Timeline off on clear QAM recording (using new mvpmcx2)

[philly_phenom]

I've come across a recording that still has wierd timelines. I've lived with this before, because playback, skipping etc were all controlled by the PCH, but with the new client GBPVR is handling the skipping (at least that's my understanding).

The comskip cuts appear to be in the correct place (when I bring up the progress bar, the dark spots match up where commercials begin & end), but when GBPVR reaches a commercial, it only jumps about a quarter to a third of the commercial. If I do a 30 second skip, it jumps backwards.

It seems that my analog recordings (pvr500 & hdpvr) are all fine, but some of the hdhomerun recordings are wierd. I chalk that up to the fact that I have all my analog recordings at a constant bitrate & digital recordings can jump around quite a bit (bitrate wise).

Anyway, is this something to chalk up to "just the way it is" or should I cut a section out w/ VideoRedo & send it somewhere?

[sub]

Is the same on the PC?

Does the file report the correct duration when you pause.

It is likely you'll have some issues with comskip jumps not happening at exactly the right instant during playback of .ts files. So there is going to be an element of "just the way it is" when it comes to .ts file, though hopefully it'll be close to correct most times.

These broadcast recording files do not have a reliable clean timeline, which makes it difficult for the application to know exactly where playback is up to. Comskip knows exactly what frame number the commerical starts at because its had the time to go through the entire file and look at every frame in sequency, but GB-PVR doesnt have that luxury, so has to guess based on the bitrate of the file, and sometimes thats not going to be correct (particularly if the bitrate is changing).

[philly_phenom]

Seems to be better on the PC than on the PCH.

On both PC & PCH, the correct duration is displayed on the progress indicator. Skipping is just off on the PCH (both when I skip/replay or with comskip).

I was a bit supprised that comskip was off because as you said, it provides a specific frame to jump to rather than time (of course, I'm not sure how GBPVR relays that to mvpmcx2 & then to the PCH)

[sub]

I was a bit supprised that comskip was off because as you said, it provides a specific frame to jump to rather than time

The problem is that there is no index of frame numbers, so the app cannot know where in the file that frame is, without counting every frame before it. Its not practical for the app to do that prior to playback, and cant be done during playback, so you pretty much have to guess where that frame might be and you have no way of knowing if you got it right or not after that guess.

[mvallevand]

Skipping in mvpmcx2 is based on a calculated file offset requested by GB-PVR not a frame. It is normally accurate within a few seconds, but the accuracy varies based on longer files and how much impact a VBR has. The file is being positioned to the requested spot in the file according to the http server request. In the testing we did, comskip time did not match the actual commercial points either, so it makes it tough to pinpoint problems. If I tweak a comskip file manually to values I see in MPC it does work like I expect it.

The best way to check your logs and see if the skips are roughly correct. What you should see is something like

Code:

MVPSetPlaybackPosition() request to set position to: 61.3690222222222 seconds
... file plays for a bit
Got Media-Progess message. PTS now:151651  time: 3.37002222222222   (0000000002d74b0000) )
... after seek not too bad
Got Media-Progess message. PTS now:2780778  time: 61.7950666666667

If you aren't seeing this upload your logs and I will have look.

Note I did request files for com skip testing and only -statik- responded. Both his files worked.

Martin

[philly_phenom]

Searched all logs for "MVPSetPlaybackPosition", but didn't find anything...

If you still want test files, I can send it to you (however, it appears I can only upload a max of 10MB on google groups & same for comcast email), which would be like a 5 second clip)

[mvallevand]

Because you have two MVP servers Auto started you aren't capturing information that you need. Set it to one, reconnect and try the test again.

Martin

[philly_phenom]

Still don't see that message (MVPSetPlaybackPosition) with autostart set to 1...

FWIW, the darkened portions of the progress indicator line up with where the commercials start & stop, just when it jumps, it doesn't make it to the end of the commercial break (jumps some fraction of the way through the dark portions).

This would seem to indicate that the comskip file has correct (or close to it) times, but the jumps aren't right.

[mvallevand]

You are still autostarting two, which will cause problem for the logs, is for manual seeks. In this example the set position is not how I calculate it (1162495094) but that is only a second or so off. What concerns me is that seeks are consistently about 5% short from the beginning so the longer the file, the worse it get. Padding does causes a little problem for com skip specifically but not enough to be this off on a one hour file.

Code:

2009-04-12 16:34:02.375    VERBOSE    [6]    MVPSetPlaybackPosition() request to set position to: 733.47 seconds
..
2009-04-12 16:34:02.390    VERBOSE    [7]    Stream Length: 5798202000
2009-04-12 16:34:02.390    VERBOSE    [7]    Stream Duration: 3658.31586666667
2009-04-12 16:34:02.390    VERBOSE    [7]    requestedPositionInSeconds: 733
2009-04-12 16:34:02.390    VERBOSE    [7]    Set position to:1161759186
2009-04-12 16:34:02.390    VERBOSE    [7]    Received request to seek to pos:1161759186
...
009-04-12 16:34:03.562    VERBOSE    [6]    Got Media-Progess message. PTS now:30743213  time: 683.182511111111

Martin

[philly_phenom]

That's wierd - I set auto start to "1" in the config app & clicked OK... I even checked after I zipped up the last log & config was showing autostart 1.

I then unplugged both PCH's & plugged one back in.

Do I need to remove one of the MVP stanza's from config.xml?