[FFmpeg-devel] [PATCH] fix MSVC compilation errors

[Aaron Levinson]

On 12/9/2017 6:15 PM, Aaron Levinson wrote:
> On 12/9/2017 1:18 AM, Hendrik Leppkes wrote:
>> On Fri, Dec 8, 2017 at 8:49 AM, Mateusz <mateuszb at poczta.onet.pl> wrote:
>>> W dniu 07.12.2017 o 22:58, Hendrik Leppkes pisze:
>>>> Am 07.12.2017 20:40 schrieb "Mateusz" <mateuszb at poczta.onet.pl>:
>>>>
>>>> W dniu 07.12.2017 o 10:42, Hendrik Leppkes pisze:
>>>>> On Thu, Dec 7, 2017 at 2:02 AM, Mateusz <mateuszb at poczta.onet.pl> 
>>>>> wrote:
>>>>>> After commit 3701d49 'error_resilience: remove avpriv_atomic usage'
>>>>>> we have included windows.h in much more files and we should
>>>>>> avoid conflicts with defines/function declarations.
>>>>>>
>>>>>> We should declare compatible variables for atomic compat wrappers
>>>>>> that expect fixed size variables in atomic_compare_exchange* macro.
>>>>>>
>>>>>> Signed-off-by: Mateusz Brzostek <mateuszb at poczta.onet.pl>
>>>>>> ---
>>>>>>   libavcodec/jpegls.h   |  2 ++
>>>>>>   libavcodec/mjpegdec.h |  2 ++
>>>>>>   libavcodec/mss2.c     |  6 +++---
>>>>>>   libavcodec/utils.c    | 12 ++++++++++++
>>>>>>   libavformat/mxfenc.c  |  2 +-
>>>>>>   5 files changed, 20 insertions(+), 4 deletions(-)
>>>>>>
>>>>>> diff --git a/libavcodec/jpegls.h b/libavcodec/jpegls.h
>>>>>> index c8997c7861..6b89b2afa3 100644
>>>>>> --- a/libavcodec/jpegls.h
>>>>>> +++ b/libavcodec/jpegls.h
>>>>>> @@ -32,6 +32,8 @@
>>>>>>   #include "avcodec.h"
>>>>>>   #include "internal.h"
>>>>>>
>>>>>> +#undef near /* This file uses struct member 'near' which in 
>>>>>> windows.h
>>>> is defined as empty. */
>>>>>> +
>>>>>>   typedef struct JpeglsContext {
>>>>>>       AVCodecContext *avctx;
>>>>>>   } JpeglsContext;
>>>>>> diff --git a/libavcodec/mjpegdec.h b/libavcodec/mjpegdec.h
>>>>>> index c84a40aa6e..c36fba5f22 100644
>>>>>> --- a/libavcodec/mjpegdec.h
>>>>>> +++ b/libavcodec/mjpegdec.h
>>>>>> @@ -39,6 +39,8 @@
>>>>>>   #include "hpeldsp.h"
>>>>>>   #include "idctdsp.h"
>>>>>>
>>>>>> +#undef near /* This file uses struct member 'near' which in 
>>>>>> windows.h
>>>> is defined as empty. */
>>>>>> +
>>>>>>   #define MAX_COMPONENTS 4
>>>>>>
>>>>>>   typedef struct MJpegDecodeContext {
>>>>>> diff --git a/libavcodec/mss2.c b/libavcodec/mss2.c
>>>>>> index 9e7cc466de..3180af1d60 100644
>>>>>> --- a/libavcodec/mss2.c
>>>>>> +++ b/libavcodec/mss2.c
>>>>>> @@ -464,9 +464,9 @@ static int decode_wmv9(AVCodecContext *avctx, 
>>>>>> const
>>>> uint8_t *buf, int buf_size,
>>>>>>       return 0;
>>>>>>   }
>>>>>>
>>>>>> -typedef struct Rectangle {
>>>>>> +struct Rectangle {
>>>>>>       int coded, x, y, w, h;
>>>>>> -} Rectangle;
>>>>>> +};
>>>>>>
>>>>>>   #define MAX_WMV9_RECTANGLES 20
>>>>>>   #define ARITH2_PADDING 2
>>>>>> @@ -485,7 +485,7 @@ static int mss2_decode_frame(AVCodecContext 
>>>>>> *avctx,
>>>> void *data, int *got_frame,
>>>>>>
>>>>>>       int keyframe, has_wmv9, has_mv, is_rle, is_555, ret;
>>>>>>
>>>>>> -    Rectangle wmv9rects[MAX_WMV9_RECTANGLES], *r;
>>>>>> +    struct Rectangle wmv9rects[MAX_WMV9_RECTANGLES], *r;
>>>>>>       int used_rects = 0, i, implicit_rect = 0, av_uninit(wmv9_mask);
>>>>>>
>>>>>>       if ((ret = init_get_bits8(&gb, buf, buf_size)) < 0)
>>>>>> diff --git a/libavcodec/utils.c b/libavcodec/utils.c
>>>>>> index baf09119fe..70a0764714 100644
>>>>>> --- a/libavcodec/utils.c
>>>>>> +++ b/libavcodec/utils.c
>>>>>> @@ -1943,7 +1943,13 @@ int av_lockmgr_register(int (*cb)(void 
>>>>>> **mutex,
>>>> enum AVLockOp op))
>>>>>>
>>>>>>   int ff_lock_avcodec(AVCodecContext *log_ctx, const AVCodec *codec)
>>>>>>   {
>>>>>> +#if !defined(COMPAT_ATOMICS_DUMMY_STDATOMIC_H) &&
>>>> !defined(COMPAT_ATOMICS_PTHREAD_STDATOMIC_H) && \
>>>>>> +    !defined(COMPAT_ATOMICS_SUNCC_STDATOMIC_H) &&
>>>> !defined(COMPAT_ATOMICS_WIN32_STDATOMIC_H)
>>>>>>       _Bool exp = 0;
>>>>>> +#else
>>>>>> +    atomic_bool exp = 0;
>>>>>> +#endif
>>>>>> +
>>>>>>       if (codec->caps_internal & FF_CODEC_CAP_INIT_THREADSAFE ||
>>>> !codec->init)
>>>>>>           return 0;
>>>>>>
>>>>>> @@ -1969,7 +1975,13 @@ int ff_lock_avcodec(AVCodecContext *log_ctx,
>>>> const AVCodec *codec)
>>>>>>
>>>>>>   int ff_unlock_avcodec(const AVCodec *codec)
>>>>>>   {
>>>>>> +#if !defined(COMPAT_ATOMICS_DUMMY_STDATOMIC_H) &&
>>>> !defined(COMPAT_ATOMICS_PTHREAD_STDATOMIC_H) && \
>>>>>> +    !defined(COMPAT_ATOMICS_SUNCC_STDATOMIC_H) &&
>>>> !defined(COMPAT_ATOMICS_WIN32_STDATOMIC_H)
>>>>>>       _Bool exp = 1;
>>>>>> +#else
>>>>>> +    atomic_bool exp = 1;
>>>>>> +#endif
>>>>>> +
>>>>>>       if (codec->caps_internal & FF_CODEC_CAP_INIT_THREADSAFE ||
>>>> !codec->init)
>>>>>>           return 0;
>>>>>>
>>>>>
>>>>> These ifdefs here are very ugly, and as mentioned in another mail, the
>>>>> atomics in those two functions arent even required - all access to
>>>>> those variables is supposed to be protected by the lockmgr anyway.
>>>>> So it would be easier to just remove any atomic nature of those
>>>>> variables (or at the very lease replace the compare_exchange with a
>>>>> store to solve this problem at hand).
>>>>
>>>> I'm not sure but are you proposed to revert commit
>>>> https://github.com/FFmpeg/FFmpeg/commit/590136e78da3d091ea99ab5432543d
>>>> 47a559a461
>>>>
>>>>
>>>> Basically, yes. Atomics are not needed for this variable, as access 
>>>> to it
>>>> should be serialized anyways.
>>>
>>> OK for me. I've sent smaller patch (only near/Rectangle stuff).
>>>
>>
>> LGTM.
> 
> This patch doesn't apply anymore to the latest code base due to changes 
> to mxfenc.c.

I should add that the changes to mxfenc.c aren't needed any longer. 
With the subpatch to mxfenc.c removed, the remain patch applies cleanly, 
and I can confirm that it fixes MSVC build issues as well.

Aaron Levinson