[libav-devel] [PATCH] nut: Experimental pipe and broadcast mode

Luca Barbato lu_zero at gentoo.org
Sat Mar 1 11:51:17 CET 2014


---

Now with the version bump.

 doc/muxers.texi             | 16 ++++++++++++++++
 doc/nut.texi                | 21 +++++++++++++++++++++
 libavformat/avformat.h      |  6 ++++++
 libavformat/nut.h           |  9 ++++++++-
 libavformat/nutdec.c        | 28 +++++++++++++++++++++++-----
 libavformat/nutenc.c        | 41 ++++++++++++++++++++++++++++++++++++++---
 libavformat/options_table.h |  5 +++++
 libavformat/version.h       |  2 +-
 8 files changed, 118 insertions(+), 10 deletions(-)

diff --git a/doc/muxers.texi b/doc/muxers.texi
index 143e595..0a26e39 100644
--- a/doc/muxers.texi
+++ b/doc/muxers.texi
@@ -419,6 +419,22 @@ avconv -i file.mpg -c copy \
      -y out.ts
 @end example

+ at section nut
+
+ at table @option
+ at item -nut_flags @var{flags}
+Modify the nut muxing behaviour in specific ways:
+ at table @option
+ at item @var{pipe} disables the syncpoints, reducing the overhead but making the stream non-seekable;
+ at item @var{broadcast} extends the syncpoint with a wallclock field.
+ at end table
+None of the flags are supposed to be used for storage purposes.
+ at end table
+
+ at example
+avconv -i INPUT -f_strict experimental -nut_flags pipe - | processor
+ at end example
+
 @section null

 Null muxer.
diff --git a/doc/nut.texi b/doc/nut.texi
index 39a22ff..042c88a 100644
--- a/doc/nut.texi
+++ b/doc/nut.texi
@@ -17,6 +17,27 @@ subtitle and user-defined streams in a simple, yet efficient, way.
 It was created by a group of FFmpeg and MPlayer developers in 2003
 and was finalized in 2008.

+ at chapter Modes
+NUT has some variants signaled by using the flags field in its main header.
+
+ at multitable @columnfractions .4 .4
+ at item BROADCAST   @tab Extend the syncpoint to report the sender wallclock
+ at item PIPE        @tab Omit completely the syncpoint
+ at end multitable
+
+ at section BROADCAST
+
+The BROADCAST variant provides a secondary time reference to facilitate
+detecting endpoint latency and network delays.
+It assumes all the endpoint clocks are syncronized.
+To be used in real-time scenarios.
+
+ at section PIPE
+
+The PIPE variant assumes NUT is used as non-seekable intermediate container,
+by not using syncpoint removes unneeded overhead and reduces the overall
+memory usage.
+
 @chapter Container-specific codec tags

 @section Generic raw YUVA formats
diff --git a/libavformat/avformat.h b/libavformat/avformat.h
index ec9c262..215476e 100644
--- a/libavformat/avformat.h
+++ b/libavformat/avformat.h
@@ -1166,6 +1166,12 @@ typedef struct AVFormatContext {
      * Must not be accessed in any way by callers.
      */
     AVFormatInternal *internal;
+
+    /**
+     * Allow non-standard and experimental extension
+     * @see AVCodecContext.strict_std_compliance
+     */
+    int strict_std_compliance;
 } AVFormatContext;

 typedef struct AVPacketList {
diff --git a/libavformat/nut.h b/libavformat/nut.h
index 6357b3d..16f3c12 100644
--- a/libavformat/nut.h
+++ b/libavformat/nut.h
@@ -36,7 +36,9 @@

 #define MAX_DISTANCE (1024*32-1)

-#define NUT_VERSION 3
+#define NUT_MAX_VERSION 4
+#define NUT_STABLE_VERSION 3
+#define NUT_MIN_VERSION 2

 typedef enum{
     FLAG_KEY        =   1, ///<if set, frame is keyframe
@@ -85,6 +87,7 @@ typedef struct ChapterContext {
 } ChapterContext;

 typedef struct NUTContext {
+    const AVClass *av_class;
     AVFormatContext *avf;
 //    int written_packet_size;
 //    int64_t packet_start;
@@ -100,6 +103,10 @@ typedef struct NUTContext {
     int header_count;
     AVRational *time_base;
     struct AVTreeNode *syncpoints;
+#define NUT_BROADCAST 1 // use extended syncpoints
+#define NUT_PIPE 2      // do not write syncpoints
+    int flags;
+    int version; // version currently in use
 } NUTContext;

 extern const AVCodecTag ff_nut_subtitle_tags[];
diff --git a/libavformat/nutdec.c b/libavformat/nutdec.c
index 6328549..069863b 100644
--- a/libavformat/nutdec.c
+++ b/libavformat/nutdec.c
@@ -213,8 +213,8 @@ static int decode_main_header(NUTContext *nut)
     end  = get_packetheader(nut, bc, 1, MAIN_STARTCODE);
     end += avio_tell(bc);

-    tmp = ffio_read_varlen(bc);
-    if (tmp < 2 && tmp > NUT_VERSION) {
+    nut->version = ffio_read_varlen(bc);
+    if (tmp < 2 && tmp > NUT_MAX_VERSION) {
         av_log(s, AV_LOG_ERROR, "Version %"PRId64" not supported.\n",
                tmp);
         return AVERROR(ENOSYS);
@@ -320,6 +320,10 @@ static int decode_main_header(NUTContext *nut)
         assert(nut->header_len[0] == 0);
     }

+    if (nut->version > 3) {
+        nut->flags = ffio_read_varlen(bc);
+    }
+
     if (skip_reserved(bc, end) || ffio_get_checksum(bc)) {
         av_log(s, AV_LOG_ERROR, "main header checksum mismatch\n");
         return AVERROR_INVALIDDATA;
@@ -547,6 +551,14 @@ static int decode_syncpoint(NUTContext *nut, int64_t *ts, int64_t *back_ptr)
     ff_nut_reset_ts(nut, nut->time_base[tmp % nut->time_base_count],
                     tmp / nut->time_base_count);

+    if (nut->flags & NUT_BROADCAST) {
+        tmp = ffio_read_varlen(bc);
+        av_log(s, AV_LOG_VERBOSE, "Syncpoint wallclock %"PRId64"\n",
+               av_rescale_q(tmp / nut->time_base_count,
+                            nut->time_base[tmp % nut->time_base_count],
+                            AV_TIME_BASE_Q));
+    }
+
     if (skip_reserved(bc, end) || ffio_get_checksum(bc)) {
         av_log(s, AV_LOG_ERROR, "sync point checksum mismatch\n");
         return AVERROR_INVALIDDATA;
@@ -728,7 +740,8 @@ static int decode_frame_header(NUTContext *nut, int64_t *pts, int *stream_id,
     int size, flags, size_mul, pts_delta, i, reserved_count;
     uint64_t tmp;

-    if (avio_tell(bc) > nut->last_syncpoint_pos + nut->max_distance) {
+    if (!(nut->flags & NUT_PIPE) &&
+        avio_tell(bc) > nut->last_syncpoint_pos + nut->max_distance) {
         av_log(s, AV_LOG_ERROR,
                "Last frame must have been damaged %"PRId64" > %"PRId64" + %d\n",
                avio_tell(bc), nut->last_syncpoint_pos, nut->max_distance);
@@ -781,8 +794,9 @@ static int decode_frame_header(NUTContext *nut, int64_t *pts, int *stream_id,

     if (flags & FLAG_CHECKSUM) {
         avio_rb32(bc); // FIXME check this
-    } else if (size > 2 * nut->max_distance || FFABS(stc->last_pts - *pts) >
-               stc->max_pts_distance) {
+    } else if (!(nut->flags & NUT_PIPE) &&
+               size > 2 * nut->max_distance ||
+               FFABS(stc->last_pts - *pts) > stc->max_pts_distance) {
         av_log(s, AV_LOG_ERROR, "frame size > 2max_distance and no checksum\n");
         return AVERROR_INVALIDDATA;
     }
@@ -933,6 +947,10 @@ static int read_seek(AVFormatContext *s, int stream_index,
     int64_t pos, pos2, ts;
     int i;

+    if (nut->flags & NUT_PIPE) {
+        return AVERROR(ENOSYS);
+    }
+
     if (st->index_entries) {
         int index = av_index_search_timestamp(st, pts, flags);
         if (index < 0)
diff --git a/libavformat/nutenc.c b/libavformat/nutenc.c
index 2d3862d..4ae76e5 100644
--- a/libavformat/nutenc.c
+++ b/libavformat/nutenc.c
@@ -25,6 +25,8 @@
 #include "libavutil/mathematics.h"
 #include "libavutil/tree.h"
 #include "libavutil/dict.h"
+#include "libavutil/time.h"
+#include "libavutil/opt.h"
 #include "libavcodec/mpegaudiodata.h"
 #include "nut.h"
 #include "internal.h"
@@ -325,7 +327,7 @@ static void write_mainheader(NUTContext *nut, AVIOContext *bc)
         tmp_head_idx;
     int64_t tmp_match;

-    ff_put_v(bc, NUT_VERSION);
+    ff_put_v(bc, nut->version);
     ff_put_v(bc, nut->avf->nb_streams);
     ff_put_v(bc, nut->max_distance);
     ff_put_v(bc, nut->time_base_count);
@@ -405,6 +407,7 @@ static void write_mainheader(NUTContext *nut, AVIOContext *bc)
         ff_put_v(bc, nut->header_len[i]);
         avio_write(bc, nut->header[i], nut->header_len[i]);
     }
+    ff_put_v(bc, nut->flags);
 }

 static int write_streamheader(AVFormatContext *avctx, AVIOContext *bc,
@@ -643,6 +646,15 @@ static int nut_write_header(AVFormatContext *s)

     nut->avf = s;

+    nut->version = NUT_STABLE_VERSION + !!nut->flags;
+    if (nut->flags && s->strict_std_compliance > FF_COMPLIANCE_EXPERIMENTAL) {
+        av_log(s, AV_LOG_ERROR,
+               "Version %d requested, please set -strict experimental in "
+               "order to enable it.\n",
+               nut->version);
+        return AVERROR_EXPERIMENTAL;
+    }
+
     nut->stream = av_mallocz(sizeof(StreamContext) * s->nb_streams);
     if (s->nb_chapters)
         nut->chapter = av_mallocz(sizeof(ChapterContext) * s->nb_chapters);
@@ -789,7 +801,8 @@ static int nut_write_packet(AVFormatContext *s, AVPacket *pkt)

 //FIXME: Ensure store_sp is 1 in the first place.

-    if (store_sp) {
+    if (store_sp &&
+        (!(nut->flags & NUT_PIPE) || nut->last_syncpoint_pos == INT_MIN)) {
         Syncpoint *sp, dummy = { .pos = INT64_MAX };

         ff_nut_reset_ts(nut, *nus->time_base, pkt->dts);
@@ -815,6 +828,11 @@ static int nut_write_packet(AVFormatContext *s, AVPacket *pkt)
             return ret;
         put_tt(nut, nus->time_base, dyn_bc, pkt->dts);
         ff_put_v(dyn_bc, sp ? (nut->last_syncpoint_pos - sp->pos) >> 4 : 0);
+
+        if (nut->flags & NUT_BROADCAST) {
+            put_tt(nut, nus->time_base, dyn_bc,
+                   av_rescale_q(av_gettime(), AV_TIME_BASE_Q, *nus->time_base));
+        }
         put_packet(nut, bc, dyn_bc, 1, SYNCPOINT_STARTCODE);

         if ((ret = ff_nut_add_sp(nut, nut->last_syncpoint_pos, 0 /*unused*/, pkt->dts)) < 0)
@@ -917,7 +935,7 @@ static int nut_write_packet(AVFormatContext *s, AVPacket *pkt)
     nus->last_pts   = pkt->pts;

     //FIXME just store one per syncpoint
-    if (flags & FLAG_KEY)
+    if (flags & FLAG_KEY && !(nut->flags & NUT_PIPE))
         av_add_index_entry(
             s->streams[pkt->stream_index],
             nut->last_syncpoint_pos,
@@ -945,6 +963,22 @@ static int nut_write_trailer(AVFormatContext *s)
     return 0;
 }

+#define OFFSET(x) offsetof(NUTContext, x)
+#define E AV_OPT_FLAG_ENCODING_PARAM
+static const AVOption options[] = {
+    { "nut_flags",    "NUT muxer flags",                                                 OFFSET(flags), AV_OPT_TYPE_FLAGS, {.i64 = 0},             INT_MIN, INT_MAX, E, "nutflags" },
+    {   "pipe",      "NUT pipe mode, syncpoints and max_distance ignored",               0,            AV_OPT_TYPE_CONST, {.i64 = NUT_PIPE},      INT_MIN, INT_MAX, E, "nutflags" },
+    {   "broadcast", "NUT broadcast mode, add a wallclock time reference to syncpoints", 0,            AV_OPT_TYPE_CONST, {.i64 = NUT_BROADCAST}, INT_MIN, INT_MAX, E, "nutflags" },
+    { NULL },
+};
+
+static const AVClass class = {
+    .class_name = "nutenc",
+    .item_name  = av_default_item_name,
+    .option     = options,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
 AVOutputFormat ff_nut_muxer = {
     .name           = "nut",
     .long_name      = NULL_IF_CONFIG_SMALL("NUT"),
@@ -959,4 +993,5 @@ AVOutputFormat ff_nut_muxer = {
     .write_trailer  = nut_write_trailer,
     .flags          = AVFMT_GLOBALHEADER | AVFMT_VARIABLE_FPS,
     .codec_tag      = ff_nut_codec_tags,
+    .priv_class     = &class,
 };
diff --git a/libavformat/options_table.h b/libavformat/options_table.h
index cc84e1c..61f9bd5 100644
--- a/libavformat/options_table.h
+++ b/libavformat/options_table.h
@@ -59,6 +59,11 @@ static const AVOption avformat_options[] = {
 {"buffer", "detect improper bitstream length", 0, AV_OPT_TYPE_CONST, {.i64 = AV_EF_BUFFER }, INT_MIN, INT_MAX, D, "err_detect"},
 {"explode", "abort decoding on minor error detection", 0, AV_OPT_TYPE_CONST, {.i64 = AV_EF_EXPLODE }, INT_MIN, INT_MAX, D, "err_detect"},
 {"max_interleave_delta", "maximum buffering duration for interleaving", OFFSET(max_interleave_delta), AV_OPT_TYPE_INT64, { .i64 = 10000000 }, 0, INT64_MAX, E },
+{"f_strict", "how strictly to follow the standards (deprecated; use strict, save via avconv)", OFFSET(strict_std_compliance), AV_OPT_TYPE_INT, {.i64 = DEFAULT }, INT_MIN, INT_MAX, D|E, "strict"},
+{"strict", "how strictly to follow the standards", OFFSET(strict_std_compliance), AV_OPT_TYPE_INT, {.i64 = DEFAULT }, INT_MIN, INT_MAX, D|E, "strict"},
+{"strict", "strictly conform to all the things in the spec no matter what the consequences", 0, AV_OPT_TYPE_CONST, {.i64 = FF_COMPLIANCE_STRICT }, INT_MIN, INT_MAX, D|E, "strict"},
+{"normal", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = FF_COMPLIANCE_NORMAL }, INT_MIN, INT_MAX, D|E, "strict"},
+{"experimental", "allow non-standardized experimental variants", 0, AV_OPT_TYPE_CONST, {.i64 = FF_COMPLIANCE_EXPERIMENTAL }, INT_MIN, INT_MAX, D|E, "strict"},
 {NULL},
 };

diff --git a/libavformat/version.h b/libavformat/version.h
index 3d1e21f..ef5a148 100644
--- a/libavformat/version.h
+++ b/libavformat/version.h
@@ -30,7 +30,7 @@
 #include "libavutil/version.h"

 #define LIBAVFORMAT_VERSION_MAJOR 55
-#define LIBAVFORMAT_VERSION_MINOR 12
+#define LIBAVFORMAT_VERSION_MINOR 13
 #define LIBAVFORMAT_VERSION_MICRO  0

 #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
--
1.8.5.1



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