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DAC USB 192kHz 24bity


okim9999

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Witam,

Przygotowuje się do zbudowania DACa USB możliwe też że spdif. Z tego co zdążyłem się dowiedzieć to próbkowanie 192kHz przy USB to duży problem.

Znalazłem jednak jednego przenośnego DACa (

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W jego wnętrzu jest pcm2705 > src4192 > DAC (WM8740). Proszę o pomoc w tym temacie i odpowiedź czy jest to w ogóle możliwe nie używając procesorów itp.

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Ogolny problem to sterowniki do UAC2 2.0 ktorych brakuje na windowsa. Kazda firma musi na wlasna reke napisac sterowniki oraz najczesciej pobawic sie w programowanie samego ukladu, ale od pewnego czasu pojawia sie coraz wiecej urzadzen wspierajacych protokol UAC 2.0 Na wlasna reke raczej nie uda Ci sie znalesc ogolnie dostepnego ukladu ze sterownikami, kory nie potrzebuje programowania oraz wspiera UAC 2.0. Zostaje zakup np. takiego urzadzenia.

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To co pokazales jest na starym PCM2705 ktory odtwarza jedynie do 48KHz, src419 najwyzej wykona upsampling do 192KHz.

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Czyli tenor te7022 nadal wygrywa pod wzgledem probkowania? Czy to prawda ze potrzebuje epromu do poprawnego dzialania z windowsem i androidem?

przynajmniej działa. proby z TE8802L nie powioda sie raczej. To informacja od GFEC'a

 

Thanks for your interesting Tenor TE8802L. However, we would like to inform you that we have three main issues – Linux OS support, Foobar2000 with WASAP in Windows7 and CPU loading, currently.

 

 

 

Let’s start from the simple one – Linux OS.

 

Basically, we didn’t do any test on Linux OS and guarantee that our TE8802 would work well before because of few inquiries from our customers and resource limitation. When customer raised the issue, our engineers set up the test environment and duplicate the failure. The most challenge came from Galaxy’s driver worked well. We will found the root cause about this. Currently, if you consider Linux support is must, please wait for we improve it.

 

 

 

Noise happen when pause to play depend on application-Foobar2000 with WASAPI in Windows 7 issue

 

The noise is happen depend on playing application of Foobar 2000 with WASAPI in Windows 7. As we study audio architecture of Windows 7/Vista that DS and WASAPI are different path in architecture. DS is running normal audio path said "Shared Mode". All stream is thru this path to Audio Engine for Mix process then input to our driver. Our driver is based on this mode to design. WASAPI ( Windows Audio Session API) is running "Exclusive Mode" and will pass stream to Audio Driver directly. It is for bypass Audio Engine (Mix process) purpose like ASIO.

 

Though WASAPI also pass stream to Audio Driver (Tenor driver) like DS but we guess they are have different method to handle stream. Our software engineers had study them and co-work with Microsoft to find out how to improve now. Currently, we will suggest user use DS mode to play and not use WASAPI plug-in until we are improved it.

 

 

 

CPU Loading –our most headache issue

 

We also received few feedbacks from customer raised the issue.

 

First, let me briefly explain our product concept. The sound data will go into buffer first to isolate the variation of the clock of PC USB. If the clock is too fast/slowly, the data will full/dry-out the buffer and cause pop noise. To prevent the situation, chip will send interrupt(s) to ask PC hold/add data packages. In case the clock of PC USB closes to typical, the interrupts will be sent out very few times. Therefore, the CPU loading will be low. However, if the clock close to edge (still meet USB standard), chip will send a lot of interrupts. CPU will be busy to handle the request and loading goes high. If CPU computing power is low, CPU may not execute all interrupts. Then, the buffers will causes data lose. The phenomenon happens more frequently in Asynchronous mode than Adaptive mode. However, as CPU computing power keeps improving, the CPU loading percentage will move down.

 

 

 

As re-construct our driver may cause years research, we are heading another direction. When the first time install driver, a program will test USB clock first, then adjust our driver’s setting. However, our engineers need to take 1 to 2 quarters to make it happen. Currently, we recommend our customers list suggest platform, such as certain CPU level above.

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