At Fri, 12 Apr 2013 22:33:59 -0500, Calvin Owens wrote:

When recording at 176.2KHz or 192Khz, the device adds a 32-bit length header to the capture packets, which obviously needs to be ignored for recording to work properly.

Userspace expected: L0 L1 L2 R0 R1 R2 ...but actually got: R2 L0 L1 L2 R0 R1

Also, the last byte of the length header being interpreted as L0 of the first sample caused spikes every 0.5ms, resulting in a loud 16KHz tone (about the highest 'B' on a piano) being present throughout captures.

Tested at all sample rates on an E-Mu 0404USB, and tested for regressions on a generic USB headset.

Signed-off-by: Calvin Owens jcalvinowens@gmail.com

Thanks, applied for 3.10 kernel (but with Cc to stable) now.

Takashi

---

sound/usb/card.h | 1 + sound/usb/pcm.c | 2 +- sound/usb/quirks.c | 1 + sound/usb/stream.c | 1 + 4 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/sound/usb/card.h b/sound/usb/card.h index 8a751b4..d32ea41 100644 --- a/sound/usb/card.h +++ b/sound/usb/card.h @@ -116,6 +116,7 @@ struct snd_usb_substream { unsigned int altset_idx; /* USB data format: index of alternate setting */ unsigned int txfr_quirk:1; /* allow sub-frame alignment */ unsigned int fmt_type; /* USB audio format type (1-3) */

• unsigned int pkt_offset_adj; /* Bytes to drop from beginning of packets (for non-compliant devices) */

  unsigned int running: 1; /* running status */

diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c index f94397b..a481fea 100644 --- a/sound/usb/pcm.c +++ b/sound/usb/pcm.c @@ -1170,7 +1170,7 @@ static void retire_capture_urb(struct snd_usb_substream *subs, stride = runtime->frame_bits >> 3;

for (i = 0; i < urb->number_of_packets; i++) {

• cp = (unsigned char *)urb->transfer_buffer + urb->iso_frame_desc[i].offset;
  

• cp = (unsigned char *)urb->transfer_buffer + urb->iso_frame_desc[i].offset + subs->pkt_offset_adj;
  

  if (urb->iso_frame_desc[i].status && printk_ratelimit()) { snd_printdd(KERN_ERR "frame %d active: %d\n", i, urb->iso_frame_desc[i].status); // continue;

diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c index 5325a38..7e292b9 100644 --- a/sound/usb/quirks.c +++ b/sound/usb/quirks.c @@ -837,6 +837,7 @@ static void set_format_emu_quirk(struct snd_usb_substream *subs, break; } snd_emuusb_set_samplerate(subs->stream->chip, emu_samplerate_id);

• subs->pkt_offset_adj = (emu_samplerate_id >= EMU_QUIRK_SR_176400HZ) ? 4 : 0;

}

void snd_usb_set_format_quirk(struct snd_usb_substream *subs, diff --git a/sound/usb/stream.c b/sound/usb/stream.c index ad181d5..0927cc6 100644 --- a/sound/usb/stream.c +++ b/sound/usb/stream.c @@ -94,6 +94,7 @@ static void snd_usb_init_substream(struct snd_usb_stream *as, subs->dev = as->chip->dev; subs->txfr_quirk = as->chip->txfr_quirk; subs->speed = snd_usb_get_speed(subs->dev);

• subs->pkt_offset_adj = 0;

  snd_usb_set_pcm_ops(as->pcm, stream);

-- 1.8.1.5