PAC7302 jpeg header problem on imx6Q sabre board

[Selea]

I have attached a USB camera to our sabre board.

solved some minor USB problems the camera was correctly recognized from USB/GSPCA/ then to V4L2.

but it says that some header (quantization table and huffman ) are missing.

Looking at the driver (pac7302.c in /driver/media/video/gspca) we can see that it doesn't add such part of headers (i think they are necessary).

So ther is something to activate some where so a part of GSPCA or V4L add such missing header stuff?

Thanks

Omar

[max_tsai]

Can yo check if "/drivers/media/video/gspca/jpeg.h" can satisfy?

[Selea]

ok, so I have to modify the pac7302.c file and add the jpeg header statically to avery frame took from the usb camera?

But of course the quantization table and huffman are not the same used by the camera to produce the jpeg image.... so i should have also a method to write those table to the camera , and says to it which quantization to use (usually there are 3 different quantizaiton table)....

So the header can be static but the info in it should be cooherent with the table used by the camera to produce the jpeg frame....

[max_tsai · Accepted solution]

Not sure if PAC7302 supports programmable Quantization table. Take W9967CF as an example, W9967CF supports programmable Quantization, so you can find its registers (CR40-CR5F) are able to updated with Quantization table.

For PAC7302, you may check with its vendor, if the table can be updated, then you update by writing its registers just like w9967CF. But according to PAC7302 driver, the tables seem unable to change.

//"drivers/media/video/gspca/pac7302.c"

789 /* JPEG header, continued */

790 static const unsigned char pac_jpeg_header2[] = {

791   0x03,                 /* Number of image components: 3 */

792   0x01, 0x21, 0x00,     /* ID=1, Subsampling 1x1, Quantization table: 0 */

793   0x02, 0x11, 0x01,     /* ID=2, Subsampling 2x1, Quantization table: 1 */

794   0x03, 0x11, 0x01,     /* ID=3, Subsampling 2x1, Quantization table: 1 */

795

796   0xff, 0xda,           /* SOS: Start Of Scan */

797   0x00, 0x0c,           /* length = 12 bytes (including this length field) */

798   0x03,                 /* number of components: 3 */

799   0x01, 0x00,           /* selector 1, table 0x00 */

800   0x02, 0x11,           /* selector 2, table 0x11 */

801   0x03, 0x11,           /* selector 3, table 0x11 */

802   0x00, 0x3f,           /* Spectral selection: 0 .. 63 */

803   0x00                  /* Successive approximation: 0 */

804 };

--//"drivers/media/video/gspca/w996Xcf.c"

144 /*--------------------------------------------------------------------------

145   Upload quantization tables for the JPEG compression.

146   This function is called by w9968cf_start_transfer().

147   Return 0 on success, a negative number otherwise.

148   --------------------------------------------------------------------------*/

149 static int w9968cf_upload_quantizationtables(struct sd *sd)

150 {

151         u16 a, b;

152         int ret = 0, i, j;

153

154         ret += reg_w(sd, 0x39, 0x0010); /* JPEG clock enable */

155

156         for (i = 0, j = 0; i < 32; i++, j += 2) {

157                 a = Y_QUANTABLE[j] | ((unsigned)(Y_QUANTABLE[j+1]) << 8);

158                 b = UV_QUANTABLE[j] | ((unsigned)(UV_QUANTABLE[j+1]) << 8);

159                 ret += reg_w(sd, 0x40+i, a);

160                 ret += reg_w(sd, 0x60+i, b);

161         }

162         ret += reg_w(sd, 0x39, 0x0012); /* JPEG encoder enable */

163

164         return ret;

165 }