Mailing List Archive

PVR-150 in "Live Preview" mode?
Howdy, I'm trying to play video games through my PVR-150 and I'm finding the
lag due to the encoder (while only about 0.9s) to be unbearable.

I've been trying to figure out how to get this card in to "Live Preview"
mode in Linux. Hauppauge includes some instructions on their site for how to
do this in Windows.. But of course, that doesn't help me a much.

When I check the available output formats, I get the following:

j@Neptune:~$ v4l2-ctl --list-formats
ioctl: VIDIOC_ENUM_FMT
Index : 0
Type : Video Capture
Pixel Format: 'HM12'
Name : HM12 (YUV 4:2:0)

Index : 1
Type : Video Capture
Pixel Format: 'MPEG' (compressed)
Name : MPEG

So then I try to change the output video format from MPEG to HM12 (hoping
that is less laggy). The operation returns as though it worked, except when
I check the settings is doesn't seem to notice the new "pixel format"..

I run the below to change the format:

j@Neptune:~$ v4l2-ctl -V
Format Video Capture:
Width/Height : 720/450
Pixel Format : 'MPEG'
Field : Interlaced
Bytes per Line: 0
Size Image : 131072
Colorspace : Broadcast NTSC/PAL (SMPTE170M/ITU601)



Immediately after that I, attempt to change the format with "j@Neptune:~$
sudo v4l2-ctl --set-fmt-video=width=720,height=480,pixelformat=0", but I get
the following (with no error messages):
j@Neptune:~$ v4l2-ctl -V
Format Video Capture:
Width/Height : 720/480
Pixel Format : 'MPEG'
Field : Interlaced
Bytes per Line: 0
Size Image : 131072
Colorspace : Broadcast NTSC/PAL (SMPTE170M/ITU601)

This nothing changed.


Please help me figure out how to watch the video content hitting my PVR-150
in as close to real time as possible!!
Re: PVR-150 in "Live Preview" mode? [ In reply to ]
On Fri, 2010-03-05 at 02:05 -0700, Doc wrote:
> Howdy, I'm trying to play video games through my PVR-150 and I'm
> finding the lag due to the encoder (while only about 0.9s) to be
> unbearable.
>
> I've been trying to figure out how to get this card in to "Live
> Preview" mode in Linux. Hauppauge includes some instructions on their
> site for how to do this in Windows.. But of course, that doesn't help
> me a much.


> Please help me figure out how to watch the video content hitting my
> PVR-150 in as close to real time as possible!!

Set the card to the proper input. The following example is the
composite 1 on most cards, being set to NTSC, and audio at 48 ksps:

$ v4l2-ctl -d /dev/video0 -i 2
$ v4l2-ctl -d /dev/video0 -s ntsc
$ v4l2-ctl -d /dev/video0 -c audio_sampling_frequency=1

Start playing the uncompressed PCM audio from the card. This example
uses aplay to play the 48 ksps captured audio to the default ALSA
playback device, and puts aplay in the background:

$ aplay -f dat < /dev/video24 &


Start playing the raw video frames being captured by the card with
mplayer:

$ mplayer /dev/video32 -demuxer rawvideo -rawvideo w=720:h=480:format=hm12:ntsc


That gets you the basic setup you want. I'm not aware of any live TV
application under linux, other than mplayer, that has native support for
drivers providing the read() method and the odd HM12 YUV video format.

Regards,
Andy


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