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Problem in Passthrough code

abhishek seth9849
Intellectual 560 points

Hi,

I downloaded the passthrough code from http://code.google.com/p/c5505-ezdsp/. Initially I thought that this is working fine. But when I tested it on few audio files, I noticed there is some problem with the code. Did anyone face similar problem? Is there any other passthrough code or any fix for this code?

Another question is that suppose I have flashed a code in C5505. Is there any USB hub or something which can be used to power eZdsp (apart from PC usb drive). Idea is to make eZdsp mobile. 

Thanks,

Abhishek Seth.

  • 0
    Intellectual 395 points

    Hi Abhishek,

    what are the problems that you are experiencing? My code compiled and ran just fine. Maybe you can give some more details about your problem. Concerning the external power supply, I am interested as well.

    Regards,

    Michael

  • 0 in reply to Michael Rietz
    Intellectual 560 points

    Hi,

    Problem is something like I am not able to hear words (as if words are filtered out from song). There is some sort of echo also. What steps u took to run your code. Did u make any changes to code?

  • 0 in reply to abhishek seth9849
    TI__Intellectual 2530 points

    Hi Abhishek,

    The example code is actually performing filtering, it is filtering out the higher frequencies of the signal.  Also the filter is switched on and off every 10 seconds.  Here is a detailed explanation of what the code is doing, this is also included in the readme file included in the package.  You may be hearing the effect of this depending on the audio content you are using. 

    This program takes audio input through I2S interface, then send back to I2S again.
    Between intput and output:
    FIR filter for 10 seconds (LED tunred on)
    No filter for 10 seconds (LED turned off)

    1) I2S interface
    - Audio Codec: ADS3204 (Master/Slave)
    - C5505 (Slave/Master)
    - Sampling rate: 48KHz

    2) Data
    - Use Pingpong buffer  (two L inputs, two R inputs, two L outs, two R outs): total 8 buffers
    - Buffer size: 48*2 words (16bit)

    3) Filter
    - FIR filter
    - Fc = 2KHz
    - -80dB@ 10KHz
    - -1dB@1KHz

    Regarding powering the eZdsp, the current board is only powered from a PC/laptop.  We are considering other ways, to make it more mobile, for future boards.

    Best regards, Vishal

  • 0 in reply to Vishal Markandey
    Intellectual 560 points

    Hi,

    I know the functioning of code. But even when filter is off it doesnt sounds like passthrough. In a varied version of this code, I switched off filter permanenetly. But that also doesnt sounds like passthrough. Did you face any such problem?

    Thanks.

  • 0 in reply to abhishek seth9849
    Intellectual 395 points

    Well, when I first tested the demo with a sound signal, I was "shocked" by the sound quality of the board (mostly the codec, I guess). After some trouble shooting, I found out that my problems were due to a number of issues that were not related to the board (1.: I used a FM radio signal as line in which was itself pretty noisy and distorted, 2.: I used a very cheap set of headphones which sounded horribly and 3.: I think the input was too strong, so that I could here saturation/clipping effects). When I removed these three things, the board sounded pretty much like a consumer piece of audio electronics.

    So, to answer your question: No, I didn't really run into any of the mentioned problems. Maybe it could help if you also try out different line signals, at perhaps different volumes. I don't know if you tested your board using you PC's sound card for outputting and inputting; if so, try using a CD player for line in and headphones for audio out, so as to rule out problems caused by your sound card. Hope this helps.