Sync Issues - Video Way Behind Audio

I hadn’t thought of the compression issue, nice job. Not sure if that would matter since it’s supposed to do that in its free time, but it made me think about what you’d said earlier about a possible playback problem.

With digital OTA, the audio and video can get separated, especially when you’re trying to save the stream. It’s very likely that there are little hiccups that happened when the recording started that we don’t see. The Tablo might not know how to recover, especially since the signal is so strong (the amp making things worse).

By checking every recording as it starts, it requires the Tablo to do even more work. It’d be interesting to see how everything faired if the actual recording was allowed to complete. Then, Tablo could take a look at those “corrupt” files and see what happened.

But… That would require someone that really wanted help to possibly open a ticket and let support dig into their situation. Apparently, it’s just easier to complain…

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I have many examples of completed recordings that were unwatchable. Many. They are NEVER watchable, no matter how long I’ve waited.

As for Tablo Tech Support, their pat answer is, “We are aware of the problem and are working on a fix ASAP.” The fix never comes. I’ve gotten MUCH more help from Reddit than from Tablo Tech Support. Yes, it’s much easier to reach out to Reddit, this community and/or the Facebook group I created, than to waste any time with an overworked Tech Support group inundated with newbies just trying to get their DVR to work the first time. I’m not going to add to their burden, only to get yet another pat answer.

My 2 cents on this issue. First off I know of only one recording from my 4th gen Tablo where the sound was out of sync. We record duplicates so we tried the other recording. The sound was fine so we watched that one.

I have a rock solid outdoor antenna setup and unless I go higher there really isn’t anything I could do to make it better with the (2) Televes antennas I have. The broadcast towers are about 45 to 50 miles to my north and south. There are days (some of the nicest ones in summer) where many of the North or South channels (but never both directions) will not come in at all. Later in the day they are fine again. It can be a real crap-shoot at times. Cold winter months everything works fine.

I have recorded many classic TV shows with my OG 2 tuner Tablo, edited out the commercials and saved them to my NAS. Through the years I’ve come across many recordings where the sound was out of sync during parts of the show. And I could always find the reason for it if I took the time. The cause was ALWAYS because of, as TabloTV said (and I quote), “corruption from poor signal within the broadcast stream”. I probably would have simply said “a bad signal”. All it took was a very brief spot in the recording where the picture went blocky, or as some people say pixelly, and after that point the sound would be out of sync. Depending on how bad the blockyness was it could be way out of sync or not at all. The interesting thing is, it would be all back in sync after the next spot where I cut out a commercial. And yes the entire show could have played just fine except for that one brief spot of blockyness and that’s all it takes to mess up the sound sync.

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@TabloTV My ABC recording in the early AM on May 8 also had this problem, where the audio was at least 6 seconds ahead of the video. Coincidence? I don’t know. I have a 4th gen 4 tuner model that I purchased back in December.

@TabloTV if you want me to set up remote access for another example of this problem, please reach out and let me know.

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Yet another night of disappointment: ABC_Nightline_240509a_sync.mp4 - Google Drive

@TabloTV @TabloEngineering @TabloSupport

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I’ve looked back at all the posts in this thread and you have yet to state whether or not you have turned off the amplifier in the Tablo.

With this statement you most likely don’t need amplification of the signal due to being so close to the towers.

If you have indeed turned off the amplifier, I apologize for bringing it up again.

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@ArtSmart That’s what I was recording also. This problem happened a few times over the last few weeks.

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Ok, I turned off amplification, and I’m recording everything on channel 13.1 (the most problematic channel) now through midnight. If any of the recordings show the same sync issue, I’ll turn amplification back on and report back.

What is your theory? The only thing I can think of is maybe over-amplification is distorting the signal just enough that when the tuner engages, its initial determination of the broadcast codec is incorrect, so then the entire broadcast is stored in the wrong format, causing it to be undecodable in real time during playback. Is that what you’re thinking, or might it be something else?

BTW, I’ll need to monitor other channels to make sure they still record perfectly with amplification off. If not, then it’s too high a price to pay.

@ArtSmart Thank you for that. I look forward to hearing the results.

I agree with what @KimchiGUN and others say that too much signal is just as bad as not enough. You really don’t want to overwhelm the tuner.

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Sorry for the delay in replying, but this site was down and none of my multiple attempts to reply would work. Gave up on it.

In answer to your query, even with amplification OFF, the sync issue reappeared. So I turned amplification back ON.

My workaround is as usual: Set most recordings to start 10 minutes early, so I can restart them if they’re out of sync. The retry almost always works. Of course, if I’m not home, I’m SOL.

Well that stinks! How many shows had the sync issue? Did you notice any poorer quality to the recordings? Being as close as you are to the towers I wouldn’t think you would need any amplification but maybe using an inline amplifier before it goes into the Tablo (with the Tablo amp off) would help? Just speculating. You might also try using an external HD just in case it is a transcoding issue when saving to the internal storage. TBH not sure that will help if you have and use multiple Gen4 quad tuner units and experience the same issue on all of them but at least it could be ruled out as an issue if it doesn’t fix it.

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Not sure what changed but this sync issue has seemed to have disappeared for the last couple of days. Rock solid recordings. I don’t know if Tablo fixed its software, or if the Houston transmitters quit using a questionable cutting-edge codec, or if I’ve just been lucky. I hope I didn’t just jinx my 4th Gen Quad.

If/when the problem reappears, I’ll answer exwxman95’s questions. Thanks!

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Thanks for the update!

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Bummer. Sync issue reappeared. Very glad I set the recording to start 10 minutes early. That gave me time for four tries to get a good recording. First 3 tries were out of sync. The 4th worked, and just in time before the show actually came on.

BTW, I’ve tried it with and without antenna amplification, and no difference, so I have amplification on. Sync issue is the same regardless of the viewing device (Roku, phone or tablet). Badly sync’d recording never gets re-coded to a good recording, no matter how long I give it. As for the quality of my recordings, they’re all pristine. Everyone, THIS IS NOT AN ANTENNA OR SIGNAL QUALITY ISSUE, so PLEASE don’t even mention it yet again. My patience answering those questions is completely gone.

The only pattern I can see is it seems to happen most on Houston’s channel 13.1 KTRK (ABC affiliate), maybe 20% of the time. Happens on other HD channels maybe 5% of the time. Almost never on really low definition channels.

I’ll keep those 3 brief badly sync’d recordings for a week or so, in case the Tablo developers want to log into my DVR to examine the recordings.

@TabloTV @TabloEngineering @TabloSupport

I don’t live in the Houston area but I do record that show as well. I will check my recording of the show though I’ve never had issues with it in the past.

I believe you that it is not signal quality issue other than maybe the signal from that station in particular but if you do not notice any difference with the amplifier on or off, I would suggest keeping it off as any noise that would come over the antenna would be amplified if it was on. One less thing to be concerned with.

I’ll let you know about my recording of the show.

@ArtSmart - My recording of the show was fine. I checked my Tablo Quad and the recording was fine there as well. I did find a show from Friday (17May) on the Tablo Quad that split into multiple files for some reason but on the Gen 4 the recording was perfect.

Have you tried an RF filter on your feed from the antenna? I know you don’t want to talk about signal and I’m not talking strong or weak but maybe there is some interference that is causing the Gen 4 Tablo to mess up the audio/video sync. I’ve read good things about the Channel Master 5G/LTE RF filter, and you can get it on Amazon for about $20. Might be worth a shot if you don’t have an RF filter already.

I saw this problem when I was watching an OTA channel live not playing back a recording. I exited and re-entered the Tablo app (on Roku) several times and the problem would not go away. What I finally had to do was reboot the Tablo and then video and audio were in sync.

System:
Roku Ultra
Tablo 4th gen 2 channel
Ethernet connections

Tablo indicted that a strong signal can cause problems. You tried turning off the amplifier with no changes. I would try putting an signal splitter in to see if that helps. If cutting the signal in half doesn’t help then maybe it is time to give up on Tablo.

I have been considering buying a Tablo for my daughter but posts like these have convince me to hold off. I currently have a Tivo that I love and has been flawless.

You are obliviously frustrated and have spent a considerable amount of time on this. I would say screw it and buy a used Tivo with lifetime on Ebay for about $250. Not as flexible as a Tablo but it works.