Mapping preview window question

[CraigD]

In another thread (Setup crashing while mapping digital channels), I mentioned the issue that I was having when trying to map the digital channels. In addition to my scan freezing before it reached the end of the available channels, I could also not preview those channels that the scan did find. I have been assuming that both of these symptoms are indications of the same problem (and maybe it is). However, I am wondering if they may be two different problems and I have to solve one before I can solve the other. Therefore I am hoping someone can explain to be exactly how the preview window in the "Digital Channel Mapping" DialogBox works.

If I stop the scan before the end is reached, I can keep the scan from hanging. At that point, I have a number of channels listed in the listbox under the preview window (box labeled "Channels found during scan"). I also have all the channels listed in the other box that were imported from the EPG source. When exactly should I see an image in the preview window? SHould it show when I select a channel in the box labeled "Channels found during scan", or should it show after I select one in the "Tuning Request" field?

In my case, I don't get any image in the preview window no matter what I select. Is that indicative of a decoder problem, an encoder problem, or something else. Also, should you also hear audio when you are previewing a channel? I do not hear anything. If you are suppose to hear the audio, it would suggest that this isn't just a decoder issue since you would think that in that case you wouldn't see the image, but would hear the audio.

Sorry for the very long post and hopefully it is clear what I am looking for. Basically an explanation on how the preview window works and what the problem might be when do preview is displayed.

As always, thanks for your help.

Craig

[dennit]

Basically an explanation on how the preview window works and what the problem might be when do preview is displayed.

Maybe this will help:

1) What your source scans is controlled by the ini file for your source. Limiting what is in that file allows you to control what it tries to find. For digital BDA sources, like QAM, DVBs etc, make a backup copy of your ini, then adjust as needed.

2) What you source finds is put into the SCAN-1.CACHE, etc where the number is the source ID and there is one line per channel found. I keep a master file that includes everything it has ever found in a scan with any version. I often add new lines to my master from a scan, then copy my master to the SCAN-1.CACHE file before entering config.

3) The last part of each line in this file is the name of the channel. This name appears in the list of channels found. I sometimes edit the name so it's easier to spot in the channel mapping step of config. This is all that the name is used for - identifying a channel found during scan during mapping so it can be correctly mapped.

4) When you start mapping in config, the first line in the SCAN-1.CACHE will be tuned by that source. I've had cases where this first line caused it to crash.

5) The mapping step copies the entire line from SCAN-1.CACHE for that channel into the gbpvr.db3 database. QAM and DVBS mapping can be very difficult when the names don't appear. I actually gave up the mapping process long ago and directly modify the db using SQL to transfer the correct scan line into the db. It was much harder to assign names, then manually map than to just write a batch file to put the scan line in the right spot. Fundamentally, I just make sure the XMLTV EPG file for my source is right, then use config to assign it to the source. This sets the db up for everything except the mapped line from the CACHE file for each channel.

6) I still occasionally get crashes in config during scans, but I sometimes use older versions to scan, keep all my scans, limit what I scan, etc. to get the scanned channels I need.

7) Recording, muxing, storing on disk and playback is different from just playing live in the display window. I tend to stay out of the mapping area unless I'm trying to scan. A new scan deletes the CACHE file for that source, so keep a copy.

8) As an aside - an XMLTV EPG file needs all the the channel definitions and at least one programme entry for the first channel defined in order to be imported by config with all the channels. I make fake XMLTV files up and import them when I have a source I want to look at, but no EPG data and don't want to map anything. Suppose I have sat source with 130 channels found in a scan. The import step gives me entries for channels 4001 to 4130, then I import the scan cache scan lines into the db for the new channels. I can then watch them without EPG to see what they are and if I want to keep them.

I doubt this answers your Q or helps much, and it may cause more problems than it solves, but it's the only way I can handle the hundreds of channels I needed to map from multiple sources.