From c837cd3d4d11b7d304ff83a448831c81a53c8c25 Mon Sep 17 00:00:00 2001
From: Ray Tiley <raytiley@gmail.com>
Date: Sun, 11 Feb 2018 16:16:45 -0800
Subject: [PATCH] avdevice/decklink_dec: extract NTSC VANC
This changes how NTSC VANC is extracted from the buffer. In NTSC the vanc data
is interleaved between luma and chroma, and not just the luma as in high
definition resolutions.
In my testing this allows a decklink card encoding valid NTSC closed
captions to pass the caption data to the x264 encoder.
Updated with reviews from Devin Heitmueller and Marton Balint.
Signed-off-by: Ray Tiley <raytiley@gmail.com>
Signed-off-by: Marton Balint <cus@passwd.hu>
---
libavdevice/decklink_dec.cpp | 23 ++++++++++++++++++++---
1 file changed, 20 insertions(+), 3 deletions(-)
diff --git a/libavdevice/decklink_dec.cpp b/libavdevice/decklink_dec.cpp
index 5c116f2d137..c3bb46e18f9 100644
--- a/libavdevice/decklink_dec.cpp
+++ b/libavdevice/decklink_dec.cpp
@@ -149,6 +149,17 @@ static void extract_luma_from_v210(uint16_t *dst, const uint8_t *src, int width)
}
}
+static void unpack_v210(uint16_t *dst, const uint8_t *src, int width)
+{
+ int i;
+ for (i = 0; i < width * 2 / 3; i++) {
+ *dst++ = src[0] + ((src[1] & 3) << 8);
+ *dst++ = (src[1] >> 2) + ((src[2] & 15) << 6);
+ *dst++ = (src[2] >> 4) + ((src[3] & 63) << 4);
+ src += 4;
+ }
+}
+
static uint8_t calc_parity_and_line_offset(int line)
{
uint8_t ret = (line < 313) << 5;
@@ -752,9 +763,15 @@ HRESULT decklink_input_callback::VideoInputFrameArrived(
for (i = vanc_line_numbers[idx].vanc_start; i <= vanc_line_numbers[idx].vanc_end; i++) {
uint8_t *buf;
if (vanc->GetBufferForVerticalBlankingLine(i, (void**)&buf) == S_OK) {
- uint16_t luma_vanc[MAX_WIDTH_VANC];
- extract_luma_from_v210(luma_vanc, buf, videoFrame->GetWidth());
- txt_buf = get_metadata(avctx, luma_vanc, videoFrame->GetWidth(),
+ uint16_t vanc[MAX_WIDTH_VANC];
+ size_t vanc_size = videoFrame->GetWidth();
+ if (ctx->bmd_mode == bmdModeNTSC && videoFrame->GetWidth() * 2 <= MAX_WIDTH_VANC) {
+ vanc_size = vanc_size * 2;
+ unpack_v210(vanc, buf, videoFrame->GetWidth());
+ } else {
+ extract_luma_from_v210(vanc, buf, videoFrame->GetWidth());
+ }
+ txt_buf = get_metadata(avctx, vanc, vanc_size,
txt_buf, sizeof(txt_buf0) - (txt_buf - txt_buf0), &pkt);
}
if (i == vanc_line_numbers[idx].field0_vanc_end)
--
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