Adding -force_cfr commandline flag

Author: srikanth-descript

fftools/ffmpeg.h

@@ -176,6 +176,7 @@ typedef struct OptionsContext {
     SpecifierOptList hwaccel_output_formats;
     SpecifierOptList autorotate;
     SpecifierOptList apply_cropping;
+    SpecifierOptList force_cfr;
 
     /* output options */
     StreamMap *stream_maps;
@@ -276,6 +277,9 @@ typedef struct InputFilterOptions {
      * accurate */
     AVRational          framerate;
 
+    /* convert input stream to CFR at this framerate before inserting additional filters */
+    AVRational                force_cfr;
+
     unsigned            crop_top;
     unsigned            crop_bottom;
     unsigned            crop_left;
@@ -451,6 +455,9 @@ typedef struct InputStream {
 
     /* framerate forced with -r */
     AVRational            framerate;
+
+    /* convert input stream to CFR at this framerate before inserting additional filters */
+    AVRational                force_cfr;
 #if FFMPEG_OPT_TOP
     int                   top_field_first;
 #endif

fftools/ffmpeg_demux.c

@@ -1032,6 +1032,10 @@ int ist_filter_add(InputStream *ist, InputFilter *ifilter, int is_simple,
                 (opts->crop_top | opts->crop_bottom | opts->crop_left | opts->crop_right))
                 opts->flags |= IFILTER_FLAG_CROP;
         }
+        if (ist->force_cfr.num > 0 && ist->force_cfr.den > 0) {
+            opts->force_cfr = ist->force_cfr;
+            opts->flags |= IFILTER_FLAG_CFR;
+        }
     } else if (ist->par->codec_type == AVMEDIA_TYPE_SUBTITLE) {
         /* Compute the size of the canvas for the subtitles stream.
            If the subtitles codecpar has set a size, use it. Otherwise use the
@@ -1241,7 +1245,7 @@ static int ist_add(const OptionsContext *o, Demuxer *d, AVStream *st, AVDictiona
     AVCodecParameters *par = st->codecpar;
     DemuxStream *ds;
     InputStream *ist;
-    const char *framerate = NULL, *hwaccel_device = NULL;
+    const char *framerate = NULL, *hwaccel_device = NULL, *forcecfr = NULL;
     const char *hwaccel = NULL;
     const char *apply_cropping = NULL;
     const char *hwaccel_output_format = NULL;
@@ -1437,6 +1441,15 @@ static int ist_add(const OptionsContext *o, Demuxer *d, AVStream *st, AVDictiona
             }
         }
 
+        opt_match_per_stream_str(ist, &o->force_cfr, ic, st, &forcecfr);
+        if (forcecfr) {
+            ret = av_parse_video_rate(&ist->force_cfr, forcecfr);
+            if (ret < 0) {
+                av_log(ist, AV_LOG_ERROR, "Error parsing framerate %s.\n", forcecfr);
+                return ret;
+            }
+        }
+
 #if FFMPEG_OPT_TOP
         ist->top_field_first = -1;
         opt_match_per_stream_int(ist, &o->top_field_first, ic, st, &ist->top_field_first);

fftools/ffmpeg_filter.c

@@ -1781,6 +1781,15 @@ static int configure_input_video_filter(FilterGraph *fg, AVFilterGraph *graph,
         ifp->displaymatrix_applied = 1;
     }
 
+    if (ifp->opts.force_cfr.num > 0 && ifp->opts.force_cfr.den > 0) {
+        char force_cfr_buf[64];
+        snprintf(force_cfr_buf, sizeof(force_cfr_buf), "%d/%d",
+                 ifp->opts.force_cfr.num, ifp->opts.force_cfr.den);
+        ret = insert_filter(&last_filter, &pad_idx, "fps", force_cfr_buf);
+        if (ret < 0)
+            return ret;
+    }
+
     snprintf(name, sizeof(name), "trim_in_%s", ifp->opts.name);
     ret = insert_trim(ifp->opts.trim_start_us, ifp->opts.trim_end_us,
                       &last_filter, &pad_idx, name);

fftools/ffmpeg_opt.c

@@ -2033,5 +2033,9 @@ const OptionDef options[] = {
         "set video sync method globally; deprecated, use -fps_mode", "" },
 #endif
 
+    { "force_cfr", OPT_TYPE_STRING, OPT_VIDEO | OPT_EXPERT | OPT_PERSTREAM | OPT_INPUT,
+        { .off = OFFSET(force_cfr) },
+        "set frame rate (Hz value, fraction or abbreviation)", "force_cfr" },
+
     { NULL, },
 };