* [PATCH] uvcvideo: extend UVC_QUIRK_FIX_BANDWIDTH to MJPEG streams
@ 2017-09-04 8:14 Pavel Rojtberg
2017-09-04 9:56 ` Laurent Pinchart
0 siblings, 1 reply; 5+ messages in thread
From: Pavel Rojtberg @ 2017-09-04 8:14 UTC (permalink / raw)
To: mchehab, laurent.pinchart, linux-media; +Cc: Pavel Rojtberg
From: Pavel Rojtberg <rojtberg@gmail.com>
attaching two Logitech C615 webcams currently results in
VIDIOC_STREAMON: No space left on device
as the required bandwidth is not estimated correctly by the device.
In fact it always requests 3060 bytes - no matter the format or resolution.
setting UVC_QUIRK_FIX_BANDWIDTH does not help either as it is only implemented
for uncompressed streams.
This patch extends UVC_QUIRK_FIX_BANDWIDTH to MJPEG streams by making a
(conservative) assumption of 4bpp for MJPEG streams.
As the actual compression ration is often closer to 1bpp this can be overridden
via the new mjpeg_bpp parameter.
Based on:
https://www.mail-archive.com/linux-uvc-devel@lists.berlios.de/msg05724.html
---
drivers/media/usb/uvc/uvc_driver.c | 14 +++++++++++++-
drivers/media/usb/uvc/uvc_video.c | 3 ++-
2 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index 70842c5..f7b759e 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -37,6 +37,7 @@ unsigned int uvc_no_drop_param;
static unsigned int uvc_quirks_param = -1;
unsigned int uvc_trace_param;
unsigned int uvc_timeout_param = UVC_CTRL_STREAMING_TIMEOUT;
+static unsigned int uvc_mjpeg_bpp_param;
/* ------------------------------------------------------------------------
* Video formats
@@ -463,7 +464,16 @@ static int uvc_parse_format(struct uvc_device *dev,
strlcpy(format->name, "MJPEG", sizeof format->name);
format->fcc = V4L2_PIX_FMT_MJPEG;
format->flags = UVC_FMT_FLAG_COMPRESSED;
- format->bpp = 0;
+ if ((uvc_mjpeg_bpp_param >= 1) && (uvc_mjpeg_bpp_param <= 16)) {
+ format->bpp = uvc_mjpeg_bpp_param;
+ } else {
+ /* conservative estimate. Actual values are around 1bpp.
+ * see e.g.
+ * https://developers.google.com/speed/webp/docs/webp_study
+ */
+ format->bpp = 4;
+ }
+
ftype = UVC_VS_FRAME_MJPEG;
break;
@@ -2274,6 +2284,8 @@ module_param_named(trace, uvc_trace_param, uint, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(trace, "Trace level bitmask");
module_param_named(timeout, uvc_timeout_param, uint, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(timeout, "Streaming control requests timeout");
+module_param_named(mjpeg_bpp, uvc_mjpeg_bpp_param, uint, S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(mjpeg_bpp, "MJPEG bits per pixel for bandwidth quirk");
/* ------------------------------------------------------------------------
* Driver initialization and cleanup
diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index fb86d6a..382a0be 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -127,7 +127,8 @@ static void uvc_fixup_video_ctrl(struct uvc_streaming *stream,
if ((ctrl->dwMaxPayloadTransferSize & 0xffff0000) == 0xffff0000)
ctrl->dwMaxPayloadTransferSize &= ~0xffff0000;
- if (!(format->flags & UVC_FMT_FLAG_COMPRESSED) &&
+ if ((!(format->flags & UVC_FMT_FLAG_COMPRESSED) ||
+ (format->fcc == V4L2_PIX_FMT_MJPEG)) &&
stream->dev->quirks & UVC_QUIRK_FIX_BANDWIDTH &&
stream->intf->num_altsetting > 1) {
u32 interval;
--
2.7.4
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH] uvcvideo: extend UVC_QUIRK_FIX_BANDWIDTH to MJPEG streams
2017-09-04 8:14 [PATCH] uvcvideo: extend UVC_QUIRK_FIX_BANDWIDTH to MJPEG streams Pavel Rojtberg
@ 2017-09-04 9:56 ` Laurent Pinchart
2017-09-05 17:27 ` Pavel Rojtberg
0 siblings, 1 reply; 5+ messages in thread
From: Laurent Pinchart @ 2017-09-04 9:56 UTC (permalink / raw)
To: Pavel Rojtberg; +Cc: mchehab, linux-media
Hi Pavel,
Thank you for the patch.
On Monday, 4 September 2017 11:14:17 EEST Pavel Rojtberg wrote:
> From: Pavel Rojtberg <rojtberg@gmail.com>
>
> attaching two Logitech C615 webcams currently results in
> VIDIOC_STREAMON: No space left on device
> as the required bandwidth is not estimated correctly by the device.
> In fact it always requests 3060 bytes - no matter the format or resolution.
>
> setting UVC_QUIRK_FIX_BANDWIDTH does not help either as it is only
> implemented for uncompressed streams.
>
> This patch extends UVC_QUIRK_FIX_BANDWIDTH to MJPEG streams by making a
> (conservative) assumption of 4bpp for MJPEG streams.
> As the actual compression ration is often closer to 1bpp this can be
> overridden via the new mjpeg_bpp parameter.
>
> Based on:
> https://www.mail-archive.com/linux-uvc-devel@lists.berlios.de/msg05724.html
> ---
> drivers/media/usb/uvc/uvc_driver.c | 14 +++++++++++++-
> drivers/media/usb/uvc/uvc_video.c | 3 ++-
> 2 files changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/media/usb/uvc/uvc_driver.c
> b/drivers/media/usb/uvc/uvc_driver.c index 70842c5..f7b759e 100644
> --- a/drivers/media/usb/uvc/uvc_driver.c
> +++ b/drivers/media/usb/uvc/uvc_driver.c
> @@ -37,6 +37,7 @@ unsigned int uvc_no_drop_param;
> static unsigned int uvc_quirks_param = -1;
> unsigned int uvc_trace_param;
> unsigned int uvc_timeout_param = UVC_CTRL_STREAMING_TIMEOUT;
> +static unsigned int uvc_mjpeg_bpp_param;
>
> /* ------------------------------------------------------------------------
> * Video formats
> @@ -463,7 +464,16 @@ static int uvc_parse_format(struct uvc_device *dev,
> strlcpy(format->name, "MJPEG", sizeof format->name);
> format->fcc = V4L2_PIX_FMT_MJPEG;
> format->flags = UVC_FMT_FLAG_COMPRESSED;
> - format->bpp = 0;
> + if ((uvc_mjpeg_bpp_param >= 1) && (uvc_mjpeg_bpp_param <= 16)) {
> + format->bpp = uvc_mjpeg_bpp_param;
> + } else {
> + /* conservative estimate. Actual values are around 1bpp.
> + * see e.g.
> + * https://developers.google.com/speed/webp/docs/webp_study
> + */
> + format->bpp = 4;
> + }
> +
> ftype = UVC_VS_FRAME_MJPEG;
> break;
>
> @@ -2274,6 +2284,8 @@ module_param_named(trace, uvc_trace_param, uint,
> S_IRUGO|S_IWUSR); MODULE_PARM_DESC(trace, "Trace level bitmask");
> module_param_named(timeout, uvc_timeout_param, uint, S_IRUGO|S_IWUSR);
> MODULE_PARM_DESC(timeout, "Streaming control requests timeout");
> +module_param_named(mjpeg_bpp, uvc_mjpeg_bpp_param, uint, S_IRUGO|S_IWUSR);
> +MODULE_PARM_DESC(mjpeg_bpp, "MJPEG bits per pixel for bandwidth quirk");
I'd rather avoid adding a new module parameter for this, it would be confusing
for users. What is your use case to make the MJPEG average BPP configurable ?
Can't we come up with a heuristic that would calculate it automatically ?
> /* ------------------------------------------------------------------------
> * Driver initialization and cleanup
> diff --git a/drivers/media/usb/uvc/uvc_video.c
> b/drivers/media/usb/uvc/uvc_video.c index fb86d6a..382a0be 100644
> --- a/drivers/media/usb/uvc/uvc_video.c
> +++ b/drivers/media/usb/uvc/uvc_video.c
> @@ -127,7 +127,8 @@ static void uvc_fixup_video_ctrl(struct uvc_streaming
> *stream, if ((ctrl->dwMaxPayloadTransferSize & 0xffff0000) == 0xffff0000)
> ctrl->dwMaxPayloadTransferSize &= ~0xffff0000;
>
> - if (!(format->flags & UVC_FMT_FLAG_COMPRESSED) &&
> + if ((!(format->flags & UVC_FMT_FLAG_COMPRESSED) ||
> + (format->fcc == V4L2_PIX_FMT_MJPEG)) &&
> stream->dev->quirks & UVC_QUIRK_FIX_BANDWIDTH &&
> stream->intf->num_altsetting > 1) {
> u32 interval;
--
Regards,
Laurent Pinchart
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] uvcvideo: extend UVC_QUIRK_FIX_BANDWIDTH to MJPEG streams
2017-09-04 9:56 ` Laurent Pinchart
@ 2017-09-05 17:27 ` Pavel Rojtberg
2018-08-06 22:02 ` Laurent Pinchart
0 siblings, 1 reply; 5+ messages in thread
From: Pavel Rojtberg @ 2017-09-05 17:27 UTC (permalink / raw)
To: Laurent Pinchart; +Cc: mchehab, linux-media
Hi Laurent,
2017-09-04 11:56 GMT+02:00 Laurent Pinchart <laurent.pinchart@ideasonboard.com>:
> Hi Pavel,
>
> Thank you for the patch.
>
> On Monday, 4 September 2017 11:14:17 EEST Pavel Rojtberg wrote:
>> From: Pavel Rojtberg <rojtberg@gmail.com>
>>
>> attaching two Logitech C615 webcams currently results in
>> VIDIOC_STREAMON: No space left on device
>> as the required bandwidth is not estimated correctly by the device.
>> In fact it always requests 3060 bytes - no matter the format or resolution.
>>
>> setting UVC_QUIRK_FIX_BANDWIDTH does not help either as it is only
>> implemented for uncompressed streams.
>>
>> This patch extends UVC_QUIRK_FIX_BANDWIDTH to MJPEG streams by making a
>> (conservative) assumption of 4bpp for MJPEG streams.
>> As the actual compression ration is often closer to 1bpp this can be
>> overridden via the new mjpeg_bpp parameter.
>>
>> Based on:
>> https://www.mail-archive.com/linux-uvc-devel@lists.berlios.de/msg05724.html
>> ---
>> drivers/media/usb/uvc/uvc_driver.c | 14 +++++++++++++-
>> drivers/media/usb/uvc/uvc_video.c | 3 ++-
>> 2 files changed, 15 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/media/usb/uvc/uvc_driver.c
>> b/drivers/media/usb/uvc/uvc_driver.c index 70842c5..f7b759e 100644
>> --- a/drivers/media/usb/uvc/uvc_driver.c
>> +++ b/drivers/media/usb/uvc/uvc_driver.c
>> @@ -37,6 +37,7 @@ unsigned int uvc_no_drop_param;
>> static unsigned int uvc_quirks_param = -1;
>> unsigned int uvc_trace_param;
>> unsigned int uvc_timeout_param = UVC_CTRL_STREAMING_TIMEOUT;
>> +static unsigned int uvc_mjpeg_bpp_param;
>>
>> /* ------------------------------------------------------------------------
>> * Video formats
>> @@ -463,7 +464,16 @@ static int uvc_parse_format(struct uvc_device *dev,
>> strlcpy(format->name, "MJPEG", sizeof format->name);
>> format->fcc = V4L2_PIX_FMT_MJPEG;
>> format->flags = UVC_FMT_FLAG_COMPRESSED;
>> - format->bpp = 0;
>> + if ((uvc_mjpeg_bpp_param >= 1) && (uvc_mjpeg_bpp_param <= 16)) {
>> + format->bpp = uvc_mjpeg_bpp_param;
>> + } else {
>> + /* conservative estimate. Actual values are around 1bpp.
>> + * see e.g.
>> + * https://developers.google.com/speed/webp/docs/webp_study
>> + */
>> + format->bpp = 4;
>> + }
>> +
>> ftype = UVC_VS_FRAME_MJPEG;
>> break;
>>
>> @@ -2274,6 +2284,8 @@ module_param_named(trace, uvc_trace_param, uint,
>> S_IRUGO|S_IWUSR); MODULE_PARM_DESC(trace, "Trace level bitmask");
>> module_param_named(timeout, uvc_timeout_param, uint, S_IRUGO|S_IWUSR);
>> MODULE_PARM_DESC(timeout, "Streaming control requests timeout");
>> +module_param_named(mjpeg_bpp, uvc_mjpeg_bpp_param, uint, S_IRUGO|S_IWUSR);
>> +MODULE_PARM_DESC(mjpeg_bpp, "MJPEG bits per pixel for bandwidth quirk");
>
> I'd rather avoid adding a new module parameter for this, it would be confusing
> for users. What is your use case to make the MJPEG average BPP configurable ?
> Can't we come up with a heuristic that would calculate it automatically ?
this is the minimal expected JPEG compression ratio. It depends on the
JPEG quality
chosen by the hardware (which we do not know) as well as the actual image (which
we can not control either).
We could hardcode it to the average bpp which 1 - but this will break
when somebody
films a high-frequency checkerborad. We could leave it at 4, but this
would again
artificially limit the number of possible cameras when not filming a
checkerboard.
4 would already be a noticable improvement over the current state though.
If you can come up with a working heuristic - I am open for that too.
>> /* ------------------------------------------------------------------------
>> * Driver initialization and cleanup
>> diff --git a/drivers/media/usb/uvc/uvc_video.c
>> b/drivers/media/usb/uvc/uvc_video.c index fb86d6a..382a0be 100644
>> --- a/drivers/media/usb/uvc/uvc_video.c
>> +++ b/drivers/media/usb/uvc/uvc_video.c
>> @@ -127,7 +127,8 @@ static void uvc_fixup_video_ctrl(struct uvc_streaming
>> *stream, if ((ctrl->dwMaxPayloadTransferSize & 0xffff0000) == 0xffff0000)
>> ctrl->dwMaxPayloadTransferSize &= ~0xffff0000;
>>
>> - if (!(format->flags & UVC_FMT_FLAG_COMPRESSED) &&
>> + if ((!(format->flags & UVC_FMT_FLAG_COMPRESSED) ||
>> + (format->fcc == V4L2_PIX_FMT_MJPEG)) &&
>> stream->dev->quirks & UVC_QUIRK_FIX_BANDWIDTH &&
>> stream->intf->num_altsetting > 1) {
>> u32 interval;
>
>
> --
> Regards,
>
> Laurent Pinchart
>
2017-09-04 11:56 GMT+02:00 Laurent Pinchart <laurent.pinchart@ideasonboard.com>:
> Hi Pavel,
>
> Thank you for the patch.
>
> On Monday, 4 September 2017 11:14:17 EEST Pavel Rojtberg wrote:
>> From: Pavel Rojtberg <rojtberg@gmail.com>
>>
>> attaching two Logitech C615 webcams currently results in
>> VIDIOC_STREAMON: No space left on device
>> as the required bandwidth is not estimated correctly by the device.
>> In fact it always requests 3060 bytes - no matter the format or resolution.
>>
>> setting UVC_QUIRK_FIX_BANDWIDTH does not help either as it is only
>> implemented for uncompressed streams.
>>
>> This patch extends UVC_QUIRK_FIX_BANDWIDTH to MJPEG streams by making a
>> (conservative) assumption of 4bpp for MJPEG streams.
>> As the actual compression ration is often closer to 1bpp this can be
>> overridden via the new mjpeg_bpp parameter.
>>
>> Based on:
>> https://www.mail-archive.com/linux-uvc-devel@lists.berlios.de/msg05724.html
>> ---
>> drivers/media/usb/uvc/uvc_driver.c | 14 +++++++++++++-
>> drivers/media/usb/uvc/uvc_video.c | 3 ++-
>> 2 files changed, 15 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/media/usb/uvc/uvc_driver.c
>> b/drivers/media/usb/uvc/uvc_driver.c index 70842c5..f7b759e 100644
>> --- a/drivers/media/usb/uvc/uvc_driver.c
>> +++ b/drivers/media/usb/uvc/uvc_driver.c
>> @@ -37,6 +37,7 @@ unsigned int uvc_no_drop_param;
>> static unsigned int uvc_quirks_param = -1;
>> unsigned int uvc_trace_param;
>> unsigned int uvc_timeout_param = UVC_CTRL_STREAMING_TIMEOUT;
>> +static unsigned int uvc_mjpeg_bpp_param;
>>
>> /* ------------------------------------------------------------------------
>> * Video formats
>> @@ -463,7 +464,16 @@ static int uvc_parse_format(struct uvc_device *dev,
>> strlcpy(format->name, "MJPEG", sizeof format->name);
>> format->fcc = V4L2_PIX_FMT_MJPEG;
>> format->flags = UVC_FMT_FLAG_COMPRESSED;
>> - format->bpp = 0;
>> + if ((uvc_mjpeg_bpp_param >= 1) && (uvc_mjpeg_bpp_param <= 16)) {
>> + format->bpp = uvc_mjpeg_bpp_param;
>> + } else {
>> + /* conservative estimate. Actual values are around 1bpp.
>> + * see e.g.
>> + * https://developers.google.com/speed/webp/docs/webp_study
>> + */
>> + format->bpp = 4;
>> + }
>> +
>> ftype = UVC_VS_FRAME_MJPEG;
>> break;
>>
>> @@ -2274,6 +2284,8 @@ module_param_named(trace, uvc_trace_param, uint,
>> S_IRUGO|S_IWUSR); MODULE_PARM_DESC(trace, "Trace level bitmask");
>> module_param_named(timeout, uvc_timeout_param, uint, S_IRUGO|S_IWUSR);
>> MODULE_PARM_DESC(timeout, "Streaming control requests timeout");
>> +module_param_named(mjpeg_bpp, uvc_mjpeg_bpp_param, uint, S_IRUGO|S_IWUSR);
>> +MODULE_PARM_DESC(mjpeg_bpp, "MJPEG bits per pixel for bandwidth quirk");
>
> I'd rather avoid adding a new module parameter for this, it would be confusing
> for users. What is your use case to make the MJPEG average BPP configurable ?
> Can't we come up with a heuristic that would calculate it automatically ?
>
>> /* ------------------------------------------------------------------------
>> * Driver initialization and cleanup
>> diff --git a/drivers/media/usb/uvc/uvc_video.c
>> b/drivers/media/usb/uvc/uvc_video.c index fb86d6a..382a0be 100644
>> --- a/drivers/media/usb/uvc/uvc_video.c
>> +++ b/drivers/media/usb/uvc/uvc_video.c
>> @@ -127,7 +127,8 @@ static void uvc_fixup_video_ctrl(struct uvc_streaming
>> *stream, if ((ctrl->dwMaxPayloadTransferSize & 0xffff0000) == 0xffff0000)
>> ctrl->dwMaxPayloadTransferSize &= ~0xffff0000;
>>
>> - if (!(format->flags & UVC_FMT_FLAG_COMPRESSED) &&
>> + if ((!(format->flags & UVC_FMT_FLAG_COMPRESSED) ||
>> + (format->fcc == V4L2_PIX_FMT_MJPEG)) &&
>> stream->dev->quirks & UVC_QUIRK_FIX_BANDWIDTH &&
>> stream->intf->num_altsetting > 1) {
>> u32 interval;
>
>
> --
> Regards,
>
> Laurent Pinchart
>
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] uvcvideo: extend UVC_QUIRK_FIX_BANDWIDTH to MJPEG streams
2017-09-05 17:27 ` Pavel Rojtberg
@ 2018-08-06 22:02 ` Laurent Pinchart
0 siblings, 0 replies; 5+ messages in thread
From: Laurent Pinchart @ 2018-08-06 22:02 UTC (permalink / raw)
To: Pavel Rojtberg; +Cc: mchehab, linux-media
Hi Pavel,
On Tuesday, 5 September 2017 20:27:39 EEST Pavel Rojtberg wrote:
> 2017-09-04 11:56 GMT+02:00 Laurent Pinchart:
> > On Monday, 4 September 2017 11:14:17 EEST Pavel Rojtberg wrote:
> >> From: Pavel Rojtberg <rojtberg@gmail.com>
> >>
> >> attaching two Logitech C615 webcams currently results in
> >>
> >> VIDIOC_STREAMON: No space left on device
> >>
> >> as the required bandwidth is not estimated correctly by the device.
> >> In fact it always requests 3060 bytes - no matter the format or
> >> resolution.
> >>
> >> setting UVC_QUIRK_FIX_BANDWIDTH does not help either as it is only
> >> implemented for uncompressed streams.
> >>
> >> This patch extends UVC_QUIRK_FIX_BANDWIDTH to MJPEG streams by making a
> >> (conservative) assumption of 4bpp for MJPEG streams.
> >> As the actual compression ration is often closer to 1bpp this can be
> >> overridden via the new mjpeg_bpp parameter.
> >>
> >> Based on:
> >> https://www.mail-archive.com/linux-uvc-devel@lists.berlios.de/msg05724.ht
> >> ml
> >> ---
> >>
> >> drivers/media/usb/uvc/uvc_driver.c | 14 +++++++++++++-
> >> drivers/media/usb/uvc/uvc_video.c | 3 ++-
> >> 2 files changed, 15 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/media/usb/uvc/uvc_driver.c
> >> b/drivers/media/usb/uvc/uvc_driver.c index 70842c5..f7b759e 100644
> >> --- a/drivers/media/usb/uvc/uvc_driver.c
> >> +++ b/drivers/media/usb/uvc/uvc_driver.c
> >> @@ -37,6 +37,7 @@ unsigned int uvc_no_drop_param;
> >> static unsigned int uvc_quirks_param = -1;
> >> unsigned int uvc_trace_param;
> >> unsigned int uvc_timeout_param = UVC_CTRL_STREAMING_TIMEOUT;
> >> +static unsigned int uvc_mjpeg_bpp_param;
> >>
> >> /* ---------------------------------------------------------------------
> >> * Video formats
> >> @@ -463,7 +464,16 @@ static int uvc_parse_format(struct uvc_device *dev,
> >> strlcpy(format->name, "MJPEG", sizeof format->name);
> >> format->fcc = V4L2_PIX_FMT_MJPEG;
> >> format->flags = UVC_FMT_FLAG_COMPRESSED;
> >> - format->bpp = 0;
> >> + if ((uvc_mjpeg_bpp_param >= 1) && (uvc_mjpeg_bpp_param <=
> >> 16)) {
> >> + format->bpp = uvc_mjpeg_bpp_param;
> >> + } else {
> >> + /* conservative estimate. Actual values are around
> >> 1bpp.
> >> + * see e.g.
> >> + *
> >> https://developers.google.com/speed/webp/docs/webp_study
> >> + */
> >> + format->bpp = 4;
> >> + }
> >> +
> >>
> >> ftype = UVC_VS_FRAME_MJPEG;
> >> break;
> >>
> >> @@ -2274,6 +2284,8 @@ module_param_named(trace, uvc_trace_param, uint,
> >> S_IRUGO|S_IWUSR); MODULE_PARM_DESC(trace, "Trace level bitmask");
> >>
> >> module_param_named(timeout, uvc_timeout_param, uint, S_IRUGO|S_IWUSR);
> >> MODULE_PARM_DESC(timeout, "Streaming control requests timeout");
> >>
> >> +module_param_named(mjpeg_bpp, uvc_mjpeg_bpp_param, uint,
> >> S_IRUGO|S_IWUSR);
> >> +MODULE_PARM_DESC(mjpeg_bpp, "MJPEG bits per pixel for bandwidth quirk");
> >
> > I'd rather avoid adding a new module parameter for this, it would be
> > confusing for users. What is your use case to make the MJPEG average BPP
> > configurable ? Can't we come up with a heuristic that would calculate it
> > automatically ?
>
> this is the minimal expected JPEG compression ratio. It depends on the
> JPEG quality chosen by the hardware (which we do not know) as well as the
> actual image (which we can not control either).
> We could hardcode it to the average bpp which 1 - but this will break
> when somebody films a high-frequency checkerborad. We could leave it at 4,
> but this would again artificially limit the number of possible cameras when
> not filming a checkerboard.
> 4 would already be a noticable improvement over the current state though.
>
> If you can come up with a working heuristic - I am open for that too.
So it's basically an estimate of the MJPEG compression ratio, which depends on
multiple parameters, some of which we could possibly control (such as the
compression quality), and some of which we have no influence on (such as the
scene in front of the camera).
What really bothers me is that if even we can't estimate the value, exposing
it as a module parameter will only confuse most users. How about starting with
a fixed conservative estimate (such as 4bpp) and see where that leads us ?
I would also not try to fake a bpp value in uvc_parse_format() for MJPEG
formats, but instead adapt uvc_fixup_video_ctrl() with MJPEG-specific
calculation. This would allow expressing a compression ratio in the code
instead of an artificial bpp value, allowing more precision in the future if
needed.
> >> /* ---------------------------------------------------------------------
> >> * Driver initialization and cleanup
> >> diff --git a/drivers/media/usb/uvc/uvc_video.c
> >> b/drivers/media/usb/uvc/uvc_video.c index fb86d6a..382a0be 100644
> >> --- a/drivers/media/usb/uvc/uvc_video.c
> >> +++ b/drivers/media/usb/uvc/uvc_video.c
> >> @@ -127,7 +127,8 @@ static void uvc_fixup_video_ctrl(struct uvc_streaming
> >> *stream,
> >> if ((ctrl->dwMaxPayloadTransferSize & 0xffff0000) == 0xffff0000)
> >> ctrl->dwMaxPayloadTransferSize &= ~0xffff0000;
> >>
> >> - if (!(format->flags & UVC_FMT_FLAG_COMPRESSED) &&
> >> + if ((!(format->flags & UVC_FMT_FLAG_COMPRESSED) ||
> >> + (format->fcc == V4L2_PIX_FMT_MJPEG)) &&
> >> stream->dev->quirks & UVC_QUIRK_FIX_BANDWIDTH &&
> >> stream->intf->num_altsetting > 1) {
> >> u32 interval;
--
Regards,
Laurent Pinchart
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH] uvcvideo: extend UVC_QUIRK_FIX_BANDWIDTH to MJPEG streams
@ 2017-08-02 17:31 Pavel Rojtberg
0 siblings, 0 replies; 5+ messages in thread
From: Pavel Rojtberg @ 2017-08-02 17:31 UTC (permalink / raw)
To: laurent.pinchart, mchehab, linux-media; +Cc: Pavel Rojtberg
From: Pavel Rojtberg <rojtberg@gmail.com>
attaching two Logitech C615 webcams currently results in
VIDIOC_STREAMON: No space left on device
as the required bandwidth is not estimated correctly by the device.
In fact it always requests 3060 bytes - no matter the format or resolution.
setting UVC_QUIRK_FIX_BANDWIDTH does not help either as it is only implemented
for uncompressed streams.
This patch extends UVC_QUIRK_FIX_BANDWIDTH to MJPEG streams by making a
(conservative) assumption of 4bpp for MJPEG streams.
As the actual compression ration is often closer to 1bpp this can be overridden
via the new mjpeg_bpp parameter.
Based on:
https://www.mail-archive.com/linux-uvc-devel@lists.berlios.de/msg05724.html
---
drivers/media/usb/uvc/uvc_driver.c | 14 +++++++++++++-
drivers/media/usb/uvc/uvc_video.c | 3 ++-
2 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index 70842c5..f7b759e 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -37,6 +37,7 @@ unsigned int uvc_no_drop_param;
static unsigned int uvc_quirks_param = -1;
unsigned int uvc_trace_param;
unsigned int uvc_timeout_param = UVC_CTRL_STREAMING_TIMEOUT;
+static unsigned int uvc_mjpeg_bpp_param;
/* ------------------------------------------------------------------------
* Video formats
@@ -463,7 +464,16 @@ static int uvc_parse_format(struct uvc_device *dev,
strlcpy(format->name, "MJPEG", sizeof format->name);
format->fcc = V4L2_PIX_FMT_MJPEG;
format->flags = UVC_FMT_FLAG_COMPRESSED;
- format->bpp = 0;
+ if ((uvc_mjpeg_bpp_param >= 1) && (uvc_mjpeg_bpp_param <= 16)) {
+ format->bpp = uvc_mjpeg_bpp_param;
+ } else {
+ /* conservative estimate. Actual values are around 1bpp.
+ * see e.g.
+ * https://developers.google.com/speed/webp/docs/webp_study
+ */
+ format->bpp = 4;
+ }
+
ftype = UVC_VS_FRAME_MJPEG;
break;
@@ -2274,6 +2284,8 @@ module_param_named(trace, uvc_trace_param, uint, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(trace, "Trace level bitmask");
module_param_named(timeout, uvc_timeout_param, uint, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(timeout, "Streaming control requests timeout");
+module_param_named(mjpeg_bpp, uvc_mjpeg_bpp_param, uint, S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(mjpeg_bpp, "MJPEG bits per pixel for bandwidth quirk");
/* ------------------------------------------------------------------------
* Driver initialization and cleanup
diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index fb86d6a..382a0be 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -127,7 +127,8 @@ static void uvc_fixup_video_ctrl(struct uvc_streaming *stream,
if ((ctrl->dwMaxPayloadTransferSize & 0xffff0000) == 0xffff0000)
ctrl->dwMaxPayloadTransferSize &= ~0xffff0000;
- if (!(format->flags & UVC_FMT_FLAG_COMPRESSED) &&
+ if ((!(format->flags & UVC_FMT_FLAG_COMPRESSED) ||
+ (format->fcc == V4L2_PIX_FMT_MJPEG)) &&
stream->dev->quirks & UVC_QUIRK_FIX_BANDWIDTH &&
stream->intf->num_altsetting > 1) {
u32 interval;
--
2.7.4
^ permalink raw reply related [flat|nested] 5+ messages in thread
end of thread, other threads:[~2018-08-07 0:12 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2017-09-04 8:14 [PATCH] uvcvideo: extend UVC_QUIRK_FIX_BANDWIDTH to MJPEG streams Pavel Rojtberg
2017-09-04 9:56 ` Laurent Pinchart
2017-09-05 17:27 ` Pavel Rojtberg
2018-08-06 22:02 ` Laurent Pinchart
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2017-08-02 17:31 Pavel Rojtberg
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