lavc: allow subtitle text format to be ASS without timing

1 files changed, 74 insertions, 0 deletions

diff --git a/libavcodec/utils.c b/libavcodec/utils.c
index 90ece2f343..49a3e88710 100644
--- a/libavcodec/utils.c
+++ b/libavcodec/utils.c
@@ -2426,6 +2426,76 @@ static int utf8_check(const uint8_t *str)
     return 1;
 }
 
+static void insert_ts(AVBPrint *buf, int ts)
+{
+    if (ts == -1) {
+        av_bprintf(buf, "9:59:59.99,");
+    } else {
+        int h, m, s;
+
+        h = ts/360000;  ts -= 360000*h;
+        m = ts/  6000;  ts -=   6000*m;
+        s = ts/   100;  ts -=    100*s;
+        av_bprintf(buf, "%d:%02d:%02d.%02d,", h, m, s, ts);
+    }
+}
+
+static int convert_sub_to_old_ass_form(AVSubtitle *sub, const AVPacket *pkt, AVRational tb)
+{
+    int i;
+    AVBPrint buf;
+
+    av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);
+
+    for (i = 0; i < sub->num_rects; i++) {
+        char *final_dialog;
+        const char *dialog;
+        AVSubtitleRect *rect = sub->rects[i];
+        int ts_start, ts_duration = -1;
+        long int layer;
+
+        if (rect->type != SUBTITLE_ASS || !strncmp(rect->ass, "Dialogue ", 10))
+            continue;
+
+        av_bprint_clear(&buf);
+
+        /* skip ReadOrder */
+        dialog = strchr(rect->ass, ',');
+        if (!dialog)
+            continue;
+        dialog++;
+
+        /* extract Layer or Marked */
+        layer = strtol(dialog, (char**)&dialog, 10);
+        if (*dialog != ',')
+            continue;
+        dialog++;
+
+        /* rescale timing to ASS time base (ms) */
+        ts_start = av_rescale_q(pkt->pts, tb, av_make_q(1, 100));
+        if (pkt->duration != -1)
+            ts_duration = av_rescale_q(pkt->duration, tb, av_make_q(1, 100));
+        sub->end_display_time = FFMAX(sub->end_display_time, 10 * ts_duration);
+
+        /* construct ASS (standalone file form with timestamps) string */
+        av_bprintf(&buf, "Dialogue: %ld,", layer);
+        insert_ts(&buf, ts_start);
+        insert_ts(&buf, ts_duration == -1 ? -1 : ts_start + ts_duration);
+        av_bprintf(&buf, "%s\r\n", dialog);
+
+        final_dialog = av_strdup(buf.str);
+        if (!av_bprint_is_complete(&buf) || !final_dialog) {
+            av_bprint_finalize(&buf, NULL);
+            return AVERROR(ENOMEM);
+        }
+        av_freep(&rect->ass);
+        rect->ass = final_dialog;
+    }
+
+    av_bprint_finalize(&buf, NULL);
+    return 0;
+}
+
 int avcodec_decode_subtitle2(AVCodecContext *avctx, AVSubtitle *sub,
                              int *got_sub_ptr,
                              AVPacket *avpkt)
@@ -2476,6 +2546,10 @@ int avcodec_decode_subtitle2(AVCodecContext *avctx, AVSubtitle *sub,
             av_assert1((ret >= 0) >= !!*got_sub_ptr &&
                        !!*got_sub_ptr >= !!sub->num_rects);
 
+            if (avctx->sub_text_format == FF_SUB_TEXT_FMT_ASS_WITH_TIMINGS
+                && *got_sub_ptr && sub->num_rects)
+                ret = convert_sub_to_old_ass_form(sub, avpkt, avctx->time_base);
+
             if (sub->num_rects && !sub->end_display_time && avpkt->duration &&
                 avctx->pkt_timebase.num) {
                 AVRational ms = { 1, 1000 };