In working on Sliced VBI for the cx18 driver, I've pared down and
commented the "struct vbi_info" definition. Did I understand
everything that's going on based on the revised definition below?
(BTW the mini MPEG-2 PS parser function borrowed from ivtv to look for
splice points was very elegant given the task it had to perform -
impressive.)
Regards,
Andy
#define CX18_VBI_FRAMES 32
struct vbi_info {
/* Current state of v4l2 VBI settings for this device */
struct v4l2_format in;
struct v4l2_sliced_vbi_format *sliced_in; /* pointer to in.fmt.sliced */
u32 count; /* Count of VBI data lines: 60 Hz: 12 or 50 Hz: 18 */
u32 start[2]; /* First VBI data line per field: 10 & 273 or 6 & 318 */
/*
* A note about "sliced" VBI data as implemented in this driver:
*
* Currently we collect the sliced VBI in the form of Ancillary Data
* packets, inserted by the AV core decoder/digitizer/slicer in the
* horizontal blanking region of the VBI lines, in "raw" mode as far as
* the Encoder is concerned. We don't tell the Encoder itself
* to provide sliced VBI. (AV Core: sliced mode - Encoder: raw mode)
*
* We then process the ancillary data ourselves to send the sliced data
* to the user application directly or build up MPEG-2 private stream 1
* packets to splice into (only!) MPEG-2 PS streams for the user app.
*
* (That's how ivtv essentially does it.)
*
* The Encoder should be able to extract certain sliced VBI data for
* us and provide it in a separate stream or splice it into any type of
* MPEG PS or TS stream, however:
* I haven't tested it,
* the Encoder may not handle every type of sliced VBI data,
* it would require some significant changes to this driver, and
* it requires some small additions to the V4L2 spec.
* But it's worth doing it someday, as manually splicing into a TS may
* not be practical in the driver.
*/
/*
* Number of "raw" VBI samples per horizontal line we tell the Enc to
* grab from the decoder/digitizer/slicer output for raw or sliced VBI
*/
u32 raw_decoder_line_size; /* 1444 = 4 byte SAV + 720 Y + 720 U/V */
u32 sliced_decoder_line_size; /* 272 for 60 Hz, 284 for 50 Hz */
/*
* Raster Reference/Protection (RP) bytes, used in Start/End Active
* Video codes emitted from the digitzer, that flag the start of VBI
* sample or VBI ancilliary data regions in the digitial ratser line.
*/
u8 raw_decoder_sav_odd_field;
u8 raw_decoder_sav_even_field;
u8 sliced_decoder_eav_odd_field;
u8 sliced_decoder_eav_even_field;
u32 frame; /* Count of VBI buffers/frames received from the Encoder */
/*
* Vars for creation and insertion of MPEG Private Stream 1 packets
* of sliced VBI data into an MPEG PS
*/
/* Boolean: create and insert Private Stream 1 packets into the PS */
int insert_mpeg;
/*
* Buffer for the maximum of 2 * 18 * packet_size sliced VBI lines.
* Used in cx18-vbi.c only for collecting sliced data, and as a source
* during conversion of sliced VBI data into MPEG Priv Stream 1 packets.
* We don't need to save state here, but the array may have been a bit
* too big (2304 bytes) to alloc from the stack.
*/
struct v4l2_sliced_vbi_data sliced_data[36];
/*
* A ring buffer of driver-generated MPEG-2 PS
* Program Pack/Private Stream 1 packets for sliced VBI data insertion
* into the MPEG PS stream.
*
* In each sliced_mpeg_data[] buffer is:
* 16 byte MPEG-2 PS Program Pack Header
* 16 byte MPEG-2 Private Stream 1 PES Header
* 4 byte magic number: "itv0" or "ITV0"
* 4 byte even field line mask, if "itv0"
* 4 byte odd field line mask, if "itv0"
* 36 lines, if "ITV0"; or <36 lines, if "itv0"; of sliced VBI data
*
* Each line in the payload is
* 1 byte line header derived from the SDID (WSS, CC, VPS, etc.)
* 42 bytes of line data
*
* That's a maximum 1552 bytes of payload in the Private Stream 1 packet
* (a holdover from ivtv), and a maximum 1584 bytes total.
*/
#define CX18_SLICED_MPEG_DATA_MAXSZ 1584
u8 *sliced_mpeg_data[CX18_VBI_FRAMES];
u32 sliced_mpeg_size[CX18_VBI_FRAMES];
/* Count of Program Pack/Program Stream 1 packets inserted into PS */
u32 inserted_frame;
/*
* A dummy driver stream transfer buffer with a copy of the next
* sliced_mpeg_data[] buffer for output to userland apps.
* Only used in cx18-fileops.c, but its state needs to persist at times.
*/
struct cx18_buffer sliced_mpeg_buf;
};
_______________________________________________
ivtv-devel mailing list
[email protected]
http://ivtvdriver.org/mailman/listinfo/ivtv-devel
