[FFmpeg-devel] [PATCH] img2dec: Add ts_from_file option

[Andrey Utkin]

This newly added option makes user able to make timelapse videos from images taken at varying rate.
Usage example:
ffmpeg -f image2 -ts_from_file 1 -pattern_type glob -i '*.jpg' -vf "settb=1/1000,setpts=(PTS-STARTPTS)/$SPEEDUP,fps=$FRAMERATE" $DSTFILE
This will result in timelapse video which plays $SPEEDUP times faster than it was taken, and giving constant framerate of $FRAMERATE fps. (Constant framerate setting is optional, depending on output format.)
---8<---
---
 doc/demuxers.texi     |  4 ++++
 libavformat/img2dec.c | 18 ++++++++++++++++--
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/doc/demuxers.texi b/doc/demuxers.texi
index c75e1ab..9cfa954 100644
--- a/doc/demuxers.texi
+++ b/doc/demuxers.texi
@@ -210,6 +210,10 @@ to read from. Default value is 0.
 Set the index interval range to check when looking for the first image
 file in the sequence, starting from @var{start_number}. Default value
 is 5.
+ at item ts_from_file
+If set to 1, will set frame timestamp to modification time of image file. Note
+that monotonity of timestamps is not provided: images go in the same order as
+without this option. Default value is 0.
 @item video_size
 Set the video size of the images to read. If not specified the video
 size is guessed from the first image file in the sequence.
diff --git a/libavformat/img2dec.c b/libavformat/img2dec.c
index e32c951..5eea2df 100644
--- a/libavformat/img2dec.c
+++ b/libavformat/img2dec.c
@@ -20,6 +20,7 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#include <sys/stat.h>
 #include "libavutil/avstring.h"
 #include "libavutil/log.h"
 #include "libavutil/opt.h"
@@ -63,6 +64,7 @@ typedef struct {
     int start_number;
     int start_number_range;
     int frame_size;
+    int ts_from_file;
 } VideoDemuxData;
 
 static const int sizes[][2] = {
@@ -223,7 +225,10 @@ static int img_read_header(AVFormatContext *s1)
         st->need_parsing = AVSTREAM_PARSE_FULL;
     }
 
-    avpriv_set_pts_info(st, 60, s->framerate.den, s->framerate.num);
+    if (s->ts_from_file)
+        avpriv_set_pts_info(st, 60, 1, 1);
+    else
+        avpriv_set_pts_info(st, 60, s->framerate.den, s->framerate.num);
 
     if (s->width && s->height) {
         st->codec->width  = s->width;
@@ -381,8 +386,14 @@ static int img_read_packet(AVFormatContext *s1, AVPacket *pkt)
         return AVERROR(ENOMEM);
     pkt->stream_index = 0;
     pkt->flags       |= AV_PKT_FLAG_KEY;
-    if (!s->is_pipe)
+    if (s->ts_from_file) {
+        struct stat img_stat;
+        if (stat(filename, &img_stat))
+            return AVERROR(EIO);
+        pkt->pts = (int64_t)img_stat.st_mtime;
+    } else if (!s->is_pipe) {
         pkt->pts      = s->pts;
+    }
 
     pkt->size = 0;
     for (i = 0; i < 3; i++) {
@@ -420,6 +431,8 @@ static int img_read_close(struct AVFormatContext* s1)
 static int img_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)
 {
     VideoDemuxData *s1 = s->priv_data;
+    if (s1->ts_from_file)  /* Seeking is not supported in this case */
+        return AVERROR(ESPIPE);
 
     if (timestamp < 0 || !s1->loop && timestamp > s1->img_last - s1->img_first)
         return -1;
@@ -444,6 +457,7 @@ static const AVOption options[] = {
     { "start_number_range", "set range for looking at the first sequence number", OFFSET(start_number_range), AV_OPT_TYPE_INT, {.i64 = 5}, 1, INT_MAX, DEC },
     { "video_size",   "set video size",                      OFFSET(width),        AV_OPT_TYPE_IMAGE_SIZE, {.str = NULL}, 0, 0,   DEC },
     { "frame_size",   "force frame size in bytes",           OFFSET(frame_size),   AV_OPT_TYPE_INT,    {.i64 = 0   }, 0, INT_MAX, DEC },
+    { "ts_from_file", "set frame timestamp from file's one", OFFSET(ts_from_file), AV_OPT_TYPE_INT,    {.i64 = 0   }, 0, 1,       DEC },
     { NULL },
 };
 
-- 
1.8.1.5