[FFmpeg-user] Causes of color bars?

Tue Jul 14 17:41:12 EEST 2020

Well, I found out more. If I connect the camera to the input through the
cabling, but remove the splitter, it works as is, with the command I
originally used i.e. autodetecting the Hp59 signal. If I include the
splitter, the decklink mediaexpress still works, and indicates 59.94
progressive, but ffmpeg doesn't see it.

Could the splitter be changing the pixel format? I'll read about those and
see if I can move forward that way.

On Tue, Jul 14, 2020 at 7:17 AM Simon Roberts <
simon at dancingcloudservices.com> wrote:

> Thanks Paul and Marton for the input. I will note that the simple command,
> entirely defaults-based, is what I used on a previous machine running with
> the same card (same, not merely "same model"), and with the same input
> device. That machine wasn't powerful enough to prores-encode four channels
> simultaneously, so I built a bigger box. Also, the input source is not
> adjustable, so it has not changed. The three things that have changed are
> a) the new box has Ubuntu 20.04, while the old one has 18.04 (Decklink
> claims support for 18.04, but doesn't mention 20.04), b) the CPU (was i7
> and is now Ryzen 7) and c) the build of ffmpeg / the installation of the
> decklink drivers (obviously in this context, I built both ffmpegs and
> though there were no reported errors in the build, I wonder if I might have
> done something wrong).
>
> Regardless, I'll try setting the input format explicitly (I know for sure
> that it's 1080, 60p, but I don't actually know for sure what the pixel
> format is--it's reporting as 4:2:2 in the decklink "media player" that
> reads the data successfully, so that seems a good start--but regardless,
> there's likely to be some experimenting there.
>
> I have also tried running with the verbose flag, but that didn't report
> anything untoward.
>
> Is there a chance there is a permission issue, or a library location
> issue, even though there are no errors reported?
>
> Anyway, I'll go tinker with the format specifications and see if anything
> changes. Fingers are crossed.
>
> Thanks again for the suggestions!
>
>
> On Tue, Jul 14, 2020 at 2:07 AM Paul Blakeman via ffmpeg-user <
> ffmpeg-user at ffmpeg.org> wrote:
>
>> You need to tell ffmpeg the Declink format you wish to use
>> 1) List the formats available
>> 2) Then use in command
>>
>> e.g.
>> 1)
>> ffmpeg -f decklink -list_formats 1 -i "UltraStudio Mini Recorder"
>> [decklink @ 0x7fe28080b800] Supported formats for 'UltraStudio Mini
>> Recorder':
>> format_code     description
>> ntsc    720x486 at 30000/1001 fps (interlaced, lower field first)
>> nt23    720x486 at 24000/1001 fps
>> pal 720x576 at 25000/1000 fps (interlaced, upper field first)
>> ntsp    720x486 at 60000/1001 fps
>> palp    720x576 at 50000/1000 fps
>> 23ps    1920x1080 at 24000/1001 fps
>> 24ps    1920x1080 at 24000/1000 fps
>> Hp25    1920x1080 at 25000/1000 fps
>> Hp29    1920x1080 at 30000/1001 fps
>> Hp30    1920x1080 at 30000/1000 fps
>> Hi50    1920x1080 at 25000/1000 fps (interlaced, upper field first)
>> Hi59    1920x1080 at 30000/1001 fps (interlaced, upper field first)
>> Hi60    1920x1080 at 30000/1000 fps (interlaced, upper field first)
>> hp50    1280x720 at 50000/1000 fps
>> hp59    1280x720 at 60000/1001 fps
>> hp60    1280x720 at 60000/1000 fps
>>
>> (And then some examples of usage)
>> https://ffmpeg.org/ffmpeg-devices.html#Examples-1
>>
>> e.g.
>> 2)
>>
>> ffmpeg -format_code Hi59 -f decklink -i "UltraStudio Mini Recorder"
>> -preset superfast -crf 18 -minrate 8M -maxrate 8M -bufsize 10M -acodec
>> libfdk_aac -vcodec libx264  -r 30 -f flv rtmp://xxxxx.com
>>
>> Hope that helps
>>
>> Regards,
>> Paul
>>
>>
>> On 14 Jul 2020, at 02:28, Simon Roberts <simon at dancingcloudservices.com>
>> wrote:
>> >
>> > Hi all,
>> >
>> > I've been working with a Decklink Quad HDMI card under Ubuntu 20.04. The
>> > kernel driver is loaded and the Blackmagic software "mediaexpress"
>> displays
>> > the input signal perfectly. However, when I try to use ffplay, it seems
>> > like it knows which of the four channels on the card has a signal,
>> because
>> > it drops out with "can't determine format" on the other three, but when
>> I
>> > ask to view the valid input signal, I simply get color bars.
>> >
>> > I just built this version of ffmpeg with the decklink support, and it
>> ran
>> > without any evident errors. I've done this before on another machine
>> that
>> > didn't have a strong enough CPU for the concurrent capture I want to do,
>> > and everything worked properly.
>> >
>> > So, my question is, what possible causes of color bars are there? I know
>> > that one is "if the input signal is lost", but it's claiming that it
>> has a
>> > signal and it correctly identifies it as 1080 60p. I'm wondering if the
>> > bars are from the Decklink drivers, and not actually anything to do with
>> > ffmpeg/ffplay. How could I determine that?
>> >
>> > This is the log output:
>> >
>> > $ ffplay -f decklink -i 'DeckLink Quad HDMI Recorder (1)'
>> > ffplay version N-98470-g7772666 Copyright (c) 2003-2020 the FFmpeg
>> > developers
>> >  built with gcc 9 (Ubuntu 9.3.0-10ubuntu2)
>> >  configuration: --prefix=/home/simon/ffmpeg_build
>> > --pkg-config-flags=--static
>> > --extra-cflags='-I/home/simon/ffmpeg_build/include
>> > -I/home/simon/ffmpeg_sources/BMD_SDK/include'
>> > --extra-ldflags=-L/home/simon/ffmpeg_build/lib --extra-libs='-lpthread
>> -lm'
>> > --bindir=/home/simon/bin --enable-gpl --enable-libass
>> --enable-libfdk-aac
>> > --enable-libfreetype --enable-libmp3lame --enable-libopus
>> > --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265
>> > --enable-nonfree --enable-decklink
>> >  libavutil      56. 55.100 / 56. 55.100
>> >  libavcodec     58. 95.100 / 58. 95.100
>> >  libavformat    58. 48.100 / 58. 48.100
>> >  libavdevice    58. 11.101 / 58. 11.101
>> >  libavfilter     7. 87.100 /  7. 87.100
>> >  libswscale      5.  8.100 /  5.  8.100
>> >  libswresample   3.  8.100 /  3.  8.100
>> >  libpostproc    55.  8.100 / 55.  8.100
>> > [decklink @ 0x7fb628000bc0] Autodetected the input mode  0B f=0/0
>> > [decklink @ 0x7fb628000bc0] Found Decklink mode 1920 x 1080 with rate
>> 59.94
>> > [decklink @ 0x7fb628000bc0] Frame received (#1) - No input signal
>> detected
>> > - Frames dropped 1
>> > Input #0, decklink, from 'DeckLink Quad HDMI Recorder (1)': f=0/0
>> >  Duration: N/A, start: 0.000000, bitrate: 1990203 kb/s
>> >    Stream #0:0: Audio: pcm_s16le, 48000 Hz, 2 channels, s16, 1536 kb/s
>> >    Stream #0:1: Video: rawvideo (UYVY / 0x59565955),
>> uyvy422(progressive),
>> > 1920x1080, 1988667 kb/s, 59.94 tbr, 1000k tbn, 1000k tbc
>> >   1.23 A-V: -1.453 fd=  62 aq=  261KB vq=16200KB sq=    0B f=0/0
>> >
>> > Thanks for any help!
>> > _______________________________________________
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>> > ffmpeg-user at ffmpeg.org
>> > https://ffmpeg.org/mailman/listinfo/ffmpeg-user
>> >
>> > To unsubscribe, visit link above, or email
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>>
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>
>
>
> --
> Simon Roberts
> (303) 249 3613
>
>

-- 
Simon Roberts
(303) 249 3613