[FFmpeg-devel] [RFC PATCH 4/5] tinterlace: Properly preserve CEA-708 closed captions
Thomas Mundt
tmundt75 at gmail.com
Sat Mar 18 19:12:09 EET 2023
Hi Devin,
Am Fr., 17. März 2023 um 21:10 Uhr schrieb Devin Heitmueller <
devin.heitmueller at ltnglobal.com>:
> Because the interlacing filter halves the effective framerate, we
> need to ensure that no CEA-708 data is lost as frames are merged.
>
Not all modes of tinterlace halve the frame rate. mergex2 and pad keep it,
interlacex2 even doubles it.
> Make use of the new ccfifo mechanism to ensure that caption data
> is properly preserved as frames pass through the filter.
>
> Signed-off-by: Devin Heitmueller <dheitmueller at ltnglobal.com>
> ---
> libavfilter/tinterlace.h | 2 ++
> libavfilter/vf_tinterlace.c | 10 ++++++++++
> 2 files changed, 12 insertions(+)
>
> diff --git a/libavfilter/tinterlace.h b/libavfilter/tinterlace.h
> index 37b6c10c08..30574c2ebf 100644
> --- a/libavfilter/tinterlace.h
> +++ b/libavfilter/tinterlace.h
> @@ -30,6 +30,7 @@
> #include "libavutil/bswap.h"
> #include "libavutil/opt.h"
> #include "libavutil/pixdesc.h"
> +#include "libavutil/ccfifo.h"
> #include "drawutils.h"
> #include "avfilter.h"
>
> @@ -77,6 +78,7 @@ typedef struct TInterlaceContext {
> const AVPixFmtDescriptor *csp;
> void (*lowpass_line)(uint8_t *dstp, ptrdiff_t width, const uint8_t
> *srcp,
> ptrdiff_t mref, ptrdiff_t pref, int clip_max);
> + AVCCFifo *cc_fifo;
> } TInterlaceContext;
>
> void ff_tinterlace_init_x86(TInterlaceContext *interlace);
> diff --git a/libavfilter/vf_tinterlace.c b/libavfilter/vf_tinterlace.c
> index 032629279a..260386a889 100644
> --- a/libavfilter/vf_tinterlace.c
> +++ b/libavfilter/vf_tinterlace.c
> @@ -291,6 +291,9 @@ static int config_out_props(AVFilterLink *outlink)
> #endif
> }
>
> + if (!(tinterlace->cc_fifo = av_ccfifo_alloc(&outlink->frame_rate,
> ctx)))
> + av_log(ctx, AV_LOG_VERBOSE, "Failure to setup CC FIFO queue.
> Captions will be passed through\n");
> +
> av_log(ctx, AV_LOG_VERBOSE, "mode:%d filter:%s h:%d -> h:%d\n",
> tinterlace->mode,
> (tinterlace->flags & TINTERLACE_FLAG_CVLPF) ? "complex" :
> (tinterlace->flags & TINTERLACE_FLAG_VLPF) ? "linear" : "off",
> @@ -375,6 +378,8 @@ static int filter_frame(AVFilterLink *inlink, AVFrame
> *picref)
> tinterlace->cur = tinterlace->next;
> tinterlace->next = picref;
>
> + av_ccfifo_extract(tinterlace->cc_fifo, picref);
> +
> cur = tinterlace->cur;
> next = tinterlace->next;
> /* we need at least two frames */
> @@ -390,6 +395,7 @@ static int filter_frame(AVFilterLink *inlink, AVFrame
> *picref)
> if (!out)
> return AVERROR(ENOMEM);
> av_frame_copy_props(out, cur);
> + av_ccfifo_inject(tinterlace->cc_fifo, out);
> out->height = outlink->h;
> out->interlaced_frame = 1;
> out->top_field_first = 1;
> @@ -423,6 +429,7 @@ static int filter_frame(AVFilterLink *inlink, AVFrame
> *picref)
>
Are the drop modes missing?
Would it perhaps be clearer to put av_ccfifo_inject before ff_filter_frame?
> if (!out)
> return AVERROR(ENOMEM);
> av_frame_copy_props(out, cur);
> + av_ccfifo_inject(tinterlace->cc_fifo, out);
> out->height = outlink->h;
> out->sample_aspect_ratio = av_mul_q(cur->sample_aspect_ratio,
> av_make_q(2, 1));
>
> @@ -459,6 +466,7 @@ static int filter_frame(AVFilterLink *inlink, AVFrame
> *picref)
> if (!out)
> return AVERROR(ENOMEM);
> av_frame_copy_props(out, cur);
> + av_ccfifo_inject(tinterlace->cc_fifo, out);
> out->interlaced_frame = 1;
> out->top_field_first = tff;
>
> @@ -481,6 +489,7 @@ static int filter_frame(AVFilterLink *inlink, AVFrame
> *picref)
> out = av_frame_clone(cur);
> if (!out)
> return AVERROR(ENOMEM);
> + av_ccfifo_inject(tinterlace->cc_fifo, out);
> out->interlaced_frame = 1;
> if (cur->pts != AV_NOPTS_VALUE)
> out->pts = cur->pts*2;
> @@ -495,6 +504,7 @@ static int filter_frame(AVFilterLink *inlink, AVFrame
> *picref)
> if (!out)
> return AVERROR(ENOMEM);
> av_frame_copy_props(out, next);
> + av_ccfifo_inject(tinterlace->cc_fifo, out);
> out->interlaced_frame = 1;
> out->top_field_first = !tff;
>
> --
>
Regards,
Thomas
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