[FFmpeg-devel] [PATCH 05/21] libavformat/movenc: mov_write_ftyp_tag: write the major brand a compatible brand

[Erkki Seppälä]

Hello,

On 08/23/2016 10:00 PM, Carl Eugen Hoyos wrote:
>> +    if (mov->mode == MODE_MP4 && mov->major_brand)
>> +        ffio_wfourcc(pb, mov->major_brand); /* write major brand as a compatible brand */
>
> How can I reproduce the issue this is trying to fix?

The issue we were fixing was that in the presence of custom major brand 
(the option "brand" is set) the custom major brand did not end up in the 
compatible brands. (In retrospect, this would have been a great commit 
message..)

Prompted by your comment, we reviewed the specification, and it does not 
seem like that the standard requires this functionality - but it doesn't 
outright prohibit it either.

An alternative for our use case would be adding the option 
"compatible_brands" for setting custom compatible brands from the client 
code. It would probably either replace all custom brands with the ones 
provided, or it would need to collect the custom brands in a list in 
order to remove duplicates (though I imagine allowing duplicates would 
only be a esthetic flaw).

Thanks for the review and input!