[FFmpeg-devel] [PATCH] lavf/segment: [WIP] add support to segmentation expression
Stefano Sabatini
stefasab at gmail.com
Fri Mar 13 19:34:14 CET 2015
TODO: add documentation, add support to chapters.
---
libavformat/segment.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 57 insertions(+)
diff --git a/libavformat/segment.c b/libavformat/segment.c
index b65a2eb..794504a 100644
--- a/libavformat/segment.c
+++ b/libavformat/segment.c
@@ -33,6 +33,7 @@
#include "internal.h"
#include "libavutil/avassert.h"
+#include "libavutil/eval.h"
#include "libavutil/log.h"
#include "libavutil/opt.h"
#include "libavutil/avstring.h"
@@ -62,6 +63,28 @@ typedef enum {
LIST_TYPE_NB,
} ListType;
+static const char *const var_names[] = {
+ "segment_n", ///< segment count
+ "segment_packets_n",
+ "segment_size",
+
+ "packet_pos", ///< position in the file
+ "packet_n",
+ "packet_t",
+ NULL
+};
+
+enum var_name {
+ VAR_SEGMENT_N,
+ VAR_SEGMENT_PACKETS_N,
+ VAR_SEGMENT_SIZE,
+
+ VAR_PACKET_POS,
+ VAR_PACKET_N,
+ VAR_PACKET_T,
+ VAR_VARS_NB
+};
+
#define SEGMENT_LIST_FLAG_CACHE 1
#define SEGMENT_LIST_FLAG_LIVE 2
@@ -71,6 +94,11 @@ typedef struct SegmentContext {
int segment_idx_wrap; ///< number after which the index wraps
int segment_idx_wrap_nb; ///< number of time the index has wraped
int segment_count; ///< number of segment files already written
+
+ char *segment_expr;
+ AVExpr *segment_pexpr;
+ double var_values[VAR_VARS_NB];
+
AVOutputFormat *oformat;
AVFormatContext *avf;
char *format; ///< format to use for output segment files
@@ -225,6 +253,10 @@ static int segment_start(AVFormatContext *s, int write_header)
}
seg->segment_idx++;
+
+ seg->var_values[VAR_SEGMENT_SIZE] = 0;
+ seg->var_values[VAR_SEGMENT_PACKETS_N] = 0;
+
if ((seg->segment_idx_wrap) && (seg->segment_idx%seg->segment_idx_wrap == 0))
seg->segment_idx_wrap_nb++;
@@ -606,6 +638,15 @@ static int seg_write_header(AVFormatContext *s)
} else if (seg->frames_str) {
if ((ret = parse_frames(s, &seg->frames, &seg->nb_frames, seg->frames_str)) < 0)
return ret;
+ } else if (seg->segment_expr) {
+ ret = av_expr_parse(&seg->segment_pexpr, seg->segment_expr, var_names,
+ NULL, NULL, NULL, NULL, 0, s);
+ if (ret < 0) {
+ av_log(s, AV_LOG_ERROR,
+ "Error when evaluating the segment expression '%s'\n",
+ seg->segment_expr);
+ return ret;
+ }
} else {
/* set default value if not specified */
if (!seg->time_str)
@@ -732,12 +773,26 @@ static int seg_write_packet(AVFormatContext *s, AVPacket *pkt)
if (!seg->avf)
return AVERROR(EINVAL);
+#define TS2T(ts, tb) ((ts) == AV_NOPTS_VALUE ? NAN : (double)(ts) * av_q2d(tb))
+ seg->var_values[VAR_SEGMENT_N] = seg->segment_count;
+
+ seg->var_values[VAR_SEGMENT_SIZE] += pkt->size;
+ seg->var_values[VAR_SEGMENT_PACKETS_N] += 1;
+
+ seg->var_values[VAR_PACKET_POS] = pkt->pos;
+ seg->var_values[VAR_PACKET_T] = TS2T(pkt->pts, st->time_base);
+ seg->var_values[VAR_PACKET_N] += 1;
+
if (seg->times) {
end_pts = seg->segment_count < seg->nb_times ?
seg->times[seg->segment_count] : INT64_MAX;
} else if (seg->frames) {
start_frame = seg->segment_count < seg->nb_frames ?
seg->frames[seg->segment_count] : INT_MAX;
+ } else if (seg->segment_expr) {
+ double res = av_expr_eval(seg->segment_pexpr, seg->var_values, NULL);
+ if (res != 0)
+ seg->cut_pending = 1;
} else {
if (seg->use_clocktime) {
int64_t avgt = av_gettime();
@@ -855,6 +910,7 @@ fail:
av_opt_free(seg);
av_freep(&seg->times);
av_freep(&seg->frames);
+ av_expr_free(seg->segment_pexpr); seg->segment_pexpr = NULL;
cur = seg->segment_list_entries;
while (cur) {
@@ -891,6 +947,7 @@ static const AVOption options[] = {
{ "m3u8", "M3U8 format", 0, AV_OPT_TYPE_CONST, {.i64=LIST_TYPE_M3U8 }, INT_MIN, INT_MAX, E, "list_type" },
{ "hls", "Apple HTTP Live Streaming compatible", 0, AV_OPT_TYPE_CONST, {.i64=LIST_TYPE_M3U8 }, INT_MIN, INT_MAX, E, "list_type" },
+ { "segment_expr", "set segmentation expression", OFFSET(segment_expr), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, E },
{ "segment_atclocktime", "set segment to be cut at clocktime", OFFSET(use_clocktime), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, E},
{ "segment_time", "set segment duration", OFFSET(time_str),AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, E },
{ "segment_time_delta","set approximation value used for the segment times", OFFSET(time_delta), AV_OPT_TYPE_DURATION, {.i64 = 0}, 0, 0, E },
--
1.8.3.2
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