[FFmpeg-user] Capture multiple streams into same container?

[Simon Roberts]

On Wed, Jun 24, 2020 at 3:41 AM Tom Sparks <tomasparks.ts at gmail.com> wrote:

> mkv is a better output format to use
>

Thanks for this Tom, can you expand on what the benefits are? I think I
ended up with mov as it seemed to be the "natural" choice for apple prores
content, but there was no thought went into it, just "what somebody said" :)




> On 24/06/2020, Simon Roberts <simon at dancingcloudservices.com> wrote:
> > Greetings all, I'm a pretty low-level ffmpeg user, just doing screen
> > captures, compressions, and some simple format conversions. I have not
> made
> > much progress understanding more advanced key concepts; I apologize if
> this
> > is a basic question.
> >
> > I have a four-input video capture card, (Blackmagic DeckLink) and I
> > successfully built ffmpeg with support for that. I can capture using the
> > card, and I can run two captures concurrently as independent processes
> > putting output into two different files. I haven't tried running all four
> > at once (though that's my long-term goal, along with another four audio
> > channels from a USB capture device).
> >
> > However, I would like to be able to put the multiple streams into a
> single
> > file. There are a couple of reasons for this, and if my expectations are
> > misplaced, now's a great time to tell me. One is that I'd like the
> > timecodes to be synchronized, another is that I'd prefer a single command
> > to start everything, and end everything, at the same instant. This, I
> hope
> > will reduce the complexity of synchronizing the channels in later
> editing.
> >
> > But I have no clue how to start with this. I tried simply adding more
> input
> > channels to my input specifications:
> >
> > ffmpeg -f decklink -i 'DeckLink Quad HDMI Recorder (1)' -f decklink -i
> > 'DeckLink Quad HDMI Recorder (4)'  -c:v copy -c:a copy -metadata
> > title=DeckLinkCapture  capture.mov
> >
> > But all I got was a ton of buffer overruns, and a file that ffprobe said
> > only contained one video stream.
> >
> > I believe that .mov can hold multiple streams, but I have not particular
> > reason for using that file format, other than I often use it when I go
> with
> > a prores compression. (I'm hoping that later in this project I might get
> > enough CPU power to go that route, and reduce bandwidth and storage
> > requirements to less insane levels)
> >
> > Can someone point me at a template for a command line that might do what
> I
> > need? If the explanation or resources might help me understand the
> concepts
> > better, that would be a bonus (and might result in my becoming a little
> > more self-sufficient!)
> >
> > Cheers,
> > Simon
> >
> >
> > --
> > Simon Roberts
> > (303) 249 3613
> > _______________________________________________
> > ffmpeg-user mailing list
> > ffmpeg-user at ffmpeg.org
> > https://ffmpeg.org/mailman/listinfo/ffmpeg-user
> >
> > To unsubscribe, visit link above, or email
> > ffmpeg-user-request at ffmpeg.org with subject "unsubscribe".
> _______________________________________________
> ffmpeg-user mailing list
> ffmpeg-user at ffmpeg.org
> https://ffmpeg.org/mailman/listinfo/ffmpeg-user
>
> To unsubscribe, visit link above, or email
> ffmpeg-user-request at ffmpeg.org with subject "unsubscribe".



-- 
Simon Roberts
(303) 249 3613