[FFmpeg-devel] [PATCH] avdevice/decklink_dec: Extract NTSC VANC

[Ray Tiley]

On Sun, Jan 28, 2018 at 9:40 PM Ray Tiley <raytiley at gmail.com> wrote:

> This changes how NTSC VANC is extracted from the buffer. In NTSC the vanc
> data interleved between the uyvy 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 rewviews from Devon Heitmueller and Marton Balint.
>
> Signed-off-by: Ray Tiley <raytiley at gmail.com>
> ---
>  libavdevice/decklink_dec.cpp | 30 +++++++++++++++++++++++++++++-
>  1 file changed, 29 insertions(+), 1 deletion(-)
>
> diff --git a/libavdevice/decklink_dec.cpp b/libavdevice/decklink_dec.cpp
> index 94dae26..c7811eb 100644
> --- a/libavdevice/decklink_dec.cpp
> +++ b/libavdevice/decklink_dec.cpp
> @@ -149,6 +149,30 @@ 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 / 6; i++) {
> +        *dst++ =  src[0]       + ((src[1] & 3)  << 8);
> +        *dst++ = (src[1] >> 2) + ((src[2] & 15) << 6);
> +        *dst++ = (src[2] >> 4) + ((src[3] & 63) << 4);
> +
> +        *dst++ =  src[4]       + ((src[5] & 3)  << 8);
> +        *dst++ = (src[5] >> 2) + ((src[6] & 15) << 6);
> +        *dst++ = (src[6] >> 4) + ((src[7] & 63) << 4);
> +
> +        *dst++ =  src[8]       + ((src[9] & 3)  << 8);
> +        *dst++ = (src[9] >> 2) + ((src[10] & 15) << 6);
> +        *dst++ = (src[10] >> 4) + ((src[11] & 63) << 4);
> +
> +        *dst++ =  src[12]       + ((src[13] & 3)  << 8);
> +        *dst++ = (src[13] >> 2) + ((src[14] & 15) << 6);
> +        *dst++ = (src[14] >> 4) + ((src[15] & 63) << 4);
> +
> +        src += 16;
> +    }
> +}
> +
>  static uint8_t calc_parity_and_line_offset(int line)
>  {
>      uint8_t ret = (line < 313) << 5;
> @@ -741,7 +765,11 @@ HRESULT
> decklink_input_callback::VideoInputFrameArrived(
>                          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());
> +                            if (ctx->bmd_mode == bmdModeNTSC) {
> +                              unpack_v210(luma_vanc, buf,
> videoFrame->GetWidth());
> +                            } else {
> +                              extract_luma_from_v210(luma_vanc, buf,
> videoFrame->GetWidth());
> +                            }
>                              txt_buf = get_metadata(avctx, luma_vanc,
> videoFrame->GetWidth(),
>                                                     txt_buf,
> sizeof(txt_buf0) - (txt_buf - txt_buf0), &pkt);
>                          }
> --
> 2.7.4
>
>

Anything else I need to do for this patch?

Thanks

-ray