[FFmpeg-user] Piping output of ffmpeg into ffmbc

Keith Reilly kreilly at retroreport.com
Thu Aug 25 18:54:12 EEST 2016

      You have solved my problem. Now i understand how IMX works and now I
don't have to rely on a pipe from ffmpeg to ffmbc in order to process
certain files. In fact i'll just use ffmpeg for everything, even what was
working with ffmbc. The quality from ffmpeg looks slightly better to me.
One last question. Is there a website dedicated to encoding media for Avid,
and other broadcast devices, with ffmpeg. I know there is the ffmpeg manual
but that is a bit overwhelming and doesn't deal with requirments Avid has.
When i last researched this not to long ago I found ffmbc and i thought
that ffmpeg could do produce media for fast import in Avid. Obviously this
was wrong. The reason I ask is because i feel at some point my boss is
going to want me to start processing archival thats HD for Avid so it would
be good to start learning. Thanks for all your help.

On Thu, Aug 25, 2016 at 3:48 AM, Erik Dobberkau <erik.dobberkau at gmail.com>

> 2016-08-24 22:12 GMT+02:00 Keith Reilly <kreilly at retroreport.com>:
> > with line 5 I get an error from the output of ffmpeg:
> > [NULL @ 0x7ff76100d200] Unable to find a suitable output format for
> > '[-rc_max_vbv_use'
> > [-rc_max_vbv_use: Invalid argument
> >
> Keith,
> I was using square brackets to indicate these parameters as optional, so
> you need to leave these square brackets out if you want to apply the
> parameters.
>         With your video filters line, "scale=720:576:interl=0:in_
> > color_matrix=bt709:out_color_matrix=bt601,pad=720:608:0:32,
> > tinterlace=4:flags=vlpf,setdar=16/9", i changed scale=720:576 to 720:486
> > since when i looked up what the NTSC standard for IMX was i read it was
> > 720X486. This worked find with your padding but when i take that out Avid
> > will fast import but not playback. After comparing this output from
> ffmpeg
> > (720x486 with no padding) to the ffmbc counterpart i saw that the
> > resolution of ffmbc was actually 720x512. So when I changed this in
> ffmpeg,
> > scale=720:512, i can fast import and playback just fine. The problem
> there
> > is that the aspect ratio is slightly off and the very top of the image is
> > cut off. Also i took note that Avid reports this file with a raster of
> > 720x486 even though it is clearly 720x512.
> >         My conclusion is that with Avid, when using the IMX format, it
> will
> > ignore the top 24 lines of resolution. So I need to create a video that
> > has, at least for NTSC, 24 lines of padding at the top since Avid will
> > treat the video as 720:486 by cutting off the top.
> >
> This seems insane but that is what i'm looking at. I can clearly see the
> > top of the video in VLC
> > but in Avid it is gone.  And I think the reason why the image is not
> > centered with your command is because i change the scale for NTSC but not
> > the padding and it threw everything off. Is this correct? It looks like
> it
> > is to me from all the testing i did but it seems so strange that things
> > would behave this way. I tried to google this but it did not clear
> anything
> > up.
> >
> >
> Well, you almost got it. IMX format requires VBI to be put somewhere,
> that's why you have 486 lines (not 480 as I stated previously) of active
> video and 26 black lines at the top (in NTSC). Avid MC reports active video
> frame size. VLC is "stupid" and will display the whole video frame,
> including areas which in terms of broadcast video are inactive and will be
> cut off after transmission. (It's always helpful to know how stuff was done
> before there were -almost- only files.)
> In conclusion you need to scale your video to 720x486 and the add 26 (not
> 24) lines/pixels at the top when encoding.
> This is not insane at all, it just makes IMX a not-so-easy format to
> handle. If you apply said changes to your command it should work out.
> Erik
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