Is 'rawvideoparse' element reading the wrong amount of bytes?

[Nicolas Dufresne]

Le lun. 30 déc. 2019 12 h 44, Antonio Ospite <ao2 at ao2.it> a écrit :

> On Mon, 30 Dec 2019 11:19:47 -0500
> Nicolas Dufresne <nicolas at ndufresne.ca> wrote:
>
> > Le lun. 30 déc. 2019 04 h 30, Aschwin Brandt <aschwin.brandt at gmail.com>
> a
> > écrit :
> >
> > > Hello all,
> > >
> > > This is my first post, so please inform me if I break any rules.
> > >
> > > I'm reading a byte-stream YUV420 at 972x720 pixels from a file with
> > > Gstreamer using the following command:
> > >
> > > gst-launch-1.0 filesrc location=testfile blocksize=1049760 !
> rawvideoparse
> > > width=972 height=720  framerate=1/1 ! xvimagesink
> > >
> > > This works in so far that I get an image but this image isn't displayed
> > > correctly. It looks like it contains part of the next YUV frame. When
> > > exporting the frames seperately using command:
> > >
> > > gst-launch-1.0 filesrc location=testfile blocksize=1049760 !
> rawvideoparse
> > > width=972 height=720  framerate=1/1 ! multifilesink
> location="rvp_%d.raw"
> > >
> > > And play it using ffmpeg command:
> > >
> > > ffplay -f rawvideo -video_size 972x720 -pixel_format yuv420p -i
> rvp_0.raw
> > >
> > > The video (one frame) is displayed correctly.
> > >
> > > I see that when using the element 'rawvideoparse' it will create a
> file of
> > > 1051200 bytes per frame instead of the expected 1049760. When I remove
> > >
> >
> > I'm not sure why this odd value. It sounds like a bug to me, or some half
> > thought feature. Best is to investigate were the buffer size get
> augmented.
> > I've checked in the video info code, and it should chose 1049760.
> >
>
> The issue is probably in
> gst-plugins-base/gst-libs/gst/video/video-info.c
>
> When fill_planes() calculates components sizes for GST_VIDEO_FORMAT_I420
> is assumes that U and V strides should be multiple of 4, is this really
> a requirement?
>

Indeed I missed it. I don't think it's a requirement, but we are likely
stuck with this legacy, as some code will assume that if there is no video
meta support.

rawvideoparse let you specify the strides and offset, can we get this file
to be parsed with that set ? (Syntax is <stride,ustride,vstride>)


> Ciao,
>    Antonio
>
> --
> Antonio Ospite
> https://ao2.it
> https://twitter.com/ao2it
>
> A: Because it messes up the order in which people normally read text.
>    See http://en.wikipedia.org/wiki/Posting_style
> Q: Why is top-posting such a bad thing?
>
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