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 <[email protected]>
---
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
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 <[email protected]>
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
>