[FFmpeg-devel] [PATCH] videotoolbox: Add SDK ifdefs for use of kVTVideoDecoderReferenceMissingErr

[Zhao Zhili]

> On Mar 25, 2025, at 18:46, Martin Storsjö <martin at martin.st> wrote:
> 
> On Tue, 25 Mar 2025, Zhao Zhili wrote:
> 
>> 
>>> 在 2025年3月25日，下午6:01，Martin Storsjö <martin at martin.st> 写道：
>>> This error constant was only added in the macOS 12 and iOS 15
>>> SDKs.
>>> If building with an older SDK, assume that the error doesn't
>>> match this constant.
>>> This fixes build errors with older SDKs after
>>> c6214b0d691566c7cb0f2ff5be08a24c3534e5bb.
>>> As this constant is declared unconditionally (without any target
>>> version guards) in the headers, one can't reproduce this issue
>>> while building with a newer SDK and targeting an older version
>>> with -mmacosx-version-min=.
>>> Technically, checking just one of MAC_OS_VERSION_12_0 and
>>> __IPHONE_15_0 is enough; the macOS SDKs and iOS SDKs share these
>>> files, so files from a similar point in time do have the same
>>> defines. Therefore, we don't really need to expand this with
>>> checks for tvOS, watchOS and other OS variants.
>>> ---
>>> libavcodec/videotoolbox.c | 5 +++++
>>> 1 file changed, 5 insertions(+)
>>> diff --git a/libavcodec/videotoolbox.c b/libavcodec/videotoolbox.c
>>> index aaa6129576..7f7b910b26 100644
>>> --- a/libavcodec/videotoolbox.c
>>> +++ b/libavcodec/videotoolbox.c
>>> @@ -728,8 +728,13 @@ static void videotoolbox_decoder_callback(void *opaque,
>>>    }
>>> 
>>>    if (!image_buffer) {
>>> +#if defined(MAC_OS_VERSION_12_0) || defined(__IPHONE_15_0)
>>> +        // kVTVideoDecoderReferenceMissingErr was defined in the macOS 12/iOS 15 SDK
>>>        if (status != kVTVideoDecoderReferenceMissingErr)
>>>            vtctx->reconfig_needed = true;
>>> +#else
>>> +        vtctx->reconfig_needed = true;
>>> +#endif
>> 
>> I used its numeric value initially, but after checking the doc,
>> 
>> kVTVideoDecoderReferenceMissingErr
>> iOS 6.0+
>> iPadOS 6.0+
>> Mac Catalyst 13.0+
>> macOS 10.8+
>> tvOS 10.2+
>> visionOS 1.0+
>> 
>> I replaced it with the enum.
>> 
>> Now I wondering what does this macOS 10.8 mean.
>> 
>> Anyway, can we use the numeric value here?
> 
> Can you link to which docs declare this to be available since macOS 10.8?

https://developer.apple.com/documentation/videotoolbox/kvtvideodecoderreferencemissingerr?language=objc

> 
> Anyway, I'm ok wth just using a numeric value instead, but then we should probably add a comment saying what the value refers to, and that it is only available since macOS 12 SDKs.
> 
> // Martin
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