Re: [PATCH RFC 4/4] v4l: 1 Hz resolution flag for tuners
On 12/12/2013 06:22 PM, Antti Palosaari wrote:
Hi Hans!
On 12.12.2013 09:55, Hans Verkuil wrote:
On 12/12/2013 12:54 AM, Antti Palosaari wrote:
Add V4L2_TUNER_CAP_1HZ for 1 Hz resolution.
Signed-off-by: Antti Palosaari cr...@iki.fi
---
include/uapi/linux/videodev2.h | 1 +
1 file changed, 1 insertion(+)
diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index 6c6a601..1bac6c4 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -1349,6 +1349,7 @@ struct v4l2_modulator {
#define V4L2_TUNER_CAP_RDS_CONTROLS 0x0200
#define V4L2_TUNER_CAP_FREQ_BANDS 0x0400
#define V4L2_TUNER_CAP_HWSEEK_PROG_LIM0x0800
+#define V4L2_TUNER_CAP_1HZ 0x1000
/* Flags for the 'rxsubchans' field */
#define V4L2_TUNER_SUB_MONO 0x0001
I was wondering, do the band modulation systems (V4L2_BAND_MODULATION_VSB
etc.) cover SDR?
There is no such modulations defined for SDR hardware level. SDR
demodulation is done by software called DSP (digital signal processing)
in host computer.
In ideal case, SDR receiver has only 1 property: ADC (analog to digital
converter) sampling rate.
So in that case the band modulation would be 0, right?
But as digital signal processing is very CPU intensive when sampling
rates are increased, there is very often RF tuner used to down-convert
actual radio frequency to low-IF / BB. Then ADC is used to sample that
baseband / low-IF signal and only small sampling rate is needed =
stream is smaller = DSP does not need so much CPU.
How does the application know that there is an RF tuner? I assume that
the app needs to know this?
As you can probably tell, I basically know nothing about SDR, so forgive
me if I am asking stupid questions. I just want to make sure all bases
are covered when it comes to the V4L2 API.
Regards,
Hans
Anyway, I'm happy with this patch series. As far as I am concerned, the next
step would
be to add documention and I would also recommend updating v4l2-compliance.
Writing docs
and adding compliance tests has proven useful in the past to discover
ambiguous API specs.
I will do these at finally when I drivers and applications are tested to
be working.
regards
Antti
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Re: [PATCH RFC 4/4] v4l: 1 Hz resolution flag for tuners
On 13.12.2013 16:05, Hans Verkuil wrote:
On 12/12/2013 06:22 PM, Antti Palosaari wrote:
Hi Hans!
On 12.12.2013 09:55, Hans Verkuil wrote:
On 12/12/2013 12:54 AM, Antti Palosaari wrote:
Add V4L2_TUNER_CAP_1HZ for 1 Hz resolution.
Signed-off-by: Antti Palosaari cr...@iki.fi
---
include/uapi/linux/videodev2.h | 1 +
1 file changed, 1 insertion(+)
diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index 6c6a601..1bac6c4 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -1349,6 +1349,7 @@ struct v4l2_modulator {
#define V4L2_TUNER_CAP_RDS_CONTROLS 0x0200
#define V4L2_TUNER_CAP_FREQ_BANDS0x0400
#define V4L2_TUNER_CAP_HWSEEK_PROG_LIM 0x0800
+#define V4L2_TUNER_CAP_1HZ 0x1000
/* Flags for the 'rxsubchans' field */
#define V4L2_TUNER_SUB_MONO 0x0001
I was wondering, do the band modulation systems (V4L2_BAND_MODULATION_VSB etc.)
cover SDR?
There is no such modulations defined for SDR hardware level. SDR
demodulation is done by software called DSP (digital signal processing)
in host computer.
In ideal case, SDR receiver has only 1 property: ADC (analog to digital
converter) sampling rate.
So in that case the band modulation would be 0, right?
Yes. If you split that radio receiver to some logic blocs, from antenna
to host computer:
1. Antenna is here
2. RF tuner (RF frontend): tuner band belongs here
3. ADC: sampling rate
4. demodulator (modulation lives here)
In a case of traditional hw based demodulator PC/host computer is
located as a number 5. In a case of a software defined radio receiver
host computer is next to ADC, between 3-4. Demodulator itself is DSP
software running on host computer.
But as digital signal processing is very CPU intensive when sampling
rates are increased, there is very often RF tuner used to down-convert
actual radio frequency to low-IF / BB. Then ADC is used to sample that
baseband / low-IF signal and only small sampling rate is needed =
stream is smaller = DSP does not need so much CPU.
How does the application know that there is an RF tuner? I assume that
the app needs to know this?
Yes, that indeed needs to be know. It is one key issue to resolve.
Something like a capability flag works or application could test it
when. Like if tuner type is ADC then enumerate if there is tuner type
SDR also. Or expect there is always RF tuner and frequency is
programmed as a 0 Hz when it is not really there. Enumeration of RF
tuner returns only supported frequency as a 0Hz to tell there is only ADC.
As you can probably tell, I basically know nothing about SDR, so forgive
me if I am asking stupid questions. I just want to make sure all bases
are covered when it comes to the V4L2 API.
I really appreciate that as simply has no enough knowledge from V4L2 API
and API changes are needed. I will try to list here shortly some SDR
devices in general level enough.
ant = antenna
host = host computer, PC (SW modulator/demodulator)
ADC = analog to digital converter
DAC = digital to analog converter
amp = amplifier
mixer = TX tuner
receiver:
ant RF tuner ADC bridge host
ant ADC bridge host
ant up-converter RF tuner ADC bridge host
transmitter:
ant amp mixer DAC bridge host
ant mixer DAC bridge host
ant DAC bridge host
Those are the used building blocks in some general view. ADC (DAC) is
most important hardware block, but RF tuner is also critical in practice.
So what I understood, V4L2 API tuner is kinda logical entity that
represent single radio device, containing RF tuner, demodulator and so.
That same logical entity in DVB API side is frontend, which is mostly
implemented by demodulator with a help of RF tuner.
So what is needed is to make V4L2 API entity (tuner I guess) that could
represent both ADC and RF tuner.
regards
Antti
--
http://palosaari.fi/
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Re: [PATCH RFC 4/4] v4l: 1 Hz resolution flag for tuners
On 12/13/2013 04:42 PM, Antti Palosaari wrote:
On 13.12.2013 16:05, Hans Verkuil wrote:
On 12/12/2013 06:22 PM, Antti Palosaari wrote:
Hi Hans!
On 12.12.2013 09:55, Hans Verkuil wrote:
On 12/12/2013 12:54 AM, Antti Palosaari wrote:
Add V4L2_TUNER_CAP_1HZ for 1 Hz resolution.
Signed-off-by: Antti Palosaari cr...@iki.fi
---
include/uapi/linux/videodev2.h | 1 +
1 file changed, 1 insertion(+)
diff --git a/include/uapi/linux/videodev2.h
b/include/uapi/linux/videodev2.h
index 6c6a601..1bac6c4 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -1349,6 +1349,7 @@ struct v4l2_modulator {
#define V4L2_TUNER_CAP_RDS_CONTROLS0x0200
#define V4L2_TUNER_CAP_FREQ_BANDS 0x0400
#define V4L2_TUNER_CAP_HWSEEK_PROG_LIM 0x0800
+#define V4L2_TUNER_CAP_1HZ 0x1000
/* Flags for the 'rxsubchans' field */
#define V4L2_TUNER_SUB_MONO0x0001
I was wondering, do the band modulation systems (V4L2_BAND_MODULATION_VSB
etc.) cover SDR?
There is no such modulations defined for SDR hardware level. SDR
demodulation is done by software called DSP (digital signal processing)
in host computer.
In ideal case, SDR receiver has only 1 property: ADC (analog to digital
converter) sampling rate.
So in that case the band modulation would be 0, right?
Yes. If you split that radio receiver to some logic blocs, from antenna
to host computer:
1. Antenna is here
2. RF tuner (RF frontend): tuner band belongs here
3. ADC: sampling rate
4. demodulator (modulation lives here)
In a case of traditional hw based demodulator PC/host computer is
located as a number 5. In a case of a software defined radio receiver
host computer is next to ADC, between 3-4. Demodulator itself is DSP
software running on host computer.
But as digital signal processing is very CPU intensive when sampling
rates are increased, there is very often RF tuner used to down-convert
actual radio frequency to low-IF / BB. Then ADC is used to sample that
baseband / low-IF signal and only small sampling rate is needed =
stream is smaller = DSP does not need so much CPU.
How does the application know that there is an RF tuner? I assume that
the app needs to know this?
Yes, that indeed needs to be know. It is one key issue to resolve.
Something like a capability flag works or application could test it
when. Like if tuner type is ADC then enumerate if there is tuner type
SDR also.
Instead of calling it TUNER_TYPE_SDR, shouldn't it be called TUNER_TYPE_RF?
Or perhaps _SDR_RF?
Or expect there is always RF tuner and frequency is
programmed as a 0 Hz when it is not really there. Enumeration of RF
tuner returns only supported frequency as a 0Hz to tell there is only ADC.
I think just enumerating tuners to see if there is a RF tuner would be
sufficient.
As you can probably tell, I basically know nothing about SDR, so forgive
me if I am asking stupid questions. I just want to make sure all bases
are covered when it comes to the V4L2 API.
I really appreciate that as simply has no enough knowledge from V4L2 API
and API changes are needed. I will try to list here shortly some SDR
devices in general level enough.
ant = antenna
host = host computer, PC (SW modulator/demodulator)
ADC = analog to digital converter
DAC = digital to analog converter
amp = amplifier
mixer = TX tuner
receiver:
ant RF tuner ADC bridge host
ant ADC bridge host
ant up-converter RF tuner ADC bridge host
transmitter:
ant amp mixer DAC bridge host
ant mixer DAC bridge host
ant DAC bridge host
Those are the used building blocks in some general view. ADC (DAC) is
most important hardware block, but RF tuner is also critical in practice.
So what I understood, V4L2 API tuner is kinda logical entity that
represent single radio device, containing RF tuner, demodulator and so.
That same logical entity in DVB API side is frontend, which is mostly
implemented by demodulator with a help of RF tuner.
So what is needed is to make V4L2 API entity (tuner I guess) that could
represent both ADC and RF tuner.
Well, a V4L2 tuner represents the hardware that requires a frequency.
Which for typical radio and TV devices means the RF tuner + demodulator
combo. So externally you see only one tuner, but internally there are
often two devices (tuner and modulator) that have to be controlled.
For SDR you have an RF Tuner with a frequency and an ADC with a frequency,
and the two frequencies can be set independently. So representing that
as two tuners seems like a sensible mapping to me.
Regards,
Hans
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Re: [PATCH RFC 4/4] v4l: 1 Hz resolution flag for tuners
On 13.12.2013 18:08, Hans Verkuil wrote: On 12/13/2013 04:42 PM, Antti Palosaari wrote: On 13.12.2013 16:05, Hans Verkuil wrote: On 12/12/2013 06:22 PM, Antti Palosaari wrote: I really appreciate that as simply has no enough knowledge from V4L2 API and API changes are needed. I will try to list here shortly some SDR devices in general level enough. ant = antenna host = host computer, PC (SW modulator/demodulator) ADC = analog to digital converter DAC = digital to analog converter amp = amplifier mixer = TX tuner receiver: ant RF tuner ADC bridge host ant ADC bridge host ant up-converter RF tuner ADC bridge host transmitter: ant amp mixer DAC bridge host ant mixer DAC bridge host ant DAC bridge host Those are the used building blocks in some general view. ADC (DAC) is most important hardware block, but RF tuner is also critical in practice. So what I understood, V4L2 API tuner is kinda logical entity that represent single radio device, containing RF tuner, demodulator and so. That same logical entity in DVB API side is frontend, which is mostly implemented by demodulator with a help of RF tuner. So what is needed is to make V4L2 API entity (tuner I guess) that could represent both ADC and RF tuner. Well, a V4L2 tuner represents the hardware that requires a frequency. Which for typical radio and TV devices means the RF tuner + demodulator combo. So externally you see only one tuner, but internally there are often two devices (tuner and modulator) that have to be controlled. For SDR you have an RF Tuner with a frequency and an ADC with a frequency, and the two frequencies can be set independently. So representing that as two tuners seems like a sensible mapping to me. Correct. Both RF tuner and ADC are independent each others and both must be possible to adjust runtime. Shortly, all-in-all, I will implement those as a tuner#0 is ADC and tuner#1 is RF tuner. Patches with corrections follow soon. regards Antti -- http://palosaari.fi/ -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH RFC 4/4] v4l: 1 Hz resolution flag for tuners
Hi Hans!
On 12.12.2013 09:55, Hans Verkuil wrote:
On 12/12/2013 12:54 AM, Antti Palosaari wrote:
Add V4L2_TUNER_CAP_1HZ for 1 Hz resolution.
Signed-off-by: Antti Palosaari cr...@iki.fi
---
include/uapi/linux/videodev2.h | 1 +
1 file changed, 1 insertion(+)
diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index 6c6a601..1bac6c4 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -1349,6 +1349,7 @@ struct v4l2_modulator {
#define V4L2_TUNER_CAP_RDS_CONTROLS 0x0200
#define V4L2_TUNER_CAP_FREQ_BANDS 0x0400
#define V4L2_TUNER_CAP_HWSEEK_PROG_LIM0x0800
+#define V4L2_TUNER_CAP_1HZ 0x1000
/* Flags for the 'rxsubchans' field */
#define V4L2_TUNER_SUB_MONO 0x0001
I was wondering, do the band modulation systems (V4L2_BAND_MODULATION_VSB etc.)
cover SDR?
There is no such modulations defined for SDR hardware level. SDR
demodulation is done by software called DSP (digital signal processing)
in host computer.
In ideal case, SDR receiver has only 1 property: ADC (analog to digital
converter) sampling rate.
But as digital signal processing is very CPU intensive when sampling
rates are increased, there is very often RF tuner used to down-convert
actual radio frequency to low-IF / BB. Then ADC is used to sample that
baseband / low-IF signal and only small sampling rate is needed =
stream is smaller = DSP does not need so much CPU.
Anyway, I'm happy with this patch series. As far as I am concerned, the next
step would
be to add documention and I would also recommend updating v4l2-compliance.
Writing docs
and adding compliance tests has proven useful in the past to discover ambiguous
API specs.
I will do these at finally when I drivers and applications are tested to
be working.
regards
Antti
--
http://palosaari.fi/
--
To unsubscribe from this list: send the line unsubscribe linux-media in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
[PATCH RFC 4/4] v4l: 1 Hz resolution flag for tuners
Add V4L2_TUNER_CAP_1HZ for 1 Hz resolution.
Signed-off-by: Antti Palosaari cr...@iki.fi
---
include/uapi/linux/videodev2.h | 1 +
1 file changed, 1 insertion(+)
diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index 6c6a601..1bac6c4 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -1349,6 +1349,7 @@ struct v4l2_modulator {
#define V4L2_TUNER_CAP_RDS_CONTROLS0x0200
#define V4L2_TUNER_CAP_FREQ_BANDS 0x0400
#define V4L2_TUNER_CAP_HWSEEK_PROG_LIM 0x0800
+#define V4L2_TUNER_CAP_1HZ 0x1000
/* Flags for the 'rxsubchans' field */
#define V4L2_TUNER_SUB_MONO0x0001
--
1.8.4.2
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Re: [PATCH RFC 4/4] v4l: 1 Hz resolution flag for tuners
On 12/12/2013 12:54 AM, Antti Palosaari wrote:
Add V4L2_TUNER_CAP_1HZ for 1 Hz resolution.
Signed-off-by: Antti Palosaari cr...@iki.fi
---
include/uapi/linux/videodev2.h | 1 +
1 file changed, 1 insertion(+)
diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index 6c6a601..1bac6c4 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -1349,6 +1349,7 @@ struct v4l2_modulator {
#define V4L2_TUNER_CAP_RDS_CONTROLS 0x0200
#define V4L2_TUNER_CAP_FREQ_BANDS0x0400
#define V4L2_TUNER_CAP_HWSEEK_PROG_LIM 0x0800
+#define V4L2_TUNER_CAP_1HZ 0x1000
/* Flags for the 'rxsubchans' field */
#define V4L2_TUNER_SUB_MONO 0x0001
I was wondering, do the band modulation systems (V4L2_BAND_MODULATION_VSB etc.)
cover SDR?
Anyway, I'm happy with this patch series. As far as I am concerned, the next
step would
be to add documention and I would also recommend updating v4l2-compliance.
Writing docs
and adding compliance tests has proven useful in the past to discover ambiguous
API specs.
Regards,
Hans
--
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the body of a message to majord...@vger.kernel.org
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