Asynchronous I2S FIFO project, an ultimate weapon to fight the jitter - Page 137 - diyAudio
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Old 30th October 2012, 02:39 AM   #1361
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Originally Posted by qusp View Post
how quickly can the buffer be emptied? Ian? is there a possibility it could ever be done between clock ticks as a matter of urgency if it came to that?

nice post Chris!
Buffer could be empty within one word for urgency.
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Old 30th October 2012, 02:51 AM   #1362
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To me, video delay unit seems like ideal solution. Even better variable delay. If the syncing is only for software source, than I believe VLC does that, but I am not 100% sure.
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Old 30th October 2012, 02:53 AM   #1363
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Originally Posted by spm View Post
Si570 interest list:

1. bigpandahk
2. tagheuer
3. hochopeper
4. qusp (of course)
5. AR2 - definitely!
6. wktk_smile
7. hirez69
8. CeeVee - you bet!
9. number9
10. analog_sa - GB maniac
11. edbk
12. atom6422
13. misterrogers - Of Course!
14. NicMac - as usual!
15. Zoran
16. PET-240
17. Coolhead
18. Slartibartfasst
19. SYklab
20. Regland
21. Neb001
22. SPWONG
23. Greg Stewart (also of course!)
24. Vitalica
25. spm
I think it would be good if we could have a ballpark price, because some of us might order more than one unit and speed up this GB.
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Old 30th October 2012, 03:00 AM   #1364
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Good idea Chris.


I'm an audiophile, so the FIFO was designed optimized to audio. That's why I use big buffer memory rather than a smaller one.

Of cause reducing the FIFO size will shorten the dealy time, but it will leave less space for the smart FIFO control stratagy hence degrade the SQ due to frequently overflow/empty, eapecially for playing long audio track, which is what I'm not tending to.
Thanks, Ian. I agree audio is the first priority in this system. I want to try to investigate solutions that will allow video to be good enough while still having excellent audio that meets the audiophile requirements.

For my application, the FIFO will be in a DAC that is sitting on my desk at my computer, I want to be able to watch TV or streaming videos (normally technical presentations for example) without having to swap audio sources around. So the video is less critical in my application. I would also like to think of ways this could be applied with minimal impact on video quality, in case a multichannel FIFO ever emanates from 'iancanada labs LLC'.

I am thinking of this as a solution that is implemented by the user and should not be a burden or require any sacrifice in the FIFO development. Hopefully proposing some solutions to this issue may remove one of the hurdles that has stopped others from using the FIFO.

Quote:
Originally Posted by iancanada View Post
But just as you mentioned, there still some possibles solutions, what I could think of are:

1, Enable the audio/video delay control function on the video player.

2, Trying to up-sampling the audio stream into higher Fs, for example, 196Khz only has 1/4 delay of 48Khz, says around just 150ms.

3, Hardware based delay controler placed between player and HDTV.

Sandy is comming now .

Ian
1 and 2 are the two basic approaches that I had in mind. I have some work to do to make #1 work transparently, but I believe it is possible. #2 I will try to document my proposed approach though I have no way of testing it for now.

#3 is harder to implement and would require some modification to the FIFO. I have a method in mind that passes a FIFO status to the computer and adjusts video delay accordingly. For example 1/4 full, 1/2 full, 3/4 full delays that can be set automatically by software depending on the current Fs. Is this possible on the FIFO end? I have a method in mind on the computer side.

For now integrating this with a HDTV and presumably HDMI is beyond my ability. Though if I was to think of a solution that would interface with a HDTV I would start by investigating HDMI-CEC protocols and devices like this - Pulse-Eight. Control your TV from XBMC, or vice versa! USB - CEC Adapter that may allow communication between computer and the TV and implement the delay on the HDTV end. I am not sure if HDMI-CEC allows audiosync control. Though if the same can be achieved inside the software playing the video that may be an overly cumbersome solution compared to others that we might develop. As a result my focus isn't on the HDTV end but in the computer software for now. The proprietary nature of blueray players and other devices means that it would very difficult to implement something that is universally applicable.


I have been using HDMI-CEC between my Denon AVR and Sony TV for a few years now in my lounge and it does allow very nice integration of those consumer type products. I now only use one remote and without any need for a universal remote control!

Cheers,
Chris

Last edited by hochopeper; 30th October 2012 at 03:04 AM.
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Old 30th October 2012, 03:29 AM   #1365
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I forgot to add, stay dry everyone on the North American continent, that storm looks mean.
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Old 30th October 2012, 03:55 AM   #1366
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I forgot to add, stay dry everyone on the North American continent, that storm looks mean.
Thanks hochopeper, just got the power supply back .
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Old 30th October 2012, 04:01 AM   #1367
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I think it would be good if we could have a ballpark price, because some of us might order more than one unit and speed up this GB.
I'm trying to get quotation from dealers of Silabs now. Will figure it out for sure.

Ian
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Old 31st October 2012, 06:08 AM   #1368
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Hi guys,
I was wondering if any of you have solved this puzzle. Ian's S/PDIF board in its output uses U.FL connectors. Acko's DAC at input uses W.FL Hirose connectors. Any idea how to connect those two? I do not think they make any crossover cable that has both types of connectors. The only idea I have is to somehow switch U.FL connectors from S/PDIF board to W.FL, which I am sure is less than optimal from mechanical stand point, but I believe only possible one. Obviously my intention is to use those prefabricated cables, as they seem like really good solution.
Now I hope someone had a same problem with better idea. I absolutely hate those ultra small connectors. U.FL are quite fine and I hope Acko will replace his at some point to the bigger ones.
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Old 31st October 2012, 06:25 AM   #1369
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nah thats what you have to do, they actually solder just fine in the u.fl pad and are just as robust as if they were soldered to a w.fl pad. acko uses them for the same reason he uses a 2mm pitch for analogue output, he got measurably better performance that way as it allows a tighter layout, so myself I prefer they stay, I havent had a problem with them. you can of course leave the ufl for the MCLK.

just ask that Ian supplies the board without them soldered

I presume you mean the clock board output, not spdif board
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Old 31st October 2012, 07:26 AM   #1370
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nah thats what you have to do, they actually solder just fine in the u.fl pad and are just as robust as if they were soldered to a w.fl pad. acko uses them for the same reason he uses a 2mm pitch for analogue output, he got measurably better performance that way as it allows a tighter layout, so myself I prefer they stay, I havent had a problem with them. you can of course leave the ufl for the MCLK.

just ask that Ian supplies the board without them soldered

I presume you mean the clock board output, not spdif board
Thank you Qusp. That is what I was afraid will need to take place. I do understand reasons, just hate those little buggers. I still think they are pain. Honestly I doubt there would be a big difference between the two, but I'll just take it. As for which board, since I decided to wait for the new clock board, I still did not put together FIFO project, so I could be quite wrong if I am sending I2S out of S/PDIF or from the clock board.

I remember last time reading the manual Ian put together, and somehow I had in my mind it goes out from S/PDIF board, but I am quite possibly wrong. I am not there yet - making connections. Still trying to figureuot space within the case, and all other issues, such as this one. Both clock and S/PDIF boards are with U.FL connectors, so that is so far what I am concerned at this point. Once I get close I will make sure all is clear. I was sure MCK goes out from clock board, but the rest... I am dragging my implementation, since I am planning to get battery management board, I2S insulator board and new clock board once they become available. You know the pain of rearranging everything, that I am trying to avoid, since I was anyway late to join the group of FIFO users. Thank you anyways for the correction.
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