[vlc-devel] [PATCH] avcodec VA: reuse the VA if possible disable thread safe buffer pool on WIN32

[Steve Lhomme]

In software everything is always possible :)

It may depend on the manufacturer, the GPU, the driver version. We'd
need a lot of testing on a lot of machines with people reporting if
decoding and seeking works properly.

IMO that's no feasable. It's better to find a common ground that works
for everyone and doesn't impact the general case too much.

On Tue, Apr 7, 2015 at 3:49 PM, Sean McGovern <gseanmcg at gmail.com> wrote:
> Is there a way to blacklist this on machines where we know it doesn't work? Would that be desirable?
>
> -- Sean McG.
> -----Original Message-----
> From: Steve Lhomme <robux4 at videolabs.io>
> Sender: "vlc-devel" <vlc-devel-bounces at videolan.org>Date: Tue, 7 Apr 2015 15:46:08
> To: Mailing list for VLC media player developers<vlc-devel at videolan.org>
> Reply-To: Mailing list for VLC media player developers <vlc-devel at videolan.org>
> Subject: Re: [vlc-devel] [PATCH] avcodec VA: reuse the VA if possible
>  disable thread safe buffer pool on WIN32
>
> On Tue, Apr 7, 2015 at 12:04 PM, Steve Lhomme <robUx4 at videolabs.io> wrote:
>> Fixes #11693
>> ---
>>  modules/codec/avcodec/video.c | 40 +++++++++++++++++++++++++---------------
>>  1 file changed, 25 insertions(+), 15 deletions(-)
>>
>> diff --git a/modules/codec/avcodec/video.c b/modules/codec/avcodec/video.c
>> index 381fe62..4e7f32f 100644
>> --- a/modules/codec/avcodec/video.c
>> +++ b/modules/codec/avcodec/video.c
>> @@ -374,7 +374,11 @@ int InitVideoDec( decoder_t *p_dec, AVCodecContext *p_context,
>>      i_thread_count = __MIN( i_thread_count, 16 );
>>      msg_Dbg( p_dec, "allowing %d thread(s) for decoding", i_thread_count );
>>      p_context->thread_count = i_thread_count;
>> +# if defined(_WIN32)
>> +    p_context->thread_safe_callbacks = false;
>> +# else
>>      p_context->thread_safe_callbacks = true;
>> +# endif
>
> I tried putting a mutex in avcodec where it feeds DXVA with its data.
> It was called by multiple threads. Even with that, decoding is still
> bogus with Intel Graphics 4000. So I don't see an other way to make it
> work with this chipset apart from disabling FF_THREAD_FRAME like we
> used to do.
>
> IMO this patch is OK. By default ffmpeg/avplay don't set
> thread_safe_callbacks, but that's because they use their own buffer
> pools and also check if their functions are used rather than custom
> ones.
>
>>      switch( p_codec->id )
>>      {
>> @@ -396,21 +400,6 @@ int InitVideoDec( decoder_t *p_dec, AVCodecContext *p_context,
>>              break;
>>      }
>>
>> -    /* Workaround: frame multithreading is not compatible with
>> -     * DXVA2. When a frame is being copied to host memory, the frame
>> -     * is locked and cannot be used as a reference frame
>> -     * simultaneously and thus decoding fails for some frames. This
>> -     * causes major image corruption. */
>> -# if defined(_WIN32)
>> -    char *avcodec_hw = var_InheritString( p_dec, "avcodec-hw" );
>> -    if( avcodec_hw == NULL || strcasecmp( avcodec_hw, "none" ) )
>> -    {
>> -        msg_Warn( p_dec, "threaded frame decoding is not compatible with DXVA2, disabled" );
>> -        p_context->thread_type &= ~FF_THREAD_FRAME;
>> -    }
>> -    free( avcodec_hw );
>> -# endif
>> -
>>      if( p_context->thread_type & FF_THREAD_FRAME )
>>          p_dec->i_extra_picture_buffers = 2 * p_context->thread_count;
>>  #endif
>> @@ -1313,7 +1302,28 @@ static enum PixelFormat ffmpeg_GetFormat( AVCodecContext *p_context,
>>      vlc_va_t *p_va = p_sys->p_va;
>>
>>      if( p_va != NULL )
>> +    {
>> +        for( size_t i = 0; pi_fmt[i] != PIX_FMT_NONE; i++ )
>> +        {
>> +            if( p_va->pix_fmt != pi_fmt[i] )
>> +                continue;
>> +
>> +            if( p_context->width <= 0 || p_context->height <= 0
>> +             || vlc_va_Setup( p_va, p_context, &p_dec->fmt_out.video.i_chroma ) )
>> +            {
>> +                msg_Err( p_dec, "reusing acceleration failed" );
>> +                break;
>> +            }
>> +
>> +            if( p_va->description )
>> +                msg_Info( p_dec, "Reusing %s for hardware decoding.",
>> +                          p_va->description );
>> +
>> +            return pi_fmt[i];
>> +        }
>> +
>>          vlc_va_Delete( p_va, p_context );
>> +    }
>>
>>      /* Enumerate available formats */
>>      bool can_hwaccel = false;
>> --
>> 2.3.2
>>
>> _______________________________________________
>> vlc-devel mailing list
>> To unsubscribe or modify your subscription options:
>> https://mailman.videolan.org/listinfo/vlc-devel
> _______________________________________________
> vlc-devel mailing list
> To unsubscribe or modify your subscription options:
> https://mailman.videolan.org/listinfo/vlc-devel
> _______________________________________________
> vlc-devel mailing list
> To unsubscribe or modify your subscription options:
> https://mailman.videolan.org/listinfo/vlc-devel