[linux-dvb] How to stream DVB-S2 channels over network?

BOUWSMA Barry freebeer.bouwsma at gmail.com
Sun Dec 21 15:39:02 CET 2008


On Sun, 21 Dec 2008, Artem Makhutov wrote:

> I have recorded the stream to a file and will try to playback it under windows.
> My CPU is too slow to playback the stream without GPU acceleration under linux.

A common occurrence, I say, fondling my beloved 200MHz
production machine that records four streams flawlessly
(save for two devices being USB1 and thus only good for
radio or selected TV clamped to a maximum bitrate, for
now)


I pass all my recordings through a two-pass process to
check for problems (for radio, obviously just one pass)

I have a script that extracts the audio payload using a
hack to `dvb_mpegtools' and passes it to `mpg123'.  The
`dvb_mpegtools' serves to check the integrity of the
Transport Stream (usually when bad weather affects my
satellite reception, or when my DVB-T receiving antenna
is placed in a poor location); `mpg123 -v -t' zips through
the file and spits out any corrupted audio frames.

(The version of mpg123 I use doesn't seem to do anything
with the CRC when used, and it gets confused when the
CRC is toggled during a stream, which has happened a few
times during recordings I've made.  That's something
which I should work on, because I have a few recordings
with audible blorps that pass the `mpg123' test, probably
due to flipped bits in the payload rather than dropped
data.)


Then I use `mplayer' to check the video, using the
options `-nosound -vo null' and in the case of MPEG-2
video, `-vc ffmpeg12'.  This will spit out errors due
to corruption of the video data -- though you need to
hack in some newlines if you want to actually see the
PTS timestamp where the error(s) occurred.

For H.264 video, there is no alternative to `-vc ffh264'
that I know of, but it will similarly spew out errors
if there's damage to your source.

Sure, it takes my machines more than a day to chew through
an hour of H.264 1080i video, but I know whether I need
to re-record the programme later to get a clean file that
I can watch in some ten years when people throw away the
gamer machines of today.  Yeah, I'm cheap.  What of it?


That's a lot easier than suffering eyestrain watching a
screen for some scarcely-visible corruption, which I
used to do long ago...


barry bouwsma
stingy scrooge



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