Corrupted recordings?

I’m getting corrupted recordings for two shows on Fox, Bob’s Burgers and The Great North. I can watch Fox live with some glitches but nothing as bad as these recordings.

When I try to watch these recordings on my ATV they glitch so bad that it causes the app to mis-behave. First, the “watch next episode” button will pop up only a few minutes in. Commercial detection often skips backwards in the episode. Neither the ATV and iOS app say there is anything wrong with the recording.

What version of the server and clients are you using?

This has been happening for a few months. Currently on server 2021.05.30.1657 and ATV client version 4.5.6

What does the dvr log show for the [SNR] entry after that recording is completed?

When I go to the episode and look at debug log, I don’t see an entry for SNR. Then I check the DVR Support logs and they don’t go back that far.

When I click details for one of the episode it says 32% of the episode was affected by signal loss. But some of them have said 98%. And others don’t say anything at all and play great.

Is there a way to see which HDHR recorded the episode? I’m wondering if it has an issue on a specific one because some recordings are perfectly clear and others are corrupted. Also wondering if it recorded on one of the HVC channels for Fox would it show up as the correct higher channel number, or would it look the same as if it recorded on a normal HD channel? It would be great if SNR, which source unit, source unit’s tuner number, and channel info was all saved in the debug log for the episode. Might help me rule out if it is a hardware issue.

You can view more of the DVR log.
https://getchannels.com/docs/getting-started/faqs/channels-plus/#how-can-i-view-more-of-the-channels-dvr-server-log

That log will also show the device ID and tuner number used for the recording.

[DVR] Starting job 1622925000-12 Rick Steves: The Alps on ch=[706]
[TNR] Opened connection to 1323AADB/0 for ch706 KVIEDT
[DVR] Recording for job 1622925000-12 from 1323AADB ch706 into "TV/Rick Steves The Alps/Rick Steves The Alps 2021-04-10 2021-06-05-1330.mpg" for 1h59m59.989562767s

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Ok now I got the data for SNR and was able to figure out which tuner was being used.

2021/05/16 21:31:00.000886 [TNR] Closed connection to 1048459A/0 for ch12.1 FOX 12
2021/05/16 21:31:00.117893 [SNR] Statistics for "TV/Bob's Burgers/Bob's Burgers S11E21 Tell Me Dumb Thing Good 2021-05-16-2100.mpg": ss=87%-89% snq=74%,43%-87% seq=75%,0%-100% bps=5656275,294784-12880256 pps=536,28-1224 sigerr=32%

2021/04/18 21:31:00.000973 [TNR] Closed connection to 1048459A/0 for ch12.1 FOX 12
2021/04/18 21:31:00.105403 [SNR] Statistics for "TV/Bob's Burgers/Bob's Burgers S11E18 Some Kind of Fender Benderful 2021-04-18-2100.mpg": ss=88%,87%-89% snq=48%,42%-85% seq=1%,0%-100% bps=4469319,0-10830304 pps=396,0-1029 sigerr=98%

2021/05/23 21:31:00.000674 [TNR] Closed connection to 1048459A/0 for ch12.1 FOX 12
2021/05/23 21:31:00.147907 [SNR] Statistics for "TV/Bob's Burgers/Bob's Burgers S11E22 Vampire Disco Death Dance 2021-05-23-2100.mpg": ss=90%,89%-91% snq=51%,46%-57% seq=0% bps=4992144,63168-10230208 pps=455,17-929 sigerr=100%

2021/05/09 21:31:00.000899 [TNR] Closed connection to 1048459A/1 for ch12.1 FOX 12
2021/05/09 21:31:00.087429 [SNR] Statistics for "TV/Bob's Burgers/Bob's Burgers S11E20 Steal Magazineolias 2021-05-09-2100.mpg": ss=90%-93% snq=75%,62%-90% seq=99%,0%-100% bps=5966690,0-12033504 pps=566,0-1143

The SNQ is dropping below the minimum requirement of 50%.

Here are some notes I copied from the SiliconDust Forum.

Signal Strength
A signal strength of 80% (-12dBmV) or higher is recommended for OTA operation, 60% (-24dBmV) minimum preferred.
100% = 0dBmV = -48.75dBm and a change of 5% is a 3dBmV difference, so every 1% change is equivilent to 0.6dBmV
OTA ATSC minimum spec is -30dBmV (50%)
OTA ATSC maximum isn't something that can easily be expressed, because overload is a cumulative result of everything going in, including non-TV signals like FM radio and LTE.
Non-TV signals often end up being a bigger problem than TV, since most people live a lot closer to a cell phone tower than they do a broadcast station, and most antennas are still designed to have peak gain at the frequencies that are now used for LTE.

SNQ & SEQ
SNQ Signal Quality is scaled for each modulation type such that 50% is the minimum signal-to-noise requirement.
For ATSC, 100% SNQ is 30dB+ SNR, 50% is 16dB SNR.
SEQ Symbol Quality is an indication of how many uncorrectable TS frames have been lost in the last second (logarithmic scale). The Symbol Quality needs to be 100%.
SEQ is a logarithmic scale of packets with errors in the last second, 50%=9, 0%=99+

Aiming an OTA antenna using the numbers
Use the Signal Strength for a rough idea of direction, but align the antenna for the highest Signal Quality, ignoring Signal Strength. When aimed correctly, Symbol Quality will show 100%, indicating no errors in the output. Splitters and amplifiers can introduce noise which will lower the Signal Quality, even if the Signal Strength increases.

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Thanks for the info. I will look into this further. Not sure why some of the recordings are clear and some are not.

But one problem remains which is strange- on the ATV these recordings show the “up next” pop up at the wrong time and skip backwards when commercial detection auto skips. Neither of these happen in the iOS app.

Is the iOS app set to Original quality while at home?

Yeah original quality at home.

Can't say why it works with one device and not another, but once you have a corrupted or not-to-spec (Live or Recorded) transport stream or HLS (chunked transport stream) with packet loss/discontinuities/timestamp jumps/etc., all bets are off.

Some players handle certain issues differently than others. MPEG Transport streams and their payloads of video/audio/etc. and timing information are complex and require things being to spec to work right. If the internal timestamps (DTS/PTS) get messed up, the playback timing will be wrong and you experience judders, jumps forward or backward, looping and freezing.