[FFmpeg-devel] [PATCH v4 3/3] avformat/mxfenc: prefer to use the configured metadta

[Marton Balint]

On Tue, 19 Jan 2021, Tobias Rapp wrote:

> On 18.01.2021 23:53, Tomas Härdin wrote:
>> lör 2021-01-16 klockan 08:43 +0800 skrev lance.lmwang at gmail.com:
>>> On Fri, Jan 15, 2021 at 09:43:58PM +0100, Marton Balint wrote:
>>>>
>>>> On Fri, 15 Jan 2021, Tomas Härdin wrote:
>>>>> Again, why? If you have a company that maintains a fork of FFmpeg then
>>>>> compile that info in here instead. Compare with FFmbc which always puts
>>>>> "FFmbc" as CompanyName.
>>>>
>>>> And how can a product based on libavformat set the company name, product
>>>> name and product version? It seems a valid use case for me that these are
>>>> overridable. Also note that this product version is only the "user 
> friendly"
>>>> version string, for the numeric version still LIBAVFORMAT_VERSION values 
> are
>>>> used.
>>>
>>> Yes, my use case is the product is using libavformat as library, so it's
>>> prefer to have way to override these information as requirements.
>> 
>> What I'm worried about here is that we're going to get files which
>> claim to have been written by something other than libavformat. I've
>> had situations like this before, and it is a source of headache. For
>> example, if mxfenc writes some field incorrectly then this might cause
>> us to hack mxfdec to accept that field instead of fixing mxfenc.
>
> I agree that especially for the MXF format with its flexible structure 
> it is more relevant to know the muxing library rather than the hosting 
> application. Have seen MXF output files of other commercial products 
> that also contain library identifiers like "libMXF" or "MXFtk" here.
>
> Other formats in FFmpeg use the "encoder" metadata key for embedding 
> library information in the output file. A quick test with AVI output 
> shows that this metadata is generated internally and cannot be 
> overridden on the command-line.

If your concern is being able to identify our mxf muxer, then why not use 
the Platform metadata item for this?

"Human readable name of the toolkit and operating system used. Best 
practice is to use the form “SDK name (OS name)”"

Seems a lot more fitting than the other metadata fields for the purpose of 
muxer identification.

Regards,
Marton