[Libav-user] MPEG-2 NTSC video shows horizontal lines on the red color

[nuo yang]

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 <yangnuo0408 at yahoo.com.cn>
To: "This list is about using libavcodec, libavformat, libavutil, libavdevice and libavfilter." <libav-user at ffmpeg.org> 
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 <lulebo at gmail.com>
To: "This list is about using libavcodec, libavformat, libavutil, libavdevice and libavfilter." <libav-user at ffmpeg.org> 
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 <lulebo at gmail.com>:
> 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 <yangnuo0408 at yahoo.com.cn>:
>> 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
>> Libav-user at ffmpeg.org
>> http://ffmpeg.org/mailman/listinfo/libav-user
>>
_______________________________________________
Libav-user mailing list
Libav-user at ffmpeg.org
http://ffmpeg.org/mailman/listinfo/libav-user


   
_______________________________________________
Libav-user mailing list
Libav-user at ffmpeg.org
http://ffmpeg.org/mailman/listinfo/libav-user
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://ffmpeg.org/pipermail/libav-user/attachments/20130519/a46ce12e/attachment.html>