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PostPosted: Mon Nov 01, 2004 12:52 pm Reply with quote
kb7oeb
 
Joined: 23 Mar 2004
Posts: 32




Is there a way to record two programs at once but not all of them? Here is my situation. The local ABC transmits an HD channel, the analog channel and abcnewsnow. The programs are 3,4 and 5. i would like to be able to record 4 and 5 but not 3. I want to leave out the HD channel since its upconverted SD and just wastes space. Is this doable?

Thanks
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PostPosted: Mon Nov 01, 2004 1:07 pm Reply with quote
pdicamillo
 
Joined: 09 Mar 2004
Posts: 68
Location: Needham, MA




kb7oeb wrote:
Is there a way to record two programs at once but not all of them? Here is my situation. The local ABC transmits an HD channel, the analog channel and abcnewsnow. The programs are 3,4 and 5. i would like to be able to record 4 and 5 but not 3. I want to leave out the HD channel since its upconverted SD and just wastes space. Is this doable?

Thanks


No, the current version of dtvstream doesn't have a way to extract two programs at once. If you use "-p all" to have all the packets saved, you can record all three programs at the time of the broadcast, and later extract programs 4 and 5 from that file (one at a time). Also, if you had two HD-2000 cards you could use one to record program 4 and one to record programs 5.
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PostPosted: Sun Nov 07, 2004 7:12 pm Reply with quote
Scott Larson
 
Joined: 15 Oct 2003
Posts: 713
Location: Portland, OR




One problem:

Code:
bash-2.05b$ dtvstream
Stream contains 1 valid program(s).
    Using program 2: 32-1 KWBP-DT:
        Video (MPEG-2), language = eng
        Audio (Dolby AC-3), language = eng
Unable to create "dtv.m2t": Permission denied
bash-2.05b$ ls -l dtv.m2t
ls: dtv.m2t: No such file or directory
bash-2.05b$
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PostPosted: Sun Nov 07, 2004 9:13 pm Reply with quote
pdicamillo
 
Joined: 09 Mar 2004
Posts: 68
Location: Needham, MA




Scott Larson wrote:
One problem:

Code:
bash-2.05b$ dtvstream
Stream contains 1 valid program(s).
    Using program 2: 32-1 KWBP-DT:
        Video (MPEG-2), language = eng
        Audio (Dolby AC-3), language = eng
Unable to create "dtv.m2t": Permission denied
bash-2.05b$ ls -l dtv.m2t
ls: dtv.m2t: No such file or directory
bash-2.05b$


Should you have been able to write in the current directory? If you only want to see the stream information, you need to use the "-q" option (and -v gives you even more information.)
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PostPosted: Tue Nov 09, 2004 1:38 pm Reply with quote
Scott Larson
 
Joined: 15 Oct 2003
Posts: 713
Location: Portland, OR




pdicamillo wrote:
[Should you have been able to write in the current directory?

Yes, it was in my home directory. Does dtv.m2t always go in the present directory?
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PostPosted: Tue Nov 09, 2004 4:14 pm Reply with quote
pdicamillo
 
Joined: 09 Mar 2004
Posts: 68
Location: Needham, MA




Scott Larson wrote:
pdicamillo wrote:
[Should you have been able to write in the current directory?

Yes, it was in my home directory. Does dtv.m2t always go in the present directory?


If you don't specify an output file with "-o", the default output file is the same as the input file, but with the extension changed to ".m2t". However, if the input file has "/dev" in its name, "/dev" is not included. Since the default input file is "/dev/dtv", the output file became "dtv.m2t".

If you can duplicate the problem, try adding the "-d" option to display debugging output. This is very strange though, since the open error message clearly indicates a permissions problem, but that shouldn't happen in your home directory (at least at the highest level). The code tries to create a file with permissions "rw-r--r--", but I don't see how that could matter either.
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PostPosted: Sat Nov 13, 2004 4:44 am Reply with quote
zwhite
Guest
 




pdicamillo wrote:
How about if you could use %m, %d, and %y in file names, and they would be replaced by the current month, day, and year?


Is there some reason the user can't use the date program for this?

Code:
dtvstream <options> filename.$(date +%Y%m%d)


Something like that should work.
PostPosted: Mon Nov 15, 2004 1:10 pm Reply with quote
Scott Larson
 
Joined: 15 Oct 2003
Posts: 713
Location: Portland, OR




pdicamillo wrote:
This is very strange though, since the open error message clearly indicates a permissions problem, but that shouldn't happen in your home directory (at least at the highest level). The code tries to create a file with permissions "rw-r--r--", but I don't see how that could matter either.

I'm sure I ran it as root at some point and now there's this .m2t file owned by root someplace. I'll try -d to see if it will tell me where it is.
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lost sync error
PostPosted: Wed Nov 17, 2004 5:32 pm Reply with quote
mspice
 
Joined: 03 Nov 2004
Posts: 36




I'm getting the following error repeated over and over but the stream still records and appears to play just fine. I have about 92% signal stregth and this happens on all channels.
Code:
Lost sync at input offset 82106368
Achieved sync after 752 bytes.

What can I do to fix it? Is the debug forced on or something?

Thanks,
Michael
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Re: lost sync error
PostPosted: Sat Nov 20, 2004 6:14 pm Reply with quote
pdicamillo
 
Joined: 09 Mar 2004
Posts: 68
Location: Needham, MA




mspice wrote:
I'm getting the following error repeated over and over but the stream still records and appears to play just fine. I have about 92% signal stregth and this happens on all channels.
Code:
Lost sync at input offset 82106368
Achieved sync after 752 bytes.

What can I do to fix it? Is the debug forced on or something?

Thanks,
Michael


Those messages are not displayed for debugging, but because they indicate a problem you should know about. The DTV data consists of a stream of packets, and each packet begins with the packet start byte. The "lost sync" messages means that when dtvstream read what should be the next packet, it didn't start with the expected start byte. The "achieved sync" message means dtvstream had to read 752 more bytes before finding the start of a packet again.

This message is not significant at the very start of capturing. But if you get it later it means you have lost some packets. Packets are 188 bytes long, and during playback you might not even notice a few missing ones. However, with a strong signal and everything configured properly on your computer, you shouldn't be losing packets at all.

There are some common causes for lost packets. One cause is that the signal strength isn't strong enough. You can check the signal strength with dtvsignal.

Another cause is that dtvstream is unable to write the stream to disk as fast as it is being received. In that case, sync is lost because the driver has to discard some unread data. The most likely cause for this is that disk I/O is too slow on your computer. Dtvstream does extensive buffering to avoid lost packets, but lost packets cannot be avoided if the average rate of writing to disk is too slow. It almost certainly will be too slow with an IDE disk if DMA is not being used. You can use "dmesg" to check for lines like this at startup:
Code:

hda: 321672960 sectors (164696 MB) w/7938KiB Cache, CHS=20023/255/63, UDMA(100)

If DMA isn't included, you may have to reconfigure your kernel to include support for your IDE chipset.

Disk I/O can also be too slow if the same disk you are doing capturing to is being used for other disk-intensive tasks.
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PostPosted: Sat Nov 20, 2004 8:46 pm Reply with quote
mspice
 
Joined: 03 Nov 2004
Posts: 36




Quote:
Disk I/O can also be too slow if the same disk you are doing capturing to is being used for other disk-intensive tasks.


I get this error message even if I am simply doing a -q. When you do a -q you don't write anything to disk right? This means that I can rule out the harddisk option right? (I have DMA turned on so I don't think it is that anyways).
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PostPosted: Sat Nov 20, 2004 8:53 pm Reply with quote
pdicamillo
 
Joined: 09 Mar 2004
Posts: 68
Location: Needham, MA




mspice wrote:
Quote:
Disk I/O can also be too slow if the same disk you are doing capturing to is being used for other disk-intensive tasks.


I get this error message even if I am simply doing a -q. When you do a -q you don't write anything to disk right? This means that I can rule out the harddisk option right? (I have DMA turned on so I don't think it is that anyways).


Yes, for -q nothing is written to disk. You may have a strong signal but be getting mutlipath reflections or some other kind of distortion. If the red LED on the card flashes at times then there is definitely a reception problem. A driver problem is another possibility.
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sync problems
PostPosted: Sat Nov 20, 2004 9:05 pm Reply with quote
mspice
 
Joined: 03 Nov 2004
Posts: 36




Ok, I'm rulling out harddisk issues because hdparm says I have DMA and it says I can do 50MB /sec.

I checked and all of the sync errors are excatly 96256 bytes appart. Is that significant at all? Is it possible that the stations in my area send longer/out of spec packets? Here is an example:

Code:
Lost sync at input offset 3080192
Achieved sync after 752 bytes.
Lost sync at input offset 3176448
Achieved sync after 752 bytes.
Lost sync at input offset 3272704
Achieved sync after 752 bytes.
Lost sync at input offset 3368960
Achieved sync after 752 bytes.
Lost sync at input offset 3465216
Achieved sync after 752 bytes.


If I use getatsc to record to a .ts file and then run your app on that .ts file I get the same error. Do you think you could help me if I send you a small .ts file? You could PM me and or I could PM you to trade email addresses.

Last, where is this LED. I looked on the back of the card and there is nothing. I tried to look at the card while installed and I couldn't see anything lit but I probably would need a mirror to look around on the board if it is a small one. I have a HD-3000. Does it have an LED or is it just the older cards?

Lastly, even though I am getting 92% signal and can record shows I have reason to believe that something is wrong here. First, the video kinda looks choppy. Its not bad at all and I sometimes think it is in my head. Second, mencoder gives all those "duplicate frame" errors when I transcode the files. Last, sometimes I get audio sync problems. I have no audio sync problems with any other video files.

Thanks so much!
Michael
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Re: sync problems
PostPosted: Sat Nov 20, 2004 9:36 pm Reply with quote
pdicamillo
 
Joined: 09 Mar 2004
Posts: 68
Location: Needham, MA




mspice wrote:
I checked and all of the sync errors are excatly 96256 bytes appart. Is that significant at all? Is it possible that the stations in my area send longer/out of spec packets? Here is an example:

Code:
Lost sync at input offset 3080192
Achieved sync after 752 bytes.
Lost sync at input offset 3176448
Achieved sync after 752 bytes.
Lost sync at input offset 3272704
Achieved sync after 752 bytes.
Lost sync at input offset 3368960
Achieved sync after 752 bytes.
Lost sync at input offset 3465216
Achieved sync after 752 bytes.


96256 bytes is 512 packets. I think it is significant. It's very unlikely it's the station. What seems most likely is a driver problem.

Quote:

If I use getatsc to record to a .ts file and then run your app on that .ts file I get the same error. Do you think you could help me if I send you a small .ts file? You could PM me and or I could PM you to trade email addresses.


I don't mind looking at a file, but I'm not sure it would help.

Quote:

Last, where is this LED. I looked on the back of the card and there is nothing. I tried to look at the card while installed and I couldn't see anything lit but I probably would need a mirror to look around on the board if it is a small one. I have a HD-3000. Does it have an LED or is it just the older cards?


The HD-2000 has small red and green LEDs on the back next to the connectors. I haven't seen an HD-3000. It sounds like it doesn't have the LEDs.

Quote:

Lastly, even though I am getting 92% signal and can record shows I have reason to believe that something is wrong here. First, the video kinda looks choppy. Its not bad at all and I sometimes think it is in my head. Second, mencoder gives all those "duplicate frame" errors when I transcode the files. Last, sometimes I get audio sync problems. I have no audio sync problems with any other video files.


Duplicate frames also points to a driver problem. Not doubt those problems are due to the missing or duplicated packets.
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PostPosted: Sat Dec 11, 2004 12:35 pm Reply with quote
CoolerQ
 
Joined: 11 Dec 2004
Posts: 9




mk500 wrote:
Here's a thought for a feature. I cron up jobs to record my TV shows, but it would be cool if there was some way to append a date at the end of the name automatically. That way if I cron a show to record daily, it will store new files each day. I haven't actually tried yet, but I'm assuming it currently will overwrite if you use the same name twice?


Hi-

This can already be done. Just embed `date +%Y-%m-%d-%H:%M`in your cron command to get YYYY-MM-DD-hh:mm.

--Quentin
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dtvstream 1.0b2 available
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