[FFmpeg-user] Piping output of ffmpeg into ffmbc

[Erik Dobberkau]

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