graphRecorder - Time Delay for Channel Change

[mikeh49]

I'm using graphRecorder for firewire capture from my Motorola STB. I've pretty much got it working for recording and preview (after finally getting a mux that works, turned out I needed the ATI mux). I'm also using firewire for channel changing. This is based on the timmmoore and ex-deus firewire driver packages and channel changer program.

I configured the channel changer exe from within graphRecorder and have no channel changer selected in the GBPVR config. Since the STB takes some time (3-5 secs as far as I can tell) to establish a stream after a channel change, I have both of the channel change delays in graphRecorder set at 10 secs (10000 msec). Lesser settings resulted in broken graphs (the decoders inputs were not connected (looking at lastgraph with Graphedit)); I'm assuming because the firewire capture device did not yet have valid outputs. However, if a graph is established, I can change channels (with the channel up/down button) reliably. The problem only occured when selecting Watch from the TV guide.

Now the questions:

Is it correct to use the channel changer from within graphRecorder and have no channel changer in the GBPVR capture source setup screen?

How are the channel changer delays in graphRecorder related to establishing/activating the graph specified in the graphRecorder configuration? How are the two delay settings related?

I have a graph specified for preview, but none for preview to timeshift. Is this OK if I never intend to timeshift live TV?

Thanks for the plug-in, HD from my STB via GBPVR.

[carpeVideo]

You should definitely not need a ten second delay mine is set to maybe 250 ms and it works fine with firewire.

What does your graph look like? - you could also try no mux and record straight to .ts since gbpvr is getting better at handling it.

As to live preview - that should need no delay really although I always use timeshift myself.

The reason to use firewire in the plugin rather than the gpbvr changer is it will tune the STB first and then start the graph. pvrx2 does it the opposite so any recording shows a channel change at the beginning which can cause issues with playback for some reason.

[mikeh49]

I could not get reliable playback of .ts files recorded with the GBPVR file writer. I tried various transcodings/repairs using ffmpeg and mencoder, but nothing was reliable. Some things worked some times.

So, I set up a graph to demux and then remux using the ATI mux to make PS files. Now I get reliable playback, at least so far.

Do you use other than default inter-digit time delays in the timmmoore channel changer? I use channelw.exe, if that makes a difference.

Further testing today showed that selecting Watch from the TV Guide is not fully reliable. It works perhaps 4 times out of 5. When it fails (black screen), a restart of PVRX2 is required to get it working again. As I noted before, once a graph is running, channel changing is no problem.

I'll get the graphs and post them later.

Thanks for the help.

[carpeVideo]

Have you tried the posted graph for firewire? (with an nvidia filter after the STB filter?)

CV

[mikeh49]

Here are my filter graphs, zipped up.

"Firewire Capture" is used to capture from firewire to a PS MPEG file

"Firewire Preview" is used to preview from firewire (entered in the Preview field of graphRecorder.

"lastgraphpreview" is last graph when Watch from TV Guide resulted in a black screen.

Regarding the last, it appears that the first attempt to watch from TV Guide works properly, but subsequent attempts involving a channel change are unreliable. In this case, the graph appears intact, but I have seen instances where the Motorola tuner device did not have the outputs connected. As noted before, once the graph is established and working, I can change channels with the channel up/down keys.

You'll see the graphs use the Nvidia TS info parser between the tuner and the subsequent filters.

Comments appreciated.

[mikeh49]

I looked at the sample moto graph that comes with graphRecorder and noticed that it uses the hdPump file writer instead of the GBPVR writer. Is this critical? Is this the hdPump from DVB Portal? Other than this, my recording graph is the same.

[carpeVideo]

The hdpump is not critical - I don't believe I use it anymore.

Your issue may be on the back end not the front - in other words the graph teardown is not occurring fast enough or a filter is not being released , on channel change a new graph is created (with new filename) and if the filters are unavailable that could cause the issue.

What happens when you watch TV, exit to the menu and go back with a bit of time in between?

CV

[mikeh49]

Good point on the filter teardown. I'll check and post back. In the meantime I've gone back to the Hauppauge blaster for channel changing to take one variable out of the mix (I was getting unreliable channel changes with the FW changer, i.e., wrong channel, wrong program recorded, Boston Legal missed, wife unhappy.)

[mikeh49]

I think it is indeed the filter teardown. After watching a channel successfully from TV Guide, and then returning to the menu, a subsequent request to watch initially shows the last frame of the previous preview for several seconds before the screen goes black. I waited up to a minute or so between attempts.

I have to stop and restart PVRX2 to get preview working again. When PVRX2 exits, the Nvidia decoder icon is still on the taskbar, which may mean it is still active.

As before, channel changes within preview work fine, so I don't think the STB is the problem.

[carpeVideo]

Try a back to back recording of different channels. If that works then we know that its not the record graph but the playback graph.

Although you did mention live preview did not work so that's probably not the culprit.

I actually built in more delay after a recording to help fix this issue (I saw the issue on back to back recordings, not timeshift or live), perhaps its something with a write buffer needing to be completed.

I could add that delay as a setting but long delays between channel changes is would still be a serious pain so it would be better to fix the issue.

What kind of STB do you have ? Does it have two fire-wire ports? You may want to try the other if it does. Also, how well shielded is the fire-wire cable?