[FFmpeg-devel] [PATCH] avdevice/decklink_dec: fix no warning message if no input signal detected

[lance.lmwang at gmail.com]

On Fri, Jun 19, 2020 at 10:46:33PM +0200, Marton Balint wrote:
> 
> 
> On Fri, 19 Jun 2020, Limin Wang wrote:
> 
> > On Thu, Jun 18, 2020 at 07:37:50PM +0200, Marton Balint wrote:
> > > 
> > > 
> > > On Thu, 18 Jun 2020, lance.lmwang at gmail.com wrote:
> > > 
> > > >From: Limin Wang <lance.lmwang at gmail.com>
> > > >
> > > >Signed-off-by: Limin Wang <lance.lmwang at gmail.com>
> > > >---
> > > >libavdevice/decklink_dec.cpp | 2 +-
> > > >1 file changed, 1 insertion(+), 1 deletion(-)
> > > >
> > > >diff --git a/libavdevice/decklink_dec.cpp b/libavdevice/decklink_dec.cpp
> > > >index 82106aa..90569dc 100644
> > > >--- a/libavdevice/decklink_dec.cpp
> > > >+++ b/libavdevice/decklink_dec.cpp
> > > >@@ -751,7 +751,7 @@ HRESULT decklink_input_callback::VideoInputFrameArrived(
> > > >                }
> > > >            }
> > > >
> > > >-            if (!no_video) {
> > > >+            if (no_video) {
> > > >                av_log(avctx, AV_LOG_WARNING, "Frame received (#%lu) - No input signal detected "
> > > >                        "- Frames dropped %u\n", ctx->frameCount, ++ctx->dropped);
> > > >            }
> > > 
> > > No, this is good as is, the !no_video condition ensures that it is
> > > only logged once when the input actually disappears, and not for
> > > every consecutive frame with no input.
> > 
> > It's good point, but if no input signal after run, no any warning message.
> 
> I don't understand what you are saying here.
> 
> > I don't think it's helpful to check the signal status,
> 
> What do you mean?

If no_video is status machine of signal, then the first status is 1(no signal).
So I think it's wrong to initialized to 0. So if the input signal is lost, 
no any warning message then. I'll submit a patch for your review.

> 
> > also the dropped message isn't correct then, as it'll not count for
> > every dropped frame by the condition.
> 
> That is true, a patch which fixes the number of dropped frames only is
> welcome.

I'll submit a patch for that. I prefer to print warning message by dropped %
25(or other mod), it's more helpful.

> 
> Thanks,
> Marton
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-- 
Thanks,
Limin Wang