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| >Video for Linux Two API Specification: Revision 0.24</TH |
| ></TR |
| ><TR |
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| ><H1 |
| ><A |
| NAME="VIDIOC-G-MODULATOR" |
| ></A |
| >ioctl VIDIOC_G_MODULATOR, VIDIOC_S_MODULATOR</H1 |
| ><DIV |
| CLASS="REFNAMEDIV" |
| ><A |
| NAME="AEN11434" |
| ></A |
| ><H2 |
| >Name</H2 |
| >VIDIOC_G_MODULATOR, VIDIOC_S_MODULATOR -- Get or set modulator attributes</DIV |
| ><DIV |
| CLASS="REFSYNOPSISDIV" |
| ><A |
| NAME="AEN11438" |
| ></A |
| ><H2 |
| >Synopsis</H2 |
| ><DIV |
| CLASS="FUNCSYNOPSIS" |
| ><P |
| ></P |
| ><A |
| NAME="AEN11439" |
| ></A |
| ><P |
| ><CODE |
| ><CODE |
| CLASS="FUNCDEF" |
| >int ioctl</CODE |
| >(int fd, int request, struct v4l2_modulator |
| *argp);</CODE |
| ></P |
| ><P |
| ></P |
| ></DIV |
| ><DIV |
| CLASS="FUNCSYNOPSIS" |
| ><P |
| ></P |
| ><A |
| NAME="AEN11449" |
| ></A |
| ><P |
| ><CODE |
| ><CODE |
| CLASS="FUNCDEF" |
| >int ioctl</CODE |
| >(int fd, int request, const struct v4l2_modulator |
| *argp);</CODE |
| ></P |
| ><P |
| ></P |
| ></DIV |
| ></DIV |
| ><DIV |
| CLASS="REFSECT1" |
| ><A |
| NAME="AEN11459" |
| ></A |
| ><H2 |
| >Arguments</H2 |
| ><P |
| ></P |
| ><DIV |
| CLASS="VARIABLELIST" |
| ><DL |
| ><DT |
| ><CODE |
| CLASS="PARAMETER" |
| >fd</CODE |
| ></DT |
| ><DD |
| ><P |
| >File descriptor returned by <A |
| HREF="r14090.htm" |
| ><CODE |
| CLASS="FUNCTION" |
| >open()</CODE |
| ></A |
| >.</P |
| ></DD |
| ><DT |
| ><CODE |
| CLASS="PARAMETER" |
| >request</CODE |
| ></DT |
| ><DD |
| ><P |
| >VIDIOC_G_MODULATOR, VIDIOC_S_MODULATOR</P |
| ></DD |
| ><DT |
| ><CODE |
| CLASS="PARAMETER" |
| >argp</CODE |
| ></DT |
| ><DD |
| ><P |
| ></P |
| ></DD |
| ></DL |
| ></DIV |
| ></DIV |
| ><DIV |
| CLASS="REFSECT1" |
| ><A |
| NAME="AEN11479" |
| ></A |
| ><H2 |
| >Description</H2 |
| ><P |
| >To query the attributes of a modulator applications initialize |
| the <CODE |
| CLASS="STRUCTFIELD" |
| >index</CODE |
| > field and zero out the |
| <CODE |
| CLASS="STRUCTFIELD" |
| >reserved</CODE |
| > array of a struct <A |
| HREF="r11430.htm#V4L2-MODULATOR" |
| >v4l2_modulator</A |
| > and |
| call the <CODE |
| CLASS="CONSTANT" |
| >VIDIOC_G_MODULATOR</CODE |
| > ioctl with a pointer |
| to this structure. Drivers fill the rest of the structure or return an |
| <SPAN |
| CLASS="ERRORCODE" |
| >EINVAL</SPAN |
| > error code when the index is out of bounds. To enumerate all modulators |
| applications shall begin at index zero, incrementing by one until the |
| driver returns <SPAN |
| CLASS="ERRORCODE" |
| >EINVAL</SPAN |
| >.</P |
| ><P |
| >Modulators have two writable properties, an audio |
| modulation set and the radio frequency. To change the modulated audio |
| subprograms, applications initialize the <CODE |
| CLASS="STRUCTFIELD" |
| >index</CODE |
| > and <CODE |
| CLASS="STRUCTFIELD" |
| >txsubchans</CODE |
| > fields and the |
| <CODE |
| CLASS="STRUCTFIELD" |
| >reserved</CODE |
| > array and call the |
| <CODE |
| CLASS="CONSTANT" |
| >VIDIOC_S_MODULATOR</CODE |
| > ioctl. Drivers may choose a |
| different audio modulation if the request cannot be satisfied. However |
| this is a write-only ioctl, it does not return the actual audio |
| modulation selected.</P |
| ><P |
| >To change the radio frequency the <A |
| HREF="r11094.htm" |
| ><CODE |
| CLASS="CONSTANT" |
| >VIDIOC_S_FREQUENCY</CODE |
| ></A |
| > ioctl |
| is available.</P |
| ><DIV |
| CLASS="TABLE" |
| ><A |
| NAME="V4L2-MODULATOR" |
| ></A |
| ><P |
| ><B |
| >Table 1. struct <CODE |
| CLASS="STRUCTNAME" |
| >v4l2_modulator</CODE |
| ></B |
| ></P |
| ><TABLE |
| BORDER="0" |
| FRAME="void" |
| WIDTH="100%" |
| CLASS="CALSTABLE" |
| ><COL |
| WIDTH="25%" |
| TITLE="C1"><COL |
| WIDTH="25%" |
| TITLE="C2"><COL |
| WIDTH="50%" |
| TITLE="C3"><TBODY |
| VALIGN="TOP" |
| ><TR |
| ><TD |
| >__u32</TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >index</CODE |
| ></TD |
| ><TD |
| >Identifies the modulator, set by the |
| application.</TD |
| ></TR |
| ><TR |
| ><TD |
| >__u8</TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >name</CODE |
| >[32]</TD |
| ><TD |
| >Name of the modulator, a NUL-terminated ASCII |
| string. This information is intended for the user.</TD |
| ></TR |
| ><TR |
| ><TD |
| >__u32</TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >capability</CODE |
| ></TD |
| ><TD |
| >Modulator capability flags. No flags are defined |
| for this field, the tuner flags in struct <A |
| HREF="r12342.htm#V4L2-TUNER" |
| >v4l2_tuner</A |
| > |
| are used accordingly. The audio flags indicate the ability |
| to encode audio subprograms. They will <SPAN |
| CLASS="emphasis" |
| ><I |
| CLASS="EMPHASIS" |
| >not</I |
| ></SPAN |
| > |
| change for example with the current video standard.</TD |
| ></TR |
| ><TR |
| ><TD |
| >__u32</TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >rangelow</CODE |
| ></TD |
| ><TD |
| >The lowest tunable frequency in units of 62.5 |
| KHz, or if the <CODE |
| CLASS="STRUCTFIELD" |
| >capability</CODE |
| > flag |
| <CODE |
| CLASS="CONSTANT" |
| >V4L2_TUNER_CAP_LOW</CODE |
| > is set, in units of 62.5 |
| Hz.</TD |
| ></TR |
| ><TR |
| ><TD |
| >__u32</TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >rangehigh</CODE |
| ></TD |
| ><TD |
| >The highest tunable frequency in units of 62.5 |
| KHz, or if the <CODE |
| CLASS="STRUCTFIELD" |
| >capability</CODE |
| > flag |
| <CODE |
| CLASS="CONSTANT" |
| >V4L2_TUNER_CAP_LOW</CODE |
| > is set, in units of 62.5 |
| Hz.</TD |
| ></TR |
| ><TR |
| ><TD |
| >__u32</TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >txsubchans</CODE |
| ></TD |
| ><TD |
| >With this field applications can determine how |
| audio sub-carriers shall be modulated. It contains a set of flags as |
| defined in <A |
| HREF="r11430.htm#MODULATOR-TXSUBCHANS" |
| >Table 2</A |
| >. Note the tuner |
| <CODE |
| CLASS="STRUCTFIELD" |
| >rxsubchans</CODE |
| > flags are reused, but the |
| semantics are different. Video output devices are assumed to have an |
| analog or PCM audio input with 1-3 channels. The |
| <CODE |
| CLASS="STRUCTFIELD" |
| >txsubchans</CODE |
| > flags select one or more |
| channels for modulation, together with some audio subprogram |
| indicator, for example a stereo pilot tone.</TD |
| ></TR |
| ><TR |
| ><TD |
| >__u32</TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >reserved</CODE |
| >[4]</TD |
| ><TD |
| >Reserved for future extensions. Drivers and |
| applications must set the array to zero.</TD |
| ></TR |
| ></TBODY |
| ></TABLE |
| ></DIV |
| ><DIV |
| CLASS="TABLE" |
| ><A |
| NAME="MODULATOR-TXSUBCHANS" |
| ></A |
| ><P |
| ><B |
| >Table 2. Modulator Audio Transmission Flags</B |
| ></P |
| ><TABLE |
| BORDER="0" |
| FRAME="void" |
| WIDTH="100%" |
| CLASS="CALSTABLE" |
| ><COL |
| WIDTH="38%" |
| TITLE="C1"><COL |
| WIDTH="12%" |
| TITLE="C2"><COL |
| WIDTH="50%" |
| TITLE="C3"><TBODY |
| VALIGN="TOP" |
| ><TR |
| ><TD |
| ><CODE |
| CLASS="CONSTANT" |
| >V4L2_TUNER_SUB_MONO</CODE |
| ></TD |
| ><TD |
| >0x0001</TD |
| ><TD |
| >Modulate channel 1 as mono audio, when the input |
| has more channels, a down-mix of channel 1 and 2. This flag does not |
| combine with <CODE |
| CLASS="CONSTANT" |
| >V4L2_TUNER_SUB_STEREO</CODE |
| > or |
| <CODE |
| CLASS="CONSTANT" |
| >V4L2_TUNER_SUB_LANG1</CODE |
| >.</TD |
| ></TR |
| ><TR |
| ><TD |
| ><CODE |
| CLASS="CONSTANT" |
| >V4L2_TUNER_SUB_STEREO</CODE |
| ></TD |
| ><TD |
| >0x0002</TD |
| ><TD |
| >Modulate channel 1 and 2 as left and right |
| channel of a stereo audio signal. When the input has only one channel |
| or two channels and <CODE |
| CLASS="CONSTANT" |
| >V4L2_TUNER_SUB_SAP</CODE |
| > is also |
| set, channel 1 is encoded as left and right channel. This flag does |
| not combine with <CODE |
| CLASS="CONSTANT" |
| >V4L2_TUNER_SUB_MONO </CODE |
| > or |
| <CODE |
| CLASS="CONSTANT" |
| >V4L2_TUNER_SUB_LANG1</CODE |
| >. When the driver does not |
| support stereo audio it shall fall back to mono.</TD |
| ></TR |
| ><TR |
| ><TD |
| ><CODE |
| CLASS="CONSTANT" |
| >V4L2_TUNER_SUB_LANG1</CODE |
| ></TD |
| ><TD |
| >0x0008</TD |
| ><TD |
| >Modulate channel 1 and 2 as primary and secondary |
| language of a bilingual audio signal. When the input has only one |
| channel it is used for both languages. It is not possible to encode |
| the primary or secondary language only. This flag does not combine |
| with <CODE |
| CLASS="CONSTANT" |
| >V4L2_TUNER_SUB_MONO </CODE |
| > or |
| <CODE |
| CLASS="CONSTANT" |
| >V4L2_TUNER_SUB_STEREO</CODE |
| >. If the hardware does not |
| support the respective audio matrix, or the current video standard |
| does not permit bilingual audio the |
| <CODE |
| CLASS="CONSTANT" |
| >VIDIOC_S_MODULATOR</CODE |
| > ioctl shall return an <SPAN |
| CLASS="ERRORCODE" |
| >EINVAL</SPAN |
| > error code |
| and the driver shall fall back to mono or stereo mode.</TD |
| ></TR |
| ><TR |
| ><TD |
| ><CODE |
| CLASS="CONSTANT" |
| >V4L2_TUNER_SUB_LANG2</CODE |
| ></TD |
| ><TD |
| >0x0004</TD |
| ><TD |
| >Same effect as |
| <CODE |
| CLASS="CONSTANT" |
| >V4L2_TUNER_SUB_LANG1</CODE |
| >.</TD |
| ></TR |
| ><TR |
| ><TD |
| ><CODE |
| CLASS="CONSTANT" |
| >V4L2_TUNER_SUB_SAP</CODE |
| ></TD |
| ><TD |
| >0x0004</TD |
| ><TD |
| >When combined with <CODE |
| CLASS="CONSTANT" |
| >V4L2_TUNER_SUB_MONO</CODE |
| > the first channel is encoded as mono audio, the last |
| channel as Second Audio Program. When the input has only one channel |
| it is used for both audio tracks. When the input has three channels |
| the mono track is a down-mix of channel 1 and 2. When combined with |
| <CODE |
| CLASS="CONSTANT" |
| >V4L2_TUNER_SUB_STEREO </CODE |
| > channel 1 and 2 are |
| encoded as left and right stereo audio, channel 3 as Second Audio |
| Program. When the input has only two channels, the first is encoded as |
| left and right channel and the second as SAP. When the input has only |
| one channel it is used for all audio tracks. It is not possible to |
| encode a Second Audio Program only. This flag must combine with |
| <CODE |
| CLASS="CONSTANT" |
| >V4L2_TUNER_SUB_MONO</CODE |
| > or |
| <CODE |
| CLASS="CONSTANT" |
| >V4L2_TUNER_SUB_STEREO</CODE |
| >. If the hardware does not |
| support the respective audio matrix, or the current video standard |
| does not permit SAP the <CODE |
| CLASS="CONSTANT" |
| > VIDIOC_S_MODULATOR</CODE |
| > ioctl |
| shall return an <SPAN |
| CLASS="ERRORCODE" |
| >EINVAL</SPAN |
| > error code and driver shall fall back to mono or stereo |
| mode.</TD |
| ></TR |
| ></TBODY |
| ></TABLE |
| ></DIV |
| ></DIV |
| ><DIV |
| CLASS="REFSECT1" |
| ><A |
| NAME="AEN11598" |
| ></A |
| ><H2 |
| >Return Value</H2 |
| ><P |
| >On success <SPAN |
| CLASS="RETURNVALUE" |
| >0</SPAN |
| > is returned, on error <SPAN |
| CLASS="RETURNVALUE" |
| >-1</SPAN |
| > and the <CODE |
| CLASS="VARNAME" |
| >errno</CODE |
| > variable is set appropriately:</P |
| ><P |
| ></P |
| ><DIV |
| CLASS="VARIABLELIST" |
| ><DL |
| ><DT |
| ><SPAN |
| CLASS="ERRORCODE" |
| >EINVAL</SPAN |
| ></DT |
| ><DD |
| ><P |
| >The struct <A |
| HREF="r11430.htm#V4L2-MODULATOR" |
| >v4l2_modulator</A |
| > |
| <CODE |
| CLASS="STRUCTFIELD" |
| >index</CODE |
| > is out of bounds.</P |
| ></DD |
| ></DL |
| ></DIV |
| ></DIV |
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