avdevice/decklink_dec: add support for decoding teletext from 10bit ancillary data

This also add supports for 4K DeckLink cards because they always output the ancillary data in 10-bit. v2: - only try teletext decoding for 576i PAL mode - some comments as requested by Aaron Levinson

Marton Balint committed 9 years ago

Commit cc0916b1 parent 4c1aac82 files · +47 −18Browse files

Unified · Split

2 files

doc/indevs.texi +2 −2
libavdevice/decklink_dec.cpp +45 −16

doc/indevs.texi+2−2

@@ -250,8 +250,8 @@ specifically lines 6 to 22, and lines 318 to 335. Line 6 is the LSB in the mask. · 249 unmodified lines
250	Selected lines which do not contain teletext information will be ignored. You	250	Selected lines which do not contain teletext information will be ignored. You
251	can use the special @option{all} constant to select all possible lines, or	251	can use the special @option{all} constant to select all possible lines, or
252	@option{standard} to skip lines 6, 318 and 319, which are not compatible with all	252	@option{standard} to skip lines 6, 318 and 319, which are not compatible with all
253	receivers. Capturing teletext only works for SD PAL sources in 8 bit mode.	253	receivers. Capturing teletext only works for SD PAL sources. To use this
254	To use this option, ffmpeg needs to be compiled with @code{--enable-libzvbi}.	254	option, ffmpeg needs to be compiled with @code{--enable-libzvbi}.
255		255
256	@item channels	256	@item channels
257	Defines number of audio channels to capture. Must be @samp{2}, @samp{8} or @samp{16}.	257	Defines number of audio channels to capture. Must be @samp{2}, @samp{8} or @samp{16}.

libavdevice/decklink_dec.cpp+45−16

 extern "C" {
 #include "config.h"
 #include "libavformat/avformat.h"
+#include "libavutil/avassert.h"
 #include "libavutil/avutil.h"
 #include "libavutil/common.h"
 #include "libavutil/imgutils.h"
     return ret;
 }
-int teletext_data_unit_from_vbi_data(int line, uint8_t *src, uint8_t *tgt)
+static void fill_data_unit_head(int line, uint8_t *tgt)
+{
+    tgt[0] = 0x02; // data_unit_id
+    tgt[1] = 0x2c; // data_unit_length
+    tgt[2] = calc_parity_and_line_offset(line); // field_parity, line_offset
+    tgt[3] = 0xe4; // framing code
+}
+static uint8_t* teletext_data_unit_from_vbi_data(int line, uint8_t *src, uint8_t *tgt, vbi_pixfmt fmt)
 {
     vbi_bit_slicer slicer;
-    vbi_bit_slicer_init(&slicer, 720, 13500000, 6937500, 6937500, 0x00aaaae4, 0xffff, 18, 6, 42 * 8, VBI_MODULATION_NRZ_MSB, VBI_PIXFMT_UYVY);
+    vbi_bit_slicer_init(&slicer, 720, 13500000, 6937500, 6937500, 0x00aaaae4, 0xffff, 18, 6, 42 * 8, VBI_MODULATION_NRZ_MSB, fmt);
     if (vbi_bit_slice(&slicer, src, tgt + 4) == FALSE)
-        return -1;
+        return tgt;
-    tgt[0] = 0x02; // data_unit_id
+    fill_data_unit_head(line, tgt);
-    tgt[1] = 0x2c; // data_unit_length
-    tgt[2] = calc_parity_and_line_offset(line); // field_parity, line_offset
-    tgt[3] = 0xe4; // framing code
-    return 0;
+    return tgt + 46;
+}
+static uint8_t* teletext_data_unit_from_vbi_data_10bit(int line, uint8_t *src, uint8_t *tgt)
+{
+    uint8_t y[720];
+    uint8_t *py = y;
+    uint8_t *pend = y + 720;
+    /* The 10-bit VBI data is packed in V210, but libzvbi only supports 8-bit,
+     * so we extract the 8 MSBs of the luma component, that is enough for
+     * teletext bit slicing. */
+    while (py < pend) {
+        *py++ = (src[1] >> 4) + ((src[2] & 15) << 4);
+        *py++ = (src[4] >> 2) + ((src[5] & 3 ) << 6);
+        *py++ = (src[6] >> 6) + ((src[7] & 63) << 2);
+        src += 8;
+    }
+    return teletext_data_unit_from_vbi_data(line, y, tgt, VBI_PIXFMT_YUV420);
 }
 #endif
         //fprintf(stderr,"Video Frame size %d ts %d\n", pkt.size, pkt.pts);
 #if CONFIG_LIBZVBI
-        if (!no_video && ctx->teletext_lines && videoFrame->GetPixelFormat() == bmdFormat8BitYUV && videoFrame->GetWidth() == 720) {
+        if (!no_video && ctx->teletext_lines) {
             IDeckLinkVideoFrameAncillary *vanc;
             AVPacket txt_pkt;
             uint8_t txt_buf0[1611]; // max 35 * 46 bytes decoded teletext lines + 1 byte data_identifier
             if (videoFrame->GetAncillaryData(&vanc) == S_OK) {
                 int i;
                 int64_t line_mask = 1;
+                BMDPixelFormat vanc_format = vanc->GetPixelFormat();
                 txt_buf[0] = 0x10;    // data_identifier - EBU_data
                 txt_buf++;
-                for (i = 6; i < 336; i++, line_mask <<= 1) {
+                if (ctx->bmd_mode == bmdModePAL && (vanc_format == bmdFormat8BitYUV || vanc_format == bmdFormat10BitYUV)) {
-                    uint8_t *buf;
+                    av_assert0(videoFrame->GetWidth() == 720);
-                    if ((ctx->teletext_lines & line_mask) && vanc->GetBufferForVerticalBlankingLine(i, (void**)&buf) == S_OK) {
+                    for (i = 6; i < 336; i++, line_mask <<= 1) {
-                        if (teletext_data_unit_from_vbi_data(i, buf, txt_buf) >= 0)
+                        uint8_t *buf;
-                            txt_buf += 46;
+                        if ((ctx->teletext_lines & line_mask) && vanc->GetBufferForVerticalBlankingLine(i, (void**)&buf) == S_OK) {
+                            if (vanc_format == bmdFormat8BitYUV)
+                                txt_buf = teletext_data_unit_from_vbi_data(i, buf, txt_buf, VBI_PIXFMT_UYVY);
+                            else
+                                txt_buf = teletext_data_unit_from_vbi_data_10bit(i, buf, txt_buf);
+                        }
+                        if (i == 22)
+                            i = 317;
                     }
-                    if (i == 22)
-                        i = 317;
                 }
                 vanc->Release();
                 if (txt_buf - txt_buf0 > 1) {

avdevice/decklink_dec: add support for decoding teletext from 10bit ancillary data

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