avformat/movenc: Added an option to disable SIDX atom

doc/muxers.texi

@@ -1330,6 +1330,10 @@ more efficient), but with this option set, the muxer writes one moof/mdat
 pair for each track, making it easier to separate tracks.
 
 This option is implicitly set when writing ismv (Smooth Streaming) files.
+@item -movflags skip_sidx
+Skip writing of sidx atom. When bitrate overhead due to sidx atom is high,
+this option could be used for cases where sidx atom is not mandatory.
+When global_sidx flag is enabled, this option will be ignored.
 @item -movflags faststart
 Run a second pass moving the index (moov atom) to the beginning of the file.
 This operation can take a while, and will not work in various situations such

libavformat/movenc.c

@@ -75,6 +75,7 @@ static const AVOption options[] = {
     { "frag_discont", "Signal that the next fragment is discontinuous from earlier ones", 0, AV_OPT_TYPE_CONST, {.i64 = FF_MOV_FLAG_FRAG_DISCONT}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "movflags" },
     { "delay_moov", "Delay writing the initial moov until the first fragment is cut, or until the first fragment flush", 0, AV_OPT_TYPE_CONST, {.i64 = FF_MOV_FLAG_DELAY_MOOV}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "movflags" },
     { "global_sidx", "Write a global sidx index at the start of the file", 0, AV_OPT_TYPE_CONST, {.i64 = FF_MOV_FLAG_GLOBAL_SIDX}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "movflags" },
+    { "skip_sidx", "Skip writing of sidx atom", 0, AV_OPT_TYPE_CONST, {.i64 = FF_MOV_FLAG_SKIP_SIDX}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "movflags" },
     { "write_colr", "Write colr atom (Experimental, may be renamed or changed, do not use from scripts)", 0, AV_OPT_TYPE_CONST, {.i64 = FF_MOV_FLAG_WRITE_COLR}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "movflags" },
     { "write_gama", "Write deprecated gama atom", 0, AV_OPT_TYPE_CONST, {.i64 = FF_MOV_FLAG_WRITE_GAMA}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "movflags" },
     { "use_metadata_tags", "Use mdta atom for metadata.", 0, AV_OPT_TYPE_CONST, {.i64 = FF_MOV_FLAG_USE_MDTA}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "movflags" },
@@ -4603,7 +4604,8 @@ static int mov_write_moof_tag(AVIOContext *pb, MOVMuxContext *mov, int tracks,
     mov_write_moof_tag_internal(avio_buf, mov, tracks, 0);
     moof_size = ffio_close_null_buf(avio_buf);
 
-    if (mov->flags & FF_MOV_FLAG_DASH && !(mov->flags & FF_MOV_FLAG_GLOBAL_SIDX))
+    if (mov->flags & FF_MOV_FLAG_DASH &&
+        !(mov->flags & (FF_MOV_FLAG_GLOBAL_SIDX | FF_MOV_FLAG_SKIP_SIDX)))
         mov_write_sidx_tags(pb, mov, tracks, moof_size + 8 + mdat_size);
 
     if (mov->write_prft > MOV_PRFT_NONE && mov->write_prft < MOV_PRFT_NB)
@@ -5422,7 +5424,8 @@ int ff_mov_write_packet(AVFormatContext *s, AVPacket *pkt)
              * the next fragment. This means the cts of the first sample must
              * be the same in all fragments, unless end_pts was updated by
              * the packet causing the fragment to be written. */
-            if ((mov->flags & FF_MOV_FLAG_DASH && !(mov->flags & FF_MOV_FLAG_GLOBAL_SIDX)) ||
+            if ((mov->flags & FF_MOV_FLAG_DASH &&
+                !(mov->flags & (FF_MOV_FLAG_GLOBAL_SIDX | FF_MOV_FLAG_SKIP_SIDX))) ||
                 mov->mode == MODE_ISM)
                 pkt->pts = pkt->dts + trk->end_pts - trk->cluster[trk->entry].dts;
         } else {
@@ -6067,6 +6070,11 @@ static int mov_init(AVFormatContext *s)
         s->flags &= ~AVFMT_FLAG_AUTO_BSF;
     }
 
+    if (mov->flags & FF_MOV_FLAG_GLOBAL_SIDX && mov->flags & FF_MOV_FLAG_SKIP_SIDX) {
+        av_log(s, AV_LOG_WARNING, "Global SIDX enabled; Ignoring skip_sidx option\n");
+        mov->flags &= ~FF_MOV_FLAG_SKIP_SIDX;
+    }
+
     if (mov->flags & FF_MOV_FLAG_FASTSTART) {
         mov->reserved_moov_size = -1;
     }

libavformat/movenc.h

@@ -257,6 +257,7 @@ typedef struct MOVMuxContext {
 #define FF_MOV_FLAG_SKIP_TRAILER          (1 << 18)
 #define FF_MOV_FLAG_NEGATIVE_CTS_OFFSETS  (1 << 19)
 #define FF_MOV_FLAG_FRAG_EVERY_FRAME      (1 << 20)
+#define FF_MOV_FLAG_SKIP_SIDX             (1 << 21)
 
 int ff_mov_write_packet(AVFormatContext *s, AVPacket *pkt);