[FFmpeg-user] Zeroing 'top_field_first' & 'repeat_pict' -- Possible?

Paul B Mahol onemda at gmail.com
Sat Apr 25 17:28:22 EEST 2020


On 4/25/20, Mark Filipak <markfilipak.windows+ffmpeg at gmail.com> wrote:
> On 04/25/2020 08:54 AM, Paul B Mahol wrote:
>> On 4/25/20, Mark Filipak <markfilipak.windows+ffmpeg at gmail.com> wrote:
>>> On 04/25/2020 05:15 AM, Paul B Mahol wrote:
>>>> On 4/25/20, Mark Filipak <markfilipak.windows+ffmpeg at gmail.com> wrote:
>>>>> ffprobe reports:
>>>>>
>>>>> frames.frame.0.interlaced_frame=0
>>>>> frames.frame.0.top_field_first=1
>>>>> frames.frame.0.repeat_pict=1
>>>>> frames.frame.1.interlaced_frame=0
>>>>> frames.frame.1.top_field_first=0
>>>>> frames.frame.1.repeat_pict=0
>>>>> frames.frame.2.interlaced_frame=0
>>>>> frames.frame.2.top_field_first=0
>>>>> frames.frame.2.repeat_pict=1
>>>>> frames.frame.3.interlaced_frame=0
>>>>> frames.frame.3.top_field_first=1
>>>>> frames.frame.3.repeat_pict=0
>>>>>
>>>>> Is there an ffmpeg way to zero those metadata flags in the input prior
>>>>> to
>>>>> the decoder so that the
>>>>> decoder thinks that the input is solely progressive?
>>>>
>>>> No, are you now mixing filtering and decoding?
>>>
>>> No. I wrote "prior to the decoder". Did you notice? In contrast to "prior
>>> to
>>> the decoder", I assume
>>> that filters operate on frames/fields/pixels prior to the output.
>>
>> Just in case:
>> INPUT->[PARSER->]DEMUXER->[BITSTREAM_FILTER->]DECODER->FILTER->MUXER->ENCODER
>
> Thanks so much. For an architecture guy like me, that process flow is pure
> gold. May I ask more?
>
> INPUT -- This means the command line, yes?

Nope, input file.

> PARSER -- (optional? or would this be a parser that I would write?)

If required it just splits input into packets that are feed to demuxer.

> BITSTREAM_FILTER -- This would filter an MPEG stream, yes? I initially
> looked at 'mpeg2_metadata' to
> manipulate the above metadata flags and was disappointed/bewildered that
> there is no such directive.

That bitstream filter can not change frame flags like interlaced/top
first etc...
But you can change it after decoder with setfield filter.


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