Hmm.... Em Wed, 27 Apr 2016 08:01:19 -0300 Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxx> escreveu: > Instead of using two tables to estimate the temporal decimation > factor, use a formula. This allows to get the closest fps, with > sounds better than the current tables. > > Compile-tested only. Please discard this patch. It is wrong. I found the datasheet for this device at: http://www.starterkit.ru/html/doc/tw6869-ds.pdf Based on what it is said on page 50, it seems that it doesn't use a decimation filter, but, instead, it just discards some fields in a way that the average fps will be reduced. So, the actual frame rate is given by the number of enabled bits that are written to VIDEO_FIELD_CTRL[vc->ch] and are at the valid bitmask range, e. g: index 0, map = 0x00000000, 30 fps (60Hz), 25 fps (50Hz), output all fields index 1, map = 0x80000006, 2 fps (60Hz), 2 fps (50Hz) index 2, map = 0x80018006, 4 fps (60Hz), 4 fps (50Hz) index 3, map = 0x80618006, 6 fps (60Hz), 6 fps (50Hz) index 4, map = 0x81818186, 8 fps (60Hz), 8 fps (50Hz) index 5, map = 0x86186186, 10 fps (60Hz), 8 fps (50Hz) index 6, map = 0x86619866, 12 fps (60Hz), 10 fps (50Hz) index 7, map = 0x86666666, 14 fps (60Hz), 12 fps (50Hz) index 8, map = 0x9999999e, 16 fps (60Hz), 14 fps (50Hz) index 9, map = 0x99e6799e, 18 fps (60Hz), 16 fps (50Hz) index 10, map = 0x9e79e79e, 20 fps (60Hz), 16 fps (50Hz) index 11, map = 0x9e7e7e7e, 22 fps (60Hz), 18 fps (50Hz) index 12, map = 0x9fe7f9fe, 24 fps (60Hz), 20 fps (50Hz) index 13, map = 0x9ffe7ffe, 26 fps (60Hz), 22 fps (50Hz) index 14, map = 0x9ffffffe, 28 fps (60Hz), 24 fps (50Hz) This was done by using the enclosed program. --- #include <stdio.h> static const unsigned int map[15] = { 0x00000000, 0x00000001, 0x00004001, 0x00104001, 0x00404041, 0x01041041, 0x01104411, 0x01111111, 0x04444445, 0x04511445, 0x05145145, 0x05151515, 0x05515455, 0x05551555, 0x05555555 }; unsigned int count_bits(unsigned int bits, unsigned int max) { unsigned int i, c= 0; for (i = 0; i < max; i++) if ((1 << i) & bits) c++; return c; } void calc_map(unsigned int i) { unsigned int m, fps_30, fps_25; m = map[i] << 1; m |= m << 1; fps_30 = count_bits(m, 30); fps_25 = count_bits(m, 25); if (m) m |= 1 << 31; else { fps_30 = 30; fps_25 = 25; } printf("index %2i, map = 0x%08x, %d fps (60Hz), %d fps (50Hz)%s\n", i, m, fps_30, fps_25, i == 0 ? ", output all fields" : "" ); } int main(void) { unsigned int i; printf ("\nmap:\n"); for (i = 0; i < 15; i++) calc_map(i); return 0; } -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
