On Wed, 27 Sep 2017, Jeyapal, Karthick wrote:
Sorry for the late reply, the last was busy week. Here are some more
comments:
Thanks for your comments. Please find the updated patch attached with your
comments incorporated.
Sorry, still not quite there... Here are some further comments:
From 9a572cb8b4ea599ee6bc1eedd6c7ca6868cfe0c6 Mon Sep 17 00:00:00 2001
From: Karthick J <kjeya...@akamai.com>
Date: Wed, 30 Aug 2017 11:43:16 +0530
Subject: [PATCH 3/4] avdevice/decklink_dec: Added Closed caption decode from
VANC
Signed-off-by: Karthick J <kjeya...@akamai.com>
---
libavcodec/avcodec.h | 7 ++
libavcodec/avpacket.c | 1 +
libavcodec/version.h | 2 +-
libavdevice/decklink_dec.cpp | 196 +++++++++++++++++++++++++++++++++++++++----
4 files changed, 188 insertions(+), 18 deletions(-)
diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index 513236a..d4a458f 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -1600,6 +1600,13 @@ enum AVPacketSideDataType {
AV_PKT_DATA_CONTENT_LIGHT_LEVEL,
/**
+ * ATSC A53 Part 4 Closed Captions. This metadata should be associated with
+ * a video stream. A53 CC bitstream is stored as uint8_t in
AVPacketSideData.data.
+ * The number of bytes of CC data is AVPacketSideData.size.
+ */
+ AV_PKT_DATA_A53_CC,
I forgot to mention that you should also add a note about this to
doc/APIChanges, sorry.
+
+ /**
* The number of side data elements (in fact a bit more than it).
* This is not part of the public API/ABI in the sense that it may
* change when new side data types are added.
diff --git a/libavcodec/avpacket.c b/libavcodec/avpacket.c
index 5ce3228..a292b15 100644
--- a/libavcodec/avpacket.c
+++ b/libavcodec/avpacket.c
@@ -387,6 +387,7 @@ const char *av_packet_side_data_name(enum
AVPacketSideDataType type)
case AV_PKT_DATA_MASTERING_DISPLAY_METADATA: return "Mastering display
metadata";
case AV_PKT_DATA_CONTENT_LIGHT_LEVEL: return "Content light level
metadata";
case AV_PKT_DATA_SPHERICAL: return "Spherical Mapping";
+ case AV_PKT_DATA_A53_CC: return "A53 Closed Captions";
}
return NULL;
}
diff --git a/libavcodec/version.h b/libavcodec/version.h
index 22cab7b..29cdb85 100644
--- a/libavcodec/version.h
+++ b/libavcodec/version.h
@@ -29,7 +29,7 @@
#define LIBAVCODEC_VERSION_MAJOR 57
#define LIBAVCODEC_VERSION_MINOR 104
-#define LIBAVCODEC_VERSION_MICRO 100
+#define LIBAVCODEC_VERSION_MICRO 101
#define LIBAVCODEC_VERSION_INT AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \
LIBAVCODEC_VERSION_MINOR, \
diff --git a/libavdevice/decklink_dec.cpp b/libavdevice/decklink_dec.cpp
index 38e6bd8..a24f563 100644
--- a/libavdevice/decklink_dec.cpp
+++ b/libavdevice/decklink_dec.cpp
@@ -1,6 +1,7 @@
/*
* Blackmagic DeckLink input
* Copyright (c) 2013-2014 Luca Barbato, Deti Fliegl
+ * Copyright (c) 2014 Rafaël Carré
* Copyright (c) 2017 Akamai Technologies, Inc.
*
* This file is part of FFmpeg.
@@ -105,6 +106,42 @@ static int get_vanc_line_idx(BMDDisplayMode mode)
return i - 1;
}
+static inline uint16_t parity (uint16_t x)
+{
+ uint16_t i;
+ for (i = 4 * sizeof (x); i > 0; i /= 2)
+ x ^= x >> i;
+ return x & 1;
+}
+
+static inline void clear_parity_bits(uint16_t *buf, int len) {
+ int i;
+ for (i = 0; i < len; i++)
+ buf[i] &= 0xff;
+}
+
+static int check_vanc_parity_checksum(uint16_t *buf, int len, uint16_t
checksum) {
+ int i;
+ uint32_t vanc_sum;
uint16_t is enough, it does not matter if it overflows. Also don't forget to
initialize this to 0, the previous patch had that.
+ for (i = 3; i < len - 1; i++) {
+ uint16_t v = buf[i];
+ int np = v >> 8;
+ int p = parity(v & 0xff);
+ if ((!!p ^ !!(v & 0x100)) || (np != 1 && np != 2)) {
+ // Parity check failed
+ return -1;
+ }
+ vanc_sum += v;
+ }
+ vanc_sum &= 0x1ff;
+ vanc_sum |= ((~vanc_sum & 0x100) << 1);
+ if (checksum != vanc_sum) {
+ // Checksum verification failed
+ return -1;
+ }
+ return 0;
+}
+
/* The 10-bit VANC data is packed in V210, we only need the luma component. */
static void extract_luma_from_v210(uint16_t *dst, const uint8_t *src, int
width)
{
@@ -232,19 +269,148 @@ static uint8_t*
teletext_data_unit_from_ancillary_packet(uint16_t *py, uint16_t
return tgt;
}
-static uint8_t* teletext_data_unit_from_vanc_data(uint16_t *py, uint8_t *tgt,
int64_t wanted_lines)
+uint8_t *vanc_to_cc(AVFormatContext *avctx, uint16_t *buf, size_t words,
+ unsigned &cc_count)
{
- uint16_t *pend = py + 1920;
+ size_t i, len = (buf[5] & 0xff) + 6 + 1;
+ uint8_t cdp_sum, rate;
+ uint16_t hdr, ftr;
+ uint8_t *cc;
+ uint16_t *cdp = &buf[6]; // CDP follows
+ if (cdp[0] != 0x96 || cdp[1] != 0x69) {
+ av_log(avctx, AV_LOG_WARNING, "Invalid CDP header 0x%.2x 0x%.2x",
cdp[0], cdp[1]);
+ return NULL;
+ }
- while (py < pend - 6) {
- if (py[0] == 0 && py[1] == 0x3ff && py[2] == 0x3ff) { //
ancillary data flag
- py += 3;
- tgt = teletext_data_unit_from_ancillary_packet(py, pend, tgt,
wanted_lines, 0);
- py += py[2] & 255;
+ len -= 7; // remove VANC header and checksum
+
+ if (cdp[2] != len) {
+ av_log(avctx, AV_LOG_WARNING, "CDP len %d != %zu", cdp[2], len);
+ return NULL;
+ }
+
+ cdp_sum = 0;
+ for (i = 0; i < len - 1; i++)
+ cdp_sum += cdp[i];
+ cdp_sum = cdp_sum ? 256 - cdp_sum : 0;
+ if (cdp[len - 1] != cdp_sum) {
+ av_log(avctx, AV_LOG_WARNING, "CDP checksum invalid 0x%.4x != 0x%.4x",
cdp_sum, cdp[len-1]);
+ return NULL;
+ }
+
+ rate = cdp[3];
+ if (!(rate & 0x0f)) {
+ av_log(avctx, AV_LOG_WARNING, "CDP frame rate invalid (0x%.2x)", rate);
+ return NULL;
+ }
+ rate >>= 4;
+ if (rate > 8) {
+ av_log(avctx, AV_LOG_WARNING, "CDP frame rate invalid (0x%.2x)", rate);
+ return NULL;
+ }
+
+ if (!(cdp[4] & 0x43)) /* ccdata_present | caption_service_active |
reserved */ {
+ av_log(avctx, AV_LOG_WARNING, "CDP flags invalid (0x%.2x)", cdp[4]);
+ return NULL;
+ }
+
+ hdr = (cdp[5] << 8) | cdp[6];
+ if (cdp[7] != 0x72) /* ccdata_id */ {
+ av_log(avctx, AV_LOG_WARNING, "Invalid ccdata_id 0x%.2x", cdp[7]);
+ return NULL;
+ }
+
+ cc_count = cdp[8];
+ if (!(cc_count & 0xe0)) {
+ av_log(avctx, AV_LOG_WARNING, "Invalid cc_count 0x%.2x", cc_count);
+ return NULL;
+ }
+
+ cc_count &= 0x1f;
+ if ((len - 13) < cc_count * 3) {
+ av_log(avctx, AV_LOG_WARNING, "Invalid cc_count %d (> %zu)", cc_count
* 3, len - 13);
+ return NULL;
+ }
+
+ if (cdp[len - 4] != 0x74) /* footer id */ {
+ av_log(avctx, AV_LOG_WARNING, "Invalid footer id 0x%.2x", cdp[len-4]);
+ return NULL;
+ }
+
+ ftr = (cdp[len - 3] << 8) | cdp[len - 2];
+ if (ftr != hdr) {
+ av_log(avctx, AV_LOG_WARNING, "Header 0x%.4x != Footer 0x%.4x", hdr,
ftr);
+ return NULL;
+ }
+
+ cc = (uint8_t *)av_malloc(cc_count * 3);
+ if (cc == NULL) {
+ av_log(avctx, AV_LOG_WARNING, "CC - av_malloc failed for cc_count =
%d", cc_count);
You should add "\n" to the end of all these warnings.
+ return NULL;
+ }
+
+ for (size_t i = 0; i < cc_count; i++) {
+ cc[3*i + 0] = cdp[9 + 3*i+0] /* & 3 */;
+ cc[3*i + 1] = cdp[9 + 3*i+1];
+ cc[3*i + 2] = cdp[9 + 3*i+2];
+ }
+
+ cc_count *= 3;
+ return cc;
+}
+
+uint8_t *get_metadata(AVFormatContext *avctx, uint16_t *buf, size_t width,
+ uint8_t *tgt, size_t tgt_size, AVPacket *pkt)
+{
+ decklink_cctx *cctx = (struct decklink_cctx *) avctx->priv_data;
+ uint16_t *max_buf = buf + width;
+
+ while (buf < max_buf - 6) {
+ int len;
+ uint16_t did = buf[3] & 0xFF; // data
id
+ uint16_t sdid = buf[4] & 0xFF; //
secondary data id
+ /* Check for VANC header */
+ if (buf[0] != 0 || buf[1] != 0x3ff || buf[2] != 0x3ff) {
+ return tgt;
+ }
+
+ len = (buf[5] & 0xff) + 6 + 1;
+ if (len > max_buf - buf) {
+ av_log(avctx, AV_LOG_WARNING, "Data Count (%d) > data left
(%zu)\n",
+ len, max_buf - buf);
+ return tgt;
+ }
+
+ if (did == 0x43 && (sdid == 0x02 || sdid == 0x03) && cctx->teletext_lines
&&
+ width == 1920 && tgt_size >= 1920) {
+ if (!check_vanc_parity_checksum(buf, len, buf[len - 1])) {
The check is inverted. Use the common ffmpeg practice: if (function() < 0) that
means error.
+ av_log(avctx, AV_LOG_WARNING, "VANC parity or checksum incorrect
\n");
no need for extra space before \n.
+ goto skip_packet;
+ }
+ tgt = teletext_data_unit_from_ancillary_packet(buf + 3, buf + len,
tgt, cctx->teletext_lines, 0);
+ } else if (did == 0x61 && sdid == 0x01) {
+ unsigned int data_len;
+ uint8_t *data;
+ if (!check_vanc_parity_checksum(buf, len, buf[len - 1])) {
The check is inverted. Use the common ffmpeg practice: if (function() < 0) that
means error.
Also please test your patches with real CC data before posting them, I
know it is tedious work with all the patch iterations, but I do the same
with teletext.
+ av_log(avctx, AV_LOG_WARNING, "VANC parity or checksum incorrect
\n");
no need for extra space before \n.
+ goto skip_packet;
+ }
+ clear_parity_bits(buf, len);
+ data = vanc_to_cc(avctx, buf, width, data_len);
+ if (data) {
+ uint8_t *pkt_cc = av_packet_new_side_data(pkt,
AV_PKT_DATA_A53_CC, data_len);
+ if (pkt_cc)
+ memcpy(pkt_cc, data, data_len);
+ av_free(data);
+ }
} else {
- py++;
+ av_log(avctx, AV_LOG_DEBUG, "Unknown meta data DID = 0x%.2x SDID =
0x%.2x\n",
+ did, sdid);
}
+skip_packet:
+ buf += len;
}
+
return tgt;
}
@@ -536,7 +702,7 @@ HRESULT decklink_input_callback::VideoInputFrameArrived(
videoFrame->GetHeight();
//fprintf(stderr,"Video Frame size %d ts %d\n", pkt.size, pkt.pts);
- if (!no_video && ctx->teletext_lines) {
+ if (!no_video) {
IDeckLinkVideoFrameAncillary *vanc;
AVPacket txt_pkt;
uint8_t txt_buf0[3531]; // 35 * 46 bytes decoded teletext lines +
1 byte data_identifier + 1920 bytes OP47 decode buffer
@@ -549,7 +715,8 @@ HRESULT decklink_input_callback::VideoInputFrameArrived(
txt_buf[0] = 0x10; // data_identifier - EBU_data
txt_buf++;
#if CONFIG_LIBZVBI
- if (ctx->bmd_mode == bmdModePAL && (vanc_format ==
bmdFormat8BitYUV || vanc_format == bmdFormat10BitYUV)) {
+ if (ctx->bmd_mode == bmdModePAL && ctx->teletext_lines &&
+ (vanc_format == bmdFormat8BitYUV || vanc_format ==
bmdFormat10BitYUV)) {
av_assert0(videoFrame->GetWidth() == 720);
for (i = 6; i < 336; i++, line_mask <<= 1) {
uint8_t *buf;
@@ -571,13 +738,8 @@ HRESULT decklink_input_callback::VideoInputFrameArrived(
if (vanc->GetBufferForVerticalBlankingLine(i,
(void**)&buf) == S_OK) {
uint16_t luma_vanc[MAX_WIDTH_VANC];
extract_luma_from_v210(luma_vanc, buf,
videoFrame->GetWidth());
- if (videoFrame->GetWidth() == 1920) {
- txt_buf =
teletext_data_unit_from_vanc_data(luma_vanc, txt_buf, ctx->teletext_lines);
- if (txt_buf - txt_buf0 > 1611) { // ensure
we still have at least 1920 bytes free in the buffer
- av_log(avctx, AV_LOG_ERROR, "Too many OP47
teletext packets.\n");
- break;
- }
- }
+ txt_buf = get_metadata(avctx, luma_vanc,
videoFrame->GetWidth(),
+ txt_buf, sizeof(txt_buf0) -
(txt_buf - txt_buf0), &pkt);
}
if (i == vanc_line_numbers[idx].field0_vanc_end)
i = vanc_line_numbers[idx].field1_vanc_start - 1;
--
1.9.1
Fingers crossed for the next patch version :)
Thanks,
Marton
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