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

[Dmitry Gumenyuk]

--
Best regards,
Dmytro

> On 11 Jan 2018, at 23:57, Paul B Mahol <onemda at gmail.com> wrote:
> 
>> On 1/11/18, Dmitry Gumenyuk <dmitry.gumenyuk at gmail.com> wrote:
>> 
>>>> On 11 Jan 2018, at 23:02, Paul B Mahol <onemda at gmail.com> wrote:
>>>> 
>>>> On 1/11/18, Dmitry Gumenyuk <dmitry.gumenyuk at gmail.com> wrote:
>>>> 
>>>>>> On 11 Jan 2018, at 22:41, Paul B Mahol <onemda at gmail.com> wrote:
>>>>>> 
>>>>>> On 1/11/18, Dmitry Gumenyuk <dmitry.gumenyuk at gmail.com> wrote:
>>>>>> Hello
>>>>>> 
>>>>>> 2018-01-10 11:33 GMT+01:00 Moritz Barsnick <barsnick at gmx.net>:
>>>>>>>> On Wed, Jan 10, 2018 at 08:58:05 +0100, dmitry.gumenyuk at gmail.com
>>>>>>>> wrote:
>>>>>>>> 
>>>>>>>> + at table @option
>>>>>>>> + at item d
>>>>>>>> +Dimensions @code{WxH}.
>>>>>>>> + at code{W} - number of data values in json, values will be scaled
>>>>>>>> according to @code{H}.
>>>>>>>> +The default value is @var{640x480}
>>>>>>>> +
>>>>>>>> + at item s
>>>>>>>> +Samples count per value per channel
>>>>>>> 
>>>>>>> In most other filters/filtersources, s+size is used for dimensions,
>>>>>>> d+duration for time, and n for an amount/number of frames/samples or
>>>>>>> so. Might be a good idea to align with this. And use aliases (i.e.
>>>>>>> implement both "s" and "size").
>>>>>>> 
>>>>>>>> +static const AVOption dumpwave_options[] = {
>>>>>>>> +    { "d", "set width and height", OFFSET(w),
>>>>>>>> AV_OPT_TYPE_IMAGE_SIZE,
>>>>>>>> {.str = "640x480"}, 0, 0, FLAGS },
>>>>>>>> +    { "s", "set number of samples per value per channel",
>>>>>>>> OFFSET(s),
>>>>>>>> AV_OPT_TYPE_INT64,  {.i64 = 0}, 0, INT64_MAX, FLAGS },
>>>>>>>> +    { "json", "set json dump file", OFFSET(json),
>>>>>>>> AV_OPT_TYPE_STRING,
>>>>>>>> {
>>>>>>>> .str = NULL }, 0, 0, FLAGS },
>>>>>>>> +    { NULL }
>>>>>>> [...]
>>>>>>>> +static av_cold int init(AVFilterContext *ctx)
>>>>>>>> +{
>>>>>>>> +    DumpWaveContext *dumpwave = ctx->priv;
>>>>>>>> +    if(!dumpwave->s) {
>>>>>>>> +        dumpwave->is_disabled = 1;
>>>>>>>> +        av_log(ctx, AV_LOG_ERROR, "Invalid samples per value
>>>>>>>> config\n");
>>>>>>>> +    }
>>>>>>>> +    return 0;
>>>>>>> 
>>>>>>> I don't like the idea of having to provide the "s" parameter. Is
>>>>>>> there
>>>>>>> really no useful default?
>>>>>>> 
>>>>>>> And now, if s=0, what does the filter do? Just sit around? Couldn't
>>>>>>> it
>>>>>>> fail instead?
>>>>>>> 
>>>>>>> Apart from that:
>>>>>>> "if (" is the bracket style ffmpeg uses.
>>>>>>> 
>>>>>>>> +        if (dumpwave->json && !(dump_fp =
>>>>>>>> av_fopen_utf8(dumpwave->json,
>>>>>>>> "w")))
>>>>>>>> +            av_log(ctx, AV_LOG_WARNING, "Flushing dump failed\n");
>>>>>>> 
>>>>>>> I would appreciate evaluation of errno and printing the appropriate
>>>>>>> string (using av_strerror(), I believe).
>>>>>>> 
>>>>>>>> +    switch (inlink->format) {
>>>>>>>> +        case AV_SAMPLE_FMT_DBLP:
>>>>>>> 
>>>>>>> As Kyle hinted: Can this not force a conversion (implicit insertion
>>>>>>> of
>>>>>>> aformat filter) to e.g. double by only supporting this format, and
>>>>>>> reducing this switch to one or two cases? (The filter's output isn't
>>>>>>> really meant for transparent reuse anyway? af_volumedetect e.g. also
>>>>>>> supports only one, meaning its output can be a different format than
>>>>>>> its input.) It's also really hard to go through and later to
>>>>>>> maintain.
>>>>>>> It the big switch/case remains, one or two code macros would be
>>>>>>> appropriate.
>>>>>> 
>>>>>> I checked solution used in volumedetect and couldn't find a way to
>>>>>> read across formats.
>>>>> 
>>>>> I do not understand what you are trying to do.
>>>> Sorry, I'm trying to add support for 8, 16, 24, 32, 64 bit sample
>>>> formats
>>>>>> How would you implement such macros? Since version 3.2 astats filter
>>>>>> uses same approach for reading different formats and as far as I know
>>>>>> macros harder to debug
>>>>> 
>>>>> astats is using all formats because of numerous reasons. astats uses
>>>>> raw
>>>>> values,
>>>>> your filter just convert each raw value to float representation.
>>>> Is this wrong, as I'd like to have high precision?
>>> 
>>> For rendering to small size image?
>> Data can be used for analysis as well. Any size I would say as user may
>> define size
> 
> Than use floats.
Ok, will give it a try
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