via ffmpeg-devel wrote:
>>>
>>>> Carl Hetherington via ffmpeg-devel (HE12025-11-03):
>>>>
>>>>> Since 3b26b782eeded9b9ab7fac013cd1a83a30d68206 it would only look at the
>>>>> first channel.
>>>>>
>>>>> Signed-off-by: cth@carlh.net
>>>>> ---
>>>>> libavfilter/f_ebur128.c | 2 +-
>>>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>>> Hi. Thanks for the patch. I suspect the issue has been here for a longer
>>>>> time, if only on one branch of the conditional build:
>>>> #if CONFIG_SWRESAMPLE
>>>> …
>>>> const double sample = fabs(swr_samples[i * nb_channels]);
>>>> #endif
>>>>
>>>> versus
>>>>
>>>> const double *restrict samples_ch = &samples[ch];
>>>> …
>>>> const double sample = fabs(samples_ch[nb_channels * i]);
>>>>
>>>> Anyway, the fix looks good to me.
>>>>
>>>> Niklas, it has become mostly your code, what do you make of it?
>>
>> Now that n8.0.1 will be tagged soonish it would be great if this fix
>> could be included.
>>
>> Regards, Tobias
> Hi Tobias,
>
> Sorry for the delay in responding. I agree that this seems to be a bug that has been around for quite a while, and that your fix seems correct.
>
> I also don't suspect the performance will be impacted as a result, unless the compiler is really very clever to eliminate the common subcalculation by reassociating the FFMAX calls.
>
> Thanks,
> Niklas
>
> P.s. In the future, it's probably faster if you submit patches directly on https://code.ffmpeg.org/

I'm not the author of the patch, just a random person that did a ping :-)

Have added you as a reviewed-by to the commit message and pushed the 
patch to master and release/8.0. Thanks Carl for the patch, and thanks 
to Nicolas, Michael and Niklas for taking a look.

Regards, Tobias

_______________________________________________
ffmpeg-devel mailing list -- ffmpeg-devel@ffmpeg.org
To unsubscribe send an email to ffmpeg-devel-leave@ffmpeg.org