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TOPIC: Re: OpenDRC Processing Delay? Video Lip Syncing?

OpenDRC Processing Delay? Video Lip Syncing? 7 years 2 months ago #6322

  • OTMOPO3OK
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Hello,

I interested in using this product however I have a few questions regarding the FIR filtering in general and specifically this product's implementation.

I read through all manuals, forums, etc and could not find any information on how long the processing takes inside the OpenDRC box in BYPASS mode and Convolving at 100% ?

Is that delay significant to cause video lip syncing if OpenDRC is used for home theater?

Thank you!
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Re: OpenDRC Processing Delay? Video Lip Syncing? 7 years 2 months ago #6323

  • curryman
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I already answered your question in the DIYaudio forum :whistle:

However here is a copy ;) :

The initial delay (without filters, Bypass mode) of the openDRC is quite low (<2ms) and will not cause any problems.

The delay with FIR filter depends on the type of filter used. In case of a symetric linear phase FIR filter (e.g. acourate will generate this type of filter) the delay will be half the number of taps divided by the sample rate. Using the maximum number of taps (6144) this will be 64ms. For minimum phase filters the delay might be much lower.

I am using openDRC together with a Panasonic Plasma (SPDIF out) and the video processing engine also has a significant delay (arround 70ms although I switched off most of the video processing :S ). The SPDIF out delay can be adjusted and switched of and so I don't have any problems with lip sync (arround 10ms will be tolerable). Not sure though if SPDIF out delay can be adjusted for all TVs

hoping this info helps ;)
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Re: OpenDRC Processing Delay? Video Lip Syncing? 7 years 1 month ago #6379

  • OTMOPO3OK
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curryman,
thank you for your thorough reply, i did not notice it on DIYAduio at first.
I decided to post the question here so everyone can reference this information.

That's excellent news that it goes to <2ms in bypass mode, i can also adjust audio delay both ways -/+ from some software players on mac/pc, but videos from some online source like YouTube will still be out of sync badly (and have no adjustments).
Well I guess i might have to include a hardwired bypass switch to bypass the whole OpenDRC box all together. Or program the intermal Bypass mode into one of the 4 presets. :)
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