[FFmpeg-devel] [PATCH 2/4] avdevice/decklink_dec: Extraction of luma from V210 VANC modularized

kjeyapal at akamai.com kjeyapal at akamai.com
Thu Aug 31 11:36:48 EEST 2017


From: Karthick J <kjeyapal at akamai.com>

In preparation to support multiple VANC data decode

Signed-off-by: Karthick J <kjeyapal at akamai.com>
---
 libavdevice/decklink_dec.cpp | 31 ++++++++++++++++++-------------
 1 file changed, 18 insertions(+), 13 deletions(-)

diff --git a/libavdevice/decklink_dec.cpp b/libavdevice/decklink_dec.cpp
index 40ef655..0b88fc8 100644
--- a/libavdevice/decklink_dec.cpp
+++ b/libavdevice/decklink_dec.cpp
@@ -106,6 +106,18 @@ static void get_vanc_lines(int bmd_field_dominance, int height, int *field0_vanc
     }
 }
 
+/* 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)
+{
+    int i;
+    for (i = 0; i < width / 3; i += 3) {
+        *dst++ = (src[1] >> 2) + ((src[2] & 15) << 6);
+        *dst++ =  src[4]       + ((src[5] &  3) << 8);
+        *dst++ = (src[6] >> 4) + ((src[7] & 63) << 4);
+        src += 8;
+    }
+}
+
 static uint8_t calc_parity_and_line_offset(int line)
 {
     uint8_t ret = (line < 313) << 5;
@@ -221,19 +233,10 @@ 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(uint8_t *src, uint8_t *tgt, int64_t wanted_lines)
+static uint8_t* teletext_data_unit_from_vanc_data(uint16_t *py, uint8_t *tgt, int64_t wanted_lines)
 {
-    uint16_t y[1920];
-    uint16_t *py = y;
-    uint16_t *pend = y + 1920;
-    /* The 10-bit VANC data is packed in V210, we only need the luma component. */
-    while (py < pend) {
-        *py++ = (src[1] >> 2) + ((src[2] & 15) << 6);
-        *py++ =  src[4]       + ((src[5] &  3) << 8);
-        *py++ = (src[6] >> 4) + ((src[7] & 63) << 4);
-        src += 8;
-    }
-    py = y;
+    uint16_t *pend = py + 1920;
+
     while (py < pend - 6) {
         if (py[0] == 0 && py[1] == 0x3ff && py[2] == 0x3ff) {           // ancillary data flag
             py += 3;
@@ -570,8 +573,10 @@ HRESULT decklink_input_callback::VideoInputFrameArrived(
                     for (i = 0; i <= vanc_end; i++) {
                         uint8_t *buf;
                         if (vanc->GetBufferForVerticalBlankingLine(i, (void**)&buf) == S_OK) {
+                            uint16_t luma_vanc[4096]; // Allocated for highest width (4K)
+                            extract_luma_from_v210(luma_vanc, buf, videoFrame->GetWidth());
                             if (videoFrame->GetWidth() == 1920) {
-                                txt_buf = teletext_data_unit_from_vanc_data(buf, txt_buf, ctx->teletext_lines);
+                                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;
-- 
1.9.1



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