[FFmpeg-devel] [PATCH] avfilter: add dumpwave filter.

[Tobias Rapp]

On 10.01.2018 09:11, Дмитрий Гуменюк wrote:
> Hi,
> In my opinion JSON is more flexible, so envelope can be rendered in web app or mobile app
> This filter is useful when you’d like to generate visual representation of audio while doing transcode

I see, but my point is: If you do the image rendering external anyway, 
why not use an existing envelope dumping format? Or alternatively 
connect the rendering application via the av* library interface in C?

Filters into the codebase should be as generic as possible to allow 
re-usage by other filters.

> 
>> On 10 Jan 2018, at 09:00, Tobias Rapp <t.rapp at noa-archive.com> wrote:
>>
>> On 08.01.2018 01:36, dmitry.gumenyuk at gmail.com wrote:
>>> From: Dmytro Humeniuk <dmitry.gumenyuk at gmail.com>
>>> Signed-off-by: Dmytro Humeniuk <dmitry.gumenyuk at gmail.com>
>>> ---
>>>   Changelog                      |   1 +
>>>   libavfilter/Makefile           |   1 +
>>>   libavfilter/af_dumpwave.c      | 273 +++++++++++++++++++++++++++++++++++++++++
>>>   libavfilter/allfilters.c       |   1 +
>>>   libavfilter/version.h          |   4 +-
>>>   tests/fate/filter-audio.mak    |   5 +
>>>   tests/ref/fate/filter-dumpwave |   1 +
>>>   7 files changed, 284 insertions(+), 2 deletions(-)
>>>   create mode 100644 libavfilter/af_dumpwave.c
>>>   create mode 100644 tests/ref/fate/filter-dumpwave
>>> [...]
>>
>> As far as I can see the filter reads audio and writes an envelope curve using JSON data format. The JSON data is then rendered into an image outside of FFmpeg.
>>
>> In my opinion it would be better to allow connecting the filter with other filters by directly rendering the image within FFmpeg. So the filter should have a generic video output instead of the JSON output. This would be similar to the existing "showvolume" filter.
>>
>> If you just want to get the raw envelope data from FFmpeg I suggest to take a look at the "write_peak" option of the WAV muxer.
>>
>> Regards,
>> Tobias
>>
> 

BTW: Top-posting is unpopular on this list.

Regards,
Tobias