[Hackrf-dev] DVB-T and DVB-T2

Sun Jul 5 09:54:38 EDT 2015

Hi Simon,

The mpeg2 TS plays fine in mplayer and VLC and I get video and sound, but
on my test bench TV I only hear the audio. I've tried a couple of different
bitrates for the video too but no luck.

I've edited dvbt-hackrf_tx_sk.py to use channel_mhz = 8 as I understand
that is what is normally used in the UK for UHF DVB-T. Any other option
other than that and I don't seem to see any signal at all on the test TV.

Craig

On Sun, Jul 5, 2015 at 2:51 PM, Simon Kennedy <simon at thekennedys.info>
wrote:

> HI Craig,
>
> just seen your emails. Try using mplayer to play the ts from the fifo
> file. This will enable you to double check that the first part of the
> process is ok, ie. the creation of the mpeg2 ts.
>
> Where have you put channel_mhz = 8?
>
> Earlier today I had someone else email me to tell me that they have had
> success with the commands and program I put on my blog post so I know it
> does work for someone else!
>
> Regards
> Simon.
>
> On 5 July 2015 at 14:41, Craig Barber <radiocraig28 at gmail.com> wrote:
>
>> Thankyou, I just found it (https://en.wikipedia.org/wiki/DVB-T), I now
>> have stable sound (getting there!) but no video oddly! The command I'm
>> using to create the TS before broadcast is as follows:
>>
>> avconv -f alsa -i hw:0,0 -f video4linux2 -s 640x480 -i /dev/video0 -vf
>> drawtext=fontfile=/usr/share/fonts/truetype/freefont/FreeMonoBold.ttf:text="TEST
>> ":x=440:y=420:fontsize=48:fontcolor=white at 0.6:box=1:boxcolor=black at 0.4
>> -vcodec mpeg2video -r 60 -b 2500000 -acodec mp2 -ar 48000 -ab 48000 -ac 2
>> -muxrate 4976000 -mpegts_transport_stream_id 1025 -mpegts_service_id 1
>> -mpegts_pmt_start_pid 4096 -mpegts_start_pid 400 -f mpegts -y test3
>>
>> I'm then using QPK, with 1/2 code rate and 1/4 guard interval which
>> expects a bitrate of 4.976mbps so should be correct?
>>
>> On Sun, Jul 5, 2015 at 2:16 PM, n0p [Luis Bernal] <lbernal at gmail.com>
>> wrote:
>>
>>> The modulator bitrate depends of it's parameters, there's a nice table
>>> with the formula but i can't find it now since I'm on mobile
>>> El 5/7/2015 14:48, "Craig Barber" <radiocraig28 at gmail.com> escribió:
>>>
>>>> Thanks for the fast response n0p but I cannot find that parameter?
>>>>
>>>> On Sun, Jul 5, 2015 at 1:34 PM, n0p [Luis Bernal] <lbernal at gmail.com>
>>>> wrote:
>>>>
>>>>> The ts mux bitrate has to match the modulator's
>>>>> Avconv parameter -muxrate
>>>>> El 5/7/2015 14:11, "Craig Barber" <radiocraig28 at gmail.com> escribió:
>>>>>
>>>>>> The good news is I got it working, sort of, using channel_mhz = 8 -
>>>>>> however the picture and audio judders really badly, and basically plays
>>>>>> back really slow! I don't have a stream of UUUUUUUUUUU appearing in my
>>>>>> console window, so can't be buffer underruns, any ideas Simon?
>>>>>>
>>>>>> On Sun, Jul 5, 2015 at 12:30 PM, Craig Barber <radiocraig28 at gmail.com
>>>>>> > wrote:
>>>>>>
>>>>>>> Hi Simon,
>>>>>>>
>>>>>>> I've tried your script today with my test TV but see no signal
>>>>>>> whatsoever on the TV although the hackrf is definitely transmitting. I've
>>>>>>> also tried with a pre-recoded mpeg2 file from avconv but no luck.
>>>>>>>
>>>>>>> Any suggestions?
>>>>>>>
>>>>>>> Craig
>>>>>>>
>>>>>>> On Tue, Jun 30, 2015 at 10:57 PM, Simon Kennedy <
>>>>>>> simon at thekennedys.info> wrote:
>>>>>>>
>>>>>>>> I feel slightly embarrassed as I subscribed to this list using an
>>>>>>>> email address that is redirected to my main email, so consequently replies
>>>>>>>> sent from my main email address were not coming from the correct address.
>>>>>>>> Hence, none of the replies I posted have been seen on the list. Oops!
>>>>>>>>
>>>>>>>> Here is my reply about this thread:
>>>>>>>>
>>>>>>>> Hi Craig,
>>>>>>>>
>>>>>>>> Check out Clayton's web page (who created the sdr-examples you
>>>>>>>> refer to) here <http://www.irrational.net/2014/03/02/digital-atv/>
>>>>>>>>
>>>>>>>> I amended his BladeRF script and I have put my HackRF version here
>>>>>>>> <https://www.dropbox.com/s/bdnzoa0kn01dfav/dvbt-hackrf_tx_sk.py?dl=0> for
>>>>>>>> download
>>>>>>>> My version transmits DVB-T on the lowest Freeview channel in the UK
>>>>>>>> at 474MHz (obviously only while using a dummy load). I successfully
>>>>>>>> received the transmission of my webcam image this way using an RTL-SDR
>>>>>>>> dongle.
>>>>>>>>
>>>>>>>> The command I used was very heavily influenced (ok, basically
>>>>>>>> copied) from Clayton's examples:
>>>>>>>> avconv -f alsa -i hw:0,0 -f video4linux2 -s 640x480 -i /dev/video0
>>>>>>>> -vf
>>>>>>>> drawtext=fontfile=/usr/share/fonts/truetype/freefont/FreeMonoBold.ttf:text="TEST
>>>>>>>> ":x=440:y=420:fontsize=48:fontcolor=white at 0.6
>>>>>>>> :box=1:boxcolor=black at 0.4 -vcodec mpeg2video -r 60 -b 2000000
>>>>>>>> -acodec mp2 -ar 48000 -ab 48000 -ac 2 -mpegts_transport_stream_id 1025
>>>>>>>> -mpegts_service_id 1 -mpegts_pmt_start_pid 4096 -mpegts_start_pid 400 -f
>>>>>>>> mpegts -y in.fifo
>>>>>>>>
>>>>>>>> I used a standard web cam to capture the image, sent the output to
>>>>>>>> a fifo file (in.fifo) and consumed the output through the python program
>>>>>>>> with the command:
>>>>>>>> ./dvbt_hackrf_tx_sk.py in.fifo
>>>>>>>>
>>>>>>>> The fifo file can be created using the command mkfifo in.fifo
>>>>>>>>
>>>>>>>> Run the avconv command and the python program in the same directory
>>>>>>>> as you created the fifo file in.
>>>>>>>>
>>>>>>>> I have also transmitted DVB-S which I have documented on my blog
>>>>>>>> here
>>>>>>>> <http://photohamrad.blogspot.co.uk/2015/06/transmitting-video-with-hackrf-blue.html>
>>>>>>>>
>>>>>>>> Simon.
>>>>>>>>
>>>>>>>>
>>>>>>>> On 30 June 2015 at 17:35, Simon Kennedy <simon at thekennedys.info>
>>>>>>>> wrote:
>>>>>>>>
>>>>>>>>> Can you tell us the command you used to get this error please.
>>>>>>>>> I remember that I got a smilar error but cannot look up how I
>>>>>>>>> solved it until I get home in a couple of hours.
>>>>>>>>> The key point is that the program is trying to open a UDP port to
>>>>>>>>> receive the data and error relates to the asignment of the argument you
>>>>>>>>> supply to the program to the variable 'port' in the program.
>>>>>>>>>
>>>>>>>>> Simon.
>>>>>>>>>
>>>>>>>>> On 30 June 2015 at 16:49, Craig Barber <radiocraig28 at gmail.com>
>>>>>>>>> wrote:
>>>>>>>>>
>>>>>>>>>> Here's the error I get:
>>>>>>>>>>
>>>>>>>>>> Traceback (most recent call last):
>>>>>>>>>>   File "./dvbt-hackrf.py", line 123, in <module>
>>>>>>>>>>     main(sys.argv[1:])
>>>>>>>>>>   File "./dvbt-hackrf.py", line 31, in main
>>>>>>>>>>     port    = int(args[0])
>>>>>>>>>> ValueError: invalid literal for int() with base 10: 'testdvbt'
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>> _______________________________________________
>>>>>>>> HackRF-dev mailing list
>>>>>>>> HackRF-dev at greatscottgadgets.com
>>>>>>>> https://pairlist9.pair.net/mailman/listinfo/hackrf-dev
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> HackRF-dev mailing list
>>>>>> HackRF-dev at greatscottgadgets.com
>>>>>> https://pairlist9.pair.net/mailman/listinfo/hackrf-dev
>>>>>>
>>>>>>
>>>>
>>
>> _______________________________________________
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>>
>
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