Video streaming on ofdm

hye…
i’m using grc for video streaming of ofdm system…
i manage to transmit the video but the quality is so bad…
and sometime the video can play,but sometime it doesn’t play at all…
how to improve the video quality?is it approriate to add buffer on it?
and i got this message…what does it meant??

gst-launch -v playbin uri=file:///root/rx
Setting pipeline to PAUSED …
Pipeline is PREROLLING …
ERROR: from element
/GstPlayBin:playbin0/GstDecodeBin:decodebin0/GstTypeFindElement:typefind:
Stream contains no data.
Additional debug info:
gsttypefindelement.c(570): gst_type_find_element_handle_event ():
/GstPlayBin:playbin0/GstDecodeBin:decodebin0/GstTypeFindElement:typefind:
Can’t typefind empty stream
ERROR: pipeline doesn’t want to preroll.
Setting pipeline to NULL …
Freeing pipeline …

tq


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On Sat, Apr 14, 2012 at 10:46 AM, rara [email protected] wrote:

hye…
i’m using grc for video streaming of ofdm system…
i manage to transmit the video but the quality is so bad…
and sometime the video can play,but sometime it doesn’t play at all…
how to improve the video quality?is it approriate to add buffer on it?
and i got this message…what does it meant??

The OFDM you’re using is just the PHY layer. There are lots of other
parts to a working video streaming application (all the other layers
of the stack). Any you probably don’t even have FEC in the system. So
yes, there are lots of other things you can do to make the stream play
better.

ERROR: pipeline doesn’t want to preroll.
Setting pipeline to NULL …
Freeing pipeline …

tq

That’s outside of GNU Radio and I have no experience with it. Sorry,
can’t help you with this one.

Tom

here is command that i use…

gst-launch -e v4l2src ! video/x-raw-yuv, framerate=10/1, width=320,
height=240 ! ffmpegcolorspace ! ffenc_mpeg4 ! avimux ! filesink
location=tx

i manage to receive the webcam,but at certain time the video stop and
suddenly play so fast showing on the previous playback…someone suggest
me
to add buffer for smooth video…but, i’m out of idea how to implement
the
buffer on my grc block…can u help me??regarding on the fps, i cant see
what value are suitable to be used n why the value should be like
that…

sumitstop wrote:

how to improve the video quality?is it approriate to add buffer on it?
/GstPlayBin:playbin0/GstDecodeBin:decodebin0/GstTypeFindElement:typefind:


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try reducing the fps. this worked for me

rara wrote:

Pipeline is PREROLLING …

tq


Sumit Kr.
Research Assistant
Communication Research center
IIIT Hyderabad
India

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actually I did this one … I was having the problem of bad video quality
so I
reduced the fps and it was better. here is the link. I am not sure if it
will be of accurate help …

(I guess u must have seen this already :-D)

http://wiki.oz9aec.net/index.php/Simple_DVB_with_Gstreamer_and_GNU_Radio

he is not using ofdm but still u can see the values which u want… hope
it
will help

rara wrote:

the buffer on my grc block…can u help me??regarding on the fps, i cant

ERROR: from element
tq


Sumit Kr.
Research Assistant
Communication Research center
IIIT Hyderabad
India

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On Sat, Apr 14, 2012 at 10:46 AM, rara [email protected] wrote:

The OFDM you’re using is just the PHY layer. There are lots of other
parts to a working video streaming application (all the other layers
of the stack). Any you probably don’t even have FEC in the system. So
yes, there are lots of other things you can do to make the stream play
better.

i’m sorry…i’m still new in this field…i cant see what u try to tell
bout
the FEC…n as i told before…someone have suggest me to implement
buffer…but u said there are others option can be use…can u suggest n
explain on it more…@ can u give me example so that i can get more
clear
view on it…


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