[MPlayer-users] I know what telecine and interlacing are, but ....

[Andy Furniss]

Ivan Kalvachev wrote:
> On 5/14/14, James Board <jpboard2 at yahoo.com> wrote:
>> I'm capturing video from the HDMI output of my DVR onto my Linux
>> PC.  I play the video with mplayer from PC->TV by connecting the
>> video card's HDMI output to the TV's HDMI input.  When I do that,
>> I see combing effects on the TV from either interlacing or
>> telecining.
>>
>> However, if I play the video straight from the DVR->TV, then
>> there's no combing effects.  But for PC->TV, I see combing effects.
>> Why is this? If I'm capturing the video off of the DVR HDMI output,
>> everything is digital, so when I play the captured video back to
>> the TV from the PC, shouldn't it look exactly the same as if I play
>> the video from the DVR->TV?
>>
>> The only answer I can think of is that maybe the TV de-interlaces,
>> or inverse telecines the video when it is played from DVR->TV.  But
>> it doesn't do so when played from PC->TV.  Is that possible?  Or am
>> I misunderstanding some other thing?
>>
>> Anyway, is it possible to play the captured video  with mplayer
>> from the PC-TV without any combing effects if I don't explicitly
>> deinterlace or inverse telecine the captured video?
>>
> Lobs commented your question in #mplayer irc channel <Lobs> he is
> asking why his captured video from his dtv box via hdmi has interlace
> artifacts on his tv when playing to it via hdmi and mplayer, yet when
> he plugs the dtv box into the same hdmi to his tv it has no interlace
> artifacts, <Lobs> the answer is his dtv box sets an interlaced video
> mode to the tv via hdmi, where as his pc is doing a progressive
> mode. <Lobs> he then asks if using mplayer to the tv with his pc can
> he play without the interlace effects without deinterlaing etc,
> answer is yes, but he would need to set the pc to use an interlaced
> mode to the tv, which may make terminal text look REALLY bad. <iive>
> I could post this replay in the maillist. <iive> so he needs to set
> e.g. 1080i instead of 1080p <iive> then the TV would deinterlace the
> video. <iive> or deinterlace the video with -vf yadif <Lobs> yes,
> that is correct, <Lobs> but using an interlaced mode may make the
> desktop or anything with fine horizontal lines flicker <Lobs> (it all
> depends on how the tv deinterlaces or processes the interlaced
> content) <Lobs> also some graphics card drivers lack the interlaced
> modes, <Lobs> (i have had issues in windows at least with that,
> trying to get 1080i for production video mixers via hdmi)

Hmm, I can see that James's mail made the archive, but I didn't get it
from the list - maybe google ate it, is this just me?

I did recently get this working on my TV, but I had to use mpv rather
than mplayer - reasons.

1. mplayer is not always so nice playing fps=refresh rate, though it is
possible with luck, but IME a bit variable, -framedrop was needed and
could be quite disruptive on h264.

2. You need to use tinterlace interlacex2 to maintain field sync. This
was recently fixed in ffmpeg which is actually the reason I noticed this
was possible at all. The filter displays full height weave and updates
the screen at field rate changing just top/bottom and leaving the other
on display.

The problem is that mplayer doesn't have the filter and trying to get it
to use ffmpeg failed for me.

The mpv (needs to be built using git tips which is not default) commend
I used was -

mpv -fs -vo vdpau:fps=50 --vf=lavfi=[tinterlace=interlacex2],ilpack

There are complications, for me at least using OSS AMD drivers/vdpau, in
fact I've just changed to a different AMD GPU and the above won't work
for me now ad I've gained UVD, but lost 422. The 422 was needed as
that's what ilpack outputs and that was needed because interlaced 420
chroma is different from progressive and gpus always assume progressive
when they do the yuv -> rgb which causes chroma to bleed between fields
confusing my TVs deinterlacer. My OSS AMD drivers only do RGB HDMI -
IIRC the closed do yuv 444/422 and my TV would take this, so that could
a different setup option.

Other observations -

My TV deinterlaces RGB HDMI input well and it's truly adaptive, pause
something and it will turn back to weave, this means that desktop looks
good.

OSS AMD drivers are slightly wrong for my 1080i modes, but I could live
with it (last quater of bottom line wraps around to top and repeats).
The SD CEA double clocked i modes are unusable though.

So in summary what's doable for you depends on the detail of your setup/tv.