[FFmpeg-devel] [PATCH] Whisper audio filter

[Marvin Scholz]

On 10 Jul 2025, at 10:34, Vittorio Palmisano wrote:

> Thanks Michael, I will try to answer your comments.
>
>>> +ffmpeg -i input.mp4 -vn -af "aformat=sample_rates=16000:channel_layouts=mono,whisper=
>>
>> Is there a reason why we convert to 16khz mono here ?
>
> It is the only format supported by the whisper.cpp library.
>
>>> +model=../whisper.cpp/models/ggml-base.en.bin\
>>
>> It would be nice if the models would be in a standard location, so teh user
>> just has to specify the model name and not the path
>
> I think that this functionality should be implemented inside the
> whisper.cpp library, so they can manage the exact model location and
> the download process. I will propose a change.
>
>> I tried this:
>>
>> ./ffmpeg -i matrixbench_mpeg2.mpg -vn -af "aformat=sample_rates=16000:channel_layouts=mono,whisper=model=/home/michael/whisper.cpp/models/ggml-base.en.bin:language=en:queue=3000:destination=output.srt:format=srt" -f null -
>>
>> but the output.srt is empty (0 bytes)
>
> Can you enable verbose logging?
>
>> libavfilter/af_whisper.c:75:49: error: parameter name omitted
>>    75 | static void cb_log_disable(enum ggml_log_level, const char *, void *) {}
>>       |                                                 ^~~~~~~~~~~~
>> libavfilter/af_whisper.c:75:63:
>
> I don't see this error using the gcc13 compiler. Do you use a
> different compiler or some other flags?
>

Leaving out parameter names is a C++ thing, its not allowed in C.

>>> +    wctx->audio_buffer_fill_size = 0;
>>> +
>>> +    wctx->next_pts = AV_NOPTS_VALUE;
>>> +
>>> +    wctx->avio_context = NULL;
>>
>> arent things already initialized to 0 ?
>
> Yes, maybe we can keep the AV_NOPTS_VALUE assignment (it is not zero).
>
> -- 
> /Vittorio Palmisano/
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