Loss of synch between video and audio

[gromit]

Hi, I am taking files from a Strong 5490 PVR and editing using VideoReDo. I then save as .mpg. The problem I have is that when I replay the saved file there is a delay between the video and audio: video first, audio half a second or so later. Any hints? Thanks.

[HyperReality]

Is this happening on every file off the Strong, or just this particular one?

What player are you using to play the edited file?

There are quite a few Strong users over on the Aussie DTV Forum that are having good results with VideoReDo to edit the recordings from the Strong, so I wonder what is going on with this particular file.

Can you please load the file into VRD and then press Ctrl-L and copy the displayed information and post it back here.

When you play the file (the original and the edited one) back in VRD, is the audio and video in sync? If not, what about if you try it in a player such as VideoLan Client? Does the original recording play with sync on the Strong prior to being transferred off it?

You can also try manually adjusting the audio sync in VRD (Tool menu->Adjust Audio).

[gromit]

Wow, you guys respond fast!

I've noticed this problem two times in a row:

1) Desperate Housewives: Strong PVR to PC, remove ads semi-automatically, save as .mpg, burn to DVD-RW and play back on a cheap Dick Smith DVD player (my $59 solution to avoid re-rendering the entire file to DVD with massive time and quality implications). Video was in advance of audio

2) "Species" movie: Strong PVR to PC, remove ads semi-automatically, save as .mpg, re-render as 320x240 for playback on Jasjam using TMPGenc. Same problem.

I don't believe that the freshly uploaded file displays the problem when played back via VideoReDo, However, I'll be away for a few days and will check that & answer the rest of your questions when I return.

Many thanks!

[gromit]

OK, here is some further information. Firstly, when I replay the saved .mpg using VideoReDo, there is NO loss of synchronisation between audio and video, at least, not over the limited time I played back part of the file. So that points a very strong finger of suspicion at my hardware DVD player AND the app on my JasJam. Mind you, I'm surprised that a dedicated piece of hardware couldn't play back a file without losing synch. More investigation required on my part, obviously.

You requsted the file info: here it is:


File Name: C:\Species.mpg
File Size: 4707020804 ( 4.38 GB )
Program Duration: 01:39:01.17
File Type: PS - MPEG2
Encoding: MPEG 2
Video stream Id: xE0
Encoding Dimensions: 720 x 576
Display Size: 720 x 576
Aspect Ratio: 16/9
Frame Rate: 25.00 FPS
Bit Rate: 15.000 Mbps
VBV_Buffer: 224 KB
Profile: Main/Main
Progressive: Prog or Int
Chroma: 4:2:0
Audio Format: Layer 2
Audio Stream Id: xC0
Audio Bit Rate: 256 Kbps
Audio Sampling Rate: 48000 Hz

I guess we are done for now unless you have any hints on why both of these playback systems would be unable play back voice and audio synchronised....

Thanks again for the great help.

[HyperReality]

What application are you using to author the DVD for playback on your DVD player? Is this tool always re-encoding the video (even though the source video is DVD compliant)? Have you tried something different?

If the tool is re-encoding then I would take a wild punt that there is something about the audio stream bit rate or sample rate that is confusing the tool (if you record a different SD channel that has a different audio bit rate, do you still end up with sync problems??).

As a test, maybe try saving out of VRD as elementary streams then trying Muxman to author (which won't re-encode), or you could wait a bit longer and then try out VRD's upcoming authoring tool. ;)

Also, make sure you get VRD to adjust the MPEG video bitrate headers to be DVD compliant when it is saving out the edited video (ie choose the 10Mbps option), just in case this is somehow tripping up your DVD player - while the video info says 15Mbps, it is in reality much less than that (probably more like 6Mbps).

Still doesn't explain the problem with your other player though, unless you are using the same tool to re-encode to a lower bitrate as you are using the author to DVD, and the tool is breaking A/V sync both times...

[gromit]

Thanks again for the support! Sorry, maybe I wasn't explicit enough. I am simply saving the edited file as .mpg, then burning a "Data DVD" and playing it on a DVD player (Dick Smith, $59) that happens to be capable of playing raw .mpg files. I wish to avoid making an authored DVD because it takes forever and the quality is compromised by the re-rendering. Re-rendering seems to be required because the MPEG output as part of the Strong PVR .trp files is apparently not "DVD compliant". That was a huge disappointment when I found it out, of course.

Anyway, it's playing back the raw .mpg that has the loss of synch. Yet when I copy the file back onto my HDD and play on the PC, (so far as I can tell, my PC-based .mpg player doesn't work very well) there is no loss of synch - so it seems that VideoReDo is NOT corrupting the synch. I took the test DVD with the .mpg on it to Dick Smith today and invited them to try playing it on a few players they have there to see if their DSE-branded player is particularly deficient in this respect. I'm expecting feedback tomorrow and will post again then. If necessary, I'll upgrade my player.

I'm planning to tackle the JasJam next after I crack the "DVD player" scenario.

Cheers for now.

[gromit]

Here are some updates:

Regarding the "DVD data disc on DSE player": the DSE shop tried my disc and reported no loss of synch on their shop model. They have given me the service centre number to call. I'm not convinced this is a serviceable issue but I'll keep plugging away.

On the Windows Mobile front, much more interesting things to report. I have now also tried a Dell Axim X5 (200 Mhz versus Jasjam 400 Mhz) and various players (PocketTV, TCPMP) and I can conclude the following:

1) Synch problems between audio and video playing back .mpg on mobile devices is definitely a device/software player issue. Each combination shows different characteristics, albeit the audio never leads the video, always the other way round.

2) A faster machine (JasJam) does not necessarily imply better synchronisation. Actually, the Axim showed better synch under all like-to-like comparisons.

3) The issue is not limited to .mpg as I also downloaded the DivX encoder and the same problem occurred.

4) READ THIS! TCPMP has got a quite well-hidden, brilliant feature that allows you to adjust (+/-), in milliseconds, the delay between audio and video. No kidding. For a piece of freeware, that is nothing short of fantastic. So even if VideoReDo had introduced a video/audio delay (which I seriously doubt now), I would be able to overcome it with this incredibly nifty feature.

I still have a little work to do before I consider all the issues completely closed but will post again next time I have something to report. If you have lost interest in the case let me know and I won't bother you further. Thanks.

[gromit]

The last piece in the puzzle is complete. I took my test .mpg disc into Dick Smith and tried it on their DSE player there. Contrary to what they told me over the phone, there WAS loss of synch. So boos to Dick Smith for wasting my time previously. I then tried another player in the store (LG, $99), and it was perfect, as was a Grundig at $129. Dick Smith kindly agreed to allow me to return my DSE player and upgrade to the LG, even though it's three months since I purchased and I ditched the original packing. So three cheers to DSE to cancel out the boos! The LG is now installed at home and working perfectly.

At the same time, three cheers for VideoRedo, your product is completely exonerated of all suspicion.

So long for now.