MP4 problems

[Johannes_L]

Hi,

Having Sighthound running 24/7 with cameras using MP4 is a little problematic. If server looses sync with MP4 framing, it more than often happens that Sighthound pattern recognition claims, there is a match with the rules. In best effort Ethernet or Wifi environment, it just happens that the framing is lost every now and then, can't help.

For sure, server knows sync with the framing errors. Is it possible to read this information somehow within Sighthound and omit the timeperiod, when framing is once again getting back to sync?

Perhaps an enhancement in the future releases. As today, using multiple MP4 cams within the same WiFi or Ethernet is creating plenty of false alarms.

Regards
Johannes

[ryan]

Hi Johannes,

It would theoretically be possible to stop responding to video when lost or damaged packets are detected, but as the distance between keyframes can be long (sometimes up to 10 seconds) this isn't ideal. You may be able to solve this problem by forcing a TCP connection (network protocol that guarantees packet delivery, vs. UDP which does not) which is currently done in Sighthound Video by appending a keyword flag to the connection path. More detail can be found here: topic11523

Best,
- ryan

[Johannes_L]

Hi Johannes,

It would theoretically be possible to stop responding to video when lost or damaged packets are detected, but as the distance between keyframes can be long (sometimes up to 10 seconds) this isn't ideal. You may be able to solve this problem by forcing a TCP connection (network protocol that guarantees packet delivery, vs. UDP which does not) which is currently done in Sighthound Video by appending a keyword flag to the connection path. More detail can be found here: topic11523

Best,
- ryan

Hi,

Thank's for your quick answer. Yes, I know TCP could be used. However, to make it working properly, it would mean that finetuning TCP stack parameters e.g to slow-start would be needed. At least in Mac OS, there is only a single TCP stack, meaning finetuning for Sighthound would affect all the TCP traffic. Not nice.

I also understand that frame sync can be long. But does the features always need to take the worst cases into account? How about e.g only for 1 - 3 seconds? The bandwidth what MP4 demands is significantly less compared to mpeg and it would justify the smaller frame windows.

Regards
Johannes

[ryan]

Hi Johannes,

We'll certainly consider all options available in trying to make improvements in future versions. With regard to the keyframe interval, this is set at the video source and isn't something that we are able to control unfortunately.

[Johannes_L]

Hi Johannes,

We'll certainly consider all options available in trying to make improvements in future versions. With regard to the keyframe interval, this is set at the video source and isn't something that we are able to control unfortunately.

Hi,

I understand that it's outside of the control for your app. Anyway, persons, who put 3+ cameras into same WiFi or 5+ into same Ethernet segment should be quite professionals and they should be provided tools they can use to optimize the whole experience

Johannes