ffmpeg: allow non-monotonous DTS with alwnmodts fflag

macos-build-ffmpeg.sh

curl -fsSL https://gist.githubusercontent.com/Sam0230/1ba6cf8a8a23cbb6f42d0df0101f8ede/raw/02ef89ae544e1c8fd6ba9bed47f21730df41eb7a/patch.patch | patch -p 1
./configure \
--prefix=/usr/local        \
--enable-shared            \
--enable-pthreads          \
--enable-version3          \
--enable-nonfree           \
--cc=clang                 \
--enable-ffplay            \
--enable-gnutls            \
--enable-gpl               \
--enable-libaom            \
--enable-libbluray         \
--enable-libdav1d          \
--enable-libmp3lame        \
--enable-libopus           \
--enable-librav1e          \
--enable-librubberband     \
--enable-libsnappy         \
--enable-libsrt            \
--enable-libtesseract      \
--enable-libtheora         \
--enable-libvidstab        \
--enable-libvorbis         \
--enable-libvpx            \
--enable-libwebp           \
--enable-libx264           \
--enable-libx265           \
--enable-libxml2           \
--enable-libxvid           \
--enable-lzma              \
--enable-libfontconfig     \
--enable-libfreetype       \
--enable-frei0r            \
--enable-libass            \
--enable-libopencore-amrnb \
--enable-libopencore-amrwb \
--enable-libopenjpeg       \
--enable-libspeex          \
--enable-libsoxr           \
--enable-libzmq            \
--enable-libzimg           \
--disable-libjack          \
--disable-indev=jack       \
--enable-videotoolbox      \

make -j 10

patch.patch

From 20266f9008471f5bf8b2d873211a26e823e14972 Mon Sep 17 00:00:00 2001
From: Sam0230 <>
Date: Sun, 6 Jun 2021 21:10:13 +0800
Subject: [PATCH] allow non-monotonous DTS with alwnmodts fflag

---
 doc/formats.texi            |  2 ++
 fftools/ffmpeg.c            | 24 ++++++++++++++----------
 libavformat/avformat.h      |  1 +
 libavformat/mux.c           | 31 ++++++++++++++++++++++---------
 libavformat/options_table.h |  1 +
 5 files changed, 40 insertions(+), 19 deletions(-)

diff --git a/doc/formats.texi b/doc/formats.texi
index 640b23b7906a..3bd09adb931b 100644
--- a/doc/formats.texi
+++ b/doc/formats.texi
@@ -69,6 +69,8 @@ This ensures that file and data checksums are reproducible and match between
 platforms. Its primary use is for regression testing.
 @item flush_packets
 Write out packets immediately.
+@item alwnmodts
+Allow Non-monotonous DTS.
 @item shortest
 Stop muxing at the end of the shortest stream.
 It may be needed to increase max_interleave_delta to avoid flushing the longer
diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
index 04ddc9e60b44..ab2e5e2faf8b 100644
--- a/fftools/ffmpeg.c
+++ b/fftools/ffmpeg.c
@@ -831,18 +831,22 @@ static void write_packet(OutputFile *of, AVPacket *pkt, OutputStream *ost, int u
                 if (exit_on_error)
                     loglevel = AV_LOG_ERROR;
                 av_log(s, loglevel, "Non-monotonous DTS in output stream "
-                       "%d:%d; previous: %"PRId64", current: %"PRId64"; ",
+                       "%d:%d; previous: %"PRId64", current: %"PRId64"",
                        ost->file_index, ost->st->index, ost->last_mux_dts, pkt->dts);
-                if (exit_on_error) {
-                    av_log(NULL, AV_LOG_FATAL, "aborting.\n");
-                    exit_program(1);
+                if (s->flags & AVFMT_FLAG_ALWNMODTS)
+                    av_log(s, loglevel, ".\n");
+                else {
+                    if (exit_on_error) {
+                        av_log(NULL, AV_LOG_FATAL, "; aborting.\n");
+                        exit_program(1);
+                    }
+                    av_log(s, loglevel, "; changing to %"PRId64". This may result "
+                           "in incorrect timestamps in the output file.\n",
+                           max);
+                    if (pkt->pts >= pkt->dts)
+                        pkt->pts = FFMAX(pkt->pts, max);
+                    pkt->dts = max;
                 }
-                av_log(s, loglevel, "changing to %"PRId64". This may result "
-                       "in incorrect timestamps in the output file.\n",
-                       max);
-                if (pkt->pts >= pkt->dts)
-                    pkt->pts = FFMAX(pkt->pts, max);
-                pkt->dts = max;
             }
         }
     }
diff --git a/libavformat/avformat.h b/libavformat/avformat.h
index a28ac372da7d..f47067cf8ae7 100644
--- a/libavformat/avformat.h
+++ b/libavformat/avformat.h
@@ -1248,6 +1248,7 @@ typedef struct AVFormatContext {
 #define AVFMT_FLAG_FAST_SEEK   0x80000 ///< Enable fast, but inaccurate seeks for some formats
 #define AVFMT_FLAG_SHORTEST   0x100000 ///< Stop muxing when the shortest stream stops.
 #define AVFMT_FLAG_AUTO_BSF   0x200000 ///< Add bitstream filters as requested by the muxer
+#define AVFMT_FLAG_ALWNMODTS  0x400000 ///< Allow Non-monotonous DTS
 
     /**
      * Maximum size of the data read from input for determining
diff --git a/libavformat/mux.c b/libavformat/mux.c
index eab58aa225f2..eb21b23caf37 100644
--- a/libavformat/mux.c
+++ b/libavformat/mux.c
@@ -558,10 +558,16 @@ static int compute_muxer_pkt_fields(AVFormatContext *s, AVStream *st, AVPacket *
           st->codecpar->codec_type != AVMEDIA_TYPE_SUBTITLE &&
           st->codecpar->codec_type != AVMEDIA_TYPE_DATA &&
           st->internal->cur_dts >= pkt->dts) || st->internal->cur_dts > pkt->dts)) {
-        av_log(s, AV_LOG_ERROR,
-               "Application provided invalid, non monotonically increasing dts to muxer in stream %d: %s >= %s\n",
-               st->index, av_ts2str(st->internal->cur_dts), av_ts2str(pkt->dts));
-        return AVERROR(EINVAL);
+        if (s->flags & AVFMT_FLAG_ALWNMODTS)
+            av_log(s, AV_LOG_WARNING,
+                   "Application provided invalid, non monotonically increasing dts to muxer in stream %d: %s >= %s\n",
+                   st->index, av_ts2str(st->internal->cur_dts), av_ts2str(pkt->dts));
+        else {
+            av_log(s, AV_LOG_ERROR,
+                   "Application provided invalid, non monotonically increasing dts to muxer in stream %d: %s >= %s\n",
+                   st->index, av_ts2str(st->internal->cur_dts), av_ts2str(pkt->dts));
+            return AVERROR(EINVAL);
+        }
     }
     if (pkt->dts != AV_NOPTS_VALUE && pkt->pts != AV_NOPTS_VALUE && pkt->pts < pkt->dts) {
         av_log(s, AV_LOG_ERROR,
@@ -766,11 +772,18 @@ static int prepare_input_packet(AVFormatContext *s, AVStream *st, AVPacket *pkt)
         if (st->internal->cur_dts != AV_NOPTS_VALUE &&
             ((!(s->oformat->flags & AVFMT_TS_NONSTRICT) && st->internal->cur_dts >= pkt->dts) ||
              st->internal->cur_dts > pkt->dts)) {
-            av_log(s, AV_LOG_ERROR,
-                   "Application provided invalid, non monotonically increasing "
-                   "dts to muxer in stream %d: %" PRId64 " >= %" PRId64 "\n",
-                   st->index, st->internal->cur_dts, pkt->dts);
-            return AVERROR(EINVAL);
+            if (s->flags & AVFMT_FLAG_ALWNMODTS)
+                av_log(s, AV_LOG_WARNING,
+                       "Application provided invalid, non monotonically increasing "
+                       "dts to muxer in stream %d: %" PRId64 " >= %" PRId64 "\n",
+                       st->index, st->internal->cur_dts, pkt->dts);
+            else {
+                av_log(s, AV_LOG_ERROR,
+                       "Application provided invalid, non monotonically increasing "
+                       "dts to muxer in stream %d: %" PRId64 " >= %" PRId64 "\n",
+                       st->index, st->internal->cur_dts, pkt->dts);
+                return AVERROR(EINVAL);
+            }
         }
 
         if (pkt->pts < pkt->dts) {
diff --git a/libavformat/options_table.h b/libavformat/options_table.h
index 62c5bb40a397..3b5f1598f43e 100644
--- a/libavformat/options_table.h
+++ b/libavformat/options_table.h
@@ -52,6 +52,7 @@ static const AVOption avformat_options[] = {
 {"nobuffer", "reduce the latency introduced by optional buffering", 0, AV_OPT_TYPE_CONST, {.i64 = AVFMT_FLAG_NOBUFFER }, 0, INT_MAX, D, "fflags"},
 {"bitexact", "do not write random/volatile data", 0, AV_OPT_TYPE_CONST, { .i64 = AVFMT_FLAG_BITEXACT }, 0, 0, E, "fflags" },
 {"shortest", "stop muxing with the shortest stream", 0, AV_OPT_TYPE_CONST, { .i64 = AVFMT_FLAG_SHORTEST }, 0, 0, E, "fflags" },
+{"alwnmodts", "allow non-monotonous dts", 0, AV_OPT_TYPE_CONST, {.i64 = AVFMT_FLAG_ALWNMODTS }, 0, 0, E, "fflags"},
 {"autobsf", "add needed bsfs automatically", 0, AV_OPT_TYPE_CONST, { .i64 = AVFMT_FLAG_AUTO_BSF }, 0, 0, E, "fflags" },
 {"seek2any", "allow seeking to non-keyframes on demuxer level when supported", OFFSET(seek2any), AV_OPT_TYPE_BOOL, {.i64 = 0 }, 0, 1, D},
 {"analyzeduration", "specify how many microseconds are analyzed to probe the input", OFFSET(max_analyze_duration), AV_OPT_TYPE_INT64, {.i64 = 0 }, 0, INT64_MAX, D},