[FFmpeg-devel] [PATCH] libavdevice: fix compilation for Mac OS X 10.7-10.12, iOS < 11

[epirat07 at gmail.com]

On 21 Aug 2024, at 3:09, Gnattu OC via ffmpeg-devel wrote:

>> On Aug 21, 2024, at 07:17, epirat07 at gmail.com wrote:
>>
>>
>>
>> On 21 Aug 2024, at 0:43, Erik Bråthen Solem wrote:
>>
>>> avfoundation.m uses constants prefixed with AVMediaType on Mac OS X > 10.6.
>>> In 10.7 through 10.12 their type was NSString*, but starting with 10.13 a
>>> new AVMediaType struct type was introduced. In avfoundation.m, the function
>>> getDevicesWithMediaType takes this struct as parameter, which breaks support
>>> for Mac OS X 10.7 through 10.12. By typedef-ing AVMediaType to NSString* for
>>> these versions, the code compiles. Prior to 10.15 the value is passed to a
>>> function that takes AVMediaType on 10.13+ and NSString* on <= 10.12. The
>>> same API change was introduced in iOS starting with iOS 11.
>>>
>>
>> Hi, thanks for the patch. Conceptually looks fine to me.
>>
>> See my remark below:
>>
>>> Signed-off-by: Erik Bråthen Solem <erikbsolem at hotmail.com>
>>> ---
>>> libavdevice/avfoundation.m | 4 ++++
>>> 1 file changed, 4 insertions(+)
>>>
>>> diff --git a/libavdevice/avfoundation.m b/libavdevice/avfoundation.m
>>> index c5a09c6563..779bc767d6 100644
>>> --- a/libavdevice/avfoundation.m
>>> +++ b/libavdevice/avfoundation.m
>>> @@ -763,6 +763,10 @@ static int get_audio_config(AVFormatContext *s)
>>>    return 0;
>>> }
>>>
>>> +#if ((TARGET_OS_IPHONE && __IPHONE_OS_VERSION_MIN_REQUIRED < 110000) || (TARGET_OS_OSX && __MAC_OS_X_VERSION_MIN_REQUIRED < 101300))
>>> +typedef NSString* AVMediaType;
>>> +#endif
>>
>> I do not think this is the proper guard here? You want to check *_MAX_ALLOWED if you want to check the SDK version,
>> which is what controls these change (as the SDK changed) not the minimum version you target when compiling.
>
> This depends on use case though. For example, compiling on high version SDK, but targeting low version SDK and selectively
> load high version symbols during the runtime should not use *_MAX_ALLOWED because that will disable higher version symbols
> at build time which prevents the usage of the runtime version check.

What I meant here is that *_MAX_ALLOWED must be checked as this is about the SDK version, while the *_MIN_REQUIRED ones are
about the targeted version. You do not runtime-load a typedef, that is purely a compile-time thing.

So you would incorrectly do the typedef even if your SDK is more recent as nothing prevents you targeting say 10.12 with a
10.14 SDK.

>
>>
>>> +
>>> static NSArray* getDevicesWithMediaType(AVMediaType mediaType) {
>>> #if ((TARGET_OS_IPHONE && __IPHONE_OS_VERSION_MIN_REQUIRED >= 100000) || (TARGET_OS_OSX && __MAC_OS_X_VERSION_MIN_REQUIRED >= 101500))
>>>    NSMutableArray *deviceTypes = nil;
>>> -- 
>>> 2.46.0
>>>
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