[FFmpeg-devel] [DECISION] scaletempo filter

[Paul B Mahol]

On 5/6/19, Marton Balint <cus at passwd.hu> wrote:
>
>
> On Mon, 6 May 2019, Marton Balint wrote:
>
>>
>>
>> On Mon, 6 May 2019, Paul B Mahol wrote:
>>
>>> On 5/6/19, Marton Balint <cus at passwd.hu> wrote:
>>>>
>>>>
>>>> On Sat, 4 May 2019, John Warburton wrote:
>>>>
>>>>> On Sat, May 4, 2019 at 3:34 PM Nicolas George <george at nsup.org> wrote:
>>>>>
>>>>>> John Warburton (12019-05-04):
>>>>>>
>>>>>> > Is there a patch I can use to test scaletempo to compare it against
>>>>>> atempo?
>>>>>> > It'll be no trouble to do that with the normal audio that is
>>>>>> time-adjusted
>>>>>> > on that radio station. It may be that its increased quality is most
>>>>>>
>>>>>> John, we would appreciate your input about whether these new
>>>>>> implementation of atempo is superior or equal to the existing one with
>>>>>> regard to your needs.
>>>>
>>>> I tested scaletempo (with default settings) and it is definitely worse
>>>> than atempo for small scaling factors like 25/24.
>>>>
>>>
>>> Have you tried other scaling factors?
>>> How you done testing?
>>
>> Simple hearing tests. I hear audible artifacts (a kind of audio
>> stuttering) with scaletempo. Here are some files where it is noticable:
>>
>> fate-suite/delphine-cin/LOGO-partial.CIN
>> fate-suite/real/spygames-2MB.rmvb
>> fate-suite/wmapro/Beethovens_9th-1_small.wma
>> fate-suite/dts/dts.ts
>>
>> The last one is noticable even with 2x scaling.
>
> Another one, audible with any (0.5, ~1, 2) scaling:
>
> fate-suite/paf/hod1-partial.paf
>

OK, vote and patch dropped.

Even by using basically same algorithm, it is very slow to get same
quality because does not use FFT for cross-correlation.