movenc: Add a flag for using default-base-is-moof in tfhd atoms

Similarly to the omit_tfhd_offset flag added in e7bf085b, this
avoids writing absolute byte positions to the file, making them
more easily streamable.

This is a new feature from 14496-12:2012, so application support
isn't necessarily too widespread yet (support for it in libav was
added in 20f95f21 in July 2014).
Signed-off-by: Martin Storsjö <martin@martin.st>

doc/muxers.texi

@@ -340,6 +340,13 @@ cause failures when the file is reprocessed with certain tagging programs.
 @item -movflags omit_tfhd_offset
 Do not write any absolute base_data_offset in tfhd atoms. This avoids
 tying fragments to absolute byte positions in the file/streams.
+@item -movflags default_base_moof
+Similarly to the omit_tfhd_offset, this flag avoids writing the
+absolute base_data_offset field in tfhd atoms, but does so by using
+the new default-base-is-moof flag instead. This flag is new from
+14496-12:2012. This may make the fragments easier to parse in certain
+circumstances (avoiding basing track fragment location calculations
+on the implicit end of the previous track fragment).
 @end table
 
 Smooth Streaming content can be pushed in real time to a publishing

libavformat/movenc.c

@@ -58,6 +58,7 @@ static const AVOption options[] = {
     { "faststart", "Run a second pass to put the index (moov atom) at the beginning of the file", 0, AV_OPT_TYPE_CONST, {.i64 = FF_MOV_FLAG_FASTSTART}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "movflags" },
     { "omit_tfhd_offset", "Omit the base data offset in tfhd atoms", 0, AV_OPT_TYPE_CONST, {.i64 = FF_MOV_FLAG_OMIT_TFHD_OFFSET}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "movflags" },
     { "disable_chpl", "Disable Nero chapter atom", 0, AV_OPT_TYPE_CONST, {.i64 = FF_MOV_FLAG_DISABLE_CHPL}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "movflags" },
+    { "default_base_moof", "Set the default-base-is-moof flag in tfhd atoms", 0, AV_OPT_TYPE_CONST, {.i64 = FF_MOV_FLAG_DEFAULT_BASE_MOOF}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "movflags" },
     FF_RTP_FLAG_OPTS(MOVMuxContext, rtp_flags),
     { "skip_iods", "Skip writing iods atom.", offsetof(MOVMuxContext, iods_skip), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, AV_OPT_FLAG_ENCODING_PARAM},
     { "iods_audio_profile", "iods audio profile atom.", offsetof(MOVMuxContext, iods_audio_profile), AV_OPT_TYPE_INT, {.i64 = -1}, -1, 255, AV_OPT_FLAG_ENCODING_PARAM},
@@ -2386,6 +2387,10 @@ static int mov_write_tfhd_tag(AVIOContext *pb, MOVMuxContext *mov,
     }
     if (mov->flags & FF_MOV_FLAG_OMIT_TFHD_OFFSET)
         flags &= ~MOV_TFHD_BASE_DATA_OFFSET;
+    if (mov->flags & FF_MOV_FLAG_DEFAULT_BASE_MOOF) {
+        flags &= ~MOV_TFHD_BASE_DATA_OFFSET;
+        flags |= MOV_TFHD_DEFAULT_BASE_IS_MOOF;
+    }
 
     /* Don't set a default sample size, the silverlight player refuses
      * to play files with that set. Don't set a default sample duration,
@@ -2457,7 +2462,7 @@ static int mov_write_trun_tag(AVIOContext *pb, MOVMuxContext *mov,
 
     avio_wb32(pb, track->entry); /* sample count */
     if (mov->flags & FF_MOV_FLAG_OMIT_TFHD_OFFSET &&
-        !(mov->flags & FF_MOV_FLAG_SEPARATE_MOOF) &&
+        !(mov->flags & (FF_MOV_FLAG_SEPARATE_MOOF | FF_MOV_FLAG_DEFAULT_BASE_MOOF)) &&
         !mov->first_trun)
         avio_wb32(pb, 0); /* Later tracks follow immediately after the previous one */
     else
@@ -2717,6 +2722,8 @@ static int mov_write_ftyp_tag(AVIOContext *pb, AVFormatContext *s)
         minor =     has_h264 ? 0x20000 : 0x10000;
     } else if (mov->mode == MODE_PSP)
         ffio_wfourcc(pb, "MSNV");
+    else if (mov->mode == MODE_MP4 && mov->flags & FF_MOV_FLAG_DEFAULT_BASE_MOOF)
+        ffio_wfourcc(pb, "iso5"); // Required when using default-base-is-moof
     else if (mov->mode == MODE_MP4)
         ffio_wfourcc(pb, "isom");
     else if (mov->mode == MODE_IPOD)
@@ -2734,8 +2741,9 @@ static int mov_write_ftyp_tag(AVIOContext *pb, AVFormatContext *s)
         ffio_wfourcc(pb, "qt  ");
     else if (mov->mode == MODE_ISM) {
         ffio_wfourcc(pb, "piff");
-        ffio_wfourcc(pb, "iso2");
-    } else {
+        if (!(mov->flags & FF_MOV_FLAG_DEFAULT_BASE_MOOF))
+            ffio_wfourcc(pb, "iso2");
+    } else if (!(mov->flags & FF_MOV_FLAG_DEFAULT_BASE_MOOF)) {
         ffio_wfourcc(pb, "isom");
         ffio_wfourcc(pb, "iso2");
         if (has_h264)

libavformat/movenc.h

@@ -178,6 +178,7 @@ typedef struct MOVMuxContext {
 #define FF_MOV_FLAG_FASTSTART 128
 #define FF_MOV_FLAG_OMIT_TFHD_OFFSET 256
 #define FF_MOV_FLAG_DISABLE_CHPL 512
+#define FF_MOV_FLAG_DEFAULT_BASE_MOOF 1024
 
 int ff_mov_write_packet(AVFormatContext *s, AVPacket *pkt);
 

libavformat/version.h

@@ -31,7 +31,7 @@
 
 #define LIBAVFORMAT_VERSION_MAJOR 56
 #define LIBAVFORMAT_VERSION_MINOR  6
-#define LIBAVFORMAT_VERSION_MICRO  1
+#define LIBAVFORMAT_VERSION_MICRO  2
 
 #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
                                                LIBAVFORMAT_VERSION_MINOR, \