From a9bf24d26fd28acaed839977e1d050c468d5a55e Mon Sep 17 00:00:00 2001 From: Mauro Carvalho Chehab Date: Wed, 16 Sep 2009 10:24:52 -0300 Subject: staging-specs: Move xml entities to kernel Documentation/DocBook From: Mauro Carvalho Chehab kernel-sync: Priority: normal Signed-off-by: Mauro Carvalho Chehab --- linux/Documentation/DocBook/v4l/dev-rds.xml | 168 ++++++++++++++++++++++++++++ 1 file changed, 168 insertions(+) create mode 100644 linux/Documentation/DocBook/v4l/dev-rds.xml (limited to 'linux/Documentation/DocBook/v4l/dev-rds.xml') diff --git a/linux/Documentation/DocBook/v4l/dev-rds.xml b/linux/Documentation/DocBook/v4l/dev-rds.xml new file mode 100644 index 000000000..0869d701b --- /dev/null +++ b/linux/Documentation/DocBook/v4l/dev-rds.xml @@ -0,0 +1,168 @@ + RDS Interface + + The Radio Data System transmits supplementary +information in binary format, for example the station name or travel +information, on an inaudible audio subcarrier of a radio program. This +interface is aimed at devices capable of receiving and decoding RDS +information. + + For more information see the core RDS standard +and the RBDS standard . + + Note that the RBDS standard as is used in the USA is almost identical +to the RDS standard. Any RDS decoder can also handle RBDS. Only some of the fields +have slightly different meanings. See the RBDS standard for more information. + + The RBDS standard also specifies support for MMBS (Modified Mobile Search). +This is a proprietary format which seems to be discontinued. The RDS interface does not +support this format. Should support for MMBS (or the so-called 'E blocks' in general) +be needed, then please contact the linux-media mailing list: &v4l-ml;. + +
+ Querying Capabilities + + Devices supporting the RDS capturing API +set the V4L2_CAP_RDS_CAPTURE flag in +the capabilities field of &v4l2-capability; +returned by the &VIDIOC-QUERYCAP; ioctl. +Any tuner that supports RDS will set the +V4L2_TUNER_CAP_RDS flag in the capability +field of &v4l2-tuner;. +Whether an RDS signal is present can be detected by looking at +the rxsubchans field of &v4l2-tuner;: the +V4L2_TUNER_SUB_RDS will be set if RDS data was detected. + + Devices supporting the RDS output API +set the V4L2_CAP_RDS_OUTPUT flag in +the capabilities field of &v4l2-capability; +returned by the &VIDIOC-QUERYCAP; ioctl. +Any modulator that supports RDS will set the +V4L2_TUNER_CAP_RDS flag in the capability +field of &v4l2-modulator;. +In order to enable the RDS transmission one must set the V4L2_TUNER_SUB_RDS +bit in the txsubchans field of &v4l2-modulator;. + +
+ +
+ Reading RDS data + + RDS data can be read from the radio device +with the &func-read; function. The data is packed in groups of three bytes, +as follows: + + struct +<structname>v4l2_rds_data</structname> + + + + + + + __u8 + lsb + Least Significant Byte of RDS Block + + + __u8 + msb + Most Significant Byte of RDS Block + + + __u8 + block + Block description + + + +
+ + Block description + + + + + + Bits 0-2 + Block (aka offset) of the received data. + + + Bits 3-5 + Deprecated. Currently identical to bits 0-2. Do not use these bits. + + + Bit 6 + Corrected bit. Indicates that an error was corrected for this data block. + + + Bit 7 + Error bit. Indicates that an uncorrectable error occurred during reception of this block. + + + +
+ + + Block defines + + + + + + + V4L2_RDS_BLOCK_MSK + 7 + Mask for bits 0-2 to get the block ID. + + + V4L2_RDS_BLOCK_A + 0 + Block A. + + + V4L2_RDS_BLOCK_B + 1 + Block B. + + + V4L2_RDS_BLOCK_C + 2 + Block C. + + + V4L2_RDS_BLOCK_D + 3 + Block D. + + + V4L2_RDS_BLOCK_C_ALT + 4 + Block C'. + + + V4L2_RDS_BLOCK_INVALID + 7 + An invalid block. + + + V4L2_RDS_BLOCK_CORRECTED + 0x40 + A bit error was detected but corrected. + + + V4L2_RDS_BLOCK_ERROR + 0x80 + An incorrectable error occurred. + + + +
+
+ + -- cgit v1.2.3