Encoding format string

[amindfv at mailbox.org]

Running on very little sleep with a deadline looming, I find myself unable to come up with a GstEncoding profile for `ges-launch-1.0` (a task that seems simple enough).

I've got input sources that are 4096x2160 with a pixel format of yuv420p10le; I'd like to preserve that as the output format (and make sure the pixel format isn't getting downgraded anywhere in the pipeline). I'd also like to make sure the bitrate stays at 200mb/s.

I've tried things from this page (https://gstreamer.freedesktop.org/documentation/pbutils/encoding-profile.html?gi-language=c), and come up with things like 

    video/quicktime,variant=iso:video/x-h264,width=4096,height=2160|target-bitrate=200000

(There's one video track, no audio)

But I get errors from ges-launch like:

    ERROR from element qtdemux27: Internal data stream error./>

    Debugging info: ../gst/isomp4/qtdemux.c(6545): gst_qtdemux_loop (): /GESPipeline:gespipeline0/GESTimeline:gestimeline0/GESVideoTrack:gesvideotrack0/NleComposition:video_nlecomposition0/GstBin:current-bin/NleSource:GESVideoUriSource:nlesource0/GstBin:videosrcbin/GstURIDecodeBin:uridecodebin0/GstDecodeBin:decodebin56/GstQTDemux:qtdemux27:
streaming stopped, reason not-negotiated (-4)


As I say, I'm on quite a deadline; any help would be very appreciated!

Thanks,
Tom