[FFmpeg-user] What does ffmpeg consider metadata? -- revision

[Mark Filipak]

On 03/04/2020 06:06 AM, James Darnley wrote:
> On 2020-03-04 01:02, Mark Filipak wrote:
>> Kindly disregard the last message. I don't know how 'metadata' got left
>> out of the command line...
>>
>> To me, metadata is such MPEG settings as 'progressive_sequence',
>> 'top_field_first', 'frame_pred_frame_dct', 'concealment_motion_vectors',
>> 'q_scale_type',
>> 'intra_vlc_format', 'alternate_scan', 'repeat_first_field',
>> 'chroma_420_type', 'progressive_frame'.
>>
>> What does ffmpeg consider metadata?
> 
> All of those look like bitstream features.  None of them you could
> change without re-encoding or a specialized tool that can parse and
> alter the bitstream.
> 
> Metadata (as ffmpeg calls it) is tags, like artist and track details on
> a music file.  Plus some other things, like chapters.  To edit those
> software need only understand the container or file format.
> 
> You probably cannot get the things you mentioned elevated into metadata
> in ffmpeg because they are only known by separate parts, namely
> libavcodec and libavformat.

Thanks for your reply. The metadata names above are from the H.262 
specification.

So, what ff* is calling metadata is not that sort of metadata. That's 
good to know and explains why ff* reports things like 'repeat_pict' 
(instead of 'repeat_first_field') and 'interlace_frame' (instead of 
'progressive_frame').

I've been assuming that 'repeat_pict' == 'repeat_first_field' and that 
'interlace_frame' == !'progressive_frame'. Now I don't know what to 
conclude.

Good grief.