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Author Topic: PCM audio/video out of sync (Bitstream is fine)  (Read 1353 times)

TorqW

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PCM audio/video out of sync (Bitstream is fine)
« on: October 28, 2013, 10:05:43 am »

Hi all,
I have been bitstreaming for years, but after reading through all the posts on the forum I decided to use the JRSS mix for the new Anthem MRX700 amp I've receieved.

Having set up the ARC room correction, I connected the HTPC (latest core-i7 based with JR19). I checked bitstream - all good, in fact sounded great.

Then I turned OFF bitstream, and used the JRSS with the "send all frequencies to sub" option selected. I would venture the sound was more detailed (but could be psychoacoutics?).

HOWEVER, there was a noticeable loss of video/audio sync, which I managed to more or less correct in the video tab by entering +"125"ms into the advanced option for video sync.

2 questions:
1) am I correct to send all frequencies to sub?
2) is this sync issue a frequent problem? Also what's the best way to more precisely determine the exact delay to precisely sync up?

Many thanks in advance,
TW
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Matt

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Re: PCM audio/video out of sync (Bitstream is fine)
« Reply #1 on: October 28, 2013, 11:32:28 am »

2) is this sync issue a frequent problem? Also what's the best way to more precisely determine the exact delay to precisely sync up?

It's normal to have to dial in the perfect sync.  This is because there are a lot of variables, like monitor lag, receiver lag, buffer settings in MC, etc.

I use this clip for getting it perfect:
http://files.jriver.com/accessories/test_clips/audio_sync_test_25hz.vob
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Matt Ashland, JRiver Media Center

Matt

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Re: PCM audio/video out of sync (Bitstream is fine)
« Reply #2 on: October 28, 2013, 11:33:33 am »

1) am I correct to send all frequencies to sub?

Only if you're trying to use the low-pass in your sub.  However, best practice is to set the low-pass in your sub as high as possible (or even off) and do the cross-over in software (where you get the advantage of 64-bit processing).
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Matt Ashland, JRiver Media Center

TorqW

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Re: PCM audio/video out of sync (Bitstream is fine)
« Reply #3 on: October 28, 2013, 11:50:01 am »

Matt - Many thanks indeed.
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Matt

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Re: PCM audio/video out of sync (Bitstream is fine)
« Reply #4 on: October 28, 2013, 12:02:12 pm »

Only if you're trying to use the low-pass in your sub.  However, best practice is to set the low-pass in your sub as high as possible (or even off) and do the cross-over in software (where you get the advantage of 64-bit processing).

Keep in mind that the low-pass shown on DSP Studio > Output Format only applies when building a subwoofer channel for material that does not have a native subwoofer channel.

When you play 5.1, 7.1, etc. content, the subwoofer channel is played as-is.

You can apply additional filtering or bass management (to move bass from other speakers to the subwoofer) using DSP Studio > Room Correction.
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