Hi Carl,
Thanks for your help, and now I fixed my issue!
You are right, my issue is with upsampling the 4:2:0 mpeg video to 4:2:2
feeding the decklink card. I read the article and found an upsampling filter to
convert chroma format from 4:2:0 to 4:2:2. The upsampling filter can handle
two types of frame, it is progressive and interlaced. Previous I used a ffmpeg
function sws_scale to convert the chroma format, it has this issue, and it is
the same issue when I convert the chroma format using this upsampling filter by
assuming the frame is progressive. But things changed when I assume the frame
is interlaced, it is difficult to see horizontal lines on the red color. I
think ffmpeg treated a frame as a progressive frame when doing the chroma
upsampling using sws_scale in my video player.
Thanks,
Nuo
________________________________
From: nuo yang <[email protected]>
To: "This list is about using libavcodec, libavformat, libavutil, libavdevice
and libavfilter." <[email protected]>
Sent: 2013-5-7
Subject: Re: [Libav-user] MPEG-2 NTSC video shows horizontal lines on the red
color
Thank you, Carl !
I will read the article and have a try, will update you later.
________________________________
From: Carl Lindqvist <[email protected]>
To: "This list is about using libavcodec, libavformat, libavutil, libavdevice
and libavfilter." <[email protected]>
Sent: 2013-5-6
Subject: Re: [Libav-user] MPEG-2 NTSC video shows horizontal lines on the red
color
Here is an article describing what is probably happening in your app,
and will hopefully give you some idea what you
need to correct:
http://web.archive.org/web/20060719025947/http://www.hometheaterhifi.com/volume_8_2/dvd-benchmark-special-report-chroma-bug-4-2001.html
2013/5/6 Carl Lindqvist <[email protected]>:
> I suspect your issue is with resampling the 4:2:0 mpeg video to 4:2:2
> feeding the decklink card.
>
> As 4:2:0 in interlaced is often poorly done or misunderstood, this is
> often an issue. And since we are pretty bad at noticing errors in
> color, it will only be obvious in very saturated colors.
>
> How do you handle the conversion now? Make sure you really specify
> that you are handling an interlaced source, since 4:2:0 is very
> different in interlaced vs progressive.
>
> 2013/4/28 nuo yang <[email protected]>:
>> Hi everyone,
>>
>> Recently I use ffmpeg sdk to develop my own player, my video source is
>> MPEG-2 NTSC video, and I use ffmpeg sdk to decode the video, then use
>> BlackMagic DeckLink sdk to receive the video frame and display the video to
>> my CRT monitor through a DeckLink PCI card. Everything is okay but a little
>> defect, when the video contains some red color objects (like red clothes),
>> and if the red color objects moving fast, there are some horizontal lines on
>> red color. My video is interlaced, and I tried some methods, including
>> change the video field order, but I didn't make it. BTW, if I use ffdshow to
>> decode the video, it does not have the issue.
>>
>> Is there someone has the same issue like me, or can someone give me some
>> advice? Many thanks in
advance!
>>
>>
>> - Nuo
>>
>> _______________________________________________
>> Libav-user mailing list
>> [email protected]
>> http://ffmpeg.org/mailman/listinfo/libav-user
>>
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