[FFmpeg-devel] [PATCH 1/4] swr: convert resample_common/linear_int16_mmx2/sse2 to yasm.

[Andreas Cadhalpun]

On 12.07.2014 19:37, Michael Niedermayer wrote:
> On Sat, Jul 12, 2014 at 06:58:49PM +0200, Andreas Cadhalpun wrote:
>> On 12.07.2014 18:46, Michael Niedermayer wrote:
>>> On Sat, Jul 12, 2014 at 05:35:12PM +0200, Hendrik Leppkes wrote:
>>>> On Sat, Jul 12, 2014 at 4:45 PM, Andreas Cadhalpun
>>>> <andreas.cadhalpun at googlemail.com> wrote:
>>>>> On 12.07.2014 15:40, Ronald S. Bultje wrote:
>>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> On Sat, Jul 12, 2014 at 9:35 AM, Andreas Cadhalpun <
>>>>>> andreas.cadhalpun at googlemail.com> wrote:
>>>>>>
>>>>>>> Hi,
>>>>>>>
>>>>>>> I'm a bit puzzled by this commit.
>>>>>>>
>>>>>>>
>>>>>>> On 30.06.2014 01:19, James Almer wrote:
>>>>>>>
>>>>>>>> From: Ronald S. Bultje <rsbultje at gmail.com>
>>>>>>>>
>>>>>>>> ---
>>>>>>>>     libswresample/resample_template.c    |  23 +---
>>>>>>>>     libswresample/x86/resample.asm       | 225
>>>>>>>> ++++++++++++++++++++++++++---------
>>>>>>>>     libswresample/x86/resample_mmx.h     | 110 -----------------
>>>>>>>>     libswresample/x86/resample_x86_dsp.c |  44 +++----
>>>>>>>>     4 files changed, 187 insertions(+), 215 deletions(-)
>>>>>>>>
>>>>>>> [...]
>>>>>>>
>>>>>>>    diff --git a/libswresample/x86/resample_mmx.h
>>>>>>>>
>>>>>>>> b/libswresample/x86/resample_mmx.h
>>>>>>>> index 94237b0..b0ea496 100644
>>>>>>>> --- a/libswresample/x86/resample_mmx.h
>>>>>>>> +++ b/libswresample/x86/resample_mmx.h
>>>>>>>> @@ -22,116 +22,6 @@
>>>>>>>>     #include "libavutil/cpu.h"
>>>>>>>>     #include "libswresample/swresample_internal.h"
>>>>>>>>
>>>>>>>> -DECLARE_ALIGNED(16, const uint64_t, ff_resample_int16_rounder)[2]    =
>>>>>>>> {
>>>>>>>> 0x0000000000004000ULL, 0x0000000000000000ULL};
>>>>>>>>
>>>>>>>
>>>>>>> This removes the symbol ff_resample_int16_rounder from libswresample,
>>>>>>> which is a backwards incompatible ABI change.
>>>>>>>
>>>>>>> So can someone explain to me, why this hasn't been accompanied by a major
>>>>>>> SOVERSION bump of libswresample?
>>>>>>
>>>>>>
>>>>>>
>>>>>> All ff_* symbols are internal.
>>>>>
>>>>>
>>>>> Then shouldn't all of them be declared with something like '__attribute__
>>>>> ((visibility ("hidden")))'?
>>>>>
>>>>
>>>> This is usually handled by a visibility file (.v), but for some reason
>>>> the swresample file doesn't hide ff_* symbols, but that doesn't really
>>>> change the fact that ff_* (and avpriv_*) are not part of the public
>>>> API/ABI and as such any changes or removals do not require a SONAME
>>>> bump.
>>>>
>>>
>>>> For the reason why they are not hidden, maybe Michael can comment.
>>>
>>> i assume this was just a copy and paste error, removed ff_* from
>>> swr
>>
>> So should ff_* also be removed from libavutil.v?
>
> yes, but there is some chance that it might break some app so ill
> wait till after the release

Yes, for example this breaks libavfilter:
undefined reference to `ff_opencl_set_parameter'

>> And what about avpriv_* in libavcodec, libavformat and libavutil?
>
> avpriv is shared between the libs so it has to be exported by each
> lib

So avpriv_* symbols shouldn't be removed without SONAME bump (in 
contrast to what Hendrik wrote)?

Best regards,
Andreas