vf_interlace.c 7.78 KB
Newer Older
Vittorio Giovara's avatar
Vittorio Giovara committed
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128
/*
 * This file is part of Libav.
 *
 * Libav is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * Libav is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with Libav; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

/**
 * @file
 * progressive to interlaced content filter, inspired by heavy debugging of tinterlace filter
 */

#include "libavutil/common.h"
#include "libavutil/opt.h"
#include "libavutil/imgutils.h"
#include "libavutil/avassert.h"

#include "formats.h"
#include "avfilter.h"
#include "internal.h"
#include "video.h"

enum ScanMode {
    MODE_TFF = 0,
    MODE_BFF = 1,
};

enum FieldType {
    FIELD_UPPER = 0,
    FIELD_LOWER = 1,
};

typedef struct {
    const AVClass *class;
    enum ScanMode scan;    // top or bottom field first scanning
    int lowpass;           // enable or disable low pass filterning
    AVFrame *cur, *next;   // the two frames from which the new one is obtained
    int got_output;        // signal an output frame is reday to request_frame()
} InterlaceContext;

#define OFFSET(x) offsetof(InterlaceContext, x)
#define V AV_OPT_FLAG_VIDEO_PARAM
static const AVOption options[] = {
    { "scan", "scanning mode", OFFSET(scan),
        AV_OPT_TYPE_INT,   {.i64 = MODE_TFF }, 0, 1, .flags = V, .unit = "scan" },
    { "tff", "top field first", 0,
        AV_OPT_TYPE_CONST, {.i64 = MODE_TFF }, INT_MIN, INT_MAX, .flags = V, .unit = "scan" },
    { "bff", "bottom field first", 0,
        AV_OPT_TYPE_CONST, {.i64 = MODE_BFF }, INT_MIN, INT_MAX, .flags = V, .unit = "scan" },
    { "lowpass", "enable vertical low-pass filter", OFFSET(lowpass),
        AV_OPT_TYPE_INT,   {.i64 = 1 },        0, 1, .flags = V },
    { NULL }
};

static const AVClass class = {
    .class_name = "interlace filter",
    .item_name  = av_default_item_name,
    .option     = options,
    .version    = LIBAVUTIL_VERSION_INT,
};


static const enum AVPixelFormat formats_supported[] = {
    AV_PIX_FMT_YUV420P,  AV_PIX_FMT_YUV422P,  AV_PIX_FMT_YUV444P,
    AV_PIX_FMT_YUV444P,  AV_PIX_FMT_YUV410P,  AV_PIX_FMT_YUVA420P,
    AV_PIX_FMT_GRAY8,    AV_PIX_FMT_YUVJ420P, AV_PIX_FMT_YUVJ422P,
    AV_PIX_FMT_YUVJ444P, AV_PIX_FMT_YUVJ440P, AV_PIX_FMT_NONE
};

static int query_formats(AVFilterContext *ctx)
{
    ff_set_common_formats(ctx, ff_make_format_list(formats_supported));
    return 0;
}

static av_cold void uninit(AVFilterContext *ctx)
{
    InterlaceContext *s = ctx->priv;

    av_frame_free(&s->cur);
    av_frame_free(&s->next);

    av_opt_free(s);
}

static int config_out_props(AVFilterLink *outlink)
{
    AVFilterContext *ctx = outlink->src;
    AVFilterLink *inlink = outlink->src->inputs[0];
    InterlaceContext *s = ctx->priv;

    if (inlink->h < 2) {
        av_log(ctx, AV_LOG_ERROR, "input video height is too small\n");
        return AVERROR_INVALIDDATA;
    }
    // same input size
    outlink->w = inlink->w;
    outlink->h = inlink->h;
    outlink->time_base = inlink->time_base;
    // half framerate
    outlink->time_base.num *= 2;

    av_log(ctx, AV_LOG_VERBOSE, "%s interlacing %s lowpass filter\n",
           s->scan == MODE_TFF ? "tff" : "bff", (s->lowpass) ? "with" : "without");

    return 0;
}

static void copy_picture_field(AVFrame *src_frame, AVFrame *dst_frame,
                               AVFilterLink *inlink, enum FieldType field_type,
                               int lowpass)
{
    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
    int vsub = desc->log2_chroma_h;
    int plane, i, j;

    for (plane = 0; plane < desc->nb_components; plane++) {
129
        int lines = (plane == 1 || plane == 2) ? -(-inlink->h) >> vsub : inlink->h;
Vittorio Giovara's avatar
Vittorio Giovara committed
130 131 132 133 134 135
        int linesize = av_image_get_linesize(inlink->format, inlink->w, plane);
        uint8_t *dstp = dst_frame->data[plane];
        const uint8_t *srcp = src_frame->data[plane];

        av_assert0(linesize >= 0);

136
        lines = (lines + (field_type == FIELD_UPPER)) / 2;
Vittorio Giovara's avatar
Vittorio Giovara committed
137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152
        if (field_type == FIELD_LOWER)
            srcp += src_frame->linesize[plane];
        if (field_type == FIELD_LOWER)
            dstp += dst_frame->linesize[plane];
        if (lowpass) {
            int srcp_linesize = src_frame->linesize[plane] * 2;
            int dstp_linesize = dst_frame->linesize[plane] * 2;
            for (j = lines; j > 0; j--) {
                const uint8_t *srcp_above = srcp - src_frame->linesize[plane];
                const uint8_t *srcp_below = srcp + src_frame->linesize[plane];
                if (j == lines)
                    srcp_above = srcp; // there is no line above
                if (j == 1)
                    srcp_below = srcp; // there is no line below
                for (i = 0; i < linesize; i++) {
                    // this calculation is an integer representation of
153
                    // '0.5 * current + 0.25 * above + 0.25 * below'
Vittorio Giovara's avatar
Vittorio Giovara committed
154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252
                    // '1 +' is for rounding.
                    dstp[i] = (1 + srcp[i] + srcp[i] + srcp_above[i] + srcp_below[i]) >> 2;
                }
                dstp += dstp_linesize;
                srcp += srcp_linesize;
            }
        } else {
            av_image_copy_plane(dstp, dst_frame->linesize[plane] * 2,
                                srcp, src_frame->linesize[plane] * 2,
                                linesize, lines);
        }
    }
}

static int filter_frame(AVFilterLink *inlink, AVFrame *buf)
{
    AVFilterContext *ctx = inlink->dst;
    AVFilterLink *outlink = ctx->outputs[0];
    InterlaceContext *s = ctx->priv;
    AVFrame *out;
    int tff, ret;

    av_frame_free(&s->cur);
    s->cur  = s->next;
    s->next = buf;

    /* we need at least two frames */
    if (!s->cur || !s->next)
        return 0;

    tff = (s->scan == MODE_TFF);
    out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
    if (!out)
        return AVERROR(ENOMEM);

    av_frame_copy_props(out, s->cur);
    out->interlaced_frame = 1;
    out->top_field_first  = tff;
    out->pts             /= 2;  // adjust pts to new framerate

    /* copy upper/lower field from cur */
    copy_picture_field(s->cur, out, inlink, tff ? FIELD_UPPER : FIELD_LOWER, s->lowpass);
    av_frame_free(&s->cur);

    /* copy lower/upper field from next */
    copy_picture_field(s->next, out, inlink, tff ? FIELD_LOWER : FIELD_UPPER, s->lowpass);
    av_frame_free(&s->next);

    ret = ff_filter_frame(outlink, out);
    s->got_output = 1;

    return ret;
}

static int request_frame(AVFilterLink *outlink)
{
    AVFilterContext *ctx = outlink->src;
    InterlaceContext *s  = ctx->priv;
    int ret = 0;

    s->got_output = 0;
    while (ret >= 0 && !s->got_output)
        ret = ff_request_frame(ctx->inputs[0]);

    return ret;
}

static const AVFilterPad inputs[] = {
    {
        .name         = "default",
        .type         = AVMEDIA_TYPE_VIDEO,
        .filter_frame = filter_frame,
    },
    { NULL }
};

static const AVFilterPad outputs[] = {
    {
        .name          = "default",
        .type          = AVMEDIA_TYPE_VIDEO,
        .config_props  = config_out_props,
        .request_frame = request_frame,
    },
    { NULL }
};

AVFilter avfilter_vf_interlace = {
    .name          = "interlace",
    .description   = NULL_IF_CONFIG_SMALL("Convert progressive video into interlaced."),
    .uninit        = uninit,

    .priv_class    = &class,
    .priv_size     = sizeof(InterlaceContext),
    .query_formats = query_formats,

    .inputs        = inputs,
    .outputs       = outputs,
};