[linux-dvb] UDP encapsulated MPEG{2,4} TS into dvbsnoop?

Alexander E. Patrakov patrakov at ums.usu.ru
Thu Oct 18 11:52:41 CEST 2007


I wrote:
> My DVB card also receives some strange multicast packets. Guys from the 
> antenna company told me that this is a TV or radio broadcast and advised 
> not to hack them, but they are interested to sell me their decoder box, 
> so I'll ignore their advice if possible. Local news sites mention that 
> DVB-H is being tested, but these packets don't look like DVB-H payload, 
> because they are IPv4.
>
> Here is a packet dump (1300 KB): http://ums.usu.ru/~patrakov/udp.dump
>
> Is this "UDP encapsulated MPEG TS"? If not, what's this and how to 
> decode it?
>
>   
Today they changed the broadcast format on this 626 MHz frequency, it is 
DVB-T now (H.264 SD video + MP2 audio), so the decoding problem no 
longer exists on 626 MHz.

However, on 482 MHz, something strange happens: w_scan says that the 
signal is present, but can't detect any PIDs.

"dvbtune -f 482000000 -bw 8 -tm 8 -gi 32 -m" returns the following:

Using DVB card "Philips TDA10046H DVB-T"
tuning DVB-T (in United Kingdom) to 482000000 Hz
polling....
Getting frontend event
Overflow error, trying again (status = -1, errno = 75)FE_STATUS:
polling....
Getting frontend event
FE_STATUS:
polling....
Getting frontend event
FE_STATUS: FE_HAS_SIGNAL FE_HAS_LOCK FE_HAS_CARRIER FE_HAS_VITERBI 
FE_HAS_SYNC
Bit error rate: 57972
Signal strength: 28784
SNR: 59110
FE_STATUS: FE_HAS_SIGNAL FE_HAS_LOCK FE_HAS_CARRIER FE_HAS_VITERBI 
FE_HAS_SYNC
Signal=29041, Verror=58018, SNR=59110dB, BlockErrors=-1, (S|L|C|V|SY|)
Signal=28013, Verror=58234, SNR=59367dB, BlockErrors=-1, (S|L|C|V|SY|)
Signal=28013, Verror=56764, SNR=58853dB, BlockErrors=-1, (S|L|C|V|SY|)
Signal=28013, Verror=57162, SNR=59367dB, BlockErrors=-1, (S|L|C|V|SY|)
Signal=26214, Verror=131070, SNR=19789dB, BlockErrors=0, (S|V|)
Signal=26471, Verror=59754, SNR=58596dB, BlockErrors=-1, (S|L|C|V|SY|)
Signal=24672, Verror=131070, SNR=20303dB, BlockErrors=0, (S|)
Signal=12336, Verror=58104, SNR=58853dB, BlockErrors=-1, (S|L|C|V|SY|)
Signal=23644, Verror=58192, SNR=58853dB, BlockErrors=-1, ()
Signal=27756, Verror=131070, SNR=19789dB, BlockErrors=0, (S|)
Signal=28270, Verror=58454, SNR=59367dB, BlockErrors=-1, (S|L|C|V|SY|)
Signal=27756, Verror=57878, SNR=59110dB, BlockErrors=0, ()
Signal=27756, Verror=131070, SNR=20817dB, BlockErrors=41, (S|)
Signal=27242, Verror=57768, SNR=59367dB, BlockErrors=-1, (S|L|C|V|SY|)
Signal=27242, Verror=131070, SNR=28270dB, BlockErrors=0, (S|)
Signal=27756, Verror=58136, SNR=59367dB, BlockErrors=-1, (S|L|C|V|SY|)

Is this just a weak signal (on 626 MHz, Signal=50115 and Verror=0), or 
something indeed strange? The raw ts dump is available on request.

-- 
Alexander E. Patrakov



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