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usb sound card PCM2904 - playing&recording together

Asked by Emmanuel on 1 Jun 2011

Hello,

It seems that the Usb codec PCM2904 can be used as a standard Windows sound card. Do you know if it works with Matlab? (which should work with any Windows sound card) Just using the audiorecorder audioplayer Matlab functions should be ok? (specially for playing and recording at the same time) Or else using the Data acquisition toolbox?

Thanks you for all advice, Emmanuel E.

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Emmanuel

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2 Answers

Answer by Daniel on 2 Jun 2011

I don't know anything about the PCM2904, but if it does behave like a standard MS Windows sound card, then playing and recording together is difficult. Syncing the start of the play back with the start of the recording, to within less than 10 ms is extremely difficult. Neither the standard audio-player/recorder nor the data acquisition toolbox will get you anywhere close (never mind the hisses, clicks and pops that audioplayer gives you). If you want synchronous playing and recording with reasonable latency in MS Windows you need an ASIO compliant soundcard (or custom hardware).

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Daniel
Answer by Emmanuel on 3 Jun 2011

Thank you for your answer. The PCM2904 doesn't seem to be a sophisticated sound card (not Asio). However, "The PCM2904/2906 employs SpAct™ architecture, TI's unique system that recovers the audio clock from USB packet data. On-chip analog PLLs with SpAct enable playback and record with low clock jitter and with independent playback and record sampling rates." http://focus.ti.com/docs/prod/folders/print/pcm2904.html

I don't think I mind about syncing the start of playing / recording (it's for postprocessing, to compare the input and output: I can do a delay adjustment afterwards, and start the recording before not to loose anything at recording).

But maybe you mean that the syncing latency of 10ms affects not only the play/record start, but also the linearity of time between playing and recording? (jitter)

Should we consider changing for another sound card, or the low clock jitter this card advertises would limit this problem like an Asio card, as well the various playing noises you talk about audioplayer? (And are theses noises also present with the data acquisition toolbox?)

Thank you! Emmanuel

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Emmanuel

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