[FFmpeg-devel] [PATCH] avpacket: RFC for ABI bump additions

[James Almer]

On 1/26/2021 1:02 PM, Anton Khirnov wrote:
> Quoting Lynne (2021-01-24 18:34:36)
>>>>
>>>> Some devs (JEEB) wanted reception timestamps and original, overflowed timestamps for MPEG-TS.
>>>> I'd be willing to add a reception timestamp as long as we add an additional time_base field
>>>> and make it independent of the packet's pts field, since those timestamps are usually on
>>>> highly precise system clock time bases, and reducing their precision would be undesirable.
>>>>
>>>
>>> This sounds like side data to me.
>>>
>>>>
>>>> I'm not sure about overflowed original timestamps or how they would help.
>>>> Perhaps we should introduce an AVBufferRef *internal_ref like with AVFrame to
>>>> store such single library-only data?
>>>>
>>>
>>> I don't like treating the libraries specially, so -1 for me.
>>> internal_ref should not exist either.
>>>
>>
>> Yeah, tbh it's a single-library only field in avframes and is mainly used
>> for hardware API weirdness reasons.
> 
> It's not even necessary, that code can work without it.
> 
>> Also another suggestion: should we add a few dozen bytes of padding at
>> the end of the avpacket structure so if anything were to happen
>> we wouldn't be block on waiting for a bump to add a field?
> 
> Ugly, but I guess acceptable? Have to be pretty careful what you add
> though.

Alternatively, we could follow through with the idea of making its size 
stop being part of the ABI.
It's a big change since AVPacket is kinda advertised as one of the few 
structs with ABI-tied size, and it wont happen until at least two years 
from now. But now that the old deprecated decode/encode API is being 
removed and non reference counted packets will no longer be a thing, 
it's probably a good time to do it.