This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

BitResolution

Hello:)

I would like to know how to change the bitresoultion to 8 bits for the keil usb audio descriptors

I have tried to change bSubFrameSize to 0x01 bBitResolution to 8 then WBVAL to 34 and I get bsod error on computer and it does not work I am running winxp.

I would like to run the usb speaker at 8bit resolution and 32000khz could you please help me make the changes to the descriptors


/* Audio Type I Format */
  AUDIO_FORMAT_TYPE_I_DESC_SZ(1),       /* bLength */
  AUDIO_INTERFACE_DESCRIPTOR_TYPE,      /* bDescriptorType */
  AUDIO_STREAMING_FORMAT_TYPE,          /* bDescriptorSubtype */
  AUDIO_FORMAT_TYPE_I,                  /* bFormatType */
  0x01,                                 /* bNrChannels */
  0x02,                                 /* bSubFrameSize */
  16,                                   /* bBitResolution */
  0x01,                                 /* bSamFreqType */
  B3VAL(32000),                         /* tSamFreq */
/* Endpoint - Standard Descriptor */
  AUDIO_STANDARD_ENDPOINT_DESC_SIZE,    /* bLength */
  USB_ENDPOINT_DESCRIPTOR_TYPE,         /* bDescriptorType */
  USB_ENDPOINT_OUT(3),                  /* bEndpointAddress */
  USB_ENDPOINT_TYPE_ISOCHRONOUS,        /* bmAttributes */
  WBVAL(64),                            /* wMaxPacketSize */
  0x01,                                 /* bInterval */
  0x00,                                 /* bRefresh */
  0x00,                                 /* bSynchAddress */
/* Audio Definitions */
#define DATA_FREQ 32000                 /* Audio Data Frequency */
#define P_S       32                    /* Packet Size */
#if USB_DMA
#define P_C       4                     /* Packet Count */
#else
#define P_C       1                     /* Packet Count */
#endif
#define B_S       (8*P_C*P_S)           /* Buffer Size */

thanks Mike pisces.

Parents
  • I just thought, I would of thought most audio on pc is 16bit do I need to convert to 8bits, like including a lossless compression method in my code or is that built into windows usb drivers. Because it manages to play 16bit audio so it seems strange it cannot do the same for 8bit without needing anything extra?

Reply
  • I just thought, I would of thought most audio on pc is 16bit do I need to convert to 8bits, like including a lossless compression method in my code or is that built into windows usb drivers. Because it manages to play 16bit audio so it seems strange it cannot do the same for 8bit without needing anything extra?

Children