On Thu, Jan 31, 2019 at 9:42 PM Philipp Zabel <p.zabel@xxxxxxxxxxxxxx> wrote: > > Hi Nicolas, > > On Wed, 2019-01-30 at 10:32 -0500, Nicolas Dufresne wrote: > > Le mercredi 30 janvier 2019 à 15:17 +0900, Tomasz Figa a écrit : > > > > I don't remember saying that, maybe I meant to say there might be a > > > > workaround ? > > > > > > > > For the fact, here we queue the headers (or first frame): > > > > > > > > https://gitlab.freedesktop.org/gstreamer/gst-plugins-good/blob/master/sys/v4l2/gstv4l2videodec.c#L624 > > > > > > > > Then few line below this helper does G_FMT internally: > > > > > > > > https://gitlab.freedesktop.org/gstreamer/gst-plugins-good/blob/master/sys/v4l2/gstv4l2videodec.c#L634 > > > > https://gitlab.freedesktop.org/gstreamer/gst-plugins-good/blob/master/sys/v4l2/gstv4l2object.c#L3907 > > > > > > > > And just plainly fails if G_FMT returns an error of any type. This was > > > > how Kamil designed it initially for MFC driver. There was no other > > > > alternative back then (no EAGAIN yet either). > > > > > > Hmm, was that ffmpeg then? > > > > > > So would it just set the OUTPUT width and height to 0? Does it mean > > > that gstreamer doesn't work with coda and mtk-vcodec, which don't have > > > such wait in their g_fmt implementations? > > > > I don't know for MTK, I don't have the hardware and didn't integrate > > their vendor pixel format. For the CODA, I know it works, if there is > > no wait in the G_FMT, then I suppose we are being really lucky with the > > timing (it would be that the drivers process the SPS/PPS synchronously, > > and a simple lock in the G_FMT call is enough to wait). Adding Philipp > > in CC, he could explain how this works, I know they use GStreamer in > > production, and he would have fixed GStreamer already if that was > > causing important issue. > > CODA predates the width/height=0 rule on the coded/OUTPUT queue. > It currently behaves more like a traditional mem2mem device. The rule in the latest spec is that if width/height is 0 then CAPTURE format is determined only after the stream is parsed. Otherwise it's instantly deduced from the OUTPUT resolution. > > When width/height is set via S_FMT(OUT) or output crop selection, the > driver will believe it and set the same (rounded up to macroblock > alignment) on the capture queue without ever having seen the SPS. That's why I asked whether gstreamer sets width and height of OUTPUT to non-zero values. If so, there is no regression, as the specs mimic the coda behavior. > > The source change event after SPS parsing that the spec requires isn't > even implemented yet. > > regards > Philipp
