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Can I modify ASRC code in C5000 CAF to support 11.025kHz sampling rate?

j-breeze
Mastermind 7560 points


Hi Champs,

I'm planning to add 11.025kHz sampling rate support to the record and playback ASRC in C5000 Connected Audio Framework.

So, can I modify the ASRC code to support the 11.025kHz sampling rate?
If so, could you please let me know how I should modify it?

Thanks in advance for your cooperation.

Best regards,
j-breeze

  • 0
    TI__Mastermind 35645 points

    Hi,

    As a Moderator. it is been assigned to right expert and it will be addressed soon.

    Thanks & regards,

    Sivaraj K

  • 0
    TI__Intellectual 1530 points

    Yes you can.

    In the file sample_rate.h, add: #define SAMP_RATE_11_025KHZ          ( 0x2B11 )
    add: #define SAMPS_PER_MSEC_11_025KHZ     ( SAMP_RATE_11_025KHZ / RATE_1KHZ )

    In the file app_asrc.c,
    change: #define AASRC_NUM_SAMP_RATES        ( 7 ) to (8)
    add: SAMP_RATE_11_025KHZ to gsAasrcSampRateHzToIdx[]
    add: #define AASRC_SAMP_RATE_11_025KHZ_IDX   ( 1 ) and accordingly increment other indices

     

    In the file app_asrc.c, add entries for 11.025KHz. Please follow the below mentioned process for the same:

    /* Nominal phase increment table
    Rows: {8, 16, 22.05, 24, 32, 44.1, 48}
    Cols: {8, 16, 22.05, 24, 32, 44.1, 48}
    Entries are row(i)/col(j) in S32Q16
    */
    Each entry in this table is a 32-bit data, lower 16 LSBits form the fractional part, higher 16 MSBits form the integral portion
    Calculation for the first entry 0x00010000:
    8/8 = 1
    Calculation for the second entry 0x00008000:
    8/16 = 0.5, Integer part(16 MSBits)=0x0000, Fractional part (Base16)=0.5x16=80, hence 16 LSBits 0x8000
    Calculation for the third entry 0x00005CE1:
    8/22.05 = 0.36281179138321995464852607709751 Integral part=0x0000,
    Fractional part = 0.36281179138321995464852607709751 x 16 = 5.8049886621315192743764172335601
    0.8049886621315192743764172335601 x 16 = 12.879818594104308390022675736961
    0.87981859410430839002267573696145 x 16 = 14.077097505668934240362811791383
    0.07709750566893424036281179138322 x 16 = 1.2335600907029478458049886621315
    Fractional part from above 4 values viz. 5,12,14,1 : 0x5CE1

    Similarly, the second row in this table is formed as follows:
    16/8 = 0x00020000
    16/16 = 0x00010000
    16/22.05 = 0x0000B9C2 and so on.

    Please insert 11.025, in the rows and columns
    Rows: {8, 11.025, 16, 22.05, 24, 32, 44.1, 48}
    Cols: {8, 11.025, 16, 22.05, 24, 32, 44.1, 48}
    and calculate the additional entries required as explained above.

     Best Regards.

  • 0 in reply to KRaviS
    Mastermind 7560 points

    Hi Sivaraj and KRaviS,

    Thank you for your prompt support.  I was able to modify the table as below.

    /* Nominal phase increment table
    Rows: {8, 11.025, 16, 22.05, 24, 32, 44.1, 48}
    Cols: {8, 11.025, 16, 22.05, 24, 32, 44.1, 48}
    Entries are row(i)/col(j) in S32Q16
    */
    static const Int32 gsAasrcNomPhsIncr[AASRC_NUM_SAMP_RATES][AASRC_NUM_SAMP_RATES] =
    {
        0x00010000, 0x0000B92C, 0x00008000, 0x00005CE1, 0x00005555, 0x00004000, 0x00002E70, 0x00002AAA,
        0x000160CC, 0x00010000, 0x0000B066, 0x00008000, 0x00007599, 0x00005833, 0x00004000, 0x00003ACC,
        0x00020000, 0x00017384, 0x00010000, 0x0000B9C2, 0x0000AAAA, 0x00008000, 0x00005CE1, 0x00005555,
        0x0002C199, 0x00020000, 0x000160CC, 0x00010000, 0x0000EB33, 0x0000B066, 0x00008000, 0x00007599,
        0x00030000, 0x00022D47, 0x00018000, 0x000116A3, 0x00010000, 0x0000C000, 0x00008B51, 0x00008000,
        0x00040000, 0x0002E709, 0x00020000, 0x00017384, 0x00015555, 0x00010000, 0x0000B9C2, 0x0000AAAA,
        0x00058333, 0x00040000, 0x0002C199, 0x00020000, 0x0001D666, 0x000160CC, 0x00010000, 0x0000EB33,
        0x00060000, 0x00045A8E, 0x00030000, 0x00022D47, 0x00020000, 0x00018000, 0x000116A3, 0x00010000
    }

    Best regards,
    j-breeze