[FFmpeg-devel] drawtext filter

Francesco Carusi klimklim at tiscali.it
Sat Jan 28 16:45:53 EET 2023


On 27/01/2023 18:31, Paul B Mahol wrote:
> On 1/27/23, Francesco Carusi <klimklim at tiscali.it> wrote:
>> On 26/01/2023 17:37, Paul B Mahol wrote:
>>> On 1/26/23, Francesco Carusi <klimklim at tiscali.it> wrote:
>>>> On 26/01/2023 14:21, Paul B Mahol wrote:
>>>>> On 1/26/23, Francesco Carusi <klimklim at tiscali.it> wrote:
>>>>>> The drawtext reinit command is also used in the docs as an example for
>>>>>> the sendcmd filter, so I thought it was fine to use commands in that
>>>>>> way. In my opinion it is also a convenient way to modify multiple
>>>>>> options at the same time.
>>>>>> Should the command match the name of a filter option instead?
>>>>>>
>>>>> Please do not top post.
>>>>>
>>>>> It is much better to use already existing options for commands that is
>>>>> more intuitive to users. Also multiple options can be set at runtime,
>>>>> there is no such limitation.
>>>> ok, I'm going to remove the "change" command and add commands that match
>>>> the options that it included.
>>> Thanks, feel free to ask questions on #ffmpeg-devel irc channel.
>> I'm attaching the updated patch, I also updated the document at
>> https://github.com/yethie/FFmpeg/blob/master/drawtext/CHANGES.md
>> Thanks
> Amazing, I like demos!
>
> Could improve code style of newly added/changed lines?
> For example opening { put on separate line. So code style is in sync
> with rest of codebase.
Sure, I'll put opening { on a new line for functions, not for control 
statements, like in the rest of the code. Is it fine?
> The commands stuff does not need to use strcmp to detect if option
> value have been changed, you could avoid strcmp by just caching old
> value prior to calling function the picks new values, and after that
> just compare old with new and then if it differs call needed code.
I'll cache the numeric values. I think that caching string values is not 
the preferred solution because in addition to the strcmp needed to check 
the value, it would also need a strdup to cache the previous value, even 
when the command does not involve those options. Does it sound reasonable?
>>>>>> On 26/01/2023 11:50, Paul B Mahol wrote:
>>>>>>> On 1/26/23, Francesco Carusi <klimklim at tiscali.it> wrote:
>>>>>>>> Hi, I'm new to contributing to ffmpeg!
>>>>>>>>
>>>>>>>> I modified the drawtext filter to improve text rendering and add
>>>>>>>> some
>>>>>>>> features. You can find a high level description of the changes at
>>>>>>>> this
>>>>>>>> link:
>>>>>>>>
>>>>>>>> https://github.com/yethie/FFmpeg/blob/master/drawtext/CHANGES.md
>>>>>>>>
>>>>>>>> I'm also attaching the patch file.
>>>>>>>> I looked for the filter maintainer to discuss about the changes I
>>>>>>>> made
>>>>>>>> but it looks like there isn't any, am I correct?
>>>>>>>>
>>>>>>>> Please let me know if this is the right way to submit my
>>>>>>>> contribution.
>>>>>>> Why filter can not support normal commands for options? Like most/all
>>>>>>> other filters that have support for changing options values at
>>>>>>> runtime.
>>>>>>>
>>>>>>> The reinit and yours added change option(s) are very
>>>>>>> strange/inconvenient things to do.
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