[FFmpeg-devel] [PATCH v2 1/4] frame: handle add side data with the same type

["zhilizhao(赵志立)"]

> On Nov 4, 2019, at 5:04 AM, Michael Niedermayer <michael at niedermayer.cc> wrote:
> 
> On Fri, Nov 01, 2019 at 06:16:38PM +0100, Marton Balint wrote:
>> 
>> 
>> On Fri, 1 Nov 2019, "zhilizhao(赵志立)" wrote:
>> 
>>> 
>>> 
>>>> On Nov 1, 2019, at 8:13 PM, Hendrik Leppkes <h.leppkes at gmail.com> wrote:
>>>> 
>>>> On Fri, Nov 1, 2019 at 1:03 PM <quinkblack at foxmail.com> wrote:
>>>>> 
>>>>> From: Zhao Zhili <zhilizhao at tencent.com>
>>>>> 
>>>>> ---
>>>>> libavutil/frame.c | 13 +++++++++++++
>>>>> libavutil/frame.h |  4 ++++
>>>>> 2 files changed, 17 insertions(+)
>>>>> 
>>>> 
>>>> I believe there have been some use-cases, especially around
>>>> closed-captions, where multiple blocks of the same type have been
>>>> used, somehow. Since this is really an API change, not sure its such a
>>>> good idea.
>>> 
>>> I guess it may be too late to change the behavior.
>> 
>> I am not sure, all our API around side data (get/remove) is based on the
>> assumption that a single entry of a type exists. Also for packet/stream side
>> data it is already assumed as far as I see. So at least for the sake of
>> consistency it should be the same way. Maybe we should print a deprecation
>> warning if something adds multiple side data of the same type. And later
>> sometime it can be changed to actually replace the old side data.
> 
> In respect to adding side data when the same type already exists,
> it may be more robust to error out in such a case instead of replacing.

I like the idea of error out.

> 
> Also we may handle deprecation in a type specific manner
> In cases where a duplicated type makes semantically no sense and also doesnt
> occur it could possibly be considered an error immedeatly
> Only cases where it makes sense or does actually happen need a deprecation
> period i think. That is if someone wants to implement this at such a
> fine grained level …

It’s hard to tell which types actually been used with multiple entries.

> 
> [...]
> 
> -- 
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
> 
> In fact, the RIAA has been known to suggest that students drop out
> of college or go to community college in order to be able to afford
> settlements. -- The RIAA
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