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

[lance.lmwang at gmail.com]

On Sat, Jun 20, 2020 at 01:31:43AM +0200, Marton Balint wrote:
> 
> 
> On Sat, 20 Jun 2020, lance.lmwang at gmail.com wrote:
> 
> > 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.
> 
> initially no_video = 0, so we assume there is valid signal. When there is no
> signal, we log the warning if no_video==0, and we set no_video to 1. So we
> do give warning message when the signal is lost.

If you don't use autodetect for the format, you'll get signal lost after runn, no
warning message for the signal lost. I'm not sure it's expected behavior.

> 
> > 
> > > 
> > > > 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.
> 
> Sorry, i don't think so.
> 
> Regards,
> Marton
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel at ffmpeg.org
> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> 
> To unsubscribe, visit link above, or email
> ffmpeg-devel-request at ffmpeg.org with subject "unsubscribe".

-- 
Thanks,
Limin Wang