ffmpeg: add per-stream input option drop_changed

This is a replacement in ffmpeg for the deprecated avcodec flag AV_CODEC_FLAG_DROPCHANGED. This option is meant to be used when the filtergraph should not be reinited upon input parameter changes as that leads to loss of state in the filtergraph potentially leading to broken or aborted output, e.g. inserting of silence with first_pts specified in aresample. Generally useful to avoid corrupted yet decodable packets in live streaming inputs. This option when enabled takes precedence over reinit_filters

Gyan Doshi committed 1 year ago

Commit cbbc9271 parent 323cb8c5 files · +36 −1Browse files

Unified · Split

5 files

doc/ffmpeg.texi +6 −0
fftools/ffmpeg.h +2 −0
fftools/ffmpeg_demux.c +14 −1
fftools/ffmpeg_filter.c +11 −0
fftools/ffmpeg_opt.c +3 −0

doc/ffmpeg.texi+6−0

 for video, frame resolution or pixel format;
 for audio, sample format, sample rate, channel count or channel layout.
+@item -drop_changed[:@var{stream_specifier}] @var{integer} (@emph{input,per-stream})
+This boolean option determines whether a frame with differing frame parameters mid-stream
+gets dropped instead of leading to filtergraph reinitialization, as that would lead to loss
+of filter state. Generally useful to avoid corrupted yet decodable packets in live streaming
+inputs. Default is false.
 @item -filter_threads @var{nb_threads} (@emph{global})
 Defines how many threads are used to process a filter pipeline. Each pipeline
 will produce a thread pool with this many threads available for parallel processing.

fftools/ffmpeg.h+2−0

     SpecifierOptList filter_scripts;
 #endif
     SpecifierOptList reinit_filters;
+    SpecifierOptList drop_changed;
     SpecifierOptList fix_sub_duration;
     SpecifierOptList fix_sub_duration_heartbeat;
     SpecifierOptList canvas_sizes;
     IFILTER_FLAG_REINIT         = (1 << 1),
     IFILTER_FLAG_CFR            = (1 << 2),
     IFILTER_FLAG_CROP           = (1 << 3),
+    IFILTER_FLAG_DROPCHANGED    = (1 << 4),
 };
 typedef struct InputFilterOptions {

fftools/ffmpeg_demux.c+14−1

     int                      reinit_filters;
     int                      autorotate;
     int                      apply_cropping;
+    int                      drop_changed;
     int                      wrap_correction_done;
         return AVERROR(ENOMEM);
     opts->flags |= IFILTER_FLAG_AUTOROTATE * !!(ds->autorotate) |
-                   IFILTER_FLAG_REINIT     * !!(ds->reinit_filters);
+                   IFILTER_FLAG_REINIT     * !!(ds->reinit_filters) |
+                   IFILTER_FLAG_DROPCHANGED* !!(ds->drop_changed);
     return 0;
 }
     ds->reinit_filters = -1;
     opt_match_per_stream_int(ist, &o->reinit_filters, ic, st, &ds->reinit_filters);
+    ds->drop_changed = 0;
+    opt_match_per_stream_int(ist, &o->drop_changed, ic, st, &ds->drop_changed);
+    if (ds->drop_changed && ds->reinit_filters) {
+        if (ds->reinit_filters > 0) {
+            av_log(ist, AV_LOG_ERROR, "drop_changed and reinit_filters both enabled. These are mutually exclusive.\n");
+            return AVERROR(EINVAL);
+        }
+        ds->reinit_filters = 0;
+    }
     ist->user_set_discard = AVDISCARD_NONE;
     if ((o->video_disable && ist->st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) ||

fftools/ffmpeg_filter.c+11−0

     int                 eof;
     int                 bound;
+    int                 drop_warned;
+    uint64_t            nb_dropped;
     // parameters configured for this input
     int                 format;
     } else if (ifp->downmixinfo_present)
         need_reinit |= DOWNMIX_CHANGED;
+    if (need_reinit && (ifp->opts.flags & IFILTER_FLAG_DROPCHANGED)) {
+            ifp->nb_dropped++;
+            av_log_once(fg, AV_LOG_WARNING, AV_LOG_DEBUG, &ifp->drop_warned, "Avoiding reinit; dropping frame pts: %s bound for %s\n", av_ts2str(frame->pts), ifilter->name);
+            av_frame_unref(frame);
+            return 0;
+    }
     if (!(ifp->opts.flags & IFILTER_FLAG_REINIT) && fgt->graph)
         need_reinit = 0;
         ret = read_frames(fg, &fgt, fgt.frame);
         if (ret == AVERROR_EOF) {
             av_log(fg, AV_LOG_VERBOSE, "All consumers returned EOF\n");
+            if (ifp->opts.flags & IFILTER_FLAG_DROPCHANGED)
+                av_log(fg, AV_LOG_INFO, "Total changed input frames dropped : %"PRId64"\n", ifp->nb_dropped);
             break;
         } else if (ret < 0) {
             av_log(fg, AV_LOG_ERROR, "Error sending frames to consumers: %s\n",

fftools/ffmpeg_opt.c+3−0

     { "reinit_filter",          OPT_TYPE_INT, OPT_PERSTREAM | OPT_INPUT | OPT_EXPERT,
         { .off = OFFSET(reinit_filters) },
         "reinit filtergraph on input parameter changes", "" },
+    { "drop_changed",          OPT_TYPE_INT, OPT_PERSTREAM | OPT_INPUT | OPT_EXPERT,
+        { .off = OFFSET(drop_changed) },
+        "drop frame instead of reiniting filtergraph on input parameter changes", "" },
     { "filter_complex",         OPT_TYPE_FUNC, OPT_FUNC_ARG | OPT_EXPERT,
         { .func_arg = opt_filter_complex },
         "create a complex filtergraph", "graph_description" },

ffmpeg: add per-stream input option drop_changed

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