[FFmpeg-user] Piping example?

[Totte Karlsson]

To follow up to this thread;

I got recording using a named pipe on windows working reliably with the following command:

ffmpeg.exe-y -hide_banner -vcodec rawvideo -f rawvideo -r 80 -s 658x492 -pix_fmt gray -i \\.\pipe\DEV_000F315BE933 -r 80 -c:v rawvideo X:\DEV_000F315BE933_2019T100914.avi

I could not get proper replay speed without using the both -r 80.

-tk


> -----Original Message-----
> From: Totte Karlsson [mailto:tottek at gmail.com]
> Sent: Wednesday, October 09, 2019 5:17 PM
> To: 'FFmpeg user questions' <ffmpeg-user at ffmpeg.org>
> Subject: RE: [FFmpeg-user] Piping example?
> 
> Hello,
> I got streaming working using a named pipe on Windows. Great!
> 
> The camera (Allied Vision) is streaming 80fps to the pipe.
> 
> I'm reading from the pipe like this:
> ffmpeg  -y -vcodec rawvideo -f rawvideo -hide_banner  -s 658x492 -pix_fmt gray -i
> \\\\.\\pipe\\Pipe -vsync vfr out.avi
> 
> The output video seem to have all the frames and the output looks good. However,
> the video plays about 3.5 times slower than the input!?
> 
> The output from ffmpeg when running looks like this:
> 
> Input #0, rawvideo, from '\\.\pipe\Pipe':
>   Duration: N/A, start: 0.000000, bitrate: 64747 kb/s
>     Stream #0:0: Video: rawvideo (Y800 / 0x30303859), gray, 658x492, 64747 kb/s,
> 25 tbr, 25 tbn, 25 tbc Stream mapping:
>   Stream #0:0 -> #0:0 (rawvideo (native) -> mpeg4 (native)) Press [q] to stop, [?] for
> help [swscaler @ 0000014f03772000] Warning: data is not aligned! This can lead to
> a speed loss Output #0, avi, to 'out.avi':
>   Metadata:
>     ISFT            : Lavf58.33.100
>     Stream #0:0: Video: mpeg4 (FMP4 / 0x34504D46), yuv420p, 658x492, q=2-31,
> 200 kb/s, 25 fps, 25 tbn, 25 tbc
>     Metadata:
>       encoder         : Lavc58.59.101 mpeg4
>     Side data:
>       cpb: bitrate max/min/avg: 0/0/200000 buffer size: 0 vbv_delay: N/A
> 
> frame=  327 fps= 81 q=5.8 size=     518kB time=00:00:13.08 bitrate= 324.1kbits/s
> speed=3.22x
> 
> and the last 'frame':
> frame=  401 fps= 66 q=8.3 Lsize=     704kB time=00:00:16.04 bitrate= 359.6kbits/s
> speed=2.65x
> 
> 
> I also tried -r 80, instead of the -vsync vfr, but the result is the same..
> 
> Any helpers appreciated!
> 
> -tk
> 
> 
> 
> 
> 
> > -----Original Message-----
> > From: ffmpeg-user [mailto:ffmpeg-user-bounces at ffmpeg.org] On Behalf Of
> > Carl Eugen Hoyos
> > Sent: Tuesday, October 01, 2019 10:55 AM
> > To: FFmpeg user questions <ffmpeg-user at ffmpeg.org>
> > Subject: Re: [FFmpeg-user] Piping example?
> >
> > Am Di., 1. Okt. 2019 um 19:53 Uhr schrieb Totte Karlsson <tottek at gmail.com>:
> > >
> > >
> > > > Did you try the following?
> > > >
> > > > $ ffmpeg -f lavfi -i testsrc -f rawvideo -
> > > >
> > > > and:
> > > >
> > > > $ ffmpeg -f rawvideo -s 320x240 -pix_fmt rgb24 -i - out.avi
> > > >
> > >
> > > I did not test that but will test later today. My bitmaps are
> > > 658 x 492 and are greyscale 8 bits and are acquired at 100fps.
> >
> > You asked for an example.
> >
> > > I assume the  line
> > > > $ ffmpeg -f lavfi -i testsrc -f rawvideo -
> > >
> > > means streaming to standard out?
> >
> > Yes.
> >
> > Carl Eugen
> > _______________________________________________
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