[FFmpeg-devel] [PATCH 2/3] lavd: add teletext quantizer
Andrey Turkin
andrey.turkin at gmail.com
Wed Jan 13 03:01:01 CET 2016
Why not use libzvbi's slicer? It should be pretty robust with
less-than-ideal signal.
Regarding your code - is there a need to calculate a frequency? I did
something similar a while back with VBI from TV signal and in my experience:
a) this kind of frequency/phase estimation doesn't work that well on a
noisy signal.
b) there's really no need to estimate frequency - it's a known constant
(well it depends on a standard but in each standard it is a constant) and
generators usually don't deviate from it; you just need to get a good phase
estimation based on, say, local maxima/minima of run-in bits.
Ideal frequency (or rather period) for WST in your code should be 127530; I
presume 4 last samples are WST so their estimated frequency is pretty far
outside specified 25ppm tolerance. Value of 127590 means that for the last
bit you get a (127590-127530)/65536*360 phase error which is about 1/3 of
period (still within the sample if initial phase was estimated accurately -
but getting close to the edge). However any additional error in estimated
frequency would cause lost or duplicate bits in the last bits of decoded
data. If SDI data is noisy there's a good chance of that happening (and
noisy SDI is not some theoretical possibility - one of local TV studios has
a rather strange setup where they do several SDI->analog and analog->SDI
conversions; frames coming from their last SDI output are already noisy).
2016-01-13 1:40 GMT+03:00 Marton Balint <cus at passwd.hu>:
> Getting teletext right from VANC/VBI data is tricky, because the teletext
> clock
> is not synced to the video clock. Therefore we have to first measure the
> frequency of the teletext clock in the reconstructed signal, and then
> resample
> the original data appropriately.
>
> What I do is that I measure the distance between the first and the last
> zero
> crossing (leading edge) in the first 3 (constant) bytes of the input to
> calculate the clock frequency and the starting point of the real teletext
> data.
>
> Based on these I can calculate the offsets where the rest of the signal
> needs
> to be quantized, and I do that by a simple linear interpolation between two
> neighbouring values in the original data, so the resampling method is
> simple
> first order hold.
>
> Fixed point arithmethic is used for frequencies and offsets to improve
> precision.
>
> I guess the DSP minded people can come up with a better way, but it works
> for
> me just fine as it is.
>
> Signed-off-by: Marton Balint <cus at passwd.hu>
> ---
> libavdevice/Makefile | 2 +-
> libavdevice/teletext_quantizer.c | 174
> ++++++++++++++++++++++++++++++++++++++
> libavdevice/teletext_quantizer.h | 32 +++++++
> tests/fate/libavdevice.mak | 5 +-
> tests/ref/fate/teletext_quantizer | 22 +++++
> 5 files changed, 233 insertions(+), 2 deletions(-)
> create mode 100644 libavdevice/teletext_quantizer.c
> create mode 100644 libavdevice/teletext_quantizer.h
> create mode 100644 tests/ref/fate/teletext_quantizer
>
> diff --git a/libavdevice/Makefile b/libavdevice/Makefile
> index f57ec0b..f889b7c 100644
> --- a/libavdevice/Makefile
> +++ b/libavdevice/Makefile
> @@ -69,4 +69,4 @@ SKIPHEADERS-$(CONFIG_V4L2_OUTDEV) += v4l2-common.h
> SKIPHEADERS-$(HAVE_ALSA_ASOUNDLIB_H) += alsa.h
> SKIPHEADERS-$(HAVE_SNDIO_H) += sndio.h
>
> -TESTPROGS = timefilter
> +TESTPROGS = timefilter teletext_quantizer
> diff --git a/libavdevice/teletext_quantizer.c
> b/libavdevice/teletext_quantizer.c
> new file mode 100644
> index 0000000..af6dbbf
> --- /dev/null
> +++ b/libavdevice/teletext_quantizer.c
> @@ -0,0 +1,174 @@
> +/*
> + * This file is part of FFmpeg.
> + *
> + * FFmpeg is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * FFmpeg is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with FFmpeg; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
> 02110-1301 USA
> + */
> +
> +#include "libavutil/common.h"
> +#include "libavutil/mem.h"
> +#include "config.h"
> +#include "teletext_quantizer.h"
> +
> +#define BLACK_LEVEL 16
> +#define WHITE_LEVEL 235
> +#define DATA_ZERO_LEVEL (BLACK_LEVEL)
> +#define DATA_ONE_LEVEL (BLACK_LEVEL + ((WHITE_LEVEL - BLACK_LEVEL) * 2 /
> 3))
> +#define DATA_ZERO_MAX ((DATA_ONE_LEVEL + DATA_ZERO_LEVEL) / 2)
> +#define MAX_FRAMING_CODE_END_POSITION 64
> +
> +#define CLOCK_RUNIN 0xaa
> +#define FRAMING_CODE 0xe4
> +
> +static inline int calc_zerocross(int i, uint8_t y1, uint8_t y2)
> +{
> + return 65536 * i + 65536 * (DATA_ZERO_MAX - y1) / (y2 - y1);
> +}
> +
> +static int calc_frequency(const uint8_t *src, int *offset)
> +{
> + int first_cross = 0, last_cross = 0;
> + int crosses = 0;
> + uint8_t last = DATA_ZERO_LEVEL;
> + int frequency;
> + int i;
> +
> + /* Teletext data starts with 3 constant bytes: 10101010 10101010
> 11100100.
> + * Lets find the 10th leading edge zero crossing, (actually
> DATA_ZERO_MAX
> + * crossing) which should be at the 6th bit of the third byte. */
> + for (i = 0; i < MAX_FRAMING_CODE_END_POSITION; src += 2, i++) {
> + uint8_t val = *src;
> + if (val > DATA_ZERO_MAX && last <= DATA_ZERO_MAX) {
> + crosses++;
> + if (crosses == 1 || crosses == 10) {
> + last_cross = calc_zerocross(i - 1, last, val);
> + if (crosses == 1)
> + first_cross = last_cross;
> + else
> + break;
> + }
> + }
> + last = val;
> + }
> +
> + if (i >= MAX_FRAMING_CODE_END_POSITION)
> + return -1;
> +
> + frequency = (last_cross - first_cross) / 21;
> + *offset = FFMAX(0, first_cross + frequency / 2);
> +
> + return frequency;
> +}
> +
> +static uint8_t calc_parity_and_line_offset(int line)
> +{
> + uint8_t ret = (line < 313) << 5;
> + if (line >= 7 && line <= 22)
> + ret += line;
> + if (line >= 320 && line <= 335)
> + ret += (line - 313);
> + return ret;
> +}
> +
> +int ff_teletext_line_from_vbi_data(int line, const uint8_t *src, uint8_t
> *tgt)
> +{
> + int i, offset, frequency;
> + uint8_t *tgt0 = tgt;
> +#ifdef TEST
> + int mindiff = 255 << 16;
> +#endif
> +
> + src++;
> +
> + if ((frequency = calc_frequency(src, &offset)) < 0)
> + return -1;
> +#ifdef TEST
> + printf("Frequency: %d, Offset: %d\n", frequency, offset);
> +#endif
> +
> + if (((offset + frequency * 359) >> 16) >= 720)
> + return -1;
> +
> + for (i = 0; i < 360; i++, offset += frequency) {
> + int y_offset = offset >> 16;
> + int y_offset2 = (y_offset >= 719 ? y_offset : y_offset + 1);
> + int offset_frac = offset % 65536;
> + int value;
> + if (i % 8 == 0)
> + *++tgt = 0;
> + else
> + *tgt <<= 1;
> + value = src[y_offset << 1] * (65536 - offset_frac) + offset_frac *
> src[y_offset2 << 1];
> + if (value > DATA_ZERO_MAX << 16)
> + *tgt |= 1;
> +#ifdef TEST
> + value = value - (DATA_ZERO_MAX << 16);
> + mindiff = FFMIN(mindiff, value > 0 ? value : -value);
> +#endif
> + }
> +
> + if (tgt0[1] != CLOCK_RUNIN || tgt0[2] != CLOCK_RUNIN || tgt0[3] !=
> FRAMING_CODE)
> + return -1;
> +
> +#ifdef TEST
> + printf("Minimum difference from data_zero_max: %d\n", mindiff >> 16);
> +#endif
> +
> + tgt0[0] = 0x02; // data_unit_id
> + tgt0[1] = 0x2c; // data_unit_length
> + tgt0[2] = calc_parity_and_line_offset(line); // field_parity,
> line_offset
> +
> + return 0;
> +}
> +
> +#ifdef TEST
> +
> +const uint8_t samples[][720] = {
> + /* Sanity check */
> + {0},
> + /* Only use the binary levels and the whole line */
> +
> {162,162,16,16,162,162,16,16,162,162,16,16,162,162,16,16,162,162,16,16,162,162,16,16,162,162,16,16,162,162,16,16,162,162,162,162,162,162,16,16,16,16,162,162,16,16,16,16,162,162,162,162,16,16,16,16,162,162,162,162,162,162,16,16,162,162,162,162,16,16,16,16,162,162,162,162,162,162,16,16,162,162,162,162,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,162,162,162,162,16,16,16,16,16,16,16,16,162,162,162,162,162,162,16,16,162,162,16,16,16,16,162,162,16,16,162,162,162,162,162,162,16,16,16,16,162,162,16,16,162,162,162,162,162,162,162,162,16,16,16,16,16,16,16,16,16,16,162,162,162,162,162,162,162,162,162,162,16,16,16,16,162,162,162,162,162,162,16,16,16,16,16,16,162,162,16,16,162,162,162,162,162,162,162,162,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16,16,16,16,16,16,16,16,16,16,16,162,162,16,16,16,16},
> + /* The rest are taken from real-world teletext generators */
> +
> {16,16,16,16,16,15,20,112,160,61,21,124,155,50,27,135,148,39,35,144,140,31,44,152,129,24,55,158,118,19,67,162,105,16,80,163,92,16,93,165,164,164,166,158,67,15,15,26,127,153,50,15,15,37,138,167,167,133,33,15,15,56,153,167,164,164,166,106,17,77,162,166,164,89,15,15,18,103,166,164,164,167,154,55,24,126,167,164,164,167,140,39,15,16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,96,163,80,15,16,16,16,16,16,16,16,16,16,16,15,37,138,167,164,164,167,129,29,15,16,16,16,16,15,73,160,166,164,164,164,87,16,99,163,76,15,15,22,118,158,55,24,126,167,164,164,167,140,39,15,15,48,152,129,24,55,154,167,164,164,164,164,165,96,17,15,16,16,16,16,16,15,21,112,167,164,164,164,164,164,164,167,142,41,15,15,46,146,167,164,164,167,118,23,15,16,16,15,80,163,96,16,90,164,164,164,164,164,166,157,64,15,16,16,16,16,16,16,15,39,144,140,35,15,16,16,16,16,16,16,16,16,16,16,15,83,163,92,15,16,16,16,16,16,16,16,16,16,16,15,29,132,150,46,15,16,16,16,16,16,16,16,16,16,16,15,67,161,109,19,15,16,16,16,16,16,16,16,16,16,15,22,118,158,59,15,16,16,16,16,16,16,16,16,16,16,15,53,155,124,25,15,16,16,16,16,16,16,16,16,16,15,17,102,162,73,15,16,16,16,16,16,16,16,16,16,16,15,41,146,137,33,15,16,16,16,16,16,16,16,16,16,16,15,86,163,89,15,16,16,16,16,16,16,16,16,16,16,15,31,135,148,43,15,16,16,16,16,16,16,16,16,16,16,15,70,162,105,18,15,16,16,16,16,16,16,16,16,16,15,23,121,156,56,15,16,16,16,16,16,16,16,16,16,16,15,56,156,121,23,15,16,16,16,16,16,16,16,16,16,15,18,105,162,70,15,16,16,16,16,16,16,16,16,16,16,15,43,148,135,31,15,16,16,16,16,16,16,16,16,16,16,15,89,163,86,15,16,16,16,16,16,16,16,16,16,16,15,33,137,146,41,15,16,16,16,16,16,16,16,16,16,16,15,73,162,102,17,15,16,16,16,16,16,16,16,16,16,15,25,124,155,53,15,16,16,16,16,16,16,16,16,16,16,15,59,158,118,22,15,16,16,16,16,16,16,16,16,16,15,19,109,161,67,15,16,16,16,16,16,16,16,16,16,16,15,46,150,132,29,15,16,16,16,16,16,16,16,16,16,16,15,92,163,83,15,16,16,16,16,16,16,16,16,16,16,15,35,140,144,39,15,16,16,16,16,16,16,16,16,16,16,15,76,163,99,17,15,16,16,16,16,16,16,16,16,16,15,26,127,153,50,15,16,16,16,16,16,16,16,16,16,16,15,61,159,115,21,15,16,16,16,16,16,16,16,16,16,15,20,112,160,64,15,16,16,16,16,16,16,16,16,16,16,15,48,152,129,28,15,16,16,16,16,16,16,16,16,16,16,16,96,163,80,15,16,16,16,16,16,16,16,16,16,16,15,37,142,142,37,15,16,16,16,16,16,16,16,16,16,16,16,16,16,16},
> +
> {16,16,16,16,16,15,20,112,160,61,21,124,155,50,27,135,148,39,35,144,140,31,44,152,129,24,55,158,118,19,67,162,105,16,80,163,92,16,93,165,164,164,166,158,67,15,15,26,127,153,50,15,16,16,15,41,146,137,33,15,16,16,16,16,16,16,16,16,15,80,163,96,16,92,163,80,16,105,162,70,15,16,16,16,16,15,31,135,148,39,35,144,140,31,44,148,167,164,164,167,115,19,67,162,105,16,80,163,92,16,93,165,164,164,164,164,164,164,167,153,52,26,129,167,167,142,41,15,15,46,146,167,167,123,23,58,159,115,18,70,162,102,17,15,16,15,17,99,163,74,17,112,160,61,21,124,155,53,15,16,16,15,39,144,140,31,44,152,129,24,55,158,118,22,15,16,16,15,83,163,92,16,96,163,77,17,109,161,67,15,16,16,15,29,129,167,167,142,41,15,15,46,146,167,164,164,167,118,20,64,158,166,164,164,165,93,16,90,164,166,161,76,15,16,16,15,25,124,155,53,15,15,35,136,167,167,136,35,15,15,53,155,124,21,61,160,112,17,74,161,166,164,90,16,96,163,77,17,109,161,67,15,16,16,16,16,16,16,16,16,16,16,16,16,15,50,153,127,23,58,159,115,18,70,162,102,17,15,15,90,164,166,161,74,17,112,160,61,21,120,167,167,148,44,31,140,144,39,15,15,48,148,167,167,120,25,15,15,70,159,166,164,164,164,90,15,16,16,16,16,16,16,16,16,16,16,15,29,132,150,42,33,142,142,33,42,150,132,26,52,156,121,20,64,161,109,19,15,15,86,163,164,164,166,161,76,15,16,16,15,25,120,167,164,164,164,164,164,164,167,136,35,15,15,53,155,124,21,61,157,166,164,164,164,164,164,90,15,16,16,16,16,16,16,15,23,121,156,56,15,16,16,16,16,16,16,16,16,16,16,15,56,156,121,23,15,16,16,16,16,16,16,16,16,16,15,18,105,162,70,15,16,16,16,16,16,16,16,16,16,16,15,43,148,135,31,15,16,16,15,64,160,112,17,74,163,99,17,15,16,96,163,77,17,109,161,67,15,16,16,16,16,15,33,133,167,167,138,37,15,15,50,150,167,164,164,167,112,18,70,160,166,165,93,16,15,17,96,165,164,164,166,157,61,21,124,155,50,27,131,167,167,140,39,15,16,16,15,53,151,167,167,115,22,15,16,16,16,16,16,16,16,15,17,99,166,166,158,64,20,121,156,52,26,129,167,164,164,167,138,33,42,150,132,26,52,153,167,164,164,166,106,19,15,16,16,16,16,16,15,18,105,162,67,19,118,158,59,15,15,31,131,167,167,140,39,15,15,48,152,129,28,15,16,16,15,70,159,166,165,96,17,15,16,15,17,102,162,70,18,112,167,164,164,167,150,47,29,133,167,164,164,167,133,33,15,15,56,153,167,167,112,18,70,160,166,164,164,164,89,15,15,18,103,166,166,157,61,21,124,155,50,27,135,148,39,35,140,167,164,164,167,126,24,55,154,167,167,109,17,74,163,99,16,87,164,166,162,77,17,106,166,164,164,164,164,167,150,47,29,133,167,167,138,37,15,16,16,16,16,16,16,16,16,16,16,16,16,16,16},
> +
> {16,16,16,16,7,20,109,159,61,22,116,155,61,28,128,148,48,37,139,139,37,37,148,128,28,48,155,116,22,61,155,102,17,74,159,88,16,80,161,169,161,170,156,77,10,1,27,121,155,58,8,13,16,16,16,16,16,16,13,8,58,149,116,22,56,149,175,164,93,17,74,161,88,16,88,161,74,17,93,164,165,161,171,150,66,7,3,36,132,141,47,5,5,45,141,174,169,121,27,6,16,16,16,10,13,77,156,169,161,169,161,88,13,1,20,99,166,165,161,171,150,55,8,13,15,7,45,132,170,162,161,161,161,161,165,166,111,27,6,16,10,13,77,161,169,161,161,161,161,161,170,156,66,10,11,16,6,35,121,168,164,161,161,161,161,162,168,121,35,6,16,11,10,66,150,170,161,161,161,161,161,169,161,88,13,10,16,7,27,111,166,165,161,161,161,161,161,170,132,45,7,14,13,8,55,141,171,161,161,161,165,164,93,17,74,161,88,16,88,161,74,17,93,164,175,149,56,22,116,148,48,27,118,170,162,162,170,132,35,3,7,55,150,175,167,106,21,68,156,170,161,169,161,88,16,1,20,99,164,176,149,56,21,106,166,164,161,171,141,45,5,5,45,132,174,169,118,27,56,149,171,161,165,164,99,20,1,16,88,161,177,161,68,17,93,164,165,161,171,150,66,7,3,35,121,172,172,130,35,35,140,171,161,164,166,111,27,1,10,77,156,176,164,80,16,80,161,169,161,170,156,77,10,1,27,111,167,174,140,45,27,130,170,162,162,170,121,35,3,7,66,150,175,167,106,17,68,156,170,161,169,161,88,16,1,20,99,164,175,149,56,21,106,168,164,161,171,132,45,5,5,45,141,174,169,118,21,56,149,171,161,167,164,99,20,1,16,88,161,177,156,68,17,93,166,165,161,171,150,55,7,3,35,132,172,172,130,35,45,140,171,161,165,166,111,27,1,13,77,156,176,161,80,16,80,161,167,161,170,156,66,10,1,27,111,169,174,140,45,35,130,170,162,162,168,121,35,3,10,66,150,175,167,93,17,68,156,169,161,169,161,88,13,1,20,99,167,175,149,56,21,118,168,164,161,170,130,35,35,130,171,161,164,168,106,21,56,149,171,161,167,164,93,16,80,161,169,161,170,156,68,17,106,166,165,161,171,140,45,27,118,170,162,162,170,130,27,45,140,171,161,165,166,106,21,68,156,170,161,169,161,80,16,80,164,167,161,170,149,56,21,106,166,164,161,171,140,35,35,130,170,162,164,168,118,27,56,149,171,161,165,164,93,17,68,161,169,161,169,161,68,17,93,164,165,161,171,149,56,27,118,168,164,162,170,130,35,35,140,171,161,164,166,106,21,56,149,170,161,167,164,80,16,80,161,169,161,170,156,68,21,106,166,165,161,171,140,45,27,130,170,162,162,170,118,27,45,140,171,161,165,166,106,17,68,156,170,161,169,161,80,16,93,164,167,161,171,149,56,21,106,168,164,161,171,130,35,35,130,170,161,164,168,118,21,56,149,175,167,93,17,74,159,96,16,1,16,96,159,84,13,1,27,111,166,165,161,161,161,171,141,45,5,5,47,141,132,36,6,15,16,16,16,16,16,16,16,16,16,16},
> +
> {16,16,16,16,7,20,109,159,61,22,116,155,61,28,128,148,48,37,139,139,37,37,148,128,28,48,155,116,22,61,155,102,17,74,159,88,16,80,161,169,161,170,156,77,10,1,27,121,155,58,7,3,35,132,170,162,161,161,164,168,118,27,61,155,121,27,6,16,10,13,84,161,96,16,8,16,16,16,16,16,16,16,6,27,111,168,164,161,171,130,35,37,139,141,36,3,7,58,155,121,27,6,16,16,16,16,16,8,16,96,161,96,13,1,20,99,167,175,150,66,10,13,15,6,36,141,141,47,7,14,16,16,16,16,11,10,71,155,116,17,68,156,176,161,80,16,80,161,176,156,77,13,11,16,6,27,121,149,58,8,13,16,16,14,7,47,149,132,36,3,10,71,155,116,22,68,156,170,161,169,161,80,16,88,159,74,17,93,167,175,149,56,22,128,148,48,28,139,139,37,35,130,174,169,118,27,56,149,171,161,161,161,167,164,99,16,8,16,16,16,16,16,7,20,111,167,175,150,66,8,13,16,16,14,7,47,141,139,28,45,140,171,161,161,161,165,166,93,17,68,156,169,161,161,161,169,156,68,17,93,167,175,149,56,21,118,169,174,140,35,37,139,139,37,48,148,132,36,1,10,66,150,171,161,167,164,99,16,1,16,96,161,84,13,1,20,111,167,175,149,56,28,128,149,58,5,5,45,132,170,161,161,161,164,166,111,27,6,16,16,16,16,16,16,16,8,16,96,159,84,13,10,16,16,16,16,16,16,16,16,15,7,47,141,141,47,6,15,16,16,16,16,16,16,16,16,10,13,84,161,96,16,8,16,16,16,16,16,16,16,16,16,6,36,132,149,58,7,14,16,16,16,16,16,16,16,16,11,10,71,155,109,20,7,16,16,16,8,16,96,159,84,13,10,16,16,16,16,16,6,36,132,148,37,35,130,170,162,164,168,121,35,1,10,71,155,116,17,68,156,176,161,88,16,8,16,16,16,7,20,111,167,175,150,66,8,13,16,16,14,7,45,132,172,169,118,27,48,155,116,22,61,155,102,17,68,156,169,161,169,161,88,13,1,20,99,167,175,150,66,10,3,35,121,168,162,162,170,132,45,6,15,16,16,16,16,11,10,71,159,109,20,7,16,16,16,8,16,109,159,84,13,11,16,6,27,111,168,164,161,171,132,45,5,5,47,149,128,28,45,149,171,161,161,161,161,161,167,164,88,16,8,16,8,20,99,164,167,161,171,150,66,10,13,15,6,36,141,139,37,35,130,174,169,121,35,6,16,16,16,16,16,16,16,10,16,96,161,96,16,1,20,99,164,175,150,66,10,1,35,121,168,164,162,170,132,45,7,15,13,8,58,155,116,22,56,149,170,161,161,161,161,161,169,161,80,17,102,159,84,10,1,27,111,166,164,161,171,141,45,7,14,14,7,58,149,128,28,56,149,175,167,111,20,7,16,10,16,96,161,88,16,93,164,167,161,161}
> +};
> +
> +int main(void) {
> + int i;
> + for (i = 0; i < FF_ARRAY_ELEMS(samples); i++) {
> + int ret, j;
> + uint8_t buf[46];
> + uint8_t src[1440];
> +
> + for (j = 0; j < 720; j++)
> + src[j*2+1] = samples[i][j];
> +
> + printf("Sample %d\n", i);
> + ret = ff_teletext_line_from_vbi_data(7, src, buf);
> + if (ret >= 0) {
> + int k;
> + printf("Teletext:");
> + for (k = 0; k < 46; k++)
> + printf(" %02x", buf[k]);
> + printf("\n");
> + } else
> + printf("Teletext decoding failed.\n");
> + }
> + return 0;
> +}
> +
> +#endif
> +
> diff --git a/libavdevice/teletext_quantizer.h
> b/libavdevice/teletext_quantizer.h
> new file mode 100644
> index 0000000..7bfa0d9
> --- /dev/null
> +++ b/libavdevice/teletext_quantizer.h
> @@ -0,0 +1,32 @@
> +/*
> + * This file is part of FFmpeg.
> + *
> + * FFmpeg is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * FFmpeg is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with FFmpeg; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
> 02110-1301 USA
> + */
> +
> +#ifndef AVDEVICE_TELETEXT_QUANTIZER_H
> +#define AVDEVICE_TELETEXT_QUANTIZER_H
> +
> +/**
> + * Decode a VBI line to a DVB teletext data unit.
> + *
> + * @param line VBI line number
> + * @param src a 720 pixel wide VBI line in AV_PIX_FMT_UYVY422 format
> + * @param tgt a 46 byte long buffer for the DVB teletext data unit
> + * @return negative on error or if no teletext data could be decoded
> + */
> +int ff_teletext_line_from_vbi_data(int line, const uint8_t *src, uint8_t
> *tgt);
> +
> +#endif /* AVDEVICE_TELETEXT_QUANTIZER_H */
> diff --git a/tests/fate/libavdevice.mak b/tests/fate/libavdevice.mak
> index cb6af51..d177dd9 100644
> --- a/tests/fate/libavdevice.mak
> +++ b/tests/fate/libavdevice.mak
> @@ -1,6 +1,9 @@
> -FATE_LIBAVDEVICE-yes += fate-timefilter
> +FATE_LIBAVDEVICE-yes += fate-timefilter fate-teletext_quantizer
> fate-timefilter: libavdevice/timefilter-test$(EXESUF)
> fate-timefilter: CMD = run libavdevice/timefilter-test
>
> +fate-teletext_quantizer: libavdevice/teletext_quantizer-test$(EXESUF)
> +fate-teletext_quantizer: CMD = run libavdevice/teletext_quantizer-test
> +
> FATE-$(CONFIG_AVDEVICE) += $(FATE_LIBAVDEVICE-yes)
> fate-libavdevice: $(FATE_LIBAVDEVICE-yes)
> diff --git a/tests/ref/fate/teletext_quantizer
> b/tests/ref/fate/teletext_quantizer
> new file mode 100644
> index 0000000..ae9187f
> --- /dev/null
> +++ b/tests/ref/fate/teletext_quantizer
> @@ -0,0 +1,22 @@
> +Sample 0
> +Teletext decoding failed.
> +Sample 1
> +Frequency: 131072, Offset: 32768
> +Minimum difference from data_zero_max: 73
> +Teletext: 02 2c 27 e4 ce ce e0 04 07 0e 97 2f 07 ce 2f 04 04 04 04 04 04
> 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04
> +Sample 2
> +Frequency: 127557, Offset: 506146
> +Minimum difference from data_zero_max: 51
> +Teletext: 02 2c 27 e4 ce ce e0 04 07 0e 97 2f 07 ce 2f 04 04 04 04 04 04
> 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04
> +Sample 3
> +Frequency: 127557, Offset: 506146
> +Minimum difference from data_zero_max: 51
> +Teletext: 02 2c 27 e4 40 a8 57 57 d9 a8 a8 a8 a8 ce ec 4c ad 40 2a 6b 4c
> e0 2a a7 1f 2f 04 04 04 04 52 86 76 75 8c 0d 75 c1 4c 8c 5d cd cd 5d ad ec
> +Sample 4
> +Frequency: 127590, Offset: 442283
> +Minimum difference from data_zero_max: 45
> +Teletext: 02 2c 27 e4 0b 57 26 1c e3 e3 e3 e3 e3 e3 d5 ae 6e 6e 6e 6e 6e
> 6e 6e 6e 6e 6e 6e 6e 6e 6e 6e 6e ee ee ee ee ee ee ee ee ee ee ee ee d2 79
> +Sample 5
> +Frequency: 127590, Offset: 442283
> +Minimum difference from data_zero_max: 46
> +Teletext: 02 2c 27 e4 f4 40 e9 04 c4 16 c4 25 d6 ad e0 c2 f7 b6 a7 26 9e
> 04 04 04 04 04 20 b9 61 86 ae 67 04 23 97 c7 16 04 ce 2f a7 16 2c 00 00 00
> --
> 2.6.2
>
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel at ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>
More information about the ffmpeg-devel
mailing list